// Copyright (c) 2004-2013 Sergey Lyubka
// Copyright (c) 2013-2025 Cesanta Software Limited
// All rights reserved
//
// This software is dual-licensed: you can redistribute it and/or modify
// it under the terms of the GNU General Public License version 2 as
// published by the Free Software Foundation. For the terms of this
// license, see http://www.gnu.org/licenses/
//
// You are free to use this software under the terms of the GNU General
// Public License, but WITHOUT ANY WARRANTY; without even the implied
// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
// See the GNU General Public License for more details.
//
// Alternatively, you can license this software under a commercial
// license, as set out in https://www.mongoose.ws/licensing/
//
// SPDX-License-Identifier: GPL-2.0-only or commercial

#include "mongoose.h"

#ifdef MG_ENABLE_LINES
#line 1 "src/base64.c"
#endif


static int mg_base64_encode_single(int c) {
  if (c < 26) {
    return c + 'A';
  } else if (c < 52) {
    return c - 26 + 'a';
  } else if (c < 62) {
    return c - 52 + '0';
  } else {
    return c == 62 ? '+' : '/';
  }
}

static int mg_base64_decode_single(int c) {
  if (c >= 'A' && c <= 'Z') {
    return c - 'A';
  } else if (c >= 'a' && c <= 'z') {
    return c + 26 - 'a';
  } else if (c >= '0' && c <= '9') {
    return c + 52 - '0';
  } else if (c == '+') {
    return 62;
  } else if (c == '/') {
    return 63;
  } else if (c == '=') {
    return 64;
  } else {
    return -1;
  }
}

size_t mg_base64_update(unsigned char ch, char *to, size_t n) {
  unsigned long rem = (n & 3) % 3;
  if (rem == 0) {
    to[n] = (char) mg_base64_encode_single(ch >> 2);
    to[++n] = (char) ((ch & 3) << 4);
  } else if (rem == 1) {
    to[n] = (char) mg_base64_encode_single(to[n] | (ch >> 4));
    to[++n] = (char) ((ch & 15) << 2);
  } else {
    to[n] = (char) mg_base64_encode_single(to[n] | (ch >> 6));
    to[++n] = (char) mg_base64_encode_single(ch & 63);
    n++;
  }
  return n;
}

size_t mg_base64_final(char *to, size_t n) {
  size_t saved = n;
  // printf("---[%.*s]\n", n, to);
  if (n & 3) n = mg_base64_update(0, to, n);
  if ((saved & 3) == 2) n--;
  // printf("    %d[%.*s]\n", n, n, to);
  while (n & 3) to[n++] = '=';
  to[n] = '\0';
  return n;
}

size_t mg_base64_encode(const unsigned char *p, size_t n, char *to, size_t dl) {
  size_t i, len = 0;
  if (dl > 0) to[0] = '\0';
  if (dl < ((n / 3) + (n % 3 ? 1 : 0)) * 4 + 1) return 0;
  for (i = 0; i < n; i++) len = mg_base64_update(p[i], to, len);
  len = mg_base64_final(to, len);
  return len;
}

size_t mg_base64_decode(const char *src, size_t n, char *dst, size_t dl) {
  const char *end = src == NULL ? NULL : src + n;  // Cannot add to NULL
  size_t len = 0;
  if (dl < n / 4 * 3 + 1) goto fail;
  while (src != NULL && src + 3 < end) {
    int a = mg_base64_decode_single(src[0]),
        b = mg_base64_decode_single(src[1]),
        c = mg_base64_decode_single(src[2]),
        d = mg_base64_decode_single(src[3]);
    if (a == 64 || a < 0 || b == 64 || b < 0 || c < 0 || d < 0) {
      goto fail;
    }
    dst[len++] = (char) ((a << 2) | (b >> 4));
    if (src[2] != '=') {
      dst[len++] = (char) ((b << 4) | (c >> 2));
      if (src[3] != '=') dst[len++] = (char) ((c << 6) | d);
    }
    src += 4;
  }
  dst[len] = '\0';
  return len;
fail:
  if (dl > 0) dst[0] = '\0';
  return 0;
}

#ifdef MG_ENABLE_LINES
#line 1 "src/dns.c"
#endif








struct dns_data {
  struct dns_data *next;
  struct mg_connection *c;
  uint64_t expire;
  uint16_t txnid;
};

static void mg_sendnsreq(struct mg_connection *, struct mg_str *, int,
                         struct mg_dns *, bool);

static void mg_dns_free(struct dns_data **head, struct dns_data *d) {
  LIST_DELETE(struct dns_data, head, d);
  mg_free(d);
}

void mg_resolve_cancel(struct mg_connection *c) {
  struct dns_data *tmp, *d;
  struct dns_data **head = (struct dns_data **) &c->mgr->active_dns_requests;
  for (d = *head; d != NULL; d = tmp) {
    tmp = d->next;
    if (d->c == c) mg_dns_free(head, d);
  }
}

static size_t mg_dns_parse_name_depth(const uint8_t *s, size_t len, size_t ofs,
                                      char *to, size_t tolen, size_t j,
                                      int depth) {
  size_t i = 0;
  if (tolen > 0 && depth == 0) to[0] = '\0';
  if (depth > 5) return 0;
  // MG_INFO(("ofs %lx %x %x", (unsigned long) ofs, s[ofs], s[ofs + 1]));
  while (ofs + i + 1 < len) {
    size_t n = s[ofs + i];
    if (n == 0) {
      i++;
      break;
    }
    if (n & 0xc0) {
      size_t ptr = (((n & 0x3f) << 8) | s[ofs + i + 1]);  // 12 is hdr len
      // MG_INFO(("PTR %lx", (unsigned long) ptr));
      if (ptr + 1 < len && (s[ptr] & 0xc0) == 0 &&
          mg_dns_parse_name_depth(s, len, ptr, to, tolen, j, depth + 1) == 0)
        return 0;
      i += 2;
      break;
    }
    if (ofs + i + n + 1 >= len) return 0;
    if (j > 0) {
      if (j < tolen) to[j] = '.';
      j++;
    }
    if (j + n < tolen) memcpy(&to[j], &s[ofs + i + 1], n);
    j += n;
    i += n + 1;
    if (j < tolen) to[j] = '\0';  // Zero-terminate this chunk
    // MG_INFO(("--> [%s]", to));
  }
  if (tolen > 0) to[tolen - 1] = '\0';  // Make sure it is nul-term
  return i;
}

static size_t mg_dns_parse_name(const uint8_t *s, size_t n, size_t ofs,
                                char *dst, size_t dstlen) {
  return mg_dns_parse_name_depth(s, n, ofs, dst, dstlen, 0, 0);
}

size_t mg_dns_parse_rr(const uint8_t *buf, size_t len, size_t ofs,
                       bool is_question, struct mg_dns_rr *rr) {
  const uint8_t *s = buf + ofs, *e = &buf[len];

  memset(rr, 0, sizeof(*rr));
  if (len < sizeof(struct mg_dns_header)) return 0;  // Too small
  if (len > 512) return 0;  //  Too large, we don't expect that
  if (s >= e) return 0;     //  Overflow

  if ((rr->nlen = (uint16_t) mg_dns_parse_name(buf, len, ofs, NULL, 0)) == 0)
    return 0;
  s += rr->nlen + 4;
  if (s > e) return 0;
  rr->atype = (uint16_t) (((uint16_t) s[-4] << 8) | s[-3]);
  rr->aclass = (uint16_t) (((uint16_t) s[-2] << 8) | s[-1]);
  if (is_question) return (size_t) (rr->nlen + 4);

  s += 6;
  if (s > e) return 0;
  rr->alen = (uint16_t) (((uint16_t) s[-2] << 8) | s[-1]);
  if (s + rr->alen > e) return 0;
  return (size_t) (rr->nlen + rr->alen + 10);
}

bool mg_dns_parse(const uint8_t *buf, size_t len, struct mg_dns_message *dm) {
  const struct mg_dns_header *h = (struct mg_dns_header *) buf;
  struct mg_dns_rr rr;
  size_t i, n, num_answers, ofs = sizeof(*h);
  bool is_response;
  memset(dm, 0, sizeof(*dm));

  if (len < sizeof(*h)) return 0;                // Too small, headers dont fit
  if (mg_ntohs(h->num_questions) > 1) return 0;  // Sanity
  num_answers = mg_ntohs(h->num_answers);
  if (num_answers > 10) {
    MG_DEBUG(("Got %u answers, ignoring beyond 10th one", num_answers));
    num_answers = 10;  // Sanity cap
  }
  dm->txnid = mg_ntohs(h->txnid);
  is_response = mg_ntohs(h->flags) & 0x8000;

  for (i = 0; i < mg_ntohs(h->num_questions); i++) {
    if ((n = mg_dns_parse_rr(buf, len, ofs, true, &rr)) == 0) return false;
    // MG_INFO(("Q %lu %lu %hu/%hu", ofs, n, rr.atype, rr.aclass));
    mg_dns_parse_name(buf, len, ofs, dm->name, sizeof(dm->name));
    ofs += n;
  }

  if (!is_response) {
    // For queries, there is no need to parse the answers. In this way,
    // we also ensure the domain name (dm->name) is parsed from
    // the question field.
    return true;
  }

  for (i = 0; i < num_answers; i++) {
    if ((n = mg_dns_parse_rr(buf, len, ofs, false, &rr)) == 0) return false;
    // MG_INFO(("A -- %lu %lu %hu/%hu %s", ofs, n, rr.atype, rr.aclass,
    // dm->name));
    mg_dns_parse_name(buf, len, ofs, dm->name, sizeof(dm->name));
    ofs += n;

    if (rr.alen == 4 && rr.atype == MG_DNS_RTYPE_A && rr.aclass == 1) {
      dm->addr.is_ip6 = false;
      memcpy(&dm->addr.addr.ip, &buf[ofs - 4], 4);
      dm->resolved = true;
      break;  // Return success
    } else if (rr.alen == 16 && rr.atype == MG_DNS_RTYPE_AAAA &&
               rr.aclass == 1) {
      dm->addr.is_ip6 = true;
      memcpy(&dm->addr.addr.ip, &buf[ofs - 16], 16);
      dm->resolved = true;
      break;  // Return success
    }
  }
  return true;
}

static void dns_cb(struct mg_connection *c, int ev, void *ev_data) {
  struct dns_data *d, *tmp;
  struct dns_data **head = (struct dns_data **) &c->mgr->active_dns_requests;
  if (ev == MG_EV_POLL) {
    uint64_t now = *(uint64_t *) ev_data;
    for (d = *head; d != NULL; d = tmp) {
      tmp = d->next;
      // MG_DEBUG ("%lu %lu dns poll", d->expire, now));
      if (now > d->expire) mg_error(d->c, "DNS timeout");
    }
  } else if (ev == MG_EV_READ) {
    struct mg_dns_message dm;
    int resolved = 0;
    if (mg_dns_parse(c->recv.buf, c->recv.len, &dm) == false) {
      MG_ERROR(("Unexpected DNS response:"));
      mg_hexdump(c->recv.buf, c->recv.len);
    } else {
      // MG_VERBOSE(("%s %d", dm.name, dm.resolved));
      for (d = *head; d != NULL; d = tmp) {
        tmp = d->next;
        // MG_INFO(("d %p %hu %hu", d, d->txnid, dm.txnid));
        if (dm.txnid != d->txnid) continue;
        if (d->c->is_resolving) {
          if (dm.resolved) {
            dm.addr.port = d->c->rem.port;  // Save port
            d->c->rem = dm.addr;            // Copy resolved address
            MG_DEBUG(
                ("%lu %s is %M", d->c->id, dm.name, mg_print_ip, &d->c->rem));
            mg_connect_resolved(d->c);
#if MG_ENABLE_IPV6
          } else if (dm.addr.is_ip6 == false && dm.name[0] != '\0' &&
                     c->mgr->use_dns6 == false) {
            struct mg_str x = mg_str(dm.name);
            mg_sendnsreq(d->c, &x, c->mgr->dnstimeout, &c->mgr->dns6, true);
#endif
          } else {
            mg_error(d->c, "%s DNS lookup failed", dm.name);
          }
        } else {
          MG_ERROR(("%lu already resolved", d->c->id));
        }
        mg_dns_free(head, d);
        resolved = 1;
      }
    }
    if (!resolved) MG_ERROR(("stray DNS reply"));
    c->recv.len = 0;
  } else if (ev == MG_EV_CLOSE) {
    for (d = *head; d != NULL; d = tmp) {
      tmp = d->next;
      mg_error(d->c, "DNS error");
      mg_dns_free(head, d);
    }
  }
}

static bool mg_dns_send(struct mg_connection *c, const struct mg_str *name,
                        uint16_t txnid, bool ipv6) {
  struct {
    struct mg_dns_header header;
    uint8_t data[256];
  } pkt;
  size_t i, n;
  memset(&pkt, 0, sizeof(pkt));
  pkt.header.txnid = mg_htons(txnid);
  pkt.header.flags = mg_htons(0x100);
  pkt.header.num_questions = mg_htons(1);
  for (i = n = 0; i < sizeof(pkt.data) - 5; i++) {
    if (name->buf[i] == '.' || i >= name->len) {
      pkt.data[n] = (uint8_t) (i - n);
      memcpy(&pkt.data[n + 1], name->buf + n, i - n);
      n = i + 1;
    }
    if (i >= name->len) break;
  }
  memcpy(&pkt.data[n], "\x00\x00\x01\x00\x01", 5);  // A query
  n += 5;
  if (ipv6) pkt.data[n - 3] = 0x1c;  // AAAA query
  // memcpy(&pkt.data[n], "\xc0\x0c\x00\x1c\x00\x01", 6);  // AAAA query
  // n += 6;
  return mg_send(c, &pkt, sizeof(pkt.header) + n);
}

bool mg_dnsc_init(struct mg_mgr *mgr, struct mg_dns *dnsc);
bool mg_dnsc_init(struct mg_mgr *mgr, struct mg_dns *dnsc) {
  if (dnsc->url == NULL) {
    mg_error(0, "DNS server URL is NULL. Call mg_mgr_init()");
    return false;
  }
  if (dnsc->c == NULL) {
    dnsc->c = mg_connect(mgr, dnsc->url, NULL, NULL);
    if (dnsc->c == NULL) return false;
    dnsc->c->pfn = dns_cb;
  }
  return true;
}

static void mg_sendnsreq(struct mg_connection *c, struct mg_str *name, int ms,
                         struct mg_dns *dnsc, bool ipv6) {
  struct dns_data *d = NULL;
  if (!mg_dnsc_init(c->mgr, dnsc)) {
    mg_error(c, "resolver");
  } else if ((d = (struct dns_data *) mg_calloc(1, sizeof(*d))) == NULL) {
    mg_error(c, "resolve OOM");
  } else {
    struct dns_data *reqs = (struct dns_data *) c->mgr->active_dns_requests;
    uint16_t id;
    mg_random(&id, sizeof(uint16_t));
    // TODO(): traverse reqs and check id != reqs->txnid; repeat otherwise
    if (reqs != NULL) id = (uint16_t) (reqs->txnid + 1);  // no collision
    d->txnid = id;
    d->next = reqs;
    c->mgr->active_dns_requests = d;
    d->expire = mg_millis() + (uint64_t) ms;
    d->c = c;
    c->is_resolving = 1;
    MG_VERBOSE(("%lu resolving %.*s @ %s, txnid %hu", c->id, (int) name->len,
                name->buf, dnsc->url, d->txnid));
    if (!mg_dns_send(dnsc->c, name, d->txnid, ipv6)) {
      mg_error(dnsc->c, "DNS send");
    }
  }
}

void mg_resolve(struct mg_connection *c, const char *url) {
  struct mg_str host = mg_url_host(url);
  c->rem.port = mg_htons(mg_url_port(url));
  if (mg_aton(host, &c->rem)) {
    // host is an IP address, do not fire name resolution
    mg_connect_resolved(c);
  } else {
    // host is not an IP, send DNS resolution request
    struct mg_dns *dns = c->mgr->use_dns6 ? &c->mgr->dns6 : &c->mgr->dns4;
    mg_sendnsreq(c, &host, c->mgr->dnstimeout, dns, c->mgr->use_dns6);
  }
}

// Response header length is 10 bytes
static const uint8_t mdns_answer[] = {
    0, 1,          // 2 bytes - record type, A
    0, 1,          // 2 bytes - address class, INET
    0, 0, 0, 120,  // 4 bytes - TTL
    0, 4           // 2 bytes - address length
};

// A name length is name->len + '.local' + 2 = name->len + 8
static uint8_t *build_name(struct mg_str *name, uint8_t *p) {
  *p++ = (uint8_t) name->len;  // label 1
  memcpy(p, name->buf, name->len), p += name->len;
  *p++ = 5;  // label 2
  memcpy(p, "local", 5), p += 5;
  *p++ = 0;  // no more labels
  return p;
}

void mg_getlocaddr(struct mg_connection *, struct mg_addr *, struct mg_addr *);

// An A record length is 10 + 4 = 14 bytes
static uint8_t *build_a_record(struct mg_connection *c, uint8_t *p,
                               struct mg_addr *addr) {
  memcpy(p, mdns_answer, sizeof(mdns_answer)), p += sizeof(mdns_answer);
  if (addr != NULL && !addr->is_ip6) {
    memcpy(p, &addr->addr.ip4, 4), p += 4;
  } else {
#if MG_ENABLE_TCPIP
    memcpy(p, &c->mgr->ifp->ip, 4), p += 4;
#else
    struct mg_addr loc, to;
    memset(&loc, 0, sizeof(loc));
    to.is_ip6 = false;
    to.port = mg_htons(5353);
    to.addr.ip4 = MG_IPV4(224, 0, 0, 51);
    mg_getlocaddr(c, &to, &loc);
    memcpy(p, &loc.addr.ip4, 4), p += 4;
#endif
  }
  return p;
}

// A srv name length is r->srvcproto.len + '.local' + 2 = r->srvcproto.len + 8
static uint8_t *build_srv_name(uint8_t *p, struct mg_dnssd_record *r) {
  *p++ = (uint8_t) r->srvcproto.len - 5;  // label 1, up to '._tcp'
  memcpy(p, r->srvcproto.buf, r->srvcproto.len), p += r->srvcproto.len;
  p[-5] = 4;  // label 2, '_tcp', overwrite '.'
  *p++ = 5;   // label 3
  memcpy(p, "local", 5), p += 5;
  *p++ = 0;  // no more labels
  return p;
}

#if 0
// TODO(): for listing
static uint8_t *build_mysrv_name(struct mg_str *name, uint8_t *p,
                                 struct mg_dnssd_record *r) {
  *p++ = name->len;  // label 1
  memcpy(p, name->buf, name->len), p += name->len;
  return build_srv_name(p, r);
}
#endif

// A PTR record length is 10 + name->len + 3 = name->len + 13
static uint8_t *build_ptr_record(struct mg_str *name, uint8_t *p, uint16_t o) {
  uint16_t offset = mg_htons(o);
  memcpy(p, mdns_answer, sizeof(mdns_answer));
  p[1] = MG_DNS_RTYPE_PTR;  // overwrite record type
  p += sizeof(mdns_answer);
  p[-1] = (uint8_t) name->len +
          3;  // overwrite response length, label length + label + offset
  *p++ = (uint8_t) name->len;                       // response: label 1
  memcpy(p, name->buf, name->len), p += name->len;  // copy label
  memcpy(p, &offset, 2);
  *p |= 0xC0, p += 2;
  return p;
}

// An SRV record length is 10 + name->len + 9 = name->len + 19
static uint8_t *build_srv_record(struct mg_str *name, uint8_t *p,
                                 struct mg_dnssd_record *r, uint16_t o) {
  uint16_t port = mg_htons(r->port);
  uint16_t offset = mg_htons(o);
  memcpy(p, mdns_answer, sizeof(mdns_answer));
  p[1] = MG_DNS_RTYPE_SRV;  // overwrite record type
  p += sizeof(mdns_answer);
  p[-1] = (uint8_t) name->len + 9;  // overwrite response length (4+2+1+2)
  *p++ = 0;                         // priority
  *p++ = 0;
  *p++ = 0;  // weight
  *p++ = 0;
  memcpy(p, &port, 2), p += 2;  // port
  *p++ = (uint8_t) name->len;   // label 1
  memcpy(p, name->buf, name->len), p += name->len;
  memcpy(p, &offset, 2);
  *p |= 0xC0, p += 2;
  return p;
}

// A TXT record length is r->txt.len (txt contents) + 10
static uint8_t *build_txt_record(uint8_t *p, struct mg_dnssd_record *r) {
  uint16_t len = mg_htons((uint16_t) r->txt.len);
  memcpy(p, mdns_answer, sizeof(mdns_answer));
  p[1] = MG_DNS_RTYPE_TXT;  // overwrite record type
  p += sizeof(mdns_answer);
  memcpy(p - 2, &len, 2);  // overwrite response length
  memcpy(p, r->txt.buf, r->txt.len), p += r->txt.len;  // copy record verbatim
  return p;
}

// Each additional record has a 2-byte field pointing to the name label

// RFC-6762 16: case-insensitivity --> RFC-1034, 1035

static void handle_mdns_query(struct mg_connection *c) {
  struct mg_dns_header *qh = (struct mg_dns_header *) c->recv.buf;
  struct mg_dns_rr rr;
  size_t n;
  // Parse first question, offset 12 is header size
  n = mg_dns_parse_rr(c->recv.buf, c->recv.len, 12, true, &rr);
  MG_VERBOSE(("mDNS request parsed, result=%d", (int) n));
  if (n > 0) {
    // RFC-6762 Appendix C, RFC2181 11: m(n + 1-63), max 255 + 0x0
    uint8_t buf[sizeof(struct mg_dns_header) + 256 + sizeof(mdns_answer) + 4];
    struct mg_dns_header *h = (struct mg_dns_header *) buf;
    uint8_t *p = &buf[sizeof(*h)];
    char name[256];
    uint8_t name_len;
    // uint16_t q = mg_ntohs(qh->num_questions);
    struct mg_str defname = mg_str((const char *) c->fn_data);
    struct mg_str *respname;
    struct mg_mdns_req req;
    memset(&req, 0, sizeof(req));
    req.is_unicast = (rr.aclass & MG_BIT(15)) != 0;  // QU
    rr.aclass &= (uint16_t) ~MG_BIT(15);  // remove "QU" (unicast response)
    qh->num_questions = mg_htons(1);      // parser sanity
    mg_dns_parse_name(c->recv.buf, c->recv.len, 12, name, sizeof(name));
    name_len = (uint8_t) strlen(name);  // verify it ends in .local
    if (name_len <= 6 || strcmp(".local", &name[name_len - 6]) != 0 ||
        (rr.aclass != 1 && rr.aclass != 0xff))
      return;
    name[name_len -= 6] = '\0';  // remove .local
    MG_VERBOSE(("RR %u %u %s", (unsigned int) rr.atype,
                (unsigned int) rr.aclass, name));
    if (rr.atype == MG_DNS_RTYPE_A) {
      // TODO(): ensure c->fn_data ends in \0
      // if we have a name to match, go; otherwise users will match and fill
      // req.r.name and set req.is_resp
      if (c->fn_data != NULL && mg_casecmp((char *) c->fn_data, name) != 0)
        return;
      req.is_resp = (c->fn_data != NULL);
      req.reqname = mg_str_n(name, name_len);
    } else  // users have to match the request to something in their db, then
            // fill req.r and set req.is_resp
      if (rr.atype == MG_DNS_RTYPE_PTR) {
        if (strcmp("_services._dns-sd._udp", name) == 0) req.is_listing = true;
        MG_DEBUG(
            ("PTR request for %s", req.is_listing ? "services listing" : name));
        req.reqname = mg_str_n(name, name_len);
      } else if (rr.atype == MG_DNS_RTYPE_SRV || rr.atype == MG_DNS_RTYPE_TXT) {
        MG_DEBUG(("%s request for %s",
                  rr.atype == MG_DNS_RTYPE_SRV ? "SRV" : "TXT", name));
        // if possible, check it starts with our name, users will check it ends
        // in a service name they handle
        if (c->fn_data != NULL) {
          if (mg_strcasecmp(defname, mg_str_n(name, defname.len)) != 0 ||
              name[defname.len] != '.')
            return;
          req.reqname =
              mg_str_n(name + defname.len + 1, name_len - defname.len - 1);
          MG_DEBUG(
              ("That's us, handing %.*s", req.reqname.len, req.reqname.buf));
        } else {
          req.reqname = mg_str_n(name, name_len);
        }
      } else {  // unhandled record
        return;
      }
    req.rr = &rr;
    mg_call(c, MG_EV_MDNS_REQ, &req);
    if (!req.is_resp) return;
    respname = req.respname.buf != NULL ? &req.respname : &defname;

    memset(h, 0, sizeof(*h));                   // clear header
    h->txnid = req.is_unicast ? qh->txnid : 0;  // RFC-6762 18.1
    h->num_answers = mg_htons(1);  // RFC-6762 6: 0 questions, 1 Answer
    h->flags = mg_htons(0x8400);   // Authoritative response
    if (req.is_listing) {
      // TODO(): RFC-6762 6: each responder SHOULD delay its response by a
      // random amount of time selected with uniform random distribution in the
      // range 20-120 ms.
      // TODO():
      return;
    } else if (rr.atype == MG_DNS_RTYPE_PTR) {  // serve PTR + SRV + TXT + A
      // TODO(): RFC-6762 6: each responder SHOULD delay its response by a
      // random amount of time selected with uniform random distribution in the
      // range 20-120 ms. Response to PTR is local_name._myservice._tcp.local
      uint8_t *o = p, *aux;
      uint16_t offset;
      if (respname->buf == NULL || respname->len == 0) return;
      if ((sizeof(*h) + req.r->srvcproto.len + 8 + respname->len + 13 + 2 +
           respname->len + 19 + 2 + req.r->txt.len + 10 + 2 + 14) >
          sizeof(buf))  // srv name + PTR + 2 + SRV + 2 + TXT + 2 + A
        return;
      h->num_other_prs = mg_htons(3);  // 3 additional records
      p = build_srv_name(p, req.r);
      aux = build_ptr_record(respname, p, (uint16_t) (o - buf));
      o = p + sizeof(mdns_answer);  // point to PTR response (full srvc name)
      offset = mg_htons((uint16_t) (o - buf));
      o = p - 7;  // point to '.local' label (\x05local\x00)
      p = aux;
      memcpy(p, &offset, 2);  // point to full srvc name, in record
      *p |= 0xC0, p += 2;
      aux = p;
      p = build_srv_record(respname, p, req.r, (uint16_t) (o - buf));
      o = aux + sizeof(mdns_answer) + 6;  // point to target in SRV
      memcpy(p, &offset, 2);              // point to full srvc name, in record
      *p |= 0xC0, p += 2;
      p = build_txt_record(p, req.r);
      offset = mg_htons((uint16_t) (o - buf));
      memcpy(p, &offset, 2);  // point to target name, in record
      *p |= 0xC0, p += 2;
      p = build_a_record(c, p, req.addr);
    } else if (rr.atype == MG_DNS_RTYPE_TXT) {
      if ((sizeof(*h) + req.r->srvcproto.len + 8 + req.r->txt.len + 10) >
          sizeof(buf))  // srv name + TXT
        return;
      p = build_srv_name(p, req.r);
      p = build_txt_record(p, req.r);
    } else if (rr.atype == MG_DNS_RTYPE_SRV) {  // serve SRV + A
      uint8_t *o, *aux;
      uint16_t offset;
      if (respname->buf == NULL || respname->len == 0) return;
      if ((sizeof(*h) + req.r->srvcproto.len + 8 + respname->len + 19 + 2 +
           14) > sizeof(buf))  // srv name + SRV + 2 + A
        return;
      h->num_other_prs = mg_htons(1);  // 1 additional record
      p = build_srv_name(p, req.r);
      o = p - 7;  // point to '.local' label (\x05local\x00)
      aux = p;
      p = build_srv_record(respname, p, req.r, (uint16_t) (o - buf));
      o = aux + sizeof(mdns_answer) + 6;  // point to target in SRV
      offset = mg_htons((uint16_t) (o - buf));
      memcpy(p, &offset, 2);  // point to target name, in record
      *p |= 0xC0, p += 2;
      p = build_a_record(c, p, req.addr);
    } else {  // A requested
      // RFC-6762 6: 0 Auth, 0 Additional RRs
      if (respname->buf == NULL || respname->len == 0) return;
      if ((sizeof(*h) + respname->len + 8 + 14) > sizeof(buf))  // name + A
        return;
      p = build_name(respname, p);
      p = build_a_record(c, p, req.addr);
    }
    if (!req.is_unicast) mg_multicast_restore(c, (uint8_t *) &c->loc);
    mg_send(c, buf, (size_t) (p - buf));  // And send it!
    MG_DEBUG(("%M > %M", mg_print_ip_port, &c->loc, mg_print_ip_port, &c->rem));
    MG_DEBUG(("mDNS %s response sent", req.is_unicast ? "unicast" : "mcast"));
  }
}

static void handle_mdns_response(struct mg_connection *c) {
  struct mg_dns_header *rh = (struct mg_dns_header *) c->recv.buf;
  struct mg_dns_rr rr;
  size_t n;
  // Parse first response, offset 12 is header size
  n = mg_dns_parse_rr(c->recv.buf, c->recv.len, 12, false, &rr);
  MG_VERBOSE(("mDNS response parsed, result=%d", (int) n));
  if (n > 0) {
    // RFC-6762 Appendix C, RFC2181 11: m(n + 1-63), max 255 + 0x0
    char name[256];
    uint8_t name_len;
    struct mg_mdns_resp resp;
    memset(&resp, 0, sizeof(resp));
    if (rh->num_answers > mg_htons(1)) MG_DEBUG(("ignoring > 1 answers"));
    mg_dns_parse_name(c->recv.buf, c->recv.len, 12, name, sizeof(name));
    name_len = (uint8_t) strlen(name);  // verify it ends in .local
    MG_VERBOSE(("RR %u %u %s", (unsigned int) rr.atype,
                (unsigned int) rr.aclass, name));
    if (rr.alen == 4 && rr.atype == MG_DNS_RTYPE_A &&
        (rr.aclass & 0x7FFF) == 1) {
      resp.addr.is_ip6 = false;
      memcpy(resp.addr.addr.ip, (char *) (rh + 1) + n - 4, 4);
      MG_DEBUG(("A response from %.*s = %M", name_len, name, mg_print_ip,
                &resp.addr));
      //    } else if (rr.alen == 16 && rr.atype == MG_DNS_RTYPE_AAAA &&
      //    (rr.aclass & 0x7FFF) == 1) {
      //      resp.addr.is_ip6 = true;
      //      memcpy(resp.addr.addr.ip, (char *)(rh + 1) + n - 16], 16);
      //      MG_DEBUG(("AAAA response from %.*s = %M", name_len, name,
      //      mg_print_ip, &resp.addr));
    } else {
      return;
    }
    resp.name = mg_str_n(name, name_len);
    resp.rr = &rr;
    mg_call(c, MG_EV_MDNS_RESP, &resp);
  }
}

static void handle_mdns_record(struct mg_connection *c) {
  struct mg_dns_header *h = (struct mg_dns_header *) c->recv.buf;
  if (c->recv.len <= 12) return;
  if ((h->flags & mg_htons(0xF800)) == 0) {
    // flags -> !resp, opcode=0 => query; ignore other opcodes
    handle_mdns_query(c);
  } else if ((h->flags & mg_htons(0xF800)) == mg_htons(0x8000)) {
    // flags -> resp, opcode=0 => response; ignore other opcodes
    handle_mdns_response(c);
  }
}

static void mdns_cb(struct mg_connection *c, int ev, void *ev_data) {
  if (ev == MG_EV_READ) {
    handle_mdns_record(c);
    mg_iobuf_del(&c->recv, 0, c->recv.len);
  }
  (void) ev_data;
}

void mg_multicast_add(struct mg_connection *c, char *ip);
struct mg_connection *mg_mdns_listen(struct mg_mgr *mgr, mg_event_handler_t fn,
                                     void *fn_data) {
  struct mg_connection *c =
      mg_listen(mgr, "udp://224.0.0.251:5353", fn, fn_data);
  if (c == NULL) return NULL;
  c->pfn = mdns_cb, c->pfn_data = fn_data;
  mg_multicast_add(c, (char *) "224.0.0.251");
  return c;
}

bool mg_mdns_query(struct mg_connection *c, const char *name,
                   unsigned int rtype) {
  struct mg_str name_;
  name_.buf = (char *) name, name_.len = strlen(name);
  mg_multicast_restore(c, (uint8_t *) &c->loc);
  (void) rtype;
  return mg_dns_send(c, &name_, 0, false);
}

#ifdef MG_ENABLE_LINES
#line 1 "src/event.c"
#endif






void mg_call(struct mg_connection *c, int ev, void *ev_data) {
#if MG_ENABLE_PROFILE
  const char *names[] = {
      "EV_ERROR",    "EV_OPEN",      "EV_POLL",      "EV_RESOLVE",
      "EV_CONNECT",  "EV_ACCEPT",    "EV_TLS_HS",    "EV_READ",
      "EV_WRITE",    "EV_CLOSE",     "EV_HTTP_MSG",  "EV_HTTP_CHUNK",
      "EV_WS_OPEN",  "EV_WS_MSG",    "EV_WS_CTL",    "EV_MQTT_CMD",
      "EV_MQTT_MSG", "EV_MQTT_OPEN", "EV_SNTP_TIME", "EV_USER"};
  if (ev != MG_EV_POLL && ev < (int) (sizeof(names) / sizeof(names[0]))) {
    MG_PROF_ADD(c, names[ev]);
  }
#endif
  // Fire protocol handler first, user handler second. See #2559
  if (c->pfn != NULL) c->pfn(c, ev, ev_data);
  if (c->fn != NULL) c->fn(c, ev, ev_data);
}

void mg_error(struct mg_connection *c, const char *fmt, ...) {
  char buf[64];
  va_list ap;
  va_start(ap, fmt);
  mg_vsnprintf(buf, sizeof(buf), fmt, &ap);
  va_end(ap);
  MG_ERROR(("%lu %ld %s", c->id, c->fd, buf));
  c->is_closing = 1;             // Set is_closing before sending MG_EV_CALL
  mg_call(c, MG_EV_ERROR, buf);  // Let user handler override it
}

#ifdef MG_ENABLE_LINES
#line 1 "src/flash.c"
#endif





#if MG_OTA != MG_OTA_NONE && MG_OTA != MG_OTA_CUSTOM

static char *s_addr;      // Current address to write to
static size_t s_size;     // Firmware size to flash. In-progress indicator
static uint32_t s_crc32;  // Firmware checksum

bool mg_ota_flash_begin(size_t new_firmware_size, struct mg_flash *flash) {
  bool ok = false;
  if (s_size) {
    MG_ERROR(("OTA already in progress. Call mg_ota_end()"));
  } else {
    size_t half = flash->size / 2;
    s_crc32 = 0;
    s_addr = (char *) flash->start + half;
    MG_DEBUG(("FW %lu bytes, max %lu", new_firmware_size, half));
    if (new_firmware_size < half) {
      ok = true;
      s_size = new_firmware_size;
      MG_INFO(("Starting OTA, firmware size %lu", s_size));
    } else {
      MG_ERROR(("Firmware %lu is too big to fit %lu", new_firmware_size, half));
    }
  }
  return ok;
}

bool mg_ota_flash_write(const void *buf, size_t len, struct mg_flash *flash) {
  bool ok = false;
  if (s_size == 0) {
    MG_ERROR(("OTA is not started, call mg_ota_begin()"));
  } else {
    size_t len_aligned_down = MG_ROUND_DOWN(len, flash->align);
    if (len_aligned_down) ok = flash->write_fn(s_addr, buf, len_aligned_down);
    if (len_aligned_down < len) {
      size_t left = len - len_aligned_down;
      char tmp[flash->align];
      memset(tmp, 0xff, sizeof(tmp));
      memcpy(tmp, (char *) buf + len_aligned_down, left);
      ok = flash->write_fn(s_addr + len_aligned_down, tmp, sizeof(tmp));
    }
    s_crc32 = mg_crc32(s_crc32, (char *) buf, len);  // Update CRC
    MG_DEBUG(("%#x %p %lu -> %d", s_addr - len, buf, len, ok));
    s_addr += len;
  }
  return ok;
}

bool mg_ota_flash_end(struct mg_flash *flash) {
  char *base = (char *) flash->start + flash->size / 2;
  bool ok = false;
  if (s_size) {
    size_t size = (size_t) (s_addr - base);
    uint32_t crc32 = mg_crc32(0, base, s_size);
    if (size == s_size && crc32 == s_crc32) ok = true;
    MG_DEBUG(("CRC: %x/%x, size: %lu/%lu, status: %s", s_crc32, crc32, s_size,
              size, ok ? "ok" : "fail"));
    s_size = 0;
    if (ok) ok = flash->swap_fn();
  }
  MG_INFO(("Finishing OTA: %s", ok ? "ok" : "fail"));
  return ok;
}

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/fmt.c"
#endif




static bool is_digit(int c) {
  return c >= '0' && c <= '9';
}

static int addexp(char *buf, int e, int sign) {
  int n = 0;
  buf[n++] = 'e';
  buf[n++] = (char) sign;
  if (e > 400) return 0;
  if (e < 10) buf[n++] = '0';
  if (e >= 100) buf[n++] = (char) (e / 100 + '0'), e -= 100 * (e / 100);
  if (e >= 10) buf[n++] = (char) (e / 10 + '0'), e -= 10 * (e / 10);
  buf[n++] = (char) (e + '0');
  return n;
}

static int xisinf(double x) {
  union {
    double f;
    uint64_t u;
  } ieee754;
  ieee754.f = x;
  return ((unsigned) (ieee754.u >> 32) & 0x7fffffff) == 0x7ff00000 &&
         ((unsigned) ieee754.u == 0);
}

static int xisnan(double x) {
  union {
    double f;
    uint64_t u;
  } ieee754;
  ieee754.f = x;
  return ((unsigned) (ieee754.u >> 32) & 0x7fffffff) +
             ((unsigned) ieee754.u != 0) >
         0x7ff00000;
}

static size_t mg_dtoa(char *dst, size_t dstlen, double d, int width, bool tz) {
  char buf[40];
  int i, s = 0, n = 0, e = 0;
  double t, mul, saved;
  if (d == 0.0) return mg_snprintf(dst, dstlen, "%s", "0");
  if (xisinf(d)) return mg_snprintf(dst, dstlen, "%s", d > 0 ? "inf" : "-inf");
  if (xisnan(d)) return mg_snprintf(dst, dstlen, "%s", "nan");
  if (d < 0.0) d = -d, buf[s++] = '-';

  // Round
  saved = d;
  if (tz) {
    mul = 1.0;
    while (d >= 10.0 && d / mul >= 10.0) mul *= 10.0;
  } else {
    mul = 0.1;
  }

  while (d <= 1.0 && d / mul <= 1.0) mul /= 10.0;
  for (i = 0, t = mul * 5; i < width; i++) t /= 10.0;

  d += t;

  // Calculate exponent, and 'mul' for scientific representation
  mul = 1.0;
  while (d >= 10.0 && d / mul >= 10.0) mul *= 10.0, e++;
  while (d < 1.0 && d / mul < 1.0) mul /= 10.0, e--;
  // printf(" --> %g %d %g %g\n", saved, e, t, mul);

  if (tz && e >= width && width > 1) {
    n = (int) mg_dtoa(buf, sizeof(buf), saved / mul, width, tz);
    // printf(" --> %.*g %d [%.*s]\n", 10, d / t, e, n, buf);
    n += addexp(buf + s + n, e, '+');
    return mg_snprintf(dst, dstlen, "%.*s", n, buf);
  } else if (tz && e <= -width && width > 1) {
    n = (int) mg_dtoa(buf, sizeof(buf), saved / mul, width, tz);
    // printf(" --> %.*g %d [%.*s]\n", 10, d / mul, e, n, buf);
    n += addexp(buf + s + n, -e, '-');
    return mg_snprintf(dst, dstlen, "%.*s", n, buf);
  } else {
    int targ_width = width;
    for (i = 0, t = mul; t >= 1.0 && s + n < (int) sizeof(buf); i++) {
      int ch = (int) (d / t);
      if (n > 0 || ch > 0) buf[s + n++] = (char) (ch + '0');
      d -= ch * t;
      t /= 10.0;
    }
    // printf(" --> [%g] -> %g %g (%d) [%.*s]\n", saved, d, t, n, s + n, buf);
    if (n == 0) buf[s++] = '0';
    while (t >= 1.0 && n + s < (int) sizeof(buf)) buf[n++] = '0', t /= 10.0;
    if (s + n < (int) sizeof(buf)) buf[n + s++] = '.';
    // printf(" 1--> [%g] -> [%.*s]\n", saved, s + n, buf);
    if (!tz && n > 0) targ_width = width + n;
    for (i = 0, t = 0.1; s + n < (int) sizeof(buf) && n < targ_width; i++) {
      int ch = (int) (d / t);
      buf[s + n++] = (char) (ch + '0');
      d -= ch * t;
      t /= 10.0;
    }
  }

  while (tz && n > 0 && buf[s + n - 1] == '0') n--;  // Trim trailing zeroes
  if (tz && n > 0 && buf[s + n - 1] == '.') n--;     // Trim trailing dot
  n += s;
  if (n >= (int) sizeof(buf)) n = (int) sizeof(buf) - 1;
  buf[n] = '\0';
  return mg_snprintf(dst, dstlen, "%s", buf);
}

static size_t mg_lld(char *buf, int64_t val, bool is_signed, bool is_hex) {
  const char *letters = "0123456789abcdef";
  uint64_t v = (uint64_t) val;
  size_t s = 0, n, i;
  if (is_signed && val < 0) buf[s++] = '-', v = (uint64_t) (-val);
  // This loop prints a number in reverse order. I guess this is because we
  // write numbers from right to left: least significant digit comes last.
  // Maybe because we use Arabic numbers, and Arabs write RTL?
  if (is_hex) {
    for (n = 0; v; v >>= 4) buf[s + n++] = letters[v & 15];
  } else {
    for (n = 0; v; v /= 10) buf[s + n++] = letters[v % 10];
  }
  // Reverse a string
  for (i = 0; i < n / 2; i++) {
    char t = buf[s + i];
    buf[s + i] = buf[s + n - i - 1], buf[s + n - i - 1] = t;
  }
  if (val == 0) buf[n++] = '0';  // Handle special case
  return n + s;
}

static size_t scpy(void (*out)(char, void *), void *ptr, char *buf,
                   size_t len) {
  size_t i = 0;
  while (i < len && buf[i] != '\0') out(buf[i++], ptr);
  return i;
}

size_t mg_xprintf(void (*out)(char, void *), void *ptr, const char *fmt, ...) {
  size_t len = 0;
  va_list ap;
  va_start(ap, fmt);
  len = mg_vxprintf(out, ptr, fmt, &ap);
  va_end(ap);
  return len;
}

size_t mg_vxprintf(void (*out)(char, void *), void *param, const char *fmt,
                   va_list *ap) {
  size_t i = 0, n = 0;
  while (fmt[i] != '\0') {
    if (fmt[i] == '%') {
      size_t j, k, x = 0, is_long = 0, w = 0 /* width */, pr = ~0U /* prec */;
      char pad = ' ', minus = 0, c = fmt[++i];
      if (c == '#') x++, c = fmt[++i];
      if (c == '-') minus++, c = fmt[++i];
      if (c == '0') pad = '0', c = fmt[++i];
      while (is_digit(c)) w *= 10, w += (size_t) (c - '0'), c = fmt[++i];
      if (c == '.') {
        c = fmt[++i];
        if (c == '*') {
          pr = (size_t) va_arg(*ap, int);
          c = fmt[++i];
        } else {
          pr = 0;
          while (is_digit(c)) pr *= 10, pr += (size_t) (c - '0'), c = fmt[++i];
        }
      }
      while (c == 'h') c = fmt[++i];  // Treat h and hh as int
      if (c == 'l') {
        is_long++, c = fmt[++i];
        if (c == 'l') is_long++, c = fmt[++i];
      }
      if (c == 'p') x = 1, is_long = 1;
      if (c == 'd' || c == 'u' || c == 'x' || c == 'X' || c == 'p' ||
          c == 'g' || c == 'f') {
        bool s = (c == 'd'), h = (c == 'x' || c == 'X' || c == 'p');
        char tmp[40];
        size_t xl = x ? 2 : 0;
        if (c == 'g' || c == 'f') {
          double v = va_arg(*ap, double);
          if (pr == ~0U) pr = 6;
          k = mg_dtoa(tmp, sizeof(tmp), v, (int) pr, c == 'g');
        } else if (is_long == 2) {
          int64_t v = va_arg(*ap, int64_t);
          k = mg_lld(tmp, v, s, h);
        } else if (is_long == 1) {
          long v = va_arg(*ap, long);
          k = mg_lld(tmp, s ? (int64_t) v : (int64_t) (unsigned long) v, s, h);
        } else {
          int v = va_arg(*ap, int);
          k = mg_lld(tmp, s ? (int64_t) v : (int64_t) (unsigned) v, s, h);
        }
        for (j = 0; j < xl && w > 0; j++) w--;
        for (j = 0; pad == ' ' && !minus && k < w && j + k < w; j++)
          n += scpy(out, param, &pad, 1);
        n += scpy(out, param, (char *) "0x", xl);
        for (j = 0; pad == '0' && k < w && j + k < w; j++)
          n += scpy(out, param, &pad, 1);
        n += scpy(out, param, tmp, k);
        for (j = 0; pad == ' ' && minus && k < w && j + k < w; j++)
          n += scpy(out, param, &pad, 1);
      } else if (c == 'm' || c == 'M') {
        mg_pm_t f = va_arg(*ap, mg_pm_t);
        if (c == 'm') out('"', param);
        n += f(out, param, ap);
        if (c == 'm') n += 2, out('"', param);
      } else if (c == 'c') {
        int ch = va_arg(*ap, int);
        out((char) ch, param);
        n++;
      } else if (c == 's') {
        char *p = va_arg(*ap, char *);
        if (pr == ~0U) pr = p == NULL ? 0 : strlen(p);
        for (j = 0; !minus && pr < w && j + pr < w; j++)
          n += scpy(out, param, &pad, 1);
        n += scpy(out, param, p, pr);
        for (j = 0; minus && pr < w && j + pr < w; j++)
          n += scpy(out, param, &pad, 1);
      } else if (c == '%') {
        out('%', param);
        n++;
      } else {
        out('%', param);
        out(c, param);
        n += 2;
      }
      i++;
    } else {
      out(fmt[i], param), n++, i++;
    }
  }
  return n;
}

#ifdef MG_ENABLE_LINES
#line 1 "src/fs.c"
#endif





struct mg_fd *mg_fs_open(struct mg_fs *fs, const char *path, int flags) {
  struct mg_fd *fd = (struct mg_fd *) mg_calloc(1, sizeof(*fd));
  if (fd != NULL) {
    fd->fd = fs->op(path, flags);
    fd->fs = fs;
    if (fd->fd == NULL) {
      mg_free(fd);
      fd = NULL;
    }
  }
  return fd;
}

void mg_fs_close(struct mg_fd *fd) {
  if (fd != NULL) {
    fd->fs->cl(fd->fd);
    mg_free(fd);
  }
}

struct mg_str mg_file_read(struct mg_fs *fs, const char *path) {
  struct mg_str result = {NULL, 0};
  void *fp;
  fs->st(path, &result.len, NULL);
  if ((fp = fs->op(path, MG_FS_READ)) != NULL) {
    result.buf = (char *) mg_calloc(1, result.len + 1);
    if (result.buf != NULL &&
        fs->rd(fp, (void *) result.buf, result.len) != result.len) {
      mg_free((void *) result.buf);
      result.buf = NULL;
    }
    fs->cl(fp);
  }
  if (result.buf == NULL) result.len = 0;
  return result;
}

bool mg_file_write(struct mg_fs *fs, const char *path, const void *buf,
                   size_t len) {
  bool result = false;
  struct mg_fd *fd;
  char tmp[MG_PATH_MAX];
  mg_snprintf(tmp, sizeof(tmp), "%s..%d", path, rand());
  if ((fd = mg_fs_open(fs, tmp, MG_FS_WRITE)) != NULL) {
    result = fs->wr(fd->fd, buf, len) == len;
    mg_fs_close(fd);
    if (result) {
      fs->rm(path);
      fs->mv(tmp, path);
    } else {
      fs->rm(tmp);
    }
  }
  return result;
}

bool mg_file_printf(struct mg_fs *fs, const char *path, const char *fmt, ...) {
  va_list ap;
  char *data;
  bool result = false;
  va_start(ap, fmt);
  data = mg_vmprintf(fmt, &ap);
  va_end(ap);
  result = mg_file_write(fs, path, data, strlen(data));
  mg_free(data);
  return result;
}

// This helper function allows to scan a filesystem in a sequential way,
// without using callback function:
//      char buf[100] = "";
//      while (mg_fs_ls(&mg_fs_posix, "./", buf, sizeof(buf))) {
//        ...
static void mg_fs_ls_fn(const char *filename, void *param) {
  struct mg_str *s = (struct mg_str *) param;
  if (s->buf[0] == '\0') {
    mg_snprintf((char *) s->buf, s->len, "%s", filename);
  } else if (strcmp(s->buf, filename) == 0) {
    ((char *) s->buf)[0] = '\0';  // Fetch next file
  }
}

bool mg_fs_ls(struct mg_fs *fs, const char *path, char *buf, size_t len) {
  struct mg_str s;
  s.buf = buf, s.len = len;
  fs->ls(path, mg_fs_ls_fn, &s);
  return buf[0] != '\0';
}

#ifdef MG_ENABLE_LINES
#line 1 "src/fs_fat.c"
#endif



#if MG_ENABLE_FATFS
#include <ff.h>

static int mg_days_from_epoch(int y, int m, int d) {
  y -= m <= 2;
  int era = y / 400;
  int yoe = y - era * 400;
  int doy = (153 * (m + (m > 2 ? -3 : 9)) + 2) / 5 + d - 1;
  int doe = yoe * 365 + yoe / 4 - yoe / 100 + doy;
  return era * 146097 + doe - 719468;
}

static time_t mg_timegm(const struct tm *t) {
  int year = t->tm_year + 1900;
  int month = t->tm_mon;  // 0-11
  if (month > 11) {
    year += month / 12;
    month %= 12;
  } else if (month < 0) {
    int years_diff = (11 - month) / 12;
    year -= years_diff;
    month += 12 * years_diff;
  }
  int x = mg_days_from_epoch(year, month + 1, t->tm_mday);
  return 60 * (60 * (24L * x + t->tm_hour) + t->tm_min) + t->tm_sec;
}

static time_t ff_time_to_epoch(uint16_t fdate, uint16_t ftime) {
  struct tm tm;
  memset(&tm, 0, sizeof(struct tm));
  tm.tm_sec = (ftime << 1) & 0x3e;
  tm.tm_min = ((ftime >> 5) & 0x3f);
  tm.tm_hour = ((ftime >> 11) & 0x1f);
  tm.tm_mday = (fdate & 0x1f);
  tm.tm_mon = ((fdate >> 5) & 0x0f) - 1;
  tm.tm_year = ((fdate >> 9) & 0x7f) + 80;
  return mg_timegm(&tm);
}

static int ff_stat(const char *path, size_t *size, time_t *mtime) {
  FILINFO fi;
  if (path[0] == '\0') {
    if (size) *size = 0;
    if (mtime) *mtime = 0;
    return MG_FS_DIR;
  } else if (f_stat(path, &fi) == 0) {
    if (size) *size = (size_t) fi.fsize;
    if (mtime) *mtime = ff_time_to_epoch(fi.fdate, fi.ftime);
    return MG_FS_READ | MG_FS_WRITE | ((fi.fattrib & AM_DIR) ? MG_FS_DIR : 0);
  } else {
    return 0;
  }
}

static void ff_list(const char *dir, void (*fn)(const char *, void *),
                    void *userdata) {
  DIR d;
  FILINFO fi;
  if (f_opendir(&d, dir) == FR_OK) {
    while (f_readdir(&d, &fi) == FR_OK && fi.fname[0] != '\0') {
      if (!strcmp(fi.fname, ".") || !strcmp(fi.fname, "..")) continue;
      fn(fi.fname, userdata);
    }
    f_closedir(&d);
  }
}

static void *ff_open(const char *path, int flags) {
  FIL f;
  unsigned char mode = FA_READ;
  if (flags & MG_FS_WRITE) mode |= FA_WRITE | FA_OPEN_ALWAYS | FA_OPEN_APPEND;
  if (f_open(&f, path, mode) == 0) {
    FIL *fp;
    if ((fp = mg_calloc(1, sizeof(*fp))) != NULL) {
      memcpy(fp, &f, sizeof(*fp));
      return fp;
    }
  }
  return NULL;
}

static void ff_close(void *fp) {
  if (fp != NULL) {
    f_close((FIL *) fp);
    mg_free(fp);
  }
}

static size_t ff_read(void *fp, void *buf, size_t len) {
  UINT n = 0, misalign = ((size_t) buf) & 3;
  if (misalign) {
    char aligned[4];
    f_read((FIL *) fp, aligned, len > misalign ? misalign : len, &n);
    memcpy(buf, aligned, n);
  } else {
    f_read((FIL *) fp, buf, len, &n);
  }
  return n;
}

static size_t ff_write(void *fp, const void *buf, size_t len) {
  UINT n = 0;
  return f_write((FIL *) fp, (char *) buf, len, &n) == FR_OK ? n : 0;
}

static size_t ff_seek(void *fp, size_t offset) {
  f_lseek((FIL *) fp, offset);
  return offset;
}

static bool ff_rename(const char *from, const char *to) {
  return f_rename(from, to) == FR_OK;
}

static bool ff_remove(const char *path) {
  return f_unlink(path) == FR_OK;
}

static bool ff_mkdir(const char *path) {
  return f_mkdir(path) == FR_OK;
}

struct mg_fs mg_fs_fat = {ff_stat,  ff_list, ff_open,   ff_close,  ff_read,
                          ff_write, ff_seek, ff_rename, ff_remove, ff_mkdir};
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/fs_packed.c"
#endif





struct packed_file {
  const char *data;
  size_t size;
  size_t pos;
};

#if MG_ENABLE_PACKED_FS
#else
const char *mg_unpack(const char *path, size_t *size, time_t *mtime) {
  if (size != NULL) *size = 0;
  if (mtime != NULL) *mtime = 0;
  (void) path;
  return NULL;
}
const char *mg_unlist(size_t no) {
  (void) no;
  return NULL;
}
#endif

struct mg_str mg_unpacked(const char *path) {
  size_t len = 0;
  const char *buf = mg_unpack(path, &len, NULL);
  return mg_str_n(buf, len);
}

static int is_dir_prefix(const char *prefix, size_t n, const char *path) {
  // MG_INFO(("[%.*s] [%s] %c", (int) n, prefix, path, path[n]));
  return n < strlen(path) && strncmp(prefix, path, n) == 0 &&
         (n == 0 || path[n] == '/' || path[n - 1] == '/');
}

static int packed_stat(const char *path, size_t *size, time_t *mtime) {
  const char *p;
  size_t i, n = strlen(path);
  if (mg_unpack(path, size, mtime)) return MG_FS_READ;  // Regular file
  // Scan all files. If `path` is a dir prefix for any of them, it's a dir
  for (i = 0; (p = mg_unlist(i)) != NULL; i++) {
    if (is_dir_prefix(path, n, p)) return MG_FS_DIR;
  }
  return 0;
}

static void packed_list(const char *dir, void (*fn)(const char *, void *),
                        void *userdata) {
  char buf[MG_PATH_MAX], tmp[sizeof(buf)];
  const char *path, *begin, *end;
  size_t i, n = strlen(dir);
  tmp[0] = '\0';  // Previously listed entry
  for (i = 0; (path = mg_unlist(i)) != NULL; i++) {
    if (!is_dir_prefix(dir, n, path)) continue;
    begin = &path[n + 1];
    end = strchr(begin, '/');
    if (end == NULL) end = begin + strlen(begin);
    mg_snprintf(buf, sizeof(buf), "%.*s", (int) (end - begin), begin);
    buf[sizeof(buf) - 1] = '\0';
    // If this entry has been already listed, skip
    // NOTE: we're assuming that file list is sorted alphabetically
    if (strcmp(buf, tmp) == 0) continue;
    fn(buf, userdata);  // Not yet listed, call user function
    strcpy(tmp, buf);   // And save this entry as listed
  }
}

static void *packed_open(const char *path, int flags) {
  size_t size = 0;
  const char *data = mg_unpack(path, &size, NULL);
  struct packed_file *fp = NULL;
  if (data == NULL) return NULL;
  if (flags & MG_FS_WRITE) return NULL;
  if ((fp = (struct packed_file *) mg_calloc(1, sizeof(*fp))) != NULL) {
    fp->size = size;
    fp->data = data;
  }
  return (void *) fp;
}

static void packed_close(void *fp) {
  if (fp != NULL) mg_free(fp);
}

static size_t packed_read(void *fd, void *buf, size_t len) {
  struct packed_file *fp = (struct packed_file *) fd;
  if (fp->pos + len > fp->size) len = fp->size - fp->pos;
  memcpy(buf, &fp->data[fp->pos], len);
  fp->pos += len;
  return len;
}

static size_t packed_write(void *fd, const void *buf, size_t len) {
  (void) fd, (void) buf, (void) len;
  return 0;
}

static size_t packed_seek(void *fd, size_t offset) {
  struct packed_file *fp = (struct packed_file *) fd;
  fp->pos = offset;
  if (fp->pos > fp->size) fp->pos = fp->size;
  return fp->pos;
}

static bool packed_rename(const char *from, const char *to) {
  (void) from, (void) to;
  return false;
}

static bool packed_remove(const char *path) {
  (void) path;
  return false;
}

static bool packed_mkdir(const char *path) {
  (void) path;
  return false;
}

struct mg_fs mg_fs_packed = {
    packed_stat,  packed_list, packed_open,   packed_close,  packed_read,
    packed_write, packed_seek, packed_rename, packed_remove, packed_mkdir};

#ifdef MG_ENABLE_LINES
#line 1 "src/fs_posix.c"
#endif


#if MG_ENABLE_POSIX_FS

#ifndef MG_STAT_STRUCT
#define MG_STAT_STRUCT stat
#endif

#ifndef MG_STAT_FUNC
#define MG_STAT_FUNC stat
#endif

static int p_stat(const char *path, size_t *size, time_t *mtime) {
#if !defined(S_ISDIR)
  MG_ERROR(("stat() API is not supported. %p %p %p", path, size, mtime));
  return 0;
#else
#if MG_ARCH == MG_ARCH_WIN32
  struct _stati64 st;
  wchar_t tmp[MG_PATH_MAX];
  MultiByteToWideChar(CP_UTF8, 0, path, -1, tmp, sizeof(tmp) / sizeof(tmp[0]));
  if (_wstati64(tmp, &st) != 0) return 0;
  // If path is a symlink, windows reports 0 in st.st_size.
  // Get a real file size by opening it and jumping to the end
  if (st.st_size == 0 && (st.st_mode & _S_IFREG)) {
    FILE *fp = _wfopen(tmp, L"rb");
    if (fp != NULL) {
      fseek(fp, 0, SEEK_END);
      if (ftell(fp) > 0) st.st_size = ftell(fp);  // Use _ftelli64 on win10+
      fclose(fp);
    }
  }
#else
  struct MG_STAT_STRUCT st;
  if (MG_STAT_FUNC(path, &st) != 0) return 0;
#endif
  if (size) *size = (size_t) st.st_size;
  if (mtime) *mtime = st.st_mtime;
  return MG_FS_READ | MG_FS_WRITE | (S_ISDIR(st.st_mode) ? MG_FS_DIR : 0);
#endif
}

#if MG_ARCH == MG_ARCH_WIN32
struct dirent {
  char d_name[MAX_PATH];
};

typedef struct win32_dir {
  HANDLE handle;
  WIN32_FIND_DATAW info;
  struct dirent result;
} DIR;

#if 0
int gettimeofday(struct timeval *tv, void *tz) {
  FILETIME ft;
  unsigned __int64 tmpres = 0;

  if (tv != NULL) {
    GetSystemTimeAsFileTime(&ft);
    tmpres |= ft.dwHighDateTime;
    tmpres <<= 32;
    tmpres |= ft.dwLowDateTime;
    tmpres /= 10;  // convert into microseconds
    tmpres -= (int64_t) 11644473600000000;
    tv->tv_sec = (long) (tmpres / 1000000UL);
    tv->tv_usec = (long) (tmpres % 1000000UL);
  }
  (void) tz;
  return 0;
}
#endif

static int to_wchar(const char *path, wchar_t *wbuf, size_t wbuf_len) {
  int ret;
  char buf[MAX_PATH * 2], buf2[MAX_PATH * 2], *p;
  strncpy(buf, path, sizeof(buf));
  buf[sizeof(buf) - 1] = '\0';
  // Trim trailing slashes. Leave backslash for paths like "X:\"
  p = buf + strlen(buf) - 1;
  while (p > buf && p[-1] != ':' && (p[0] == '\\' || p[0] == '/')) *p-- = '\0';
  memset(wbuf, 0, wbuf_len * sizeof(wchar_t));
  ret = MultiByteToWideChar(CP_UTF8, 0, buf, -1, wbuf, (int) wbuf_len);
  // Convert back to Unicode. If doubly-converted string does not match the
  // original, something is fishy, reject.
  WideCharToMultiByte(CP_UTF8, 0, wbuf, (int) wbuf_len, buf2, sizeof(buf2),
                      NULL, NULL);
  if (strcmp(buf, buf2) != 0) {
    wbuf[0] = L'\0';
    ret = 0;
  }
  return ret;
}

DIR *opendir(const char *name) {
  DIR *d = NULL;
  wchar_t wpath[MAX_PATH];
  DWORD attrs;

  if (name == NULL) {
    SetLastError(ERROR_BAD_ARGUMENTS);
  } else if ((d = (DIR *) mg_calloc(1, sizeof(*d))) == NULL) {
    SetLastError(ERROR_NOT_ENOUGH_MEMORY);
  } else {
    to_wchar(name, wpath, sizeof(wpath) / sizeof(wpath[0]));
    attrs = GetFileAttributesW(wpath);
    if (attrs != 0Xffffffff && (attrs & FILE_ATTRIBUTE_DIRECTORY)) {
      (void) wcscat(wpath, L"\\*");
      d->handle = FindFirstFileW(wpath, &d->info);
      d->result.d_name[0] = '\0';
    } else {
      mg_free(d);
      d = NULL;
    }
  }
  return d;
}

int closedir(DIR *d) {
  int result = 0;
  if (d != NULL) {
    if (d->handle != INVALID_HANDLE_VALUE)
      result = FindClose(d->handle) ? 0 : -1;
    mg_free(d);
  } else {
    result = -1;
    SetLastError(ERROR_BAD_ARGUMENTS);
  }
  return result;
}

struct dirent *readdir(DIR *d) {
  struct dirent *result = NULL;
  if (d != NULL) {
    memset(&d->result, 0, sizeof(d->result));
    if (d->handle != INVALID_HANDLE_VALUE) {
      result = &d->result;
      WideCharToMultiByte(CP_UTF8, 0, d->info.cFileName, -1, result->d_name,
                          sizeof(result->d_name), NULL, NULL);
      if (!FindNextFileW(d->handle, &d->info)) {
        FindClose(d->handle);
        d->handle = INVALID_HANDLE_VALUE;
      }
    } else {
      SetLastError(ERROR_FILE_NOT_FOUND);
    }
  } else {
    SetLastError(ERROR_BAD_ARGUMENTS);
  }
  return result;
}
#endif

static void p_list(const char *dir, void (*fn)(const char *, void *),
                   void *userdata) {
#if MG_ENABLE_DIRLIST
  struct dirent *dp;
  DIR *dirp;
  if ((dirp = (opendir(dir))) == NULL) return;
  while ((dp = readdir(dirp)) != NULL) {
    if (!strcmp(dp->d_name, ".") || !strcmp(dp->d_name, "..")) continue;
    fn(dp->d_name, userdata);
  }
  closedir(dirp);
#else
  (void) dir, (void) fn, (void) userdata;
#endif
}

static void *p_open(const char *path, int flags) {
#if MG_ARCH == MG_ARCH_WIN32
  const char *mode = flags == MG_FS_READ ? "rb" : "a+b";
  wchar_t b1[MG_PATH_MAX], b2[10];
  MultiByteToWideChar(CP_UTF8, 0, path, -1, b1, sizeof(b1) / sizeof(b1[0]));
  MultiByteToWideChar(CP_UTF8, 0, mode, -1, b2, sizeof(b2) / sizeof(b2[0]));
  return (void *) _wfopen(b1, b2);
#else
  const char *mode = flags == MG_FS_READ ? "rbe" : "a+be";  // e for CLOEXEC
  return (void *) fopen(path, mode);
#endif
}

static void p_close(void *fp) {
  fclose((FILE *) fp);
}

static size_t p_read(void *fp, void *buf, size_t len) {
  return fread(buf, 1, len, (FILE *) fp);
}

static size_t p_write(void *fp, const void *buf, size_t len) {
  return fwrite(buf, 1, len, (FILE *) fp);
}

static size_t p_seek(void *fp, size_t offset) {
#if (defined(_FILE_OFFSET_BITS) && _FILE_OFFSET_BITS == 64) ||  \
    (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L) || \
    (defined(_XOPEN_SOURCE) && _XOPEN_SOURCE >= 600)
  if (fseeko((FILE *) fp, (off_t) offset, SEEK_SET) != 0) (void) 0;
#else
  if (fseek((FILE *) fp, (long) offset, SEEK_SET) != 0) (void) 0;
#endif
  return (size_t) ftell((FILE *) fp);
}

static bool p_rename(const char *from, const char *to) {
  return rename(from, to) == 0;
}

static bool p_remove(const char *path) {
  return remove(path) == 0;
}

static bool p_mkdir(const char *path) {
  return mkdir(path, 0775) == 0;
}

#else

static int p_stat(const char *path, size_t *size, time_t *mtime) {
  (void) path, (void) size, (void) mtime;
  return 0;
}
static void p_list(const char *path, void (*fn)(const char *, void *),
                   void *userdata) {
  (void) path, (void) fn, (void) userdata;
}
static void *p_open(const char *path, int flags) {
  (void) path, (void) flags;
  return NULL;
}
static void p_close(void *fp) {
  (void) fp;
}
static size_t p_read(void *fd, void *buf, size_t len) {
  (void) fd, (void) buf, (void) len;
  return 0;
}
static size_t p_write(void *fd, const void *buf, size_t len) {
  (void) fd, (void) buf, (void) len;
  return 0;
}
static size_t p_seek(void *fd, size_t offset) {
  (void) fd, (void) offset;
  return (size_t) ~0;
}
static bool p_rename(const char *from, const char *to) {
  (void) from, (void) to;
  return false;
}
static bool p_remove(const char *path) {
  (void) path;
  return false;
}
static bool p_mkdir(const char *path) {
  (void) path;
  return false;
}
#endif

struct mg_fs mg_fs_posix = {p_stat,  p_list, p_open,   p_close,  p_read,
                            p_write, p_seek, p_rename, p_remove, p_mkdir};

#ifdef MG_ENABLE_LINES
#line 1 "src/http.c"
#endif













static int mg_ncasecmp(const char *s1, const char *s2, size_t len) {
  int diff = 0;
  if (len > 0) do {
      int c = *s1++, d = *s2++;
      if (c >= 'A' && c <= 'Z') c += 'a' - 'A';
      if (d >= 'A' && d <= 'Z') d += 'a' - 'A';
      diff = c - d;
    } while (diff == 0 && s1[-1] != '\0' && --len > 0);
  return diff;
}

bool mg_to_size_t(struct mg_str str, size_t *val);
bool mg_to_size_t(struct mg_str str, size_t *val) {
  size_t i = 0, max = (size_t) -1, max2 = max / 10, result = 0, ndigits = 0;
  while (i < str.len && (str.buf[i] == ' ' || str.buf[i] == '\t')) i++;
  if (i < str.len && str.buf[i] == '-') return false;
  while (i < str.len && str.buf[i] >= '0' && str.buf[i] <= '9') {
    size_t digit = (size_t) (str.buf[i] - '0');
    if (result > max2) return false;  // Overflow
    result *= 10;
    if (result > max - digit) return false;  // Overflow
    result += digit;
    i++, ndigits++;
  }
  while (i < str.len && (str.buf[i] == ' ' || str.buf[i] == '\t')) i++;
  if (ndigits == 0) return false;  // #2322: Content-Length = 1 * DIGIT
  if (i != str.len) return false;  // Ditto
  *val = (size_t) result;
  return true;
}

// Chunk deletion marker is the MSB in the "processed" counter
#define MG_DMARK ((size_t) 1 << (sizeof(size_t) * 8 - 1))

// Multipart POST example:
// --xyz
// Content-Disposition: form-data; name="val"
//
// abcdef
// --xyz
// Content-Disposition: form-data; name="foo"; filename="a.txt"
// Content-Type: text/plain
//
// hello world
//
// --xyz--
size_t mg_http_next_multipart(struct mg_str body, size_t ofs,
                              struct mg_http_part *part) {
  struct mg_str cd = mg_str_n("Content-Disposition", 19);
  const char *s = body.buf;
  size_t b = ofs, h1, h2, b1, b2, max = body.len;

  // Init part params
  if (part != NULL) part->name = part->filename = part->body = mg_str_n(0, 0);

  // Skip boundary
  while (b + 2 < max && s[b] != '\r' && s[b + 1] != '\n') b++;
  if (b <= ofs || b + 2 >= max) return 0;
  // MG_INFO(("B: %zu %zu [%.*s]", ofs, b - ofs, (int) (b - ofs), s));

  // Skip headers
  h1 = h2 = b + 2;
  for (;;) {
    while (h2 + 2 < max && s[h2] != '\r' && s[h2 + 1] != '\n') h2++;
    if (h2 == h1) break;
    if (h2 + 2 >= max) return 0;
    // MG_INFO(("Header: [%.*s]", (int) (h2 - h1), &s[h1]));
    if (part != NULL && h1 + cd.len + 2 < h2 && s[h1 + cd.len] == ':' &&
        mg_ncasecmp(&s[h1], cd.buf, cd.len) == 0) {
      struct mg_str v = mg_str_n(&s[h1 + cd.len + 2], h2 - (h1 + cd.len + 2));
      part->name = mg_http_get_header_var(v, mg_str_n("name", 4));
      part->filename = mg_http_get_header_var(v, mg_str_n("filename", 8));
    }
    h1 = h2 = h2 + 2;
  }
  b1 = b2 = h2 + 2;
  while (b2 + 2 + (b - ofs) + 2 < max && !(s[b2] == '\r' && s[b2 + 1] == '\n' &&
                                           memcmp(&s[b2 + 2], s, b - ofs) == 0))
    b2++;

  if (b2 + 2 >= max) return 0;
  if (part != NULL) part->body = mg_str_n(&s[b1], b2 - b1);
  // MG_INFO(("Body: [%.*s]", (int) (b2 - b1), &s[b1]));
  return b2 + 2;
}

void mg_http_bauth(struct mg_connection *c, const char *user,
                   const char *pass) {
  struct mg_str u = mg_str(user), p = mg_str(pass);
  size_t need = c->send.len + 36 + (u.len + p.len) * 2;
  if (c->send.size < need) mg_iobuf_resize(&c->send, need);
  if (c->send.size >= need) {
    size_t i, n = 0;
    char *buf = (char *) &c->send.buf[c->send.len];
    memcpy(buf, "Authorization: Basic ", 21);  // DON'T use mg_send!
    for (i = 0; i < u.len; i++) {
      n = mg_base64_update(((unsigned char *) u.buf)[i], buf + 21, n);
    }
    if (p.len > 0) {
      n = mg_base64_update(':', buf + 21, n);
      for (i = 0; i < p.len; i++) {
        n = mg_base64_update(((unsigned char *) p.buf)[i], buf + 21, n);
      }
    }
    n = mg_base64_final(buf + 21, n);
    c->send.len += 21 + (size_t) n + 2;
    memcpy(&c->send.buf[c->send.len - 2], "\r\n", 2);
  } else {
    MG_ERROR(("%lu oom %d->%d ", c->id, (int) c->send.size, (int) need));
  }
}

struct mg_str mg_http_var(struct mg_str buf, struct mg_str name) {
  struct mg_str entry, k, v, result = mg_str_n(NULL, 0);
  while (mg_span(buf, &entry, &buf, '&')) {
    if (mg_span(entry, &k, &v, '=') && name.len == k.len &&
        mg_ncasecmp(name.buf, k.buf, k.len) == 0) {
      result = v;
      break;
    }
  }
  return result;
}

int mg_http_get_var(const struct mg_str *buf, const char *name, char *dst,
                    size_t dst_len) {
  int len;
  if (dst != NULL && dst_len > 0) {
    dst[0] = '\0';  // If destination buffer is valid, always nul-terminate it
  }
  if (dst == NULL || dst_len == 0) {
    len = -2;  // Bad destination
  } else if (buf->buf == NULL || name == NULL || buf->len == 0) {
    len = -1;  // Bad source
  } else {
    struct mg_str v = mg_http_var(*buf, mg_str(name));
    if (v.buf == NULL) {
      len = -4;  // Name does not exist
    } else {
      len = mg_url_decode(v.buf, v.len, dst, dst_len, 1);
      if (len < 0) len = -3;  // Failed to decode
    }
  }
  return len;
}

static bool isx(int c) {
  return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') ||
         (c >= 'A' && c <= 'F');
}

int mg_url_decode(const char *src, size_t src_len, char *dst, size_t dst_len,
                  int is_form_url_encoded) {
  size_t i, j;
  for (i = j = 0; i < src_len && j + 1 < dst_len; i++, j++) {
    if (src[i] == '%') {
      // Use `i + 2 < src_len`, not `i < src_len - 2`, note small src_len
      if (i + 2 < src_len && isx(src[i + 1]) && isx(src[i + 2])) {
        mg_str_to_num(mg_str_n(src + i + 1, 2), 16, &dst[j], sizeof(uint8_t));
        i += 2;
      } else {
        return -1;
      }
    } else if (is_form_url_encoded && src[i] == '+') {
      dst[j] = ' ';
    } else {
      dst[j] = src[i];
    }
  }
  if (j < dst_len) dst[j] = '\0';  // Null-terminate the destination
  return i >= src_len && j < dst_len ? (int) j : -1;
}

static bool isok(uint8_t c) {
  return c == '\n' || c == '\r' || c == '\t' || c >= ' ';
}

int mg_http_get_request_len(const unsigned char *buf, size_t buf_len) {
  size_t i;
  for (i = 0; i < buf_len; i++) {
    if (!isok(buf[i])) return -1;
    if ((i > 0 && buf[i] == '\n' && buf[i - 1] == '\n') ||
        (i > 3 && buf[i] == '\n' && buf[i - 1] == '\r' && buf[i - 2] == '\n'))
      return (int) i + 1;
  }
  return 0;
}
struct mg_str *mg_http_get_header(struct mg_http_message *h, const char *name) {
  size_t i, n = strlen(name), max = sizeof(h->headers) / sizeof(h->headers[0]);
  for (i = 0; i < max && h->headers[i].name.len > 0; i++) {
    struct mg_str *k = &h->headers[i].name, *v = &h->headers[i].value;
    if (n == k->len && mg_ncasecmp(k->buf, name, n) == 0) return v;
  }
  return NULL;
}

// Is it a valid utf-8 continuation byte
static bool vcb(uint8_t c) {
  return (c & 0xc0) == 0x80;
}

// Get character length (valid utf-8). Used to parse method, URI, headers
static size_t clen(const char *s, const char *end) {
  const unsigned char *u = (unsigned char *) s, c = *u;
  long n = (long) (end - s);
  if (c > ' ' && c <= '~') return 1;  // Usual ascii printed char
  if ((c & 0xe0) == 0xc0 && n > 1 && vcb(u[1])) return 2;  // 2-byte UTF8
  if ((c & 0xf0) == 0xe0 && n > 2 && vcb(u[1]) && vcb(u[2])) return 3;
  if ((c & 0xf8) == 0xf0 && n > 3 && vcb(u[1]) && vcb(u[2]) && vcb(u[3]))
    return 4;
  return 0;
}

// Skip until the newline. Return advanced `s`, or NULL on error
static const char *skiptorn(const char *s, const char *end, struct mg_str *v) {
  v->buf = (char *) s;
  while (s < end && s[0] != '\n' && s[0] != '\r') s++, v->len++;  // To newline
  if (s >= end || (s[0] == '\r' && s[1] != '\n')) return NULL;    // Stray \r
  if (s < end && s[0] == '\r') s++;                               // Skip \r
  if (s >= end || *s++ != '\n') return NULL;                      // Skip \n
  return s;
}

static bool mg_http_parse_headers(const char *s, const char *end,
                                  struct mg_http_header *h, size_t max_hdrs) {
  size_t i, n;
  int cl_count = 0, te_count = 0, auth_count = 0;
  int conn_count = 0, cookie_count = 0;
  for (i = 0; i < max_hdrs; i++) {
    struct mg_str k = {NULL, 0}, v = {NULL, 0};
    if (s >= end) return false;
    if (s[0] == '\n' || (s[0] == '\r' && s[1] == '\n')) break;
    k.buf = (char *) s;
    while (s < end && s[0] != ':' && (n = clen(s, end)) > 0) s += n, k.len += n;
    if (k.len == 0) return false;                     // Empty name
    if (s >= end || clen(s, end) == 0) return false;  // Invalid UTF-8
    if (*s++ != ':') return false;  // Invalid, not followed by :
    // if (clen(s, end) == 0) return false;        // Invalid UTF-8
    while (s < end && (s[0] == ' ' || s[0] == '\t')) s++;  // Skip spaces
    if ((s = skiptorn(s, end, &v)) == NULL) return false;
    while (v.len > 0 && (v.buf[v.len - 1] == ' ' || v.buf[v.len - 1] == '\t')) {
      v.len--;  // Trim spaces
    }
    // detect duplicated headers -> discard
    if (((mg_strcasecmp(k, mg_str("Content-Length")) == 0) && (++cl_count > 1)) ||
      ((mg_strcasecmp(k, mg_str("Transfer-Encoding")) == 0) && (++te_count > 1)) ||
      ((mg_strcasecmp(k, mg_str("Authorization")) == 0) && (++auth_count > 1)) ||
      ((mg_strcasecmp(k, mg_str("Cookie")) == 0) && (++cookie_count > 1)) ||
      ((mg_strcasecmp(k, mg_str("Connection")) == 0) && (++conn_count > 1)))
      return false;
    // MG_INFO(("--HH [%.*s] [%.*s]", (int) k.len, k.buf, (int) v.len, v.buf));
    h[i].name = k, h[i].value = v;  // Success. Assign values
  }
  return true;
}

int mg_http_parse(const char *s, size_t len, struct mg_http_message *hm) {
  int is_response, req_len = mg_http_get_request_len((unsigned char *) s, len);
  const char *end = s == NULL ? NULL : s + req_len, *qs;  // Cannot add to NULL
  const struct mg_str *cl;
  size_t n;
  bool version_prefix_valid;

  memset(hm, 0, sizeof(*hm));
  if (req_len <= 0) return req_len;

  hm->message.buf = hm->head.buf = (char *) s;
  hm->body.buf = (char *) end;
  hm->head.len = (size_t) req_len;
  hm->message.len = hm->body.len = (size_t) -1;  // Set body length to infinite

  // Parse request line
  hm->method.buf = (char *) s;
  while (s < end && (n = clen(s, end)) > 0) s += n, hm->method.len += n;
  while (s < end && s[0] == ' ') s++;  // Skip spaces
  hm->uri.buf = (char *) s;
  while (s < end && (n = clen(s, end)) > 0) s += n, hm->uri.len += n;
  while (s < end && s[0] == ' ') s++;  // Skip spaces
  is_response =
      hm->method.len > 5 && (mg_ncasecmp(hm->method.buf, "HTTP/", 5) == 0);
  if ((s = skiptorn(s, end, &hm->proto)) == NULL) return false;
  // If we're given a version, check that it is HTTP/x.x
  version_prefix_valid =
      hm->proto.len > 5 && (mg_ncasecmp(hm->proto.buf, "HTTP/", 5) == 0);
  if (!is_response && !version_prefix_valid)
    return -1; // no version detected in request
  if (!is_response && hm->proto.len > 0 &&
      (!version_prefix_valid || hm->proto.len != 8 ||
       (hm->proto.buf[5] < '0' || hm->proto.buf[5] > '9') ||
       (hm->proto.buf[6] != '.') ||
       (hm->proto.buf[7] < '0' || hm->proto.buf[7] > '9'))) {
    return -1;
  }

  // If URI contains '?' character, setup query string
  if ((qs = (const char *) memchr(hm->uri.buf, '?', hm->uri.len)) != NULL) {
    hm->query.buf = (char *) qs + 1;
    hm->query.len = (size_t) (&hm->uri.buf[hm->uri.len] - (qs + 1));
    hm->uri.len = (size_t) (qs - hm->uri.buf);
  }

  // Sanity check. Allow protocol/reason to be empty
  // Do this check after hm->method.len and hm->uri.len are finalised
  if (hm->method.len == 0 || hm->uri.len == 0) return -1;

  if (!mg_http_parse_headers(s, end, hm->headers,
                             sizeof(hm->headers) / sizeof(hm->headers[0])))
    return -1;  // error when parsing
  if ((cl = mg_http_get_header(hm, "Content-Length")) != NULL) {
    if (mg_to_size_t(*cl, &hm->body.len) == false) return -1;
    hm->message.len = (size_t) req_len + hm->body.len;
  }

  // mg_http_parse() is used to parse both HTTP requests and HTTP
  // responses. If HTTP response does not have Content-Length set, then
  // body is read until socket is closed, i.e. body.len is infinite (~0).
  //
  // For HTTP requests though, if Content-Length is not specified
  // set body length to 0.
  if (hm->body.len == (size_t) ~0 && !is_response) {
    hm->body.len = 0;
    hm->message.len = (size_t) req_len;
  }

  // The 204 (No content) responses also have 0 body length
  if (hm->body.len == (size_t) ~0 && is_response &&
      mg_strcasecmp(hm->uri, mg_str("204")) == 0) {
    hm->body.len = 0;
    hm->message.len = (size_t) req_len;
  }
  if (hm->message.len < (size_t) req_len) return -1;  // Overflow protection

  return req_len;
}

static void mg_http_vprintf_chunk(struct mg_connection *c, const char *fmt,
                                  va_list *ap) {
  size_t len = c->send.len;
  if (!mg_send(c, "        \r\n", 10)) mg_error(c, "OOM");
  mg_vxprintf(mg_pfn_iobuf, &c->send, fmt, ap);
  if (c->send.len >= len + 10) {
    mg_snprintf((char *) c->send.buf + len, 9, "%08lx", c->send.len - len - 10);
    c->send.buf[len + 8] = '\r';
    if (c->send.len == len + 10) c->is_resp = 0;  // Last chunk, reset marker
  }
  if (!mg_send(c, "\r\n", 2)) mg_error(c, "OOM");
}

void mg_http_printf_chunk(struct mg_connection *c, const char *fmt, ...) {
  va_list ap;
  va_start(ap, fmt);
  mg_http_vprintf_chunk(c, fmt, &ap);
  va_end(ap);
}

void mg_http_write_chunk(struct mg_connection *c, const char *buf, size_t len) {
  mg_printf(c, "%lx\r\n", (unsigned long) len);
  if (!mg_send(c, buf, len) || !mg_send(c, "\r\n", 2)) mg_error(c, "OOM");
  if (len == 0) c->is_resp = 0;
}

// clang-format off
static const char *mg_http_status_code_str(int status_code) {
  switch (status_code) {
    case 100: return "Continue";
    case 101: return "Switching Protocols";
    case 102: return "Processing";
    case 200: return "OK";
    case 201: return "Created";
    case 202: return "Accepted";
    case 203: return "Non-authoritative Information";
    case 204: return "No Content";
    case 205: return "Reset Content";
    case 206: return "Partial Content";
    case 207: return "Multi-Status";
    case 208: return "Already Reported";
    case 226: return "IM Used";
    case 300: return "Multiple Choices";
    case 301: return "Moved Permanently";
    case 302: return "Found";
    case 303: return "See Other";
    case 304: return "Not Modified";
    case 305: return "Use Proxy";
    case 307: return "Temporary Redirect";
    case 308: return "Permanent Redirect";
    case 400: return "Bad Request";
    case 401: return "Unauthorized";
    case 402: return "Payment Required";
    case 403: return "Forbidden";
    case 404: return "Not Found";
    case 405: return "Method Not Allowed";
    case 406: return "Not Acceptable";
    case 407: return "Proxy Authentication Required";
    case 408: return "Request Timeout";
    case 409: return "Conflict";
    case 410: return "Gone";
    case 411: return "Length Required";
    case 412: return "Precondition Failed";
    case 413: return "Payload Too Large";
    case 414: return "Request-URI Too Long";
    case 415: return "Unsupported Media Type";
    case 416: return "Requested Range Not Satisfiable";
    case 417: return "Expectation Failed";
    case 418: return "I'm a teapot";
    case 421: return "Misdirected Request";
    case 422: return "Unprocessable Entity";
    case 423: return "Locked";
    case 424: return "Failed Dependency";
    case 426: return "Upgrade Required";
    case 428: return "Precondition Required";
    case 429: return "Too Many Requests";
    case 431: return "Request Header Fields Too Large";
    case 444: return "Connection Closed Without Response";
    case 451: return "Unavailable For Legal Reasons";
    case 499: return "Client Closed Request";
    case 500: return "Internal Server Error";
    case 501: return "Not Implemented";
    case 502: return "Bad Gateway";
    case 503: return "Service Unavailable";
    case 504: return "Gateway Timeout";
    case 505: return "HTTP Version Not Supported";
    case 506: return "Variant Also Negotiates";
    case 507: return "Insufficient Storage";
    case 508: return "Loop Detected";
    case 510: return "Not Extended";
    case 511: return "Network Authentication Required";
    case 599: return "Network Connect Timeout Error";
    default: return "";
  }
}
// clang-format on

void mg_http_reply(struct mg_connection *c, int code, const char *headers,
                   const char *fmt, ...) {
  va_list ap;
  size_t len;
  mg_printf(c, "HTTP/1.1 %d %s\r\n%sContent-Length:            \r\n\r\n", code,
            mg_http_status_code_str(code), headers == NULL ? "" : headers);
  len = c->send.len;
  va_start(ap, fmt);
  mg_vxprintf(mg_pfn_iobuf, &c->send, fmt, &ap);
  va_end(ap);
  if (c->send.len > 16) {
    size_t n = mg_snprintf((char *) &c->send.buf[len - 15], 11, "%-10lu",
                           (unsigned long) (c->send.len - len));
    c->send.buf[len - 15 + n] = ' ';  // Change ending 0 to space
  }
  c->is_resp = 0;
}

static void http_cb(struct mg_connection *, int, void *);
static void restore_http_cb(struct mg_connection *c) {
  mg_fs_close((struct mg_fd *) c->pfn_data);
  c->pfn_data = NULL;
  c->pfn = http_cb;
  c->is_resp = 0;
}

char *mg_http_etag(char *buf, size_t len, size_t size, time_t mtime);
char *mg_http_etag(char *buf, size_t len, size_t size, time_t mtime) {
  mg_snprintf(buf, len, "\"%lld.%lld\"", (int64_t) mtime, (int64_t) size);
  return buf;
}

static void static_cb(struct mg_connection *c, int ev, void *ev_data) {
  if (ev == MG_EV_WRITE || ev == MG_EV_POLL) {
    struct mg_fd *fd = (struct mg_fd *) c->pfn_data;
    // Read to send IO buffer directly, avoid extra on-stack buffer
    size_t n, max = MG_IO_SIZE, space;
    size_t *cl = (size_t *) &c->data[(sizeof(c->data) - sizeof(size_t)) /
                                     sizeof(size_t) * sizeof(size_t)];
    if (c->send.size < max) mg_iobuf_resize(&c->send, max);
    if (c->send.len >= c->send.size) return;  // Rate limit
    if ((space = c->send.size - c->send.len) > *cl) space = *cl;
    n = fd->fs->rd(fd->fd, c->send.buf + c->send.len, space);
    c->send.len += n;
    *cl -= n;
    if (n == 0) restore_http_cb(c);
  } else if (ev == MG_EV_CLOSE) {
    restore_http_cb(c);
  }
  (void) ev_data;
}

// Known mime types. Keep it outside guess_content_type() function, since
// some environments don't like it defined there.
// clang-format off
#define MG_C_STR(a) { (char *) (a), sizeof(a) - 1 }
static struct mg_str s_known_types[] = {
    MG_C_STR("html"), MG_C_STR("text/html; charset=utf-8"),
    MG_C_STR("htm"), MG_C_STR("text/html; charset=utf-8"),
    MG_C_STR("css"), MG_C_STR("text/css; charset=utf-8"),
    MG_C_STR("js"), MG_C_STR("text/javascript; charset=utf-8"),
    MG_C_STR("mjs"), MG_C_STR("text/javascript; charset=utf-8"),
    MG_C_STR("gif"), MG_C_STR("image/gif"),
    MG_C_STR("png"), MG_C_STR("image/png"),
    MG_C_STR("jpg"), MG_C_STR("image/jpeg"),
    MG_C_STR("jpeg"), MG_C_STR("image/jpeg"),
    MG_C_STR("woff"), MG_C_STR("font/woff"),
    MG_C_STR("ttf"), MG_C_STR("font/ttf"),
    MG_C_STR("svg"), MG_C_STR("image/svg+xml"),
    MG_C_STR("txt"), MG_C_STR("text/plain; charset=utf-8"),
    MG_C_STR("avi"), MG_C_STR("video/x-msvideo"),
    MG_C_STR("csv"), MG_C_STR("text/csv"),
    MG_C_STR("doc"), MG_C_STR("application/msword"),
    MG_C_STR("exe"), MG_C_STR("application/octet-stream"),
    MG_C_STR("gz"), MG_C_STR("application/gzip"),
    MG_C_STR("ico"), MG_C_STR("image/x-icon"),
    MG_C_STR("json"), MG_C_STR("application/json"),
    MG_C_STR("mov"), MG_C_STR("video/quicktime"),
    MG_C_STR("mp3"), MG_C_STR("audio/mpeg"),
    MG_C_STR("mp4"), MG_C_STR("video/mp4"),
    MG_C_STR("mpeg"), MG_C_STR("video/mpeg"),
    MG_C_STR("pdf"), MG_C_STR("application/pdf"),
    MG_C_STR("shtml"), MG_C_STR("text/html; charset=utf-8"),
    MG_C_STR("tgz"), MG_C_STR("application/tar-gz"),
    MG_C_STR("wav"), MG_C_STR("audio/wav"),
    MG_C_STR("webp"), MG_C_STR("image/webp"),
    MG_C_STR("zip"), MG_C_STR("application/zip"),
    MG_C_STR("3gp"), MG_C_STR("video/3gpp"),
    {0, 0},
};
// clang-format on

static struct mg_str guess_content_type(struct mg_str path, const char *extra) {
  struct mg_str entry, k, v, s = mg_str(extra), asterisk = mg_str_n("*", 1);
  size_t i = 0;

  // Shrink path to its extension only
  while (i < path.len && path.buf[path.len - i - 1] != '.') i++;
  path.buf += path.len - i;
  path.len = i;

  // Process user-provided mime type overrides, if any
  while (mg_span(s, &entry, &s, ',')) {
    if (mg_span(entry, &k, &v, '=') &&
        (mg_strcmp(asterisk, k) == 0 || mg_strcmp(path, k) == 0))
      return v;
  }

  // Process built-in mime types
  for (i = 0; s_known_types[i].buf != NULL; i += 2) {
    if (mg_strcmp(path, s_known_types[i]) == 0) return s_known_types[i + 1];
  }

  return mg_str("text/plain; charset=utf-8");
}

static int getrange(struct mg_str *s, size_t *a, size_t *b) {
  size_t i, numparsed = 0;
  for (i = 0; i + 6 < s->len; i++) {
    struct mg_str k, v = mg_str_n(s->buf + i + 6, s->len - i - 6);
    if (memcmp(&s->buf[i], "bytes=", 6) != 0) continue;
    if (mg_span(v, &k, &v, '-')) {
      if (mg_to_size_t(k, a)) numparsed++;
      if (v.len > 0 && mg_to_size_t(v, b)) numparsed++;
    } else {
      if (mg_to_size_t(v, a)) numparsed++;
    }
    break;
  }
  return (int) numparsed;
}

void mg_http_serve_file(struct mg_connection *c, struct mg_http_message *hm,
                        const char *path,
                        const struct mg_http_serve_opts *opts) {
  char etag[64], tmp[MG_PATH_MAX];
  struct mg_fs *fs = opts->fs == NULL ? &mg_fs_posix : opts->fs;
  struct mg_fd *fd = NULL;
  size_t size = 0;
  time_t mtime = 0;
  struct mg_str *inm = NULL;
  struct mg_str mime = guess_content_type(mg_str(path), opts->mime_types);
  bool gzip = false;

  if (path != NULL) {
    // If a browser sends us "Accept-Encoding: gzip", try to open .gz first
    struct mg_str *ae = mg_http_get_header(hm, "Accept-Encoding");
    if (ae != NULL) {
      if (mg_match(*ae, mg_str("*gzip*"), NULL)) {
        mg_snprintf(tmp, sizeof(tmp), "%s.gz", path);
        fd = mg_fs_open(fs, tmp, MG_FS_READ);
        if (fd != NULL) gzip = true, path = tmp;
      }
    }
    // No luck opening .gz? Open what we've told to open
    if (fd == NULL) fd = mg_fs_open(fs, path, MG_FS_READ);
  }

  // Failed to open, and page404 is configured? Open it, then
  if (fd == NULL && opts->page404 != NULL) {
    fd = mg_fs_open(fs, opts->page404, MG_FS_READ);
    path = opts->page404;
    mime = guess_content_type(mg_str(path), opts->mime_types);
  }

  if (fd == NULL || fs->st(path, &size, &mtime) == 0) {
    mg_http_reply(c, 404, opts->extra_headers, "Not found\n");
    mg_fs_close(fd);
    // NOTE: mg_http_etag() call should go first!
  } else if (mg_http_etag(etag, sizeof(etag), size, mtime) != NULL &&
             (inm = mg_http_get_header(hm, "If-None-Match")) != NULL &&
             mg_strcasecmp(*inm, mg_str(etag)) == 0) {
    mg_fs_close(fd);
    mg_http_reply(c, 304, opts->extra_headers, "");
  } else {
    int n, status = 200;
    char range[100];
    size_t r1 = 0, r2 = 0, cl = size;

    // Handle Range header
    struct mg_str *rh = mg_http_get_header(hm, "Range");
    range[0] = '\0';
    if (rh != NULL && (n = getrange(rh, &r1, &r2)) > 0) {
      // If range is specified like "400-", set second limit to content len
      if (n == 1) r2 = cl - 1;
      if (r1 > r2 || r2 >= cl) {
        status = 416;
        cl = 0;
        mg_snprintf(range, sizeof(range), "Content-Range: bytes */%lld\r\n",
                    (int64_t) size);
      } else {
        status = 206;
        cl = r2 - r1 + 1;
        mg_snprintf(range, sizeof(range),
                    "Content-Range: bytes %llu-%llu/%llu\r\n", (uint64_t) r1,
                    (uint64_t) (r1 + cl - 1), (uint64_t) size);
        fs->sk(fd->fd, r1);
      }
    }
    mg_printf(c,
              "HTTP/1.1 %d %s\r\n"
              "Content-Type: %.*s\r\n"
              "Etag: %s\r\n"
              "Content-Length: %llu\r\n"
              "%s%s%s\r\n",
              status, mg_http_status_code_str(status), (int) mime.len, mime.buf,
              etag, (uint64_t) cl, gzip ? "Content-Encoding: gzip\r\n" : "",
              range, opts->extra_headers ? opts->extra_headers : "");
    if (mg_strcasecmp(hm->method, mg_str("HEAD")) == 0 || c->is_closing) {
      c->is_resp = 0;
      mg_fs_close(fd);
    } else { // start serving static content only if not closing, see #3354
      // Track to-be-sent content length at the end of c->data, aligned
      size_t *clp = (size_t *) &c->data[(sizeof(c->data) - sizeof(size_t)) /
                                        sizeof(size_t) * sizeof(size_t)];
      c->pfn = static_cb;
      c->pfn_data = fd;
      *clp = cl;
    }
  }
}

struct printdirentrydata {
  struct mg_connection *c;
  struct mg_http_message *hm;
  const struct mg_http_serve_opts *opts;
  const char *dir;
};

#if MG_ENABLE_DIRLIST
static void printdirentry(const char *name, void *userdata) {
  struct printdirentrydata *d = (struct printdirentrydata *) userdata;
  struct mg_fs *fs = d->opts->fs == NULL ? &mg_fs_posix : d->opts->fs;
  size_t size = 0;
  time_t t = 0;
  char path[MG_PATH_MAX], sz[40], mod[40];
  int flags, n = 0;

  // MG_DEBUG(("[%s] [%s]", d->dir, name));
  if (mg_snprintf(path, sizeof(path), "%s%c%s", d->dir, '/', name) >
      sizeof(path)) {
    MG_ERROR(("%s truncated", name));
  } else if ((flags = fs->st(path, &size, &t)) == 0) {
    MG_ERROR(("%lu stat(%s)", d->c->id, path));
  } else {
    const char *slash = flags & MG_FS_DIR ? "/" : "";
    if (flags & MG_FS_DIR) {
      mg_snprintf(sz, sizeof(sz), "%s", "[DIR]");
    } else {
      mg_snprintf(sz, sizeof(sz), "%lld", (uint64_t) size);
    }
#if defined(MG_HTTP_DIRLIST_TIME_FMT)
    {
      char time_str[40];
      struct tm *time_info = localtime(&t);
      strftime(time_str, sizeof time_str, "%Y/%m/%d %H:%M:%S", time_info);
      mg_snprintf(mod, sizeof(mod), "%s", time_str);
    }
#else
    mg_snprintf(mod, sizeof(mod), "%lu", (unsigned long) t);
#endif
    n = (int) mg_url_encode(name, strlen(name), path, sizeof(path));
    mg_printf(d->c,
              "  <tr><td><a href=\"%.*s%s\">%s%s</a></td>"
              "<td name=%lu>%s</td><td name=%lld>%s</td></tr>\n",
              n, path, slash, name, slash, (unsigned long) t, mod,
              flags & MG_FS_DIR ? (int64_t) -1 : (int64_t) size, sz);
  }
}

static void listdir(struct mg_connection *c, struct mg_http_message *hm,
                    const struct mg_http_serve_opts *opts, char *dir) {
  const char *sort_js_code =
      "<script>function srt(tb, sc, so, d) {"
      "var tr = Array.prototype.slice.call(tb.rows, 0),"
      "tr = tr.sort(function (a, b) { var c1 = a.cells[sc], c2 = b.cells[sc],"
      "n1 = c1.getAttribute('name'), n2 = c2.getAttribute('name'), "
      "t1 = a.cells[2].getAttribute('name'), "
      "t2 = b.cells[2].getAttribute('name'); "
      "return so * (t1 < 0 && t2 >= 0 ? -1 : t2 < 0 && t1 >= 0 ? 1 : "
      "n1 ? parseInt(n2) - parseInt(n1) : "
      "c1.textContent.trim().localeCompare(c2.textContent.trim())); });";
  const char *sort_js_code2 =
      "for (var i = 0; i < tr.length; i++) tb.appendChild(tr[i]); "
      "if (!d) window.location.hash = ('sc=' + sc + '&so=' + so); "
      "};"
      "window.onload = function() {"
      "var tb = document.getElementById('tb');"
      "var m = /sc=([012]).so=(1|-1)/.exec(window.location.hash) || [0, 2, 1];"
      "var sc = m[1], so = m[2]; document.onclick = function(ev) { "
      "var c = ev.target.rel; if (c) {if (c == sc) so *= -1; srt(tb, c, so); "
      "sc = c; ev.preventDefault();}};"
      "srt(tb, sc, so, true);"
      "}"
      "</script>";
  struct mg_fs *fs = opts->fs == NULL ? &mg_fs_posix : opts->fs;
  struct printdirentrydata d = {c, hm, opts, dir};
  char tmp[10], buf[MG_PATH_MAX];
  size_t off, n;
  int len = mg_url_decode(hm->uri.buf, hm->uri.len, buf, sizeof(buf), 0);
  struct mg_str uri = len > 0 ? mg_str_n(buf, (size_t) len) : hm->uri;

  mg_printf(c,
            "HTTP/1.1 200 OK\r\n"
            "Content-Type: text/html; charset=utf-8\r\n"
            "%s"
            "Content-Length:         \r\n\r\n",
            opts->extra_headers == NULL ? "" : opts->extra_headers);
  off = c->send.len;  // Start of body
  mg_printf(c,
            "<!DOCTYPE html><html><head><title>Index of %.*s</title>%s%s"
            "<style>th,td {text-align: left; padding-right: 1em; "
            "font-family: monospace; }</style></head>"
            "<body><h1>Index of %.*s</h1><table cellpadding=\"0\"><thead>"
            "<tr><th><a href=\"#\" rel=\"0\">Name</a></th><th>"
            "<a href=\"#\" rel=\"1\">Modified</a></th>"
            "<th><a href=\"#\" rel=\"2\">Size</a></th></tr>"
            "<tr><td colspan=\"3\"><hr></td></tr>"
            "</thead>"
            "<tbody id=\"tb\">\n",
            (int) uri.len, uri.buf, sort_js_code, sort_js_code2, (int) uri.len,
            uri.buf);
  mg_printf(c, "%s",
            "  <tr><td><a href=\"..\">..</a></td>"
            "<td name=-1></td><td name=-1>[DIR]</td></tr>\n");

  fs->ls(dir, printdirentry, &d);
  mg_printf(c,
            "</tbody><tfoot><tr><td colspan=\"3\"><hr></td></tr></tfoot>"
            "</table><address>Mongoose v.%s</address></body></html>\n",
            MG_VERSION);
  n = mg_snprintf(tmp, sizeof(tmp), "%lu", (unsigned long) (c->send.len - off));
  if (n > sizeof(tmp)) n = 0;
  memcpy(c->send.buf + off - 12, tmp, n);  // Set content length
  c->is_resp = 0;                          // Mark response end
}
#endif

// Resolve requested file into `path` and return its fs->st() result
static int uri_to_path2(struct mg_connection *c, struct mg_http_message *hm,
                        struct mg_fs *fs, struct mg_str url, struct mg_str dir,
                        char *path, size_t path_size) {
  int flags, tmp;
  // Append URI to the root_dir, and sanitize it
  size_t n = mg_snprintf(path, path_size, "%.*s", (int) dir.len, dir.buf);
  if (n + 2 >= path_size) {
    mg_http_reply(c, 400, "", "Exceeded path size");
    return -1;
  }
  path[path_size - 1] = '\0';
  // Terminate root dir with slash
  if (n > 0 && path[n - 1] != '/') path[n++] = '/', path[n] = '\0';
  if (url.len < hm->uri.len) {
    mg_url_decode(hm->uri.buf + url.len, hm->uri.len - url.len, path + n,
                  path_size - n, 0);
  }
  path[path_size - 1] = '\0';  // Double-check
  if (!mg_path_is_sane(mg_str_n(path, path_size))) {
    mg_http_reply(c, 400, "", "Invalid path");
    return -1;
  }
  n = strlen(path);
  while (n > 1 && path[n - 1] == '/') path[--n] = 0;  // Trim trailing slashes
  flags = mg_strcmp(hm->uri, mg_str("/")) == 0 ? MG_FS_DIR
                                               : fs->st(path, NULL, NULL);
  MG_VERBOSE(("%lu %.*s -> %s %d", c->id, (int) hm->uri.len, hm->uri.buf, path,
              flags));
  if (flags == 0) {
    // Do nothing - let's caller decide
  } else if ((flags & MG_FS_DIR) && hm->uri.len > 0 &&
             hm->uri.buf[hm->uri.len - 1] != '/') {
    mg_printf(c,
              "HTTP/1.1 301 Moved\r\n"
              "Location: %.*s/\r\n"
              "Content-Length: 0\r\n"
              "\r\n",
              (int) hm->uri.len, hm->uri.buf);
    c->is_resp = 0;
    flags = -1;
  } else if (flags & MG_FS_DIR) {
    if (((mg_snprintf(path + n, path_size - n, "/" MG_HTTP_INDEX) > 0 &&
          (tmp = fs->st(path, NULL, NULL)) != 0) ||
         (mg_snprintf(path + n, path_size - n, "/index.shtml") > 0 &&
          (tmp = fs->st(path, NULL, NULL)) != 0))) {
      flags = tmp;
    } else if ((mg_snprintf(path + n, path_size - n, "/" MG_HTTP_INDEX ".gz") >
                    0 &&
                (tmp = fs->st(path, NULL, NULL)) !=
                    0)) {  // check for gzipped index
      flags = tmp;
      path[n + 1 + strlen(MG_HTTP_INDEX)] =
          '\0';  // Remove appended .gz in index file name
    } else {
      path[n] = '\0';  // Remove appended index file name
    }
  }
  return flags;
}

static int uri_to_path(struct mg_connection *c, struct mg_http_message *hm,
                       const struct mg_http_serve_opts *opts, char *path,
                       size_t path_size) {
  struct mg_fs *fs = opts->fs == NULL ? &mg_fs_posix : opts->fs;
  struct mg_str k, v, part, s = mg_str(opts->root_dir), u = {NULL, 0}, p = u;
  while (mg_span(s, &part, &s, ',')) {
    if (!mg_span(part, &k, &v, '=')) k = part, v = mg_str_n(NULL, 0);
    if (v.len == 0) v = k, k = mg_str("/"), u = k, p = v;
    if (hm->uri.len < k.len) continue;
    if (mg_strcmp(k, mg_str_n(hm->uri.buf, k.len)) != 0) continue;
    u = k, p = v;
  }
  return uri_to_path2(c, hm, fs, u, p, path, path_size);
}

void mg_http_serve_dir(struct mg_connection *c, struct mg_http_message *hm,
                       const struct mg_http_serve_opts *opts) {
  char path[MG_PATH_MAX];
  const char *sp = opts->ssi_pattern;
  int flags = uri_to_path(c, hm, opts, path, sizeof(path));
  if (flags < 0) {
    // Do nothing: the response has already been sent by uri_to_path()
  } else if (flags & MG_FS_DIR) {
#if MG_ENABLE_DIRLIST
    listdir(c, hm, opts, path);
#else
    mg_http_reply(c, 403, "", "Forbidden\n");
#endif
  } else if (flags && sp != NULL && mg_match(mg_str(path), mg_str(sp), NULL)) {
    mg_http_serve_ssi(c, opts->root_dir, path);
  } else {
    mg_http_serve_file(c, hm, path, opts);
  }
}

static bool mg_is_url_safe(int c) {
  return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'z') ||
         (c >= 'A' && c <= 'Z') || c == '.' || c == '_' || c == '-' || c == '~';
}

size_t mg_url_encode(const char *s, size_t sl, char *buf, size_t len) {
  size_t i, n = 0;
  for (i = 0; i < sl; i++) {
    int c = *(unsigned char *) &s[i];
    if (n + 4 >= len) return 0;
    if (mg_is_url_safe(c)) {
      buf[n++] = s[i];
    } else {
      mg_snprintf(&buf[n], 4, "%%%M", mg_print_hex, 1, &s[i]);
      n += 3;
    }
  }
  if (len > 0 && n < len - 1) buf[n] = '\0';  // Null-terminate the destination
  if (len > 0) buf[len - 1] = '\0';           // Always.
  return n;
}

void mg_http_creds(struct mg_http_message *hm, char *user, size_t userlen,
                   char *pass, size_t passlen) {
  struct mg_str *v = mg_http_get_header(hm, "Authorization");
  user[0] = pass[0] = '\0';
  if (v != NULL && v->len > 6 && memcmp(v->buf, "Basic ", 6) == 0) {
    char buf[256];
    size_t n = mg_base64_decode(v->buf + 6, v->len - 6, buf, sizeof(buf));
    const char *p = (const char *) memchr(buf, ':', n > 0 ? n : 0);
    if (p != NULL) {
      mg_snprintf(user, userlen, "%.*s", p - buf, buf);
      mg_snprintf(pass, passlen, "%.*s", n - (size_t) (p - buf) - 1, p + 1);
    }
  } else if (v != NULL && v->len > 7 && memcmp(v->buf, "Bearer ", 7) == 0) {
    mg_snprintf(pass, passlen, "%.*s", (int) v->len - 7, v->buf + 7);
  } else if ((v = mg_http_get_header(hm, "Cookie")) != NULL) {
    struct mg_str t = mg_http_get_header_var(*v, mg_str_n("access_token", 12));
    if (t.len > 0) mg_snprintf(pass, passlen, "%.*s", (int) t.len, t.buf);
  } else {
    mg_http_get_var(&hm->query, "access_token", pass, passlen);
  }
}

static struct mg_str stripquotes(struct mg_str s) {
  return s.len > 1 && s.buf[0] == '"' && s.buf[s.len - 1] == '"'
             ? mg_str_n(s.buf + 1, s.len - 2)
             : s;
}

struct mg_str mg_http_get_header_var(struct mg_str s, struct mg_str v) {
  size_t i;
  for (i = 0; v.len > 0 && i + v.len + 2 < s.len; i++) {
    if (s.buf[i + v.len] == '=' && memcmp(&s.buf[i], v.buf, v.len) == 0) {
      const char *p = &s.buf[i + v.len + 1], *b = p, *x = &s.buf[s.len];
      int q = p < x && *p == '"' ? 1 : 0;
      while (p < x &&
             (q ? p == b || *p != '"' : *p != ';' && *p != ' ' && *p != ','))
        p++;
      // MG_INFO(("[%.*s] [%.*s] [%.*s]", (int) s.len, s.buf, (int) v.len,
      // v.buf, (int) (p - b), b));
      return stripquotes(mg_str_n(b, (size_t) (p - b + q)));
    }
  }
  return mg_str_n(NULL, 0);
}

long mg_http_upload(struct mg_connection *c, struct mg_http_message *hm,
                    struct mg_fs *fs, const char *dir, size_t max_size) {
  char buf[20] = "0", file[MG_PATH_MAX], path[MG_PATH_MAX];
  long res = 0, offset;
  mg_http_get_var(&hm->query, "offset", buf, sizeof(buf));
  mg_http_get_var(&hm->query, "file", file, sizeof(file));
  offset = strtol(buf, NULL, 0);
  mg_snprintf(path, sizeof(path), "%s%c%s", dir, MG_DIRSEP, file);
  if (hm->body.len == 0) {
    mg_http_reply(c, 200, "", "%ld", res);  // Nothing to write
  } else if (file[0] == '\0') {
    mg_http_reply(c, 400, "", "file required");
    res = -1;
  } else if (mg_path_is_sane(mg_str(file)) == false) {
    mg_http_reply(c, 400, "", "%s: invalid file", file);
    res = -2;
  } else if (offset < 0) {
    mg_http_reply(c, 400, "", "offset required");
    res = -3;
  } else if ((size_t) offset + hm->body.len > max_size) {
    mg_http_reply(c, 400, "", "%s: over max size of %lu", path,
                  (unsigned long) max_size);
    res = -4;
  } else {
    struct mg_fd *fd;
    size_t current_size = 0;
    MG_DEBUG(("%s -> %lu bytes @ %ld", path, hm->body.len, offset));
    if (offset == 0) fs->rm(path);  // If offset if 0, truncate file
    fs->st(path, &current_size, NULL);
    if (offset > 0 && current_size != (size_t) offset) {
      mg_http_reply(c, 400, "", "%s: offset mismatch", path);
      res = -5;
    } else if ((fd = mg_fs_open(fs, path, MG_FS_WRITE)) == NULL) {
      mg_http_reply(c, 400, "", "open(%s)", path);
      res = -6;
    } else {
      res = offset + (long) fs->wr(fd->fd, hm->body.buf, hm->body.len);
      mg_fs_close(fd);
      mg_http_reply(c, 200, "", "%ld", res);
    }
  }
  return res;
}

int mg_http_status(const struct mg_http_message *hm) {
  return atoi(hm->uri.buf);
}

static bool is_hex_digit(int c) {
  return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') ||
         (c >= 'A' && c <= 'F');
}

static int skip_chunk(const char *buf, int len, int *pl, int *dl) {
  int i = 0, n = 0;
  if (len < 3) return 0;
  while (i < len && is_hex_digit(buf[i])) i++;
  if (i == 0) return -1;                     // Error, no length specified
  if (i > (int) sizeof(int) * 2) return -1;  // Chunk length is too big
  if (len < i + 1 || buf[i] != '\r' || buf[i + 1] != '\n') return -1;  // Error
  if (mg_str_to_num(mg_str_n(buf, (size_t) i), 16, &n, sizeof(int)) == false)
    return -1;                    // Decode chunk length, overflow
  if (n < 0) return -1;           // Error. TODO(): some checks now redundant
  if (n > len - i - 4) return 0;  // Chunk not yet fully buffered
  if (buf[i + n + 2] != '\r' || buf[i + n + 3] != '\n') return -1;  // Error
  *pl = i + 2, *dl = n;
  return i + 2 + n + 2;
}

static void http_cb(struct mg_connection *c, int ev, void *ev_data) {
  if (ev == MG_EV_READ || ev == MG_EV_CLOSE ||
      (ev == MG_EV_POLL && c->is_accepted && !c->is_draining &&
       c->recv.len > 0)) {  // see #2796
    struct mg_http_message hm;
    size_t ofs = 0;  // Parsing offset
    while (c->is_resp == 0 && ofs < c->recv.len) {
      const char *buf = (char *) c->recv.buf + ofs;
      int n = mg_http_parse(buf, c->recv.len - ofs, &hm);
      struct mg_str *te;  // Transfer - encoding header
      bool is_chunked = false, is_http_1_0 = false;
      size_t old_len = c->recv.len;
      if (n < 0) {
        // We don't use mg_error() here, to avoid closing pipelined requests
        // prematurely, see #2592
        MG_ERROR(("HTTP parse, %lu bytes", c->recv.len));
        c->is_draining = 1;
        mg_hexdump(buf, c->recv.len - ofs > 16 ? 16 : c->recv.len - ofs);
        c->recv.len = 0;
        return;
      }
      if (n == 0) break;                 // Request is not buffered yet
      mg_call(c, MG_EV_HTTP_HDRS, &hm);  // Got all HTTP headers
      if (c->recv.len != old_len) {
        // User manipulated received data. Wash our hands
        MG_DEBUG(("%lu detaching HTTP handler", c->id));
        c->pfn = NULL;
        return;
      }
      if (ev == MG_EV_CLOSE) {  // If client did not set Content-Length
        hm.message.len = c->recv.len - ofs;  // and closes now, deliver MSG
        hm.body.len = hm.message.len - (size_t) (hm.body.buf - hm.message.buf);
      }
      is_http_1_0 =
          hm.proto.len > 8 && mg_ncasecmp(hm.proto.buf, "HTTP/1.0", 8) == 0;
      // HTTP/1.0 does not use "Transfer-Encoding: chunked"
      if (!is_http_1_0 &&
          (te = mg_http_get_header(&hm, "Transfer-Encoding")) != NULL) {
        if (mg_strcasecmp(*te, mg_str("chunked")) == 0) {
          is_chunked = true;
        } else {
          mg_error(c, "Invalid Transfer-Encoding");  // See #2460
          return;
        }
      } else if (mg_http_get_header(&hm, "Content-length") == NULL) {
        // #2593: HTTP packets must contain either Transfer-Encoding or
        // Content-length
        bool is_response = mg_ncasecmp(hm.method.buf, "HTTP/", 5) == 0;
        bool require_content_len = false;
        if (!is_response && (mg_strcasecmp(hm.method, mg_str("POST")) == 0 ||
                             mg_strcasecmp(hm.method, mg_str("PUT")) == 0)) {
          // POST and PUT should include an entity body. Therefore, they should
          // contain a Content-length header (unless the body length is 0, in
          // which case it can be omitted). Other requests can also contain a
          // body, but their content has no defined semantics (RFC 7231)
          if (hm.body.len != 0) require_content_len = true;
          ofs += (size_t) n;  // this request has been processed
        } else if (is_response) {
          // HTTP spec 7.2 Entity body: All other responses must include a body
          // or Content-Length header field defined with a value of 0.
          int status = mg_http_status(&hm);
          require_content_len = status >= 200 && status != 204 && status != 304;
        }
        if (require_content_len) {
          if (!c->is_client) mg_http_reply(c, 411, "", "");
          MG_ERROR(("Content length missing from %s",
                    is_response ? "response" : "request"));
        }
      }

      if (is_chunked) {
        // For chunked data, strip off prefixes and suffixes from chunks
        // and relocate them right after the headers, then report a message
        char *s = (char *) c->recv.buf + ofs + n;
        int o = 0, pl, dl, cl, len = (int) (c->recv.len - ofs - (size_t) n);

        // Find zero-length chunk (the end of the body)
        while ((cl = skip_chunk(s + o, len - o, &pl, &dl)) > 0 && dl) o += cl;
        if (cl == 0) break;  // No zero-len chunk, buffer more data
        if (cl < 0) {
          mg_error(c, "Invalid chunk");
          break;
        }

        // Zero chunk found. Second pass: strip + relocate
        o = 0, hm.body.len = 0, hm.message.len = (size_t) n;
        while ((cl = skip_chunk(s + o, len - o, &pl, &dl)) > 0) {
          memmove(s + hm.body.len, s + o + pl, (size_t) dl);
          o += cl, hm.body.len += (size_t) dl, hm.message.len += (size_t) dl;
          if (dl == 0) break;
        }
        ofs += (size_t) (n + o);
      } else {  // Normal, non-chunked data
        size_t len = c->recv.len - ofs - (size_t) n;
        if (hm.body.len > len) break;  // Buffer more data
        ofs += (size_t) n + hm.body.len;
      }

      if (c->is_accepted) c->is_resp = 1;  // Start generating response
      mg_call(c, MG_EV_HTTP_MSG, &hm);     // User handler can clear is_resp
      if (c->is_accepted && !c->is_resp) {
        struct mg_str *cc = mg_http_get_header(&hm, "Connection");
        if (cc != NULL && mg_strcasecmp(*cc, mg_str("close")) == 0) {
          c->is_draining = 1;  // honor "Connection: close"
          break;
        }
      }
    }
    if (ofs > 0) mg_iobuf_del(&c->recv, 0, ofs);  // Delete processed data
  }
  (void) ev_data;
}

struct mg_connection *mg_http_connect(struct mg_mgr *mgr, const char *url,
                                      mg_event_handler_t fn, void *fn_data) {
  return mg_connect_svc(mgr, url, fn, fn_data, http_cb, NULL);
}

struct mg_connection *mg_http_listen(struct mg_mgr *mgr, const char *url,
                                     mg_event_handler_t fn, void *fn_data) {
  struct mg_connection *c = mg_listen(mgr, url, fn, fn_data);
  if (c != NULL) c->pfn = http_cb;
  return c;
}

#ifdef MG_ENABLE_LINES
#line 1 "src/iobuf.c"
#endif





static size_t roundup(size_t size, size_t align) {
  return align == 0 ? size : (size + align - 1) / align * align;
}

bool mg_iobuf_resize(struct mg_iobuf *io, size_t new_size) {
  bool ok = true;
  new_size = roundup(new_size, io->align);
  if (new_size == 0) {
    mg_bzero(io->buf, io->size);
    mg_free(io->buf);
    io->buf = NULL;
    io->len = io->size = 0;
  } else if (new_size != io->size) {
    // NOTE(lsm): do not use realloc here. Use mg_calloc/mg_free only
    void *p = mg_calloc(1, new_size);
    if (p != NULL) {
      size_t len = new_size < io->len ? new_size : io->len;
      if (len > 0 && io->buf != NULL) memmove(p, io->buf, len);
      mg_bzero(io->buf, io->size);
      mg_free(io->buf);
      io->buf = (unsigned char *) p;
      io->size = new_size;
      io->len = len;
    } else {
      ok = false;
      MG_ERROR(("%lld->%lld", (uint64_t) io->size, (uint64_t) new_size));
    }
  }
  return ok;
}

bool mg_iobuf_init(struct mg_iobuf *io, size_t size, size_t align) {
  io->buf = NULL;
  io->align = align;
  io->size = io->len = 0;
  return mg_iobuf_resize(io, size);
}

size_t mg_iobuf_add(struct mg_iobuf *io, size_t ofs, const void *buf,
                    size_t len) {
  size_t new_size = roundup(io->len + len, io->align);
  mg_iobuf_resize(io, new_size);      // Attempt to resize
  if (new_size != io->size) len = 0;  // Resize failure, append nothing
  if (ofs < io->len) memmove(io->buf + ofs + len, io->buf + ofs, io->len - ofs);
  if (buf != NULL) memmove(io->buf + ofs, buf, len);
  if (ofs > io->len) io->len += ofs - io->len;
  io->len += len;
  return len;
}

size_t mg_iobuf_del(struct mg_iobuf *io, size_t ofs, size_t len) {
  if (ofs > io->len) ofs = io->len;
  if (ofs + len > io->len) len = io->len - ofs;
  if (io->buf) memmove(io->buf + ofs, io->buf + ofs + len, io->len - ofs - len);
  if (io->buf) mg_bzero(io->buf + io->len - len, len);
  io->len -= len;
  return len;
}

void mg_iobuf_free(struct mg_iobuf *io) {
  mg_iobuf_resize(io, 0);
}

#ifdef MG_ENABLE_LINES
#line 1 "src/json.c"
#endif





static const char *escapeseq(int esc) {
  return esc ? "\b\f\n\r\t\\\"" : "bfnrt\\\"";
}

static char json_esc(int c, int esc) {
  const char *p, *esc1 = escapeseq(esc), *esc2 = escapeseq(!esc);
  for (p = esc1; *p != '\0'; p++) {
    if (*p == c) return esc2[p - esc1];
  }
  return 0;
}

static int mg_pass_string(const char *s, int len) {
  int i;
  for (i = 0; i < len; i++) {
    if (s[i] == '\\' && i + 1 < len && json_esc(s[i + 1], 1)) {
      i++;
    } else if (s[i] == '\0') {
      return MG_JSON_INVALID;
    } else if (s[i] == '"') {
      return i;
    }
  }
  return MG_JSON_INVALID;
}

static double mg_atod(const char *p, int len, int *numlen) {
  double d = 0.0;
  int i = 0, sign = 1;

  // Sign
  if (i < len && *p == '-') {
    sign = -1, i++;
  } else if (i < len && *p == '+') {
    i++;
  }

  // Decimal
  for (; i < len && p[i] >= '0' && p[i] <= '9'; i++) {
    d *= 10.0;
    d += p[i] - '0';
  }
  d *= sign;

  // Fractional
  if (i < len && p[i] == '.') {
    double frac = 0.0, base = 0.1;
    i++;
    for (; i < len && p[i] >= '0' && p[i] <= '9'; i++) {
      frac += base * (p[i] - '0');
      base /= 10.0;
    }
    d += frac * sign;
  }

  // Exponential
  if (i < len && (p[i] == 'e' || p[i] == 'E')) {
    int exp = 0, minus = 0;
    i++;
    if (i < len && p[i] == '-') minus = 1, i++;
    if (i < len && p[i] == '+') i++;
    while (i < len && p[i] >= '0' && p[i] <= '9' && exp < 308)
      exp = exp * 10 + (p[i++] - '0');
    // use fast exponentiation
    // https://en.wikipedia.org/wiki/Exponentiation_by_squaring
    if (exp != 0) {
      double x = 10, y = 1;
      if (exp > 308) exp = 308;
      if (minus) x = 0.1;
      while (exp > 1) {
        if (exp & 1) {
          y *= x;
          --exp;
        }
        x *= x;
        exp >>= 1;
      }
      d *= x * y;
    }
  }

  if (numlen != NULL) *numlen = i;
  return d;
}

// Iterate over object or array elements
size_t mg_json_next(struct mg_str obj, size_t ofs, struct mg_str *key,
                    struct mg_str *val) {
  if (ofs >= obj.len) {
    ofs = 0;  // Out of boundaries, stop scanning
  } else if (obj.len < 2 || (*obj.buf != '{' && *obj.buf != '[')) {
    ofs = 0;  // Not an array or object, stop
  } else {
    struct mg_str sub = mg_str_n(obj.buf + ofs, obj.len - ofs);
    if (ofs == 0) ofs++, sub.buf++, sub.len--;
    if (*obj.buf == '[') {  // Iterate over an array
      int n = 0, o = mg_json_get(sub, "$", &n);
      if (n < 0 || o < 0 || (size_t) (o + n) > sub.len) {
        ofs = 0;  // Error parsing key, stop scanning
      } else {
        if (key) *key = mg_str_n(NULL, 0);
        if (val) *val = mg_str_n(sub.buf + o, (size_t) n);
        ofs = (size_t) (&sub.buf[o + n] - obj.buf);
      }
    } else {  // Iterate over an object
      int n = 0, o = mg_json_get(sub, "$", &n);
      if (n < 0 || o < 0 || (size_t) (o + n) > sub.len) {
        ofs = 0;  // Error parsing key, stop scanning
      } else {
        if (key) *key = mg_str_n(sub.buf + o, (size_t) n);
        sub.buf += o + n, sub.len -= (size_t) (o + n);
        while (sub.len > 0 && *sub.buf != ':') sub.len--, sub.buf++;
        if (sub.len > 0 && *sub.buf == ':') sub.len--, sub.buf++;
        n = 0, o = mg_json_get(sub, "$", &n);
        if (n < 0 || o < 0 || (size_t) (o + n) > sub.len) {
          ofs = 0;  // Error parsing value, stop scanning
        } else {
          if (val) *val = mg_str_n(sub.buf + o, (size_t) n);
          ofs = (size_t) (&sub.buf[o + n] - obj.buf);
        }
      }
    }
    // MG_INFO(("SUB ofs %u %.*s", ofs, sub.len, sub.buf));
    while (ofs && ofs < obj.len &&
           (obj.buf[ofs] == ' ' || obj.buf[ofs] == '\t' ||
            obj.buf[ofs] == '\n' || obj.buf[ofs] == '\r')) {
      ofs++;
    }
    if (ofs && ofs < obj.len && obj.buf[ofs] == ',') ofs++;
    if (ofs > obj.len) ofs = 0;
  }
  return ofs;
}

int mg_json_get(struct mg_str json, const char *path, int *toklen) {
  const char *s = json.buf;
  int len = (int) json.len;
  enum { S_VALUE, S_KEY, S_COLON, S_COMMA_OR_EOO } expecting = S_VALUE;
  unsigned char nesting[MG_JSON_MAX_DEPTH];
  int i = 0;             // Current offset in `s`
  int j = 0;             // Offset in `s` we're looking for (return value)
  int depth = 0;         // Current depth (nesting level)
  int ed = 0;            // Expected depth
  int pos = 1;           // Current position in `path`
  int ci = -1, ei = -1;  // Current and expected index in array

  if (toklen) *toklen = 0;
  if (path[0] != '$') return MG_JSON_INVALID;

#define MG_CHECKRET(x)                                  \
  do {                                                  \
    if (depth == ed && path[pos] == '\0' && ci == ei) { \
      if (toklen) *toklen = i - j + 1;                  \
      return j;                                         \
    }                                                   \
  } while (0)

// In the ascii table, the distance between `[` and `]` is 2.
// Ditto for `{` and `}`. Hence +2 in the code below.
#define MG_EOO(x)                                            \
  do {                                                       \
    if (depth == ed && ci != ei) return MG_JSON_NOT_FOUND;   \
    if (c != nesting[depth - 1] + 2) return MG_JSON_INVALID; \
    depth--;                                                 \
    MG_CHECKRET(x);                                          \
  } while (0)

  for (i = 0; i < len; i++) {
    unsigned char c = ((unsigned char *) s)[i];
    if (c == ' ' || c == '\t' || c == '\n' || c == '\r') continue;
    switch (expecting) {
      case S_VALUE:
        // p("V %s [%.*s] %d %d %d %d\n", path, pos, path, depth, ed, ci, ei);
        if (depth == ed) j = i;
        if (c == '{') {
          if (depth >= (int) sizeof(nesting)) return MG_JSON_TOO_DEEP;
          if (depth == ed && path[pos] == '.' && ci == ei) {
            // If we start the object, reset array indices
            ed++, pos++, ci = ei = -1;
          }
          nesting[depth++] = c;
          expecting = S_KEY;
          break;
        } else if (c == '[') {
          if (depth >= (int) sizeof(nesting)) return MG_JSON_TOO_DEEP;
          if (depth == ed && path[pos] == '[' && ei == ci) {
            ed++, pos++, ci = 0;
            for (ei = 0; path[pos] != ']' && path[pos] != '\0'; pos++) {
              ei *= 10;
              ei += path[pos] - '0';
            }
            if (path[pos] != 0) pos++;
          }
          nesting[depth++] = c;
          break;
        } else if (c == ']' && depth > 0) {  // Empty array
          MG_EOO(']');
        } else if (c == 't' && i + 3 < len && memcmp(&s[i], "true", 4) == 0) {
          i += 3;
        } else if (c == 'n' && i + 3 < len && memcmp(&s[i], "null", 4) == 0) {
          i += 3;
        } else if (c == 'f' && i + 4 < len && memcmp(&s[i], "false", 5) == 0) {
          i += 4;
        } else if (c == '-' || ((c >= '0' && c <= '9'))) {
          int numlen = 0;
          mg_atod(&s[i], len - i, &numlen);
          i += numlen - 1;
        } else if (c == '"') {
          int n = mg_pass_string(&s[i + 1], len - i - 1);
          if (n < 0) return n;
          i += n + 1;
        } else {
          return MG_JSON_INVALID;
        }
        MG_CHECKRET('V');
        if (depth == ed && ei >= 0) ci++;
        expecting = S_COMMA_OR_EOO;
        break;

      case S_KEY:
        if (c == '"') {
          int n = mg_pass_string(&s[i + 1], len - i - 1);
          if (n < 0) return n;
          if (i + 1 + n >= len) return MG_JSON_NOT_FOUND;
          if (depth < ed) return MG_JSON_NOT_FOUND;
          if (depth == ed && path[pos - 1] != '.') return MG_JSON_NOT_FOUND;
          // printf("K %s [%.*s] [%.*s] %d %d %d %d %d\n", path, pos, path, n,
          //        &s[i + 1], n, depth, ed, ci, ei);
          //  NOTE(cpq): in the check sequence below is important.
          //  strncmp() must go first: it fails fast if the remaining length
          //  of the path is smaller than `n`.
          if (depth == ed && path[pos - 1] == '.' &&
              strncmp(&s[i + 1], &path[pos], (size_t) n) == 0 &&
              (path[pos + n] == '\0' || path[pos + n] == '.' ||
               path[pos + n] == '[')) {
            pos += n;
          }
          i += n + 1;
          expecting = S_COLON;
        } else if (c == '}') {  // Empty object
          MG_EOO('}');
          expecting = S_COMMA_OR_EOO;
          if (depth == ed && ei >= 0) ci++;
        } else {
          return MG_JSON_INVALID;
        }
        break;

      case S_COLON:
        if (c == ':') {
          expecting = S_VALUE;
        } else {
          return MG_JSON_INVALID;
        }
        break;

      case S_COMMA_OR_EOO:
        if (depth <= 0) {
          return MG_JSON_INVALID;
        } else if (c == ',') {
          expecting = (nesting[depth - 1] == '{') ? S_KEY : S_VALUE;
        } else if (c == ']' || c == '}') {
          if (depth == ed && c == '}' && path[pos - 1] == '.')
            return MG_JSON_NOT_FOUND;
          if (depth == ed && c == ']' && path[pos - 1] == ',')
            return MG_JSON_NOT_FOUND;
          MG_EOO('O');
          if (depth == ed && ei >= 0) ci++;
        } else {
          return MG_JSON_INVALID;
        }
        break;
    }
  }
  return MG_JSON_NOT_FOUND;
}

struct mg_str mg_json_get_tok(struct mg_str json, const char *path) {
  int len = 0, ofs = mg_json_get(json, path, &len);
  return mg_str_n(ofs < 0 ? NULL : json.buf + ofs,
                  (size_t) (len < 0 ? 0 : len));
}

bool mg_json_get_num(struct mg_str json, const char *path, double *v) {
  int n, toklen, found = 0;
  if ((n = mg_json_get(json, path, &toklen)) >= 0 &&
      (json.buf[n] == '-' || (json.buf[n] >= '0' && json.buf[n] <= '9'))) {
    if (v != NULL) *v = mg_atod(json.buf + n, toklen, NULL);
    found = 1;
  }
  return found;
}

bool mg_json_get_bool(struct mg_str json, const char *path, bool *v) {
  int found = 0, off = mg_json_get(json, path, NULL);
  if (off >= 0 && (json.buf[off] == 't' || json.buf[off] == 'f')) {
    if (v != NULL) *v = json.buf[off] == 't';
    found = 1;
  }
  return found;
}

bool mg_json_unescape(struct mg_str s, char *to, size_t n) {
  size_t i, j;
  for (i = 0, j = 0; i < s.len && j < n; i++, j++) {
    if (s.buf[i] == '\\' && i + 5 < s.len && s.buf[i + 1] == 'u') {
      //  \uXXXX escape. We process simple one-byte chars \u00xx within ASCII
      //  range. More complex chars would require dragging in a UTF8 library,
      //  which is too much for us
      if (mg_str_to_num(mg_str_n(s.buf + i + 2, 4), 16, &to[j],
                        sizeof(uint8_t)) == false)
        return false;
      i += 5;
    } else if (s.buf[i] == '\\' && i + 1 < s.len) {
      char c = json_esc(s.buf[i + 1], 0);
      if (c == 0) return false;
      to[j] = c;
      i++;
    } else {
      to[j] = s.buf[i];
    }
  }
  if (j >= n) return false;
  if (n > 0) to[j] = '\0';
  return true;
}

char *mg_json_get_str(struct mg_str json, const char *path) {
  char *result = NULL;
  int len = 0, off = mg_json_get(json, path, &len);
  if (off >= 0 && len > 1 && json.buf[off] == '"') {
    if ((result = (char *) mg_calloc(1, (size_t) len)) != NULL &&
        !mg_json_unescape(mg_str_n(json.buf + off + 1, (size_t) (len - 2)),
                          result, (size_t) len)) {
      mg_free(result);
      result = NULL;
    }
  }
  return result;
}

char *mg_json_get_b64(struct mg_str json, const char *path, int *slen) {
  char *result = NULL;
  int len = 0, off = mg_json_get(json, path, &len);
  if (off >= 0 && json.buf[off] == '"' && len > 1 &&
      (result = (char *) mg_calloc(1, (size_t) len)) != NULL) {
    size_t k = mg_base64_decode(json.buf + off + 1, (size_t) (len - 2), result,
                                (size_t) len);
    if (slen != NULL) *slen = (int) k;
  }
  return result;
}

char *mg_json_get_hex(struct mg_str json, const char *path, int *slen) {
  char *result = NULL;
  int len = 0, off = mg_json_get(json, path, &len);
  if (off >= 0 && json.buf[off] == '"' && len > 1 &&
      (result = (char *) mg_calloc(1, (size_t) len / 2)) != NULL) {
    int i;
    for (i = 0; i < len - 2; i += 2) {
      mg_str_to_num(mg_str_n(json.buf + off + 1 + i, 2), 16, &result[i >> 1],
                    sizeof(uint8_t));
    }
    result[len / 2 - 1] = '\0';
    if (slen != NULL) *slen = len / 2 - 1;
  }
  return result;
}

long mg_json_get_long(struct mg_str json, const char *path, long dflt) {
  double dv;
  long result = dflt;
  if (mg_json_get_num(json, path, &dv)) result = (long) dv;
  return result;
}

#ifdef MG_ENABLE_LINES
#line 1 "src/l2.c"
#endif




#if MG_ENABLE_TCPIP

// L2 API
void mg_l2_init(enum mg_l2type type, uint8_t *addr, uint16_t *mtu,
                uint16_t *framesize);
uint8_t *mg_l2_header(enum mg_l2type type, enum mg_l2proto proto, uint8_t *src,
                      uint8_t *dst, uint8_t *frame);
size_t mg_l2_footer(enum mg_l2type type, size_t len, uint8_t *frame);
bool mg_l2_rx(struct mg_tcpip_if *ifp, enum mg_l2proto *proto,
              struct mg_str *pay, struct mg_str *raw);
// TODO(): ? bool mg_l2_rx(enum mg_l2type type, struct mg_l2opts *opts, uint8_t
// *addr, enum mg_l2proto *proto, struct mg_str *pay, struct mg_str *raw);
uint8_t *mg_l2_getaddr(enum mg_l2type type, uint8_t *frame);
uint8_t *mg_l2_mapip(enum mg_l2type type, enum mg_l2addrtype addrtype,
                     struct mg_addr *ip);
bool mg_l2_genip6(enum mg_l2type type, uint64_t *ip6, uint8_t prefix_len,
                  uint8_t *addr);
bool mg_l2_ip6get(enum mg_l2type type, uint8_t *addr, uint8_t *opts,
                  uint8_t len);
uint8_t mg_l2_ip6put(enum mg_l2type type, uint8_t *addr, uint8_t *opts);

// clang-format off
extern void mg_l2_eth_init(struct mg_l2addr *, uint16_t *, uint16_t *);
extern uint8_t *mg_l2_eth_header(enum mg_l2proto, struct mg_l2addr *, struct mg_l2addr *, uint8_t *);
extern size_t mg_l2_eth_footer(size_t, uint8_t *);
extern bool mg_l2_eth_rx(struct mg_tcpip_if *, enum mg_l2proto *, struct mg_str *, struct mg_str *);
extern struct mg_l2addr *mg_l2_eth_getaddr(uint8_t *);
extern struct mg_l2addr *mg_l2_eth_mapip(enum mg_l2addrtype, struct mg_addr *);
extern bool mg_l2_eth_genip6(uint64_t *, uint8_t, struct mg_l2addr *);
extern bool mg_l2_eth_ip6get(struct mg_l2addr *, uint8_t *, uint8_t);
extern uint8_t mg_l2_eth_ip6put(struct mg_l2addr *, uint8_t *);

extern void mg_l2_ppp_init(struct mg_l2addr *, uint16_t *, uint16_t *);
extern uint8_t *mg_l2_ppp_header(enum mg_l2proto, struct mg_l2addr *, struct mg_l2addr *, uint8_t *);
extern size_t mg_l2_ppp_footer(size_t, uint8_t *);
extern bool mg_l2_ppp_rx(struct mg_tcpip_if *, enum mg_l2proto *, struct mg_str *, struct mg_str *);
extern struct mg_l2addr *mg_l2_ppp_getaddr(uint8_t *);
extern struct mg_l2addr *mg_l2_ppp_mapip(enum mg_l2addrtype, struct mg_addr *);
#if MG_ENABLE_IPV6
extern bool mg_l2_ppp_genip6(uint64_t *, uint8_t, struct mg_l2addr *);
extern bool mg_l2_ppp_ip6get(struct mg_l2addr *, uint8_t *, uint8_t);
extern uint8_t mg_l2_ppp_ip6put(struct mg_l2addr *, uint8_t *);
#endif

typedef void (*l2_init_fn)(struct mg_l2addr *, uint16_t *, uint16_t *);
typedef uint8_t *((*l2_header_fn)(enum mg_l2proto, struct mg_l2addr *, struct mg_l2addr *, uint8_t *));
typedef size_t (*l2_footer_fn)(size_t, uint8_t *);
typedef bool (*l2_rx_fn)(struct mg_tcpip_if *, enum mg_l2proto *, struct mg_str *, struct mg_str *);
typedef struct mg_l2addr (*(*l2_getaddr_fn)(uint8_t *));
typedef struct mg_l2addr (*(*l2_mapip_fn)(enum mg_l2addrtype, struct mg_addr *));
#if MG_ENABLE_IPV6
typedef bool (*l2_genip6_fn)(uint64_t *, uint8_t, struct mg_l2addr *);
typedef bool (*l2_ip6get_fn)(struct mg_l2addr *, uint8_t *, uint8_t);
typedef uint8_t (*l2_ip6put_fn)(struct mg_l2addr *, uint8_t *);
#endif
// clang-format on

static const l2_init_fn l2_init[] = {mg_l2_eth_init, mg_l2_ppp_init};
static const l2_header_fn l2_header[] = {mg_l2_eth_header, mg_l2_ppp_header};
static const l2_footer_fn l2_footer[] = {mg_l2_eth_footer, mg_l2_ppp_footer};
static const l2_rx_fn l2_rx[] = {mg_l2_eth_rx, mg_l2_ppp_rx};
static const l2_getaddr_fn l2_getaddr[] = {mg_l2_eth_getaddr,
                                           mg_l2_ppp_getaddr};
static const l2_mapip_fn l2_mapip[] = {mg_l2_eth_mapip, mg_l2_ppp_mapip};
#if MG_ENABLE_IPV6
static const l2_genip6_fn l2_genip6[] = {mg_l2_eth_genip6, mg_l2_ppp_genip6};
static const l2_ip6get_fn l2_ip6get[] = {mg_l2_eth_ip6get, mg_l2_ppp_ip6get};
static const l2_ip6put_fn l2_ip6put[] = {mg_l2_eth_ip6put, mg_l2_ppp_ip6put};
#endif

void mg_l2_init(enum mg_l2type type, uint8_t *addr, uint16_t *mtu,
                uint16_t *framesize) {
  l2_init[type]((struct mg_l2addr *) addr, mtu, framesize);
}

uint8_t *mg_l2_header(enum mg_l2type type, enum mg_l2proto proto, uint8_t *src,
                      uint8_t *dst, uint8_t *frame) {
  return l2_header[type](proto, (struct mg_l2addr *) src,
                         (struct mg_l2addr *) dst, frame);
}

size_t mg_l2_footer(enum mg_l2type type, size_t len, uint8_t *frame) {
  return l2_footer[type](len, frame);
}

bool mg_l2_rx(struct mg_tcpip_if *ifp, enum mg_l2proto *proto,
              struct mg_str *pay, struct mg_str *raw) {
  return l2_rx[ifp->l2type](ifp, proto, pay, raw);
}

uint8_t *mg_l2_getaddr(enum mg_l2type type, uint8_t *frame) {
  return (uint8_t *) l2_getaddr[type](frame);
}

struct mg_l2addr s_mapip;

uint8_t *mg_l2_mapip(enum mg_l2type type, enum mg_l2addrtype addrtype,
                     struct mg_addr *ip) {
  return (uint8_t *) l2_mapip[type](addrtype, ip);
}

#if MG_ENABLE_IPV6
bool mg_l2_genip6(enum mg_l2type type, uint64_t *ip6, uint8_t prefix_len,
                  uint8_t *addr) {
  return l2_genip6[type](ip6, prefix_len, (struct mg_l2addr *) addr);
}

bool mg_l2_ip6get(enum mg_l2type type, uint8_t *addr, uint8_t *opts,
                  uint8_t len) {
  return l2_ip6get[type]((struct mg_l2addr *) addr, opts, len);
}
uint8_t mg_l2_ip6put(enum mg_l2type type, uint8_t *addr, uint8_t *opts) {
  return l2_ip6put[type]((struct mg_l2addr *) addr, opts);
}
#endif

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/l2_eth.c"
#endif







#if MG_ENABLE_TCPIP

#if defined(__DCC__)
#pragma pack(1)
#else
#pragma pack(push, 1)
#endif

struct eth {
  uint8_t dst[6];  // Destination MAC address
  uint8_t src[6];  // Source MAC address
  uint16_t type;   // Ethernet type
};

#if defined(__DCC__)
#pragma pack(0)
#else
#pragma pack(pop)
#endif

static const uint16_t eth_types[] = {
    // order is vital, see l2.h
    0x800,   // IPv4
    0x86dd,  // IPv6
    0x806,   // ARP
    0x8863,  // PPPoE Discovery Stage
    0x8864   // PPPoE Session Stage
};

void mg_l2_eth_init(struct mg_l2addr *l2addr, uint16_t *mtu,
                    uint16_t *framesize) {
  // If MAC is not set, make a random one
  if (l2addr->addr.mac[0] == 0 && l2addr->addr.mac[1] == 0 &&
      l2addr->addr.mac[2] == 0 && l2addr->addr.mac[3] == 0 &&
      l2addr->addr.mac[4] == 0 && l2addr->addr.mac[5] == 0) {
    l2addr->addr.mac[0] = 0x02;  // Locally administered, unicast
    mg_random(&l2addr->addr.mac[1], sizeof(l2addr->addr.mac) - 1);
    MG_INFO(
        ("MAC not set. Generated random: %M", mg_print_mac, l2addr->addr.mac));
  }
  *mtu = 1500;
  *framesize = 1540;
}

uint8_t *mg_l2_eth_header(enum mg_l2proto proto, struct mg_l2addr *src,
                          struct mg_l2addr *dst, uint8_t *frame) {
  struct eth *eth = (struct eth *) frame;
  eth->type = mg_htons(eth_types[(unsigned int) proto]);
  memcpy(eth->src, src->addr.mac, sizeof(eth->dst));
  memcpy(eth->dst, dst->addr.mac, sizeof(eth->dst));
  return (uint8_t *) (eth + 1);
}

size_t mg_l2_eth_footer(size_t len, uint8_t *frame) {
  struct eth *eth = (struct eth *) frame;
  // nothing to do; there is no len field in Ethernet, CRC is hw-calculated
  return len + sizeof(*eth);
}

struct mg_l2addr *mg_l2_eth_mapip(enum mg_l2addrtype addrtype,
                                  struct mg_addr *addr);

bool mg_l2_eth_rx(struct mg_tcpip_if *ifp, enum mg_l2proto *proto,
                  struct mg_str *pay, struct mg_str *raw) {
  struct eth *eth = (struct eth *) raw->buf;
  uint16_t type, len;
  unsigned int i;
  if (raw->len < sizeof(*eth)) return false;  // Truncated - runt?
  len = (uint16_t) raw->len;
  if (ifp->enable_mac_check &&
      memcmp(eth->dst, ifp->mac, sizeof(eth->dst)) != 0 &&
      memcmp(eth->dst, mg_l2_eth_mapip(MG_TCPIP_L2ADDR_BCAST, NULL),
             sizeof(eth->dst)) != 0)
    return false;  // TODO(): add multicast addresses
  if (ifp->enable_crc32_check && len > sizeof(*eth) + 4) {
    uint32_t crc;
    len -= 4;  // TODO(scaprile): check on bigendian
    crc = mg_crc32(0, (const char *) raw->buf, len);
    if (memcmp((void *) ((size_t) raw->buf + len), &crc, sizeof(crc)))
      return false;
  }
  pay->buf = (char *) (eth + 1);
  pay->len = len - sizeof(*eth);

  type = mg_htons(eth->type);
  for (i = 0; i < sizeof(eth_types) / sizeof(uint16_t); i++) {
    if (type == eth_types[i]) break;
  }
  if (i == sizeof(eth_types)) {
    MG_DEBUG(("Unknown eth type %x", type));
    if (mg_log_level >= MG_LL_VERBOSE)
      mg_hexdump(raw->buf, raw->len >= 32 ? 32 : raw->len);
    return false;
  }
  *proto = (enum mg_l2proto) i;
  return true;
}

struct mg_l2addr *mg_l2_eth_getaddr(uint8_t *frame) {
  struct eth *eth = (struct eth *) frame;
  return (struct mg_l2addr *) &eth->src;
}

extern struct mg_l2addr s_mapip;

struct mg_l2addr *mg_l2_eth_mapip(enum mg_l2addrtype addrtype,
                                  struct mg_addr *addr) {
  switch (addrtype) {
    case MG_TCPIP_L2ADDR_BCAST:
      memset(s_mapip.addr.mac, 0xff, sizeof(s_mapip.addr.mac));
      break;
    case MG_TCPIP_L2ADDR_MCAST: {
      uint8_t *ip = (uint8_t *) &addr->addr.ip4;
      // IP multicast group MAC, RFC-1112 6.4
      s_mapip.addr.mac[0] = 0x01, s_mapip.addr.mac[1] = 0x00,
      s_mapip.addr.mac[2] = 0x5E;
      s_mapip.addr.mac[3] = ip[1] & 0x7F;  // 23 LSb
      s_mapip.addr.mac[4] = ip[2];
      s_mapip.addr.mac[5] = ip[3];
      break;
    }
    case MG_TCPIP_L2ADDR_MCAST6: {
      // IPv6 multicast address mapping, RFC-2464 7
      uint8_t *ip = (uint8_t *) &addr->addr.ip6;
      s_mapip.addr.mac[0] = 0x33, s_mapip.addr.mac[1] = 0x33;
      s_mapip.addr.mac[2] = ip[12], s_mapip.addr.mac[3] = ip[13],
      s_mapip.addr.mac[4] = ip[14], s_mapip.addr.mac[5] = ip[15];
      break;
    }
  }
  return &s_mapip;
}

#if MG_ENABLE_IPV6
static void meui64(uint8_t *addr, uint8_t *mac) {
  *addr++ = *mac++ ^ (uint8_t) 0x02, *addr++ = *mac++, *addr++ = *mac++;
  *addr++ = 0xff, *addr++ = 0xfe;
  *addr++ = *mac++, *addr++ = *mac++, *addr = *mac;
}

bool mg_l2_eth_genip6(uint64_t *ip6, uint8_t prefix_len,
                      struct mg_l2addr *l2addr) {
  if (prefix_len > 64) {
    MG_ERROR(("Prefix length > 64, UNSUPPORTED"));
    return false;
  }
  ip6[0] = 0;
  meui64(((uint8_t *) &ip6[1]), l2addr->addr.mac);  // RFC-4291 2.5.4, 2.5.1
  return true;
}

bool mg_l2_eth_ip6get(struct mg_l2addr *l2addr, uint8_t *opts, uint8_t len) {
  if (len != 1) return false;
  memcpy(l2addr->addr.mac, opts, 6);
  return true;
}

uint8_t mg_l2_eth_ip6put(struct mg_l2addr *l2addr, uint8_t *opts) {
  memcpy(opts, l2addr->addr.mac, 6);
  return 1;
}
#endif

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/l2_ppp.c"
#endif







#if MG_ENABLE_TCPIP

#if defined(__DCC__)
#pragma pack(1)
#else
#pragma pack(push, 1)
#endif

struct ppp {  // RFC-1662
  uint8_t addr, ctrl;
  uint16_t proto;
};

struct lcp {  // RFC-1661
  uint8_t code, id, len[2];
};

struct ipcp { // RFC-1332
  uint8_t code;
};

struct ipv6cp { // RFC-5072
  uint8_t code;
};

#if defined(__DCC__)
#pragma pack(0)
#else
#pragma pack(pop)
#endif


void mg_l2_ppp_init(struct mg_l2addr *addr, uint16_t *mtu,
                    uint16_t *framesize) {
  (void) addr;
  *mtu = 1500;        // 1492 for PPPoE
  *framesize = 1540;  // *** TODO(scaprile): actual value, check for PPPoE too
}

uint8_t *mg_l2_ppp_header(enum mg_l2proto proto, struct mg_l2addr *src,
                          struct mg_l2addr *dst, uint8_t *frame) {
  (void) src;
  (void) dst;
  (void) proto;
  return frame;
}

size_t mg_l2_ppp_footer(size_t len, uint8_t *frame) {
  (void) frame;
  return len;
}

bool mg_l2_ppp_rx(struct mg_tcpip_if *ifp, enum mg_l2proto *proto,
                  struct mg_str *pay, struct mg_str *raw) {
#if 0
if (ppp->addr == MG_PPP_ADDR && ppp->ctrl == MG_PPP_CTRL) {
  code = ntohs(ppp->proto);
  payload = (uint8_t *) (ppp + 1);
} else { // Address-and-Control-Field-Compressed PPP header
  uint16_t *cppp = (uint16_t *) ppp;
  code = ntohs(*cppp);
  payload = (uint8_t *) (cppp + 1);
}
#endif
  *pay = *raw;
  *proto = MG_TCPIP_L2PROTO_IPV4;
  (void) ifp;
  return true;
}

struct mg_l2addr *mg_l2_ppp_getaddr(uint8_t *frame) {
  (void) frame;
  return &s_mapip;  // bogus
}

extern struct mg_l2addr s_mapip;

struct mg_l2addr *mg_l2_ppp_mapip(enum mg_l2addrtype addrtype,
                                  struct mg_addr *addr) {
  (void) addrtype;
  (void) addr;
  return &s_mapip;  // bogus
}

#if MG_ENABLE_IPV6
bool mg_l2_ppp_genip6(uint64_t *ip6, uint8_t prefix_len,
                      struct mg_l2addr *addr) {
  (void) ip6;
  (void) prefix_len;
  (void) addr;
  return false;
}

bool mg_l2_ppp_ip6get(struct mg_l2addr *addr, uint8_t *opts, uint8_t len) {
  (void) addr;
  (void) opts;
  (void) len;
  return false;
}

uint8_t mg_l2_ppp_ip6put(struct mg_l2addr *addr, uint8_t *opts) {
  (void) addr;
  (void) opts;
  return 0;
}
#endif

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/log.c"
#endif





int mg_log_level = MG_LL_DEBUG;
static mg_pfn_t s_log_func = mg_pfn_stdout;
static void *s_log_func_param = NULL;

void mg_log_set_fn(mg_pfn_t fn, void *param) {
  s_log_func = fn;
  s_log_func_param = param;
}

static void logc(unsigned char c) {
  s_log_func((char) c, s_log_func_param);
}

static void logs(const char *buf, size_t len) {
  size_t i;
  for (i = 0; i < len; i++) logc(((unsigned char *) buf)[i]);
}

#if MG_ENABLE_CUSTOM_LOG
// Let user define their own mg_log_prefix() and mg_log()
#else
void mg_log_prefix(int level, const char *file, int line, const char *fname) {
  const char *p = strrchr(file, '/');
  char buf[41];
  size_t n;
  if (p == NULL) p = strrchr(file, '\\');
  n = mg_snprintf(buf, sizeof(buf), "%-6llx %d %s:%d:%s", mg_millis(), level,
                  p == NULL ? file : p + 1, line, fname);
  if (n > sizeof(buf) - 2) n = sizeof(buf) - 2;
  while (n < sizeof(buf)) buf[n++] = ' ';
  logs(buf, n - 1);
}

void mg_log(const char *fmt, ...) {
  va_list ap;
  va_start(ap, fmt);
  mg_vxprintf(s_log_func, s_log_func_param, fmt, &ap);
  va_end(ap);
  logs("\r\n", 2);
}
#endif

static unsigned char nibble(unsigned c) {
  return (unsigned char) (c < 10 ? c + '0' : c + 'W');
}

#define ISPRINT(x) ((x) >= ' ' && (x) <= '~')
void mg_hexdump(const void *buf, size_t len) {
  const unsigned char *p = (const unsigned char *) buf;
  unsigned char ascii[16], alen = 0;
  size_t i;
  for (i = 0; i < len; i++) {
    if ((i % 16) == 0) {
      // Print buffered ascii chars
      if (i > 0)
        logs("  ", 2), logs((char *) ascii, 16), logs("\r\n", 2), alen = 0;
      // Print hex address, then \t
      logc(nibble((i >> 12) & 15)), logc(nibble((i >> 8) & 15)),
          logc(nibble((i >> 4) & 15)), logc('0'), logs("   ", 3);
    }
    logc(nibble(p[i] >> 4)), logc(nibble(p[i] & 15));  // Two nibbles, e.g. c5
    logc(' ');                                         // Space after hex number
    ascii[alen++] = ISPRINT(p[i]) ? p[i] : '.';        // Add to the ascii buf
  }
  while (alen < 16) logs("   ", 3), ascii[alen++] = ' ';
  logs("  ", 2), logs((char *) ascii, 16), logs("\r\n", 2);
}

#ifdef MG_ENABLE_LINES
#line 1 "src/md5.c"
#endif



//  This code implements the MD5 message-digest algorithm.
//  The algorithm is due to Ron Rivest.  This code was
//  written by Colin Plumb in 1993, no copyright is claimed.
//  This code is in the public domain; do with it what you wish.
//
//  Equivalent code is available from RSA Data Security, Inc.
//  This code has been tested against that, and is equivalent,
//  except that you don't need to include two pages of legalese
//  with every copy.
//
//  To compute the message digest of a chunk of bytes, declare an
//  MD5Context structure, pass it to MD5Init, call MD5Update as
//  needed on buffers full of bytes, and then call MD5Final, which
//  will fill a supplied 16-byte array with the digest.

#if defined(MG_ENABLE_MD5) && MG_ENABLE_MD5

static void mg_byte_reverse(unsigned char *buf, unsigned longs) {
  if (MG_BIG_ENDIAN) {
    do {
      uint32_t t = (uint32_t) ((unsigned) buf[3] << 8 | buf[2]) << 16 |
                   ((unsigned) buf[1] << 8 | buf[0]);
      *(uint32_t *) buf = t;
      buf += 4;
    } while (--longs);
  } else {
    (void) buf, (void) longs;  // Little endian. Do nothing
  }
}

#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))

#define MD5STEP(f, w, x, y, z, data, s) \
  (w += f(x, y, z) + data, w = w << s | w >> (32 - s), w += x)

/*
 * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
 * initialization constants.
 */
void mg_md5_init(mg_md5_ctx *ctx) {
  ctx->buf[0] = 0x67452301;
  ctx->buf[1] = 0xefcdab89;
  ctx->buf[2] = 0x98badcfe;
  ctx->buf[3] = 0x10325476;

  ctx->bits[0] = 0;
  ctx->bits[1] = 0;
}

static void mg_md5_transform(uint32_t buf[4], uint32_t const in[16]) {
  uint32_t a, b, c, d;

  a = buf[0];
  b = buf[1];
  c = buf[2];
  d = buf[3];

  MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
  MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
  MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
  MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
  MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
  MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
  MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
  MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
  MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
  MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
  MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
  MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
  MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
  MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
  MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
  MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);

  MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
  MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
  MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
  MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
  MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
  MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
  MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
  MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
  MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
  MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
  MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
  MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
  MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
  MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
  MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
  MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);

  MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
  MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
  MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
  MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
  MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
  MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
  MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
  MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
  MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
  MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
  MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
  MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
  MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
  MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
  MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
  MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);

  MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
  MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
  MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
  MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
  MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
  MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
  MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
  MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
  MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
  MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
  MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
  MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
  MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
  MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
  MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
  MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);

  buf[0] += a;
  buf[1] += b;
  buf[2] += c;
  buf[3] += d;
}

void mg_md5_update(mg_md5_ctx *ctx, const unsigned char *buf, size_t len) {
  uint32_t t;

  t = ctx->bits[0];
  if ((ctx->bits[0] = t + ((uint32_t) len << 3)) < t) ctx->bits[1]++;
  ctx->bits[1] += (uint32_t) len >> 29;

  t = (t >> 3) & 0x3f;

  if (t) {
    unsigned char *p = (unsigned char *) ctx->in + t;

    t = 64 - t;
    if (len < t) {
      memcpy(p, buf, len);
      return;
    }
    memcpy(p, buf, t);
    mg_byte_reverse(ctx->in, 16);
    mg_md5_transform(ctx->buf, (uint32_t *) ctx->in);
    buf += t;
    len -= t;
  }

  while (len >= 64) {
    memcpy(ctx->in, buf, 64);
    mg_byte_reverse(ctx->in, 16);
    mg_md5_transform(ctx->buf, (uint32_t *) ctx->in);
    buf += 64;
    len -= 64;
  }

  memcpy(ctx->in, buf, len);
}

void mg_md5_final(mg_md5_ctx *ctx, unsigned char digest[16]) {
  unsigned count;
  unsigned char *p;
  uint32_t *a;

  count = (ctx->bits[0] >> 3) & 0x3F;

  p = ctx->in + count;
  *p++ = 0x80;
  count = 64 - 1 - count;
  if (count < 8) {
    memset(p, 0, count);
    mg_byte_reverse(ctx->in, 16);
    mg_md5_transform(ctx->buf, (uint32_t *) ctx->in);
    memset(ctx->in, 0, 56);
  } else {
    memset(p, 0, count - 8);
  }
  mg_byte_reverse(ctx->in, 14);

  a = (uint32_t *) ctx->in;
  a[14] = ctx->bits[0];
  a[15] = ctx->bits[1];

  mg_md5_transform(ctx->buf, (uint32_t *) ctx->in);
  mg_byte_reverse((unsigned char *) ctx->buf, 4);
  memcpy(digest, ctx->buf, 16);
  memset((char *) ctx, 0, sizeof(*ctx));
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/mqtt.c"
#endif








#define MQTT_CLEAN_SESSION 0x02
#define MQTT_HAS_WILL 0x04
#define MQTT_WILL_RETAIN 0x20
#define MQTT_HAS_PASSWORD 0x40
#define MQTT_HAS_USER_NAME 0x80

struct mg_mqtt_pmap {
  uint8_t id;
  uint8_t type;
};

static const struct mg_mqtt_pmap s_prop_map[] = {
    {MQTT_PROP_PAYLOAD_FORMAT_INDICATOR, MQTT_PROP_TYPE_BYTE},
    {MQTT_PROP_MESSAGE_EXPIRY_INTERVAL, MQTT_PROP_TYPE_INT},
    {MQTT_PROP_CONTENT_TYPE, MQTT_PROP_TYPE_STRING},
    {MQTT_PROP_RESPONSE_TOPIC, MQTT_PROP_TYPE_STRING},
    {MQTT_PROP_CORRELATION_DATA, MQTT_PROP_TYPE_BINARY_DATA},
    {MQTT_PROP_SUBSCRIPTION_IDENTIFIER, MQTT_PROP_TYPE_VARIABLE_INT},
    {MQTT_PROP_SESSION_EXPIRY_INTERVAL, MQTT_PROP_TYPE_INT},
    {MQTT_PROP_ASSIGNED_CLIENT_IDENTIFIER, MQTT_PROP_TYPE_STRING},
    {MQTT_PROP_SERVER_KEEP_ALIVE, MQTT_PROP_TYPE_SHORT},
    {MQTT_PROP_AUTHENTICATION_METHOD, MQTT_PROP_TYPE_STRING},
    {MQTT_PROP_AUTHENTICATION_DATA, MQTT_PROP_TYPE_BINARY_DATA},
    {MQTT_PROP_REQUEST_PROBLEM_INFORMATION, MQTT_PROP_TYPE_BYTE},
    {MQTT_PROP_WILL_DELAY_INTERVAL, MQTT_PROP_TYPE_INT},
    {MQTT_PROP_REQUEST_RESPONSE_INFORMATION, MQTT_PROP_TYPE_BYTE},
    {MQTT_PROP_RESPONSE_INFORMATION, MQTT_PROP_TYPE_STRING},
    {MQTT_PROP_SERVER_REFERENCE, MQTT_PROP_TYPE_STRING},
    {MQTT_PROP_REASON_STRING, MQTT_PROP_TYPE_STRING},
    {MQTT_PROP_RECEIVE_MAXIMUM, MQTT_PROP_TYPE_SHORT},
    {MQTT_PROP_TOPIC_ALIAS_MAXIMUM, MQTT_PROP_TYPE_SHORT},
    {MQTT_PROP_TOPIC_ALIAS, MQTT_PROP_TYPE_SHORT},
    {MQTT_PROP_MAXIMUM_QOS, MQTT_PROP_TYPE_BYTE},
    {MQTT_PROP_RETAIN_AVAILABLE, MQTT_PROP_TYPE_BYTE},
    {MQTT_PROP_USER_PROPERTY, MQTT_PROP_TYPE_STRING_PAIR},
    {MQTT_PROP_MAXIMUM_PACKET_SIZE, MQTT_PROP_TYPE_INT},
    {MQTT_PROP_WILDCARD_SUBSCRIPTION_AVAILABLE, MQTT_PROP_TYPE_BYTE},
    {MQTT_PROP_SUBSCRIPTION_IDENTIFIER_AVAILABLE, MQTT_PROP_TYPE_BYTE},
    {MQTT_PROP_SHARED_SUBSCRIPTION_AVAILABLE, MQTT_PROP_TYPE_BYTE}};

static bool mqtt_send_header(struct mg_connection *c, uint8_t cmd,
                             uint8_t flags, uint32_t len) {
  uint8_t buf[1 + sizeof(len)], *vlen = &buf[1];
  buf[0] = (uint8_t) ((cmd << 4) | flags);
  do {
    *vlen = len % 0x80;
    len /= 0x80;
    if (len > 0) *vlen |= 0x80;
    vlen++;
  } while (len > 0 && vlen < &buf[sizeof(buf)]);
  return mg_send(c, buf, (size_t) (vlen - buf));
}

void mg_mqtt_send_header(struct mg_connection *c, uint8_t cmd, uint8_t flags,
                         uint32_t len) {
  if (!mqtt_send_header(c, cmd, flags, len)) mg_error(c, "OOM");
}

static bool mg_send_u16(struct mg_connection *c, uint16_t value) {
  return mg_send(c, &value, sizeof(value));
}

static bool mg_send_u32(struct mg_connection *c, uint32_t value) {
  return mg_send(c, &value, sizeof(value));
}

static uint8_t varint_size(size_t length) {
  uint8_t bytes_needed = 0;
  do {
    bytes_needed++;
    length /= 0x80;
  } while (length > 0);
  return bytes_needed;
}

static size_t encode_varint(uint8_t *buf, size_t value) {
  size_t len = 0;

  do {
    uint8_t b = (uint8_t) (value % 128);
    value /= 128;
    if (value > 0) b |= 0x80;
    buf[len++] = b;
  } while (value > 0);

  return len;
}

static size_t decode_varint(const uint8_t *buf, size_t len, size_t *value) {
  size_t multiplier = 1, offset;
  *value = 0;

  for (offset = 0; offset < 4 && offset < len; offset++) {
    uint8_t encoded_byte = buf[offset];
    *value += (encoded_byte & 0x7f) * multiplier;
    multiplier *= 128;

    if ((encoded_byte & 0x80) == 0) return offset + 1;
  }

  return 0;
}

static int mqtt_prop_type_by_id(uint8_t prop_id) {
  size_t i, num_properties = sizeof(s_prop_map) / sizeof(s_prop_map[0]);
  for (i = 0; i < num_properties; ++i) {
    if (s_prop_map[i].id == prop_id) return s_prop_map[i].type;
  }
  return -1;  // Property ID not found
}

// Returns the size of the properties section, without the
// size of the content's length
static size_t get_properties_length(struct mg_mqtt_prop *props, size_t count) {
  size_t i, size = 0;
  for (i = 0; i < count; i++) {
    size++;  // identifier
    switch (mqtt_prop_type_by_id(props[i].id)) {
      case MQTT_PROP_TYPE_STRING_PAIR:
        size += (uint32_t) (props[i].val.len + props[i].key.len +
                            2 * sizeof(uint16_t));
        break;
      case MQTT_PROP_TYPE_STRING:
        size += (uint32_t) (props[i].val.len + sizeof(uint16_t));
        break;
      case MQTT_PROP_TYPE_BINARY_DATA:
        size += (uint32_t) (props[i].val.len + sizeof(uint16_t));
        break;
      case MQTT_PROP_TYPE_VARIABLE_INT:
        size += varint_size((uint32_t) props[i].iv);
        break;
      case MQTT_PROP_TYPE_INT: size += (uint32_t) sizeof(uint32_t); break;
      case MQTT_PROP_TYPE_SHORT: size += (uint32_t) sizeof(uint16_t); break;
      case MQTT_PROP_TYPE_BYTE: size += (uint32_t) sizeof(uint8_t); break;
      default: return size;  // cannot parse further down
    }
  }

  return size;
}

// returns the entire size of the properties section, including the
// size of the variable length of the content
static size_t get_props_size(struct mg_mqtt_prop *props, size_t count) {
  size_t size = get_properties_length(props, count);
  size += varint_size(size);
  return size;
}

static bool mg_send_mqtt_properties(struct mg_connection *c,
                                    struct mg_mqtt_prop *props, size_t nprops) {
  size_t total_size = get_properties_length(props, nprops);
  uint8_t buf_v[4] = {0, 0, 0, 0};
  uint8_t buf[4] = {0, 0, 0, 0};
  size_t i, len = encode_varint(buf, total_size);

  if (!mg_send(c, buf, (size_t) len)) return false;
  for (i = 0; i < nprops; i++) {
    if (!mg_send(c, &props[i].id, sizeof(props[i].id))) return false;
    switch (mqtt_prop_type_by_id(props[i].id)) {
      case MQTT_PROP_TYPE_STRING_PAIR:
        if (!mg_send_u16(c, mg_htons((uint16_t) props[i].key.len)) ||
            !mg_send(c, props[i].key.buf, props[i].key.len) ||
            !mg_send_u16(c, mg_htons((uint16_t) props[i].val.len)) ||
            !mg_send(c, props[i].val.buf, props[i].val.len))
          return false;
        break;
      case MQTT_PROP_TYPE_BYTE:
        if (!mg_send(c, &props[i].iv, sizeof(uint8_t))) return false;
        break;
      case MQTT_PROP_TYPE_SHORT:
        if (!mg_send_u16(c, mg_htons((uint16_t) props[i].iv))) return false;
        break;
      case MQTT_PROP_TYPE_INT:
        if (!mg_send_u32(c, mg_htonl((uint32_t) props[i].iv))) return false;
        break;
      case MQTT_PROP_TYPE_STRING:
        if (!mg_send_u16(c, mg_htons((uint16_t) props[i].val.len)) ||
            !mg_send(c, props[i].val.buf, props[i].val.len))
          return false;
        break;
      case MQTT_PROP_TYPE_BINARY_DATA:
        if (!mg_send_u16(c, mg_htons((uint16_t) props[i].val.len)) ||
            !mg_send(c, props[i].val.buf, props[i].val.len))
          return false;
        break;
      case MQTT_PROP_TYPE_VARIABLE_INT:
        len = encode_varint(buf_v, props[i].iv);
        if (!mg_send(c, buf_v, (size_t) len)) return false;
        break;
    }
  }
  return true;
}

size_t mg_mqtt_next_prop(struct mg_mqtt_message *msg, struct mg_mqtt_prop *prop,
                         size_t ofs) {
  uint8_t *i = (uint8_t *) msg->dgram.buf + msg->props_start + ofs;
  uint8_t *end = (uint8_t *) msg->dgram.buf + msg->dgram.len;
  size_t new_pos = ofs, len;

  if (ofs >= msg->dgram.len || ofs >= msg->props_start + msg->props_size || (i + 1) >= end)
    return 0;

  memset(prop, 0, sizeof(struct mg_mqtt_prop));
  prop->id = i[0];
  i++, new_pos++;

  switch (mqtt_prop_type_by_id(prop->id)) {
    case MQTT_PROP_TYPE_STRING_PAIR:
      if (i + 2 >= end) return 0;
      prop->key.len = (uint16_t) ((((uint16_t) i[0]) << 8) | i[1]);
      prop->key.buf = (char *) i + 2;
      i += 2 + prop->key.len;
      if (i + 2 >= end) return 0;
      prop->val.len = (uint16_t) ((((uint16_t) i[0]) << 8) | i[1]);
      prop->val.buf = (char *) i + 2;
      if (i + 2 + prop->val.len >= end) return 0;
      new_pos += 2 * sizeof(uint16_t) + prop->val.len + prop->key.len;
      break;
    case MQTT_PROP_TYPE_BYTE:
      if (i + 1 >= end) return 0;
      prop->iv = (uint8_t) i[0];
      new_pos++;
      break;
    case MQTT_PROP_TYPE_SHORT:
      if (i + 2 >= end) return 0;
      prop->iv = (uint16_t) ((((uint16_t) i[0]) << 8) | i[1]);
      new_pos += sizeof(uint16_t);
      break;
    case MQTT_PROP_TYPE_INT:
      if (i + 4 >= end) return 0;
      prop->iv = ((uint32_t) i[0] << 24) | ((uint32_t) i[1] << 16) |
                 ((uint32_t) i[2] << 8) | i[3];
      new_pos += sizeof(uint32_t);
      break;
    case MQTT_PROP_TYPE_STRING:
      if (i + 2 >= end) return 0;
      prop->val.len = (uint16_t) ((((uint16_t) i[0]) << 8) | i[1]);
      prop->val.buf = (char *) i + 2;
      if (i + 2 + prop->val.len >= end) return 0;
      new_pos += 2 + prop->val.len;
      break;
    case MQTT_PROP_TYPE_BINARY_DATA:
      if (i + 2 >= end) return 0;
      prop->val.len = (uint16_t) ((((uint16_t) i[0]) << 8) | i[1]);
      prop->val.buf = (char *) i + 2;
      if (i + 2 + prop->val.len >= end) return 0;
      new_pos += 2 + prop->val.len;
      break;
    case MQTT_PROP_TYPE_VARIABLE_INT:
      len = decode_varint(i, (size_t) (end - i), (size_t *) &prop->iv);
      if (i + len >= end) return 0;
      new_pos = (len == 0) ? 0 : new_pos + len;
      break;
    default:
      new_pos = 0;
      break;
  }

  return new_pos;
}

void mg_mqtt_login(struct mg_connection *c, const struct mg_mqtt_opts *opts) {
  char client_id[21];
  struct mg_str cid = opts->client_id;
  size_t total_len = 7 + 1 + 2 + 2;
  uint8_t hdr[8] = {0, 4, 'M', 'Q', 'T', 'T', 0, 0};
  hdr[6] = opts->version;

  if (cid.len == 0) {
    mg_random_str(client_id, sizeof(client_id) - 1);
    client_id[sizeof(client_id) - 1] = '\0';
    cid = mg_str(client_id);
  }

  if (hdr[6] == 0) hdr[6] = 4;  // If version is not set, use 4 (3.1.1)
  c->is_mqtt5 = hdr[6] == 5;    // Set version 5 flag
  hdr[7] = (uint8_t) ((opts->qos & 3) << 3);  // Connection flags
  if (opts->user.len > 0) {
    total_len += 2 + (uint32_t) opts->user.len;
    hdr[7] |= MQTT_HAS_USER_NAME;
  }
  if (opts->pass.len > 0) {
    total_len += 2 + (uint32_t) opts->pass.len;
    hdr[7] |= MQTT_HAS_PASSWORD;
  }
  if (opts->topic.len > 0) {  // allow zero-length msgs, message.len is size_t
    total_len += 4 + (uint32_t) opts->topic.len + (uint32_t) opts->message.len;
    hdr[7] |= MQTT_HAS_WILL;
  }
  if (opts->clean || cid.len == 0) hdr[7] |= MQTT_CLEAN_SESSION;
  if (opts->retain) hdr[7] |= MQTT_WILL_RETAIN;
  total_len += (uint32_t) cid.len;
  if (c->is_mqtt5) {
    total_len += get_props_size(opts->props, opts->num_props);
    if (hdr[7] & MQTT_HAS_WILL)
      total_len += get_props_size(opts->will_props, opts->num_will_props);
  }

  // keepalive == 0 means "do not disconnect us!"
  if (!mqtt_send_header(c, MQTT_CMD_CONNECT, 0, (uint32_t) total_len) ||
      !mg_send(c, hdr, sizeof(hdr)) ||
      !mg_send_u16(c, mg_htons((uint16_t) opts->keepalive)))
    goto fail;

  if (c->is_mqtt5 && !mg_send_mqtt_properties(c, opts->props, opts->num_props))
    goto fail;

  if (!mg_send_u16(c, mg_htons((uint16_t) cid.len)) ||
      !mg_send(c, cid.buf, cid.len))
    goto fail;

  if (hdr[7] & MQTT_HAS_WILL) {
    if (c->is_mqtt5 &&
        !mg_send_mqtt_properties(c, opts->will_props, opts->num_will_props))
      goto fail;

    if (!mg_send_u16(c, mg_htons((uint16_t) opts->topic.len)) ||
        !mg_send(c, opts->topic.buf, opts->topic.len) ||
        !mg_send_u16(c, mg_htons((uint16_t) opts->message.len)) ||
        !mg_send(c, opts->message.buf, opts->message.len))
      goto fail;
  }
  if (opts->user.len > 0 &&
      (!mg_send_u16(c, mg_htons((uint16_t) opts->user.len)) ||
       !mg_send(c, opts->user.buf, opts->user.len)))
    goto fail;
  if (opts->pass.len > 0 &&
      (!mg_send_u16(c, mg_htons((uint16_t) opts->pass.len)) ||
       !mg_send(c, opts->pass.buf, opts->pass.len)))
    goto fail;
  return;
fail:
  mg_error(c, "OOM");
}

uint16_t mg_mqtt_pub(struct mg_connection *c, const struct mg_mqtt_opts *opts) {
  uint16_t id = opts->retransmit_id;
  uint8_t flags = (uint8_t) (((opts->qos & 3) << 1) | (opts->retain ? 1 : 0));
  size_t len = 2 + opts->topic.len + opts->message.len;
  MG_DEBUG(("%lu [%.*s] <- [%.*s%c", c->id, (int) opts->topic.len,
            (char *) opts->topic.buf,
            (int) (opts->message.len <= 10 ? opts->message.len : 10),
            (char *) opts->message.buf, opts->message.len <= 10 ? ']' : ' '));
  if (opts->qos > 0) len += 2;
  if (c->is_mqtt5) len += get_props_size(opts->props, opts->num_props);

  if (opts->qos > 0 && id != 0) flags |= 1 << 3;
  if (!mqtt_send_header(c, MQTT_CMD_PUBLISH, flags, (uint32_t) len) ||
      !mg_send_u16(c, mg_htons((uint16_t) opts->topic.len)) ||
      !mg_send(c, opts->topic.buf, opts->topic.len))
    goto fail;
  if (opts->qos > 0) {  // need to send 'id' field
    if (id == 0) {      // generate new one if not resending
      if (++c->mgr->mqtt_id == 0) ++c->mgr->mqtt_id;
      id = c->mgr->mqtt_id;
    }
    if (!mg_send_u16(c, mg_htons(id))) goto fail;
  }

  if (c->is_mqtt5 && !mg_send_mqtt_properties(c, opts->props, opts->num_props))
    goto fail;

  if (opts->message.len > 0 &&
      !mg_send(c, opts->message.buf, opts->message.len))
    goto fail;
  return id;

fail:
  mg_error(c, "OOM");
  return id;
}

static void mg_mqtt_sub_unsub(struct mg_connection *c,
                              const struct mg_mqtt_opts *opts, uint8_t cmd) {
  uint8_t qos_ = opts->qos & 3;
  bool is_sub = cmd == MQTT_CMD_SUBSCRIBE;
  size_t plen = c->is_mqtt5 ? get_props_size(opts->props, opts->num_props) : 0;
  size_t len = 2 + opts->topic.len + 2 + (is_sub ? 1 : 0) + plen;

  if (!mqtt_send_header(c, cmd, 2, (uint32_t) len)) goto fail;
  if (++c->mgr->mqtt_id == 0) ++c->mgr->mqtt_id;
  if (!mg_send_u16(c, mg_htons(c->mgr->mqtt_id))) goto fail;

  if (c->is_mqtt5 && !mg_send_mqtt_properties(c, opts->props, opts->num_props))
    goto fail;

  if (!mg_send_u16(c, mg_htons((uint16_t) opts->topic.len)) ||
      !mg_send(c, opts->topic.buf, opts->topic.len))
    goto fail;
  if (is_sub && !mg_send(c, &qos_, sizeof(qos_))) goto fail;
  return;
fail:
  mg_error(c, "OOM");
}

void mg_mqtt_sub(struct mg_connection *c, const struct mg_mqtt_opts *opts) {
  mg_mqtt_sub_unsub(c, opts, MQTT_CMD_SUBSCRIBE);
}

void mg_mqtt_unsub(struct mg_connection *c, const struct mg_mqtt_opts *opts) {
  mg_mqtt_sub_unsub(c, opts, MQTT_CMD_UNSUBSCRIBE);
}

int mg_mqtt_parse(const uint8_t *buf, size_t len, uint8_t version,
                  struct mg_mqtt_message *m) {
  uint8_t lc = 0, *p, *end;
  uint32_t n = 0, len_len = 0;

  memset(m, 0, sizeof(*m));
  m->dgram.buf = (char *) buf;
  if (len < 2) return MQTT_INCOMPLETE;
  m->cmd = (uint8_t) (buf[0] >> 4);
  m->qos = (buf[0] >> 1) & 3;

  n = len_len = 0;
  p = (uint8_t *) buf + 1;
  while ((size_t) (p - buf) < len) {
    lc = *((uint8_t *) p++);
    n += (uint32_t) ((lc & 0x7f) << 7 * len_len);
    len_len++;
    if (!(lc & 0x80)) break;
    if (len_len >= 4) return MQTT_MALFORMED;
  }
  end = p + n;
  if ((lc & 0x80) || (end > buf + len)) return MQTT_INCOMPLETE;
  m->dgram.len = (size_t) (end - buf);

  switch (m->cmd) {
    case MQTT_CMD_CONNACK:
      if (end - p < 2) return MQTT_MALFORMED;
      m->ack = p[1];
      break;
    case MQTT_CMD_PUBACK:
    case MQTT_CMD_PUBREC:
    case MQTT_CMD_PUBREL:
    case MQTT_CMD_PUBCOMP:
    case MQTT_CMD_SUBSCRIBE:
    case MQTT_CMD_SUBACK:
    case MQTT_CMD_UNSUBSCRIBE:
    case MQTT_CMD_UNSUBACK:
      if (p + 2 > end) return MQTT_MALFORMED;
      m->id = (uint16_t) ((((uint16_t) p[0]) << 8) | p[1]);
      p += 2;
      break;
    case MQTT_CMD_PUBLISH: {
      if (p + 2 > end) return MQTT_MALFORMED;
      m->topic.len = (uint16_t) ((((uint16_t) p[0]) << 8) | p[1]);
      m->topic.buf = (char *) p + 2;
      p += 2 + m->topic.len;
      if (p > end) return MQTT_MALFORMED;
      if (m->qos > 0) {
        if (p + 2 > end) return MQTT_MALFORMED;
        m->id = (uint16_t) ((((uint16_t) p[0]) << 8) | p[1]);
        p += 2;
      }
      if (p > end) return MQTT_MALFORMED;
      if (version == 5 && p + 2 < end) {
        len_len =
            (uint32_t) decode_varint(p, (size_t) (end - p), &m->props_size);
        if (!len_len) return MQTT_MALFORMED;
        m->props_start = (size_t) (p + len_len - buf);
        p += len_len + m->props_size;
      }
      if (p > end) return MQTT_MALFORMED;
      m->data.buf = (char *) p;
      m->data.len = (size_t) (end - p);
      break;
    }
    default: break;
  }
  return MQTT_OK;
}

static void mqtt_cb(struct mg_connection *c, int ev, void *ev_data) {
  if (ev == MG_EV_READ) {
    for (;;) {
      uint8_t version = c->is_mqtt5 ? 5 : 4;
      struct mg_mqtt_message mm;
      int rc = mg_mqtt_parse(c->recv.buf, c->recv.len, version, &mm);
      if (rc == MQTT_MALFORMED) {
        MG_ERROR(("%lu MQTT malformed message", c->id));
        c->is_closing = 1;
        break;
      } else if (rc == MQTT_OK) {
        MG_VERBOSE(("%lu MQTT CMD %d len %d [%.*s]", c->id, mm.cmd,
                    (int) mm.dgram.len, (int) mm.data.len, mm.data.buf));
        switch (mm.cmd) {
          case MQTT_CMD_CONNACK:
            mg_call(c, MG_EV_MQTT_OPEN, &mm.ack);
            if (mm.ack == 0) {
              MG_DEBUG(("%lu Connected", c->id));
            } else {
              MG_ERROR(("%lu MQTT auth failed, code %d", c->id, mm.ack));
              c->is_closing = 1;
            }
            break;
          case MQTT_CMD_PUBLISH: {
            MG_DEBUG(("%lu [%.*s] -> [%.*s%c", c->id, (int) mm.topic.len,
                      mm.topic.buf,
                      (int) (mm.data.len <= 10 ? mm.data.len : 10), mm.data.buf,
                      mm.data.len <= 10 ? ']' : ' '));
            if (mm.qos > 0) {
              uint16_t id = mg_ntohs(mm.id);
              uint32_t remaining_len = sizeof(id);
              if (c->is_mqtt5) remaining_len += 2;  // 3.4.2

              if (!mqtt_send_header(c,
                                    (uint8_t) (mm.qos == 2 ? MQTT_CMD_PUBREC
                                                           : MQTT_CMD_PUBACK),
                                    0, remaining_len) ||
                  !mg_send(c, &id, sizeof(id)))
                goto fail;

              if (c->is_mqtt5) {
                uint16_t zero = 0;
                if (!mg_send(c, &zero, sizeof(zero))) goto fail;
              }
            }
            mg_call(c, MG_EV_MQTT_MSG, &mm);  // let the app handle qos stuff
            break;
          }
          case MQTT_CMD_PUBREC: {  // MQTT5: 3.5.2-1 TODO(): variable header rc
            uint16_t id = mg_ntohs(mm.id);
            uint32_t remaining_len = sizeof(id);  // MQTT5 3.6.2-1
            if (!mqtt_send_header(c, MQTT_CMD_PUBREL, 2,
                                  remaining_len)  // MQTT5 3.6.1-1, flags = 2
                || !mg_send(c, &id, sizeof(id)))
              goto fail;
            break;
          }
          case MQTT_CMD_PUBREL: {  // MQTT5: 3.6.2-1 TODO(): variable header rc
            uint16_t id = mg_ntohs(mm.id);
            uint32_t remaining_len = sizeof(id);  // MQTT5 3.7.2-1
            if (!mqtt_send_header(c, MQTT_CMD_PUBCOMP, 0, remaining_len) ||
                !mg_send(c, &id, sizeof(id)))
              goto fail;
            break;
          }
        }
        mg_call(c, MG_EV_MQTT_CMD, &mm);
        mg_iobuf_del(&c->recv, 0, mm.dgram.len);
      } else {
        break;
      }
    }
  }
  (void) ev_data;
  return;
fail:
  mg_error(c, "OOM");
}

void mg_mqtt_ping(struct mg_connection *nc) {
  mg_mqtt_send_header(nc, MQTT_CMD_PINGREQ, 0, 0);
}

void mg_mqtt_pong(struct mg_connection *nc) {
  mg_mqtt_send_header(nc, MQTT_CMD_PINGRESP, 0, 0);
}

void mg_mqtt_disconnect(struct mg_connection *c,
                        const struct mg_mqtt_opts *opts) {
  size_t len = 0;
  if (c->is_mqtt5) len = 1 + get_props_size(opts->props, opts->num_props);
  if (!mqtt_send_header(c, MQTT_CMD_DISCONNECT, 0, (uint32_t) len)) goto fail;

  if (c->is_mqtt5) {
    uint8_t zero = 0;
    if (!mg_send(c, &zero, sizeof(zero))  // reason code
        || !mg_send_mqtt_properties(c, opts->props, opts->num_props))
      goto fail;
  }
  return;
fail:
  mg_error(c, "OOM");
}

struct mg_connection *mg_mqtt_connect(struct mg_mgr *mgr, const char *url,
                                      const struct mg_mqtt_opts *opts,
                                      mg_event_handler_t fn, void *fn_data) {
  struct mg_connection *c =
      mg_connect_svc(mgr, url, fn, fn_data, mqtt_cb, NULL);
  if (c != NULL) {
    struct mg_mqtt_opts empty;
    memset(&empty, 0, sizeof(empty));
    mg_mqtt_login(c, opts == NULL ? &empty : opts);
  }
  return c;
}

struct mg_connection *mg_mqtt_listen(struct mg_mgr *mgr, const char *url,
                                     mg_event_handler_t fn, void *fn_data) {
  struct mg_connection *c = mg_listen(mgr, url, fn, fn_data);
  if (c != NULL) c->pfn = mqtt_cb, c->pfn_data = mgr;
  return c;
}

#ifdef MG_ENABLE_LINES
#line 1 "src/net.c"
#endif









size_t mg_vprintf(struct mg_connection *c, const char *fmt, va_list *ap) {
  size_t old = c->send.len;
  size_t expected = mg_vxprintf(mg_pfn_iobuf, &c->send, fmt, ap);
  size_t actual = c->send.len - old;
  if (actual != expected) {
    mg_error(c, "OOM");
    c->send.len = old;
    actual = 0;
  }
  return actual;
}

size_t mg_printf(struct mg_connection *c, const char *fmt, ...) {
  size_t len = 0;
  va_list ap;
  va_start(ap, fmt);
  len = mg_vprintf(c, fmt, &ap);
  va_end(ap);
  return len;
}

static bool mg_atonl(struct mg_str str, struct mg_addr *addr) {
  uint32_t localhost = mg_htonl(0x7f000001);
  if (mg_strcasecmp(str, mg_str("localhost")) != 0) return false;
  memcpy(addr->addr.ip, &localhost, sizeof(uint32_t));
  addr->is_ip6 = false;
  return true;
}

static bool mg_atone(struct mg_str str, struct mg_addr *addr) {
  if (str.len > 0) return false;
  memset(addr->addr.ip, 0, sizeof(addr->addr.ip));
  addr->is_ip6 = false;
  return true;
}

static bool mg_aton4(struct mg_str str, struct mg_addr *addr) {
  uint8_t data[4] = {0, 0, 0, 0};
  size_t i, num_dots = 0;
  for (i = 0; i < str.len; i++) {
    if (str.buf[i] >= '0' && str.buf[i] <= '9') {
      int octet = data[num_dots] * 10 + (str.buf[i] - '0');
      if (octet > 255) return false;
      data[num_dots] = (uint8_t) octet;
    } else if (str.buf[i] == '.') {
      if (num_dots >= 3 || i == 0 || str.buf[i - 1] == '.') return false;
      num_dots++;
    } else {
      return false;
    }
  }
  if (num_dots != 3 || str.buf[i - 1] == '.') return false;
  memcpy(&addr->addr.ip, data, sizeof(data));
  addr->is_ip6 = false;
  return true;
}

static bool mg_v4mapped(struct mg_str str, struct mg_addr *addr) {
  int i;
  uint32_t ipv4;
  if (str.len < 14) return false;
  if (str.buf[0] != ':' || str.buf[1] != ':' || str.buf[6] != ':') return false;
  for (i = 2; i < 6; i++) {
    if (str.buf[i] != 'f' && str.buf[i] != 'F') return false;
  }
  // struct mg_str s = mg_str_n(&str.buf[7], str.len - 7);
  if (!mg_aton4(mg_str_n(&str.buf[7], str.len - 7), addr)) return false;
  memcpy(&ipv4, addr->addr.ip, sizeof(ipv4));
  memset(addr->addr.ip, 0, sizeof(addr->addr.ip));
  addr->addr.ip[10] = addr->addr.ip[11] = 255;
  memcpy(&addr->addr.ip[12], &ipv4, 4);
  addr->is_ip6 = true;
  return true;
}

static bool mg_aton6(struct mg_str str, struct mg_addr *addr) {
  size_t i, j = 0, n = 0, dc = 42;
  addr->scope_id = 0;
  if (str.len > 2 && str.buf[0] == '[') str.buf++, str.len -= 2;
  if (mg_v4mapped(str, addr)) return true;  // sets addr->is_ip6
  for (i = 0; i < str.len; i++) {
    if ((str.buf[i] >= '0' && str.buf[i] <= '9') ||
        (str.buf[i] >= 'a' && str.buf[i] <= 'f') ||
        (str.buf[i] >= 'A' && str.buf[i] <= 'F')) {
      unsigned long val = 0;  // TODO(): This loops on chars, refactor
      if (i > j + 3) return false;
      // MG_DEBUG(("%lu %lu [%.*s]", i, j, (int) (i - j + 1), &str.buf[j]));
      mg_str_to_num(mg_str_n(&str.buf[j], i - j + 1), 16, &val, sizeof(val));
      addr->addr.ip[n] = (uint8_t) ((val >> 8) & 255);
      addr->addr.ip[n + 1] = (uint8_t) (val & 255);
    } else if (str.buf[i] == ':') {
      j = i + 1;
      if (i > 0 && str.buf[i - 1] == ':') {
        dc = n;  // Double colon
        if (i > 1 && str.buf[i - 2] == ':') return false;
      } else if (i > 0) {
        n += 2;
      }
      if (n > 14) return false;
      addr->addr.ip[n] = addr->addr.ip[n + 1] = 0;  // For trailing ::
    } else if (str.buf[i] == '%') {                 // Scope ID, last in string
      if (mg_str_to_num(mg_str_n(&str.buf[i + 1], str.len - i - 1), 10,
                        &addr->scope_id, sizeof(uint8_t))) {
        addr->is_ip6 = true;
        return true;
      } else {
        return false;
      }
    } else {
      return false;
    }
  }
  if (n < 14 && dc == 42) return false;
  if (n < 14) {
    memmove(&addr->addr.ip[dc + (14 - n)], &addr->addr.ip[dc], n - dc + 2);
    memset(&addr->addr.ip[dc], 0, 14 - n);
  }

  addr->is_ip6 = true;
  return true;
}

bool mg_aton(struct mg_str str, struct mg_addr *addr) {
  // MG_INFO(("[%.*s]", (int) str.len, str.buf));
  return mg_atone(str, addr) || mg_atonl(str, addr) || mg_aton4(str, addr) ||
         mg_aton6(str, addr);
}

struct mg_connection *mg_alloc_conn(struct mg_mgr *mgr) {
  struct mg_connection *c =
      (struct mg_connection *) mg_calloc(1, sizeof(*c) + mgr->extraconnsize);
  if (c != NULL) {
    c->mgr = mgr;
    c->send.align = c->recv.align = c->rtls.align = MG_IO_SIZE;
    c->id = ++mgr->nextid;
    MG_PROF_INIT(c);
  }
  return c;
}

void mg_close_conn(struct mg_connection *c) {
  mg_resolve_cancel(c);  // Close any pending DNS query
  LIST_DELETE(struct mg_connection, &c->mgr->conns, c);
  if (c == c->mgr->dns4.c) c->mgr->dns4.c = NULL;
  if (c == c->mgr->dns6.c) c->mgr->dns6.c = NULL;
  // Order of operations is important. `MG_EV_CLOSE` event must be fired
  // before we deallocate received data, see #1331
  mg_call(c, MG_EV_CLOSE, NULL);
  MG_DEBUG(("%lu %ld closed", c->id, c->fd));
  MG_PROF_DUMP(c);
  MG_PROF_FREE(c);

  mg_tls_free(c);
  mg_iobuf_free(&c->recv);
  mg_iobuf_free(&c->send);
  mg_iobuf_free(&c->rtls);
  mg_bzero((unsigned char *) c, sizeof(*c));
  mg_free(c);
}

struct mg_connection *mg_connect_svc(struct mg_mgr *mgr, const char *url,
                                     mg_event_handler_t fn, void *fn_data,
                                     mg_event_handler_t pfn, void *pfn_data) {
  struct mg_connection *c = NULL;
  if (url == NULL || url[0] == '\0') {
    MG_ERROR(("null url"));
#if MG_ENABLE_TCPIP
  } else if (mgr->ifp != NULL && mgr->ifp->state != MG_TCPIP_STATE_READY) {
    MG_ERROR(("Network is down"));
#endif
  } else if ((c = mg_alloc_conn(mgr)) == NULL) {
    MG_ERROR(("OOM"));
  } else {
    LIST_ADD_HEAD(struct mg_connection, &mgr->conns, c);
    c->is_udp = (strncmp(url, "udp:", 4) == 0);
    c->fd = (void *) (size_t) MG_INVALID_SOCKET;
    c->fn = fn;
    c->is_client = true;
    c->fn_data = fn_data;
    c->is_tls = (mg_url_is_ssl(url) != 0);
    c->pfn = pfn;
    c->pfn_data = pfn_data;
    mg_call(c, MG_EV_OPEN, (void *) url);
    MG_DEBUG(("%lu %ld %s", c->id, c->fd, url));
    mg_resolve(c, url);
  }
  return c;
}

struct mg_connection *mg_connect(struct mg_mgr *mgr, const char *url,
                                 mg_event_handler_t fn, void *fn_data) {
  return mg_connect_svc(mgr, url, fn, fn_data, NULL, NULL);
}

struct mg_connection *mg_listen(struct mg_mgr *mgr, const char *url,
                                mg_event_handler_t fn, void *fn_data) {
  struct mg_connection *c = NULL;
  if ((c = mg_alloc_conn(mgr)) == NULL) {
    MG_ERROR(("OOM %s", url));
  } else if (!mg_open_listener(c, url)) {
    MG_ERROR(("Failed: %s", url));
    MG_PROF_FREE(c);
    mg_free(c);
    c = NULL;
  } else {
    c->is_listening = 1;
    c->is_udp = strncmp(url, "udp:", 4) == 0;
    LIST_ADD_HEAD(struct mg_connection, &mgr->conns, c);
    c->fn = fn;
    c->fn_data = fn_data;
    c->is_tls = (mg_url_is_ssl(url) != 0);
    mg_call(c, MG_EV_OPEN, NULL);
    MG_DEBUG(("%lu %ld %s", c->id, c->fd, url));
  }
  return c;
}

struct mg_connection *mg_wrapfd(struct mg_mgr *mgr, int fd,
                                mg_event_handler_t fn, void *fn_data) {
  struct mg_connection *c = mg_alloc_conn(mgr);
  if (c != NULL) {
    c->fd = (void *) (size_t) fd;
    c->fn = fn;
    c->fn_data = fn_data;
    MG_EPOLL_ADD(c);
    mg_call(c, MG_EV_OPEN, NULL);
    LIST_ADD_HEAD(struct mg_connection, &mgr->conns, c);
  }
  return c;
}

struct mg_timer *mg_timer_add(struct mg_mgr *mgr, uint64_t milliseconds,
                              unsigned flags, void (*fn)(void *), void *arg) {
  struct mg_timer *t = (struct mg_timer *) mg_calloc(1, sizeof(*t));
  if (t != NULL) {
    flags |= MG_TIMER_AUTODELETE;  // We have alloc'ed it, so autodelete
    mg_timer_init(&mgr->timers, t, milliseconds, flags, fn, arg);
  }
  return t;
}

long mg_io_recv(struct mg_connection *c, void *buf, size_t len) {
  if (c->rtls.len == 0) return MG_IO_WAIT;
  if (len > c->rtls.len) len = c->rtls.len;
  memcpy(buf, c->rtls.buf, len);
  mg_iobuf_del(&c->rtls, 0, len);
  return (long) len;
}

void mg_mgr_free(struct mg_mgr *mgr) {
  struct mg_connection *c;
  struct mg_timer *tmp, *t = mgr->timers;
  while (t != NULL) tmp = t->next, mg_free(t), t = tmp;
  mgr->timers = NULL;  // Important. Next call to poll won't touch timers
  for (c = mgr->conns; c != NULL; c = c->next) c->is_closing = 1;
  mg_mgr_poll(mgr, 0);
#if MG_ENABLE_FREERTOS_TCP
  FreeRTOS_DeleteSocketSet(mgr->ss);
#endif
  MG_DEBUG(("All connections closed"));
#if MG_ENABLE_EPOLL
  if (mgr->epoll_fd >= 0) close(mgr->epoll_fd), mgr->epoll_fd = -1;
#endif
  mg_tls_ctx_free(mgr);
#if MG_ENABLE_TCPIP
  if (mgr->ifp) mg_tcpip_free(mgr->ifp);
#endif
}

void mg_mgr_init(struct mg_mgr *mgr) {
  memset(mgr, 0, sizeof(*mgr));
#if MG_ENABLE_EPOLL
  if ((mgr->epoll_fd = epoll_create1(EPOLL_CLOEXEC)) < 0)
    MG_ERROR(("epoll_create1 errno %d", errno));
#else
  mgr->epoll_fd = -1;
#endif
#if MG_ARCH == MG_ARCH_WIN32 && MG_ENABLE_WINSOCK
  // clang-format off
  { WSADATA data; WSAStartup(MAKEWORD(2, 2), &data); }
  // clang-format on
#elif MG_ENABLE_FREERTOS_TCP
  mgr->ss = FreeRTOS_CreateSocketSet();
#elif MG_ARCH == MG_ARCH_UNIX
  // Ignore SIGPIPE signal, so if client cancels the request, it
  // won't kill the whole process.
  signal(SIGPIPE, SIG_IGN);
#elif MG_ENABLE_TCPIP_DRIVER_INIT && defined(MG_TCPIP_DRIVER_INIT)
  MG_TCPIP_DRIVER_INIT(mgr);
#endif
  mgr->pipe = MG_INVALID_SOCKET;
  mgr->dnstimeout = 3000;
  mgr->dns4.url = "udp://8.8.8.8:53";
  mgr->dns6.url = "udp://[2001:4860:4860::8888]:53";
  mg_tls_ctx_init(mgr);
  MG_DEBUG(("MG_IO_SIZE: %lu, TLS: %s", MG_IO_SIZE,
            MG_TLS == MG_TLS_NONE      ? "none"
            : MG_TLS == MG_TLS_MBED    ? "MbedTLS"
            : MG_TLS == MG_TLS_OPENSSL ? "OpenSSL"
            : MG_TLS == MG_TLS_BUILTIN ? "builtin"
            : MG_TLS == MG_TLS_WOLFSSL ? "WolfSSL"
                                       : "custom"));
}

#if MG_ENABLE_TCPIP
void mg_tcpip_mapip(struct mg_connection *, struct mg_addr *);
#endif
void mg_multicast_restore(struct mg_connection *c, uint8_t *from) {
  memcpy(&c->rem, from, sizeof(c->rem));
#if MG_ENABLE_TCPIP
  mg_tcpip_mapip(c, &c->rem);
#endif
}

#ifdef MG_ENABLE_LINES
#line 1 "src/net_builtin.c"
#endif



#if MG_ENABLE_TCPIP
#define MG_EPHEMERAL_PORT_BASE 32768
#define PDIFF(a, b) ((size_t) (((char *) (b)) - ((char *) (a))))

#ifndef MG_TCPIP_KEEPALIVE_MS
#define MG_TCPIP_KEEPALIVE_MS 45000  // TCP keep-alive period, ms
#endif

#define MG_TCPIP_ACK_MS 150    // Timeout for ACKing
#define MG_TCPIP_ARP_MS 100    // Timeout for ARP response
#define MG_TCPIP_SYN_MS 15000  // Timeout for connection establishment
#define MG_TCPIP_FIN_MS 1000   // Timeout for closing connection

#ifndef MG_TCPIP_WIN
#define MG_TCPIP_WIN 6000  // TCP window size
#endif

struct connstate {
  uint32_t seq, ack;                      // TCP seq/ack counters
  uint64_t timer;                         // TCP timer (see 'ttype' below)
  uint32_t acked;                         // Last ACK-ed number
  size_t unacked;                         // Not acked bytes
  uint16_t dmss;                          // destination MSS (from TCP opts)
  uint8_t mac[sizeof(struct mg_l2addr)];  // Peer hw address
  uint8_t ttype;                          // Timer type:
#define MIP_TTYPE_KEEPALIVE 0  // Connection is idle for long, send keepalive
#define MIP_TTYPE_ACK 1        // Peer sent us data, we have to ack it soon
#define MIP_TTYPE_ARP 2        // ARP resolve sent, waiting for response
#define MIP_TTYPE_SYN 3        // SYN sent, waiting for response
#define MIP_TTYPE_FIN 4  // FIN sent, waiting until terminating the connection
  uint8_t tmiss;         // Number of keep-alive misses
  struct mg_iobuf raw;   // For TLS only. Incoming raw data
  bool fin_rcvd;         // We have received FIN from the peer
  bool twclosure;        // 3-way closure done
};

#if defined(__DCC__)
#pragma pack(1)
#else
#pragma pack(push, 1)
#endif

struct ip {
  uint8_t ver;    // Version
  uint8_t tos;    // Unused
  uint16_t len;   // Datagram length
  uint16_t id;    // Unused
  uint16_t frag;  // Fragmentation
#define IP_FRAG_OFFSET_MSK 0x1fff
#define IP_MORE_FRAGS_MSK 0x2000
  uint8_t ttl;    // Time to live
  uint8_t proto;  // Upper level protocol
  uint16_t csum;  // Checksum
  uint32_t src;   // Source IP
  uint32_t dst;   // Destination IP
};

struct ip6 {
  uint8_t ver;       // Version
  uint8_t label[3];  // Flow label
  uint16_t plen;     // Payload length
  uint8_t next;      // Upper level protocol
  uint8_t hops;      // Hop limit
  uint64_t src[2];   // Source IP
  uint64_t dst[2];   // Destination IP
};

struct icmp {
  uint8_t type;
  uint8_t code;
  uint16_t csum;
};

struct icmp6 {
  uint8_t type;
  uint8_t code;
  uint16_t csum;
};

struct ndp_na {
  uint8_t res[4];    // R S O, reserved
  uint64_t addr[2];  // Target address
};

struct ndp_ra {
  uint8_t cur_hop_limit;
  uint8_t flags;  // M,O,Prf,Resvd
  uint16_t router_lifetime;
  uint32_t reachable_time;
  uint32_t retrans_timer;
};

struct arp {
  uint16_t fmt;    // Format of hardware address
  uint16_t pro;    // Format of protocol address
  uint8_t hlen;    // Length of hardware address
  uint8_t plen;    // Length of protocol address
  uint16_t op;     // Operation
  uint8_t sha[6];  // Sender hardware address
  uint32_t spa;    // Sender protocol address
  uint8_t tha[6];  // Target hardware address
  uint32_t tpa;    // Target protocol address
};

struct tcp {
  uint16_t sport;  // Source port
  uint16_t dport;  // Destination port
  uint32_t seq;    // Sequence number
  uint32_t ack;    // Acknowledgement number
  uint8_t off;     // Data offset
  uint8_t flags;   // TCP flags
#define TH_FIN 0x01
#define TH_SYN 0x02
#define TH_RST 0x04
#define TH_PUSH 0x08
#define TH_ACK 0x10
#define TH_URG 0x20
#define TH_STDFLAGS 0x3f
  // #define TH_ECE 0x40 // not part of TCP but RFC-3168 (ECN)
  // #define TH_CWR 0x80
  uint16_t win;   // Window
  uint16_t csum;  // Checksum
  uint16_t urp;   // Urgent pointer
};

struct udp {
  uint16_t sport;  // Source port
  uint16_t dport;  // Destination port
  uint16_t len;    // UDP length
  uint16_t csum;   // UDP checksum
};

struct dhcp {
  uint8_t op, htype, hlen, hops;
  uint32_t xid;
  uint16_t secs, flags;
  uint32_t ciaddr, yiaddr, siaddr, giaddr;
  uint8_t hwaddr[208];
  uint32_t magic;
  uint8_t options[30 + sizeof(((struct mg_tcpip_if *) 0)->dhcp_name)];
};

struct dhcp6 {
  union {
    uint8_t type;
    uint32_t xid;
  };
  uint8_t options[30 + sizeof(((struct mg_tcpip_if *) 0)->dhcp_name)];
};

struct pseudoip {
  uint32_t src;  // Source IP
  uint32_t dst;  // Destination IP
  uint8_t zero;
  uint8_t proto;  // Upper level protocol
  uint16_t len;   // Datagram length
};

struct pseudoip6 {
  uint64_t src[2];  // Source IP
  uint64_t dst[2];  // Destination IP
  uint32_t plen;    // Payload length
  uint8_t zero[3];
  uint8_t next;  // Upper level protocol
};

#if defined(__DCC__)
#pragma pack(0)
#else
#pragma pack(pop)
#endif

// pkt is 8-bit aligned, pointers to headers hint compilers to generate
// byte-copy code for micros with alignment constraints
struct pkt {
  struct mg_str raw;  // Raw packet data
  struct mg_str pay;  // Payload data
  uint8_t *l2;        // Ethernet, PPP [, etc] frame data
  struct arp *arp;
  struct ip *ip;
  struct ip6 *ip6;
  struct icmp *icmp;
  struct icmp6 *icmp6;
  struct tcp *tcp;
  struct udp *udp;
  struct dhcp *dhcp;
  struct dhcp6 *dhcp6;
};

// L2 API
void mg_l2_init(enum mg_l2type type, uint8_t *addr, uint16_t *mtu,
                uint16_t *framesize);
uint8_t *mg_l2_header(enum mg_l2type type, enum mg_l2proto proto, uint8_t *src,
                      uint8_t *dst, uint8_t *frame);
size_t mg_l2_footer(enum mg_l2type type, size_t len, uint8_t *frame);
bool mg_l2_rx(struct mg_tcpip_if *ifp, enum mg_l2proto *proto,
              struct mg_str *pay, struct mg_str *raw);
uint8_t *mg_l2_getaddr(enum mg_l2type type, uint8_t *frame);
uint8_t *mg_l2_mapip(enum mg_l2type type, enum mg_l2addrtype addrtype,
                     struct mg_addr *ip);
#if MG_ENABLE_IPV6
bool mg_l2_genip6(enum mg_l2type type, uint64_t *ip6, uint8_t prefix_len,
                  uint8_t *addr);
bool mg_l2_ip6get(enum mg_l2type type, uint8_t *addr, uint8_t *opts,
                  uint8_t len);
uint8_t mg_l2_ip6put(enum mg_l2type type, uint8_t *addr, uint8_t *opts);
#endif

static void mg_tcpip_call(struct mg_tcpip_if *ifp, int ev, void *ev_data) {
#if MG_ENABLE_PROFILE
  const char *names[] = {"TCPIP_EV_ST_CHG",        "TCPIP_EV_DHCP_DNS",
                         "TCPIP_EV_DHCP_SNTP",     "TCPIP_EV_ARP",
                         "TCPIP_EV_TIMER_1S",      "TCPIP_EV_WIFI_SCAN_RESULT",
                         "TCPIP_EV_WIFI_SCAN_END", "TCPIP_EV_WIFI_CONNECT_ERR",
                         "TCPIP_EV_DRIVER",        "TCPIP_EV_USER"};
  if (ev != MG_TCPIP_EV_POLL && ev < (int) (sizeof(names) / sizeof(names[0]))) {
    MG_PROF_ADD(c, names[ev]);
  }
#endif
  // Fire protocol handler first, user handler second. See #2559
  if (ifp->pfn != NULL) ifp->pfn(ifp, ev, ev_data);
  if (ifp->fn != NULL) ifp->fn(ifp, ev, ev_data);
}

static void send_syn(struct mg_connection *c);

static void mkpay(struct pkt *pkt, void *p) {
  pkt->pay =
      mg_str_n((char *) p, (size_t) (&pkt->pay.buf[pkt->pay.len] - (char *) p));
}

// NOTE(): DOES NOT handle reentries after odd length, use last
static uint32_t csumup(uint32_t sum, const void *buf, size_t len) {
  size_t i;
  const uint8_t *p = (const uint8_t *) buf;
  for (i = 0; i < len; i++) sum += i & 1 ? p[i] : ((uint32_t) p[i]) << 8;
  return sum;
}

static uint16_t csumfin(uint32_t sum) {
  while (sum >> 16) sum = (sum & 0xffff) + (sum >> 16);
  return mg_htons((uint16_t) ((uint16_t) ~sum & 0xffff));
}

static uint16_t ipcsum(const void *buf, size_t len) {
  uint32_t sum = csumup(0, buf, len);
  return csumfin(sum);
}

static bool ipcsum_ok(const void *d) {
  struct ip *ip = (struct ip *) d;
  return (ipcsum(d, (ip->ver & 0x0F) * 4) == 0);
}

static bool icmpcsum_ok(const void *d, size_t len) {
  return (ipcsum(d, len) == 0);
}

static uint16_t pcsum(void *d, void *p, size_t plen) {
  uint32_t sum;
  struct ip *ip = (struct ip *) d;
#if defined(__DCC__)
  volatile  /* Makes PPC & Diab4.3 happy */
#endif
  struct pseudoip pip;
  pip.src = ip->src;
  pip.dst = ip->dst;
  pip.zero = 0;
  pip.proto = ip->proto;
  pip.len = mg_htons((uint16_t) plen);
  sum = csumup(0, &pip, sizeof(pip));  // even length
  sum = csumup(sum, p, plen);          // possibly odd length: last
  return csumfin(sum);
}

static bool udpcsum_ok(void *d, void *u) {
  struct udp *udp = (struct udp *) u;
  if (udp->csum == 0) return true;
  if (udp->csum == 0xFFFF) udp->csum = 0;
  return (pcsum(d, u, (size_t) mg_ntohs(udp->len)) == 0);
}

static bool tcpcsum_ok(void *d, void *t) {
  struct ip *ip = (struct ip *) d;
  return (pcsum(d, t, (size_t) (mg_ntohs(ip->len) - (ip->ver & 0x0F) * 4)) ==
          0);
}

#if MG_ENABLE_IPV6
static uint16_t p6csum(void *d, void *p, size_t plen) {
  uint32_t sum;
  struct ip6 *ip6 = (struct ip6 *) d;
#if defined(__DCC__)
  volatile  /* Makes PPC & Diab4.3 happy */
#endif
  struct pseudoip6 pip6;
  pip6.src[0] = ip6->src[0], pip6.src[1] = ip6->src[1];
  pip6.dst[0] = ip6->dst[0], pip6.dst[1] = ip6->dst[1];
  pip6.zero[0] = 0, pip6.zero[1] = 0, pip6.zero[2] = 0;
  pip6.plen = mg_htonl((uint32_t) plen);
  pip6.next = ip6->next;
  sum = csumup(0, &pip6, sizeof(pip6));  // even length
  sum = csumup(sum, p, plen);            // possibly odd length: last
  return csumfin(sum);
}

static bool udp6csum_ok(void *d, void *u) {
  struct udp *udp = (struct udp *) u;
  if (udp->csum == 0) return false;  // mandatory in IPv6
  if (udp->csum == 0xFFFF) udp->csum = 0;
  return (p6csum(d, u, (size_t) mg_ntohs(udp->len)) == 0);
}
static bool tcp6csum_ok(void *d, void *t) {
  struct ip6 *ip6 = (struct ip6 *) d;
  return (p6csum(d, t, (size_t) mg_ntohs(ip6->plen)) == 0);
}
static bool icmp6csum_ok(void *d, void *i) {
  struct ip6 *ip6 = (struct ip6 *) d;
  return (p6csum(d, i, (size_t) mg_ntohs(ip6->plen)) == 0);
}

static void ip6sn(uint64_t *addr, uint64_t *sn_addr) {
  // Build solicited-node multicast address from a given unicast IP
  // RFC-4291 2.7
  uint8_t *sn = (uint8_t *) sn_addr;
  memset(sn_addr, 0, 16);
  sn[0] = 0xff;
  sn[1] = 0x02;
  sn[11] = 0x01;
  sn[12] = 0xff;
  sn[13] = ((uint8_t *) addr)[13];
  sn[14] = ((uint8_t *) addr)[14];
  sn[15] = ((uint8_t *) addr)[15];
}

static const struct mg_addr ip6_allrouters = {
    {{0xFF, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x02}}, 0, 0, true};
static const struct mg_addr ip6_allnodes = {
    {{0xFF, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x01}}, 0, 0, true};

#define MG_IP6MATCH(a, b) (a[0] == b[0] && a[1] == b[1])
#endif

static void settmout(struct mg_connection *c, uint8_t type) {
  struct mg_tcpip_if *ifp = c->mgr->ifp;
  struct connstate *s = (struct connstate *) (c + 1);
  unsigned n = type == MIP_TTYPE_ACK   ? MG_TCPIP_ACK_MS
               : type == MIP_TTYPE_ARP ? MG_TCPIP_ARP_MS
               : type == MIP_TTYPE_SYN ? MG_TCPIP_SYN_MS
               : type == MIP_TTYPE_FIN ? MG_TCPIP_FIN_MS
                                       : MG_TCPIP_KEEPALIVE_MS;
  if (s->ttype == MIP_TTYPE_FIN) return;  // skip if 3-way closing
  s->timer = ifp->now + n;
  s->ttype = type;
  MG_VERBOSE(("%lu %d -> %llx", c->id, type, s->timer));
}

static size_t driver_output(struct mg_tcpip_if *ifp, size_t len) {
  size_t n = ifp->driver->tx(ifp->tx.buf, len, ifp);
  if (n == len) ifp->nsent++;
  return n;
}

// RFC826, ARP assumes Ethernet MAC addresses
void mg_tcpip_arp_request(struct mg_tcpip_if *ifp, uint32_t ip, uint8_t *mac) {
  uint8_t *l2p = (uint8_t *) ifp->tx.buf;
  struct arp *arp = (struct arp *) mg_l2_header(
      ifp->l2type, MG_TCPIP_L2PROTO_ARP, ifp->mac,
      mg_l2_mapip(ifp->l2type, MG_TCPIP_L2ADDR_BCAST, NULL), l2p);
  memset(arp, 0, sizeof(*arp));
  arp->fmt = mg_htons(1), arp->pro = mg_htons(0x800), arp->hlen = 6,
  arp->plen = 4;
  arp->op = mg_htons(1), arp->tpa = ip, arp->spa = ifp->ip;
  memcpy(arp->sha, ifp->mac, sizeof(arp->sha));
  if (mac != NULL) memcpy(arp->tha, mac, sizeof(arp->tha));
  driver_output(ifp, mg_l2_footer(ifp->l2type, PDIFF(l2p, arp + 1), l2p));
}

static void onstatechange(struct mg_tcpip_if *ifp) {
  if (ifp->state == MG_TCPIP_STATE_READY) {
    MG_INFO(("READY, IP: %M", mg_print_ip4, &ifp->ip));
    MG_INFO(("       GW: %M", mg_print_ip4, &ifp->gw));
    if (ifp->l2type == MG_TCPIP_L2_ETH)  // TODO(): print other l2
      MG_INFO(("      MAC: %M", mg_print_mac, ifp->mac));
  } else if (ifp->state == MG_TCPIP_STATE_IP) {
    if (ifp->gw != 0)
      mg_tcpip_arp_request(ifp, ifp->gw, NULL);  // unsolicited GW ARP request
  } else if (ifp->state == MG_TCPIP_STATE_UP) {
    srand((unsigned int) mg_millis());
  } else if (ifp->state == MG_TCPIP_STATE_DOWN) {
    MG_ERROR(("Link down"));
  }
  mg_tcpip_call(ifp, MG_TCPIP_EV_ST_CHG, &ifp->state);
}

static struct ip *tx_ip(struct mg_tcpip_if *ifp, uint8_t *l2_dst, uint8_t proto,
                        uint32_t ip_src, uint32_t ip_dst, size_t plen) {
  // ifp->tx.buf is 8-bit aligned, keep other headers as pointers, see pkt
  uint8_t *l2p = (uint8_t *) ifp->tx.buf;
  struct ip *ip = (struct ip *) mg_l2_header(ifp->l2type, MG_TCPIP_L2PROTO_IPV4,
                                             ifp->mac, l2_dst, l2p);
  memset(ip, 0, sizeof(*ip));
  ip->ver = 0x45;               // Version 4, header length 5 words
  ip->frag = mg_htons(0x4000);  // Don't fragment
  ip->len = mg_htons((uint16_t) (sizeof(*ip) + plen));
  ip->ttl = 64;
  ip->proto = proto;
  ip->src = ip_src;
  ip->dst = ip_dst;
  ip->csum = ipcsum(ip, sizeof(*ip));
  return ip;
}

#if MG_ENABLE_IPV6
static struct ip6 *tx_ip6(struct mg_tcpip_if *ifp, uint8_t *l2_dst,
                          uint8_t next, uint64_t *ip_src, uint64_t *ip_dst,
                          size_t plen);
#endif

static bool tx_udp(struct mg_tcpip_if *ifp, uint8_t *l2_dst,
                   struct mg_addr *ip_src, struct mg_addr *ip_dst,
                   const void *buf, size_t len) {
  uint8_t *l2p = (uint8_t *) ifp->tx.buf;
  size_t l2_len;
  struct ip *ip = NULL;
  struct udp *udp;
#if MG_ENABLE_IPV6
  struct ip6 *ip6 = NULL;
  if (ip_dst->is_ip6) {
    ip6 = tx_ip6(ifp, l2_dst, 17, ip_src->addr.ip6, ip_dst->addr.ip6,
                 len + sizeof(struct udp));
    udp = (struct udp *) (ip6 + 1);
    l2_len = sizeof(*ip6) + sizeof(*udp) + len;
  } else
#endif
  {
    ip = tx_ip(ifp, l2_dst, 17, ip_src->addr.ip4, ip_dst->addr.ip4,
               len + sizeof(struct udp));
    udp = (struct udp *) (ip + 1);
    l2_len = sizeof(*ip) + sizeof(*udp) + len;
  }
  udp->sport = ip_src->port;
  udp->dport = ip_dst->port;
  udp->len = mg_htons((uint16_t) (sizeof(*udp) + len));
  udp->csum = 0;
  memmove(udp + 1, buf, len);
#if MG_ENABLE_IPV6
  if (ip_dst->is_ip6) {
    udp->csum = p6csum(ip6, udp, sizeof(*udp) + len);
  } else
#endif
  {
    udp->csum = pcsum(ip, udp, sizeof(*udp) + len);
  }
  l2_len = mg_l2_footer(ifp->l2type, l2_len, l2p);
  return (driver_output(ifp, l2_len) == l2_len);
}

static bool tx_udp4(struct mg_tcpip_if *ifp, uint8_t *l2_dst, uint32_t ip_src,
                    uint16_t sport, uint32_t ip_dst, uint16_t dport,
                    const void *buf, size_t len) {
  struct mg_addr ips, ipd;
  memset(&ips, 0, sizeof(ips));
  ips.addr.ip4 = ip_src;
  ips.port = sport;
  memset(&ipd, 0, sizeof(ipd));
  ipd.addr.ip4 = ip_dst;
  ipd.port = dport;
  return tx_udp(ifp, l2_dst, &ips, &ipd, buf, len);
}

static void tx_dhcp(struct mg_tcpip_if *ifp, uint8_t *l2_dst, uint32_t ip_src,
                    uint32_t ip_dst, uint8_t *opts, size_t optslen,
                    bool ciaddr) {
  // https://datatracker.ietf.org/doc/html/rfc2132#section-9.6
  // NOTE(): assumes Ethernet: htype=1 hlen=6, copy 6 bytes
  struct dhcp dhcp = {1, 1, 6, 0, 0, 0, 0, 0, 0, 0, 0, {0}, 0, {0}};
  dhcp.magic = mg_htonl(0x63825363);
  memcpy(&dhcp.hwaddr, ifp->mac, 6);
  memcpy(&dhcp.xid, ifp->mac + 2, sizeof(dhcp.xid));
  memcpy(&dhcp.options, opts, optslen);
  if (ciaddr) dhcp.ciaddr = ip_src;
  tx_udp4(ifp, l2_dst, ip_src, mg_htons(68), ip_dst, mg_htons(67), &dhcp,
          sizeof(dhcp));
}

// RFC-2131 #4.3.6, #4.4.1; RFC-2132 #9.8
static void tx_dhcp_request_sel(struct mg_tcpip_if *ifp, uint32_t ip_req,
                                uint32_t ip_srv) {
  uint8_t extra = (uint8_t) ((ifp->enable_req_dns ? 1 : 0) +
                             (ifp->enable_req_sntp ? 1 : 0));
  size_t len = strlen(ifp->dhcp_name);
  size_t olen = 21 + len + extra + 2 + 1;  // Total length of options
#define OPTS_MAXLEN (21 + sizeof(ifp->dhcp_name) + 2 + 2 + 1)
  uint8_t opts[OPTS_MAXLEN];  // Allocate options (max size possible)
  uint8_t *p = opts;
  assert(olen <= sizeof(opts));
  memset(opts, 0, sizeof(opts));
  *p++ = 53, *p++ = 1, *p++ = 3;                       // Type: DHCP request
  *p++ = 54, *p++ = 4, memcpy(p, &ip_srv, 4), p += 4;  // DHCP server ID
  *p++ = 50, *p++ = 4, memcpy(p, &ip_req, 4), p += 4;  // Requested IP
  *p++ = 12, *p++ = (uint8_t) (len & 255);             // DHCP host
  memcpy(p, ifp->dhcp_name, len), p += len;            // name
  *p++ = 55, *p++ = 2 + extra, *p++ = 1, *p++ = 3;     // GW, MASK
  if (ifp->enable_req_dns) *p++ = 6;                   // DNS
  if (ifp->enable_req_sntp) *p++ = 42;                 // SNTP
  *p++ = 255;                                          // End of options
  // assert((size_t) (p - opts) < olen);
  tx_dhcp(ifp, mg_l2_mapip(ifp->l2type, MG_TCPIP_L2ADDR_BCAST, NULL), 0,
          0xffffffff, opts, olen, 0);
  MG_DEBUG(("DHCP req sent"));
}

// RFC-2131 #4.3.6, #4.4.5 (renewing: unicast, rebinding: bcast)
static void tx_dhcp_request_re(struct mg_tcpip_if *ifp, uint8_t *l2_dst,
                               uint32_t ip_src, uint32_t ip_dst) {
  uint8_t opts[] = {
      53, 1, 3,  // Type: DHCP request
      255        // End of options
  };
  tx_dhcp(ifp, l2_dst, ip_src, ip_dst, opts, sizeof(opts), true);
  MG_DEBUG(("DHCP req sent"));
}

static void tx_dhcp_discover(struct mg_tcpip_if *ifp) {
  uint8_t opts[] = {
      53, 1, 1,     // Type: DHCP discover
      55, 2, 1, 3,  // Parameters: ip, mask
      255           // End of options
  };
  tx_dhcp(ifp, mg_l2_mapip(ifp->l2type, MG_TCPIP_L2ADDR_BCAST, NULL), 0,
          0xffffffff, opts, sizeof(opts), false);
  MG_DEBUG(("DHCP discover sent. Our MAC: %M", mg_print_mac, ifp->mac));
}

static struct mg_connection *getpeer(struct mg_mgr *mgr, struct pkt *pkt,
                                     bool lsn) {
  struct mg_connection *c = NULL;
  for (c = mgr->conns; c != NULL; c = c->next) {
    if (c->is_arplooking && pkt->arp && pkt->arp->spa == c->rem.addr.ip4) break;
#if MG_ENABLE_IPV6
    if (c->is_arplooking && pkt->icmp6 && pkt->icmp6->type == 136) {
      struct ndp_na *na = (struct ndp_na *) (pkt->icmp6 + 1);
      if (MG_IP6MATCH(na->addr, c->rem.addr.ip6)) break;
    }
#endif
    if (c->is_udp && pkt->udp && c->loc.port == pkt->udp->dport &&
        !(c->loc.is_ip6 ^ (pkt->ip6 != NULL)))  // IP or IPv6 to same dest
      break;
    if (!c->is_udp && pkt->tcp && c->loc.port == pkt->tcp->dport &&
        ((lsn && c->is_listening && !(c->loc.is_ip6 ^ (pkt->ip6 != NULL))) ||
         (!lsn && !c->is_listening && c->rem.port == pkt->tcp->sport &&
          ((!c->loc.is_ip6 && c->rem.addr.ip4 == pkt->ip->src)
#if MG_ENABLE_IPV6
           || (c->loc.is_ip6 && MG_IP6MATCH(c->rem.addr.ip6, pkt->ip6->src))
#endif
               )))) // validate addr for established (not listening) conns
      break;
  }
  return c;
}

static void l2addr_resolved(struct mg_connection *c);
static uint8_t *get_return_l2addr(struct mg_tcpip_if *ifp, struct mg_addr *rem,
                                  bool is_udp, struct pkt *pkt);

// RFC826, ARP assumes Ethernet MAC addresses
static void rx_arp(struct mg_tcpip_if *ifp, struct pkt *pkt) {
  if (pkt->arp->op == mg_htons(1) && pkt->arp->tpa == ifp->ip) {
    // ARP request. Make a response, then send
    // MG_VERBOSE(("ARP req from %M", mg_print_ip4, &pkt->arp->spa));
    uint8_t *l2p = (uint8_t *) ifp->tx.buf;
    struct arp *arp =
        (struct arp *) mg_l2_header(ifp->l2type, MG_TCPIP_L2PROTO_ARP, ifp->mac,
                                    mg_l2_getaddr(ifp->l2type, pkt->l2), l2p);
    *arp = *pkt->arp;
    arp->op = mg_htons(2);
    memcpy(arp->tha, pkt->arp->sha, sizeof(pkt->arp->tha));
    memcpy(arp->sha, ifp->mac, sizeof(pkt->arp->sha));
    arp->tpa = pkt->arp->spa;
    arp->spa = ifp->ip;
    MG_DEBUG(("ARP: tell %M we're %M", mg_print_ip4, &arp->tpa, mg_print_mac,
              ifp->mac));
    driver_output(ifp, mg_l2_footer(ifp->l2type, PDIFF(l2p, arp + 1), l2p));
  } else if (pkt->arp->op == mg_htons(2)) {
    if (memcmp(pkt->arp->tha, ifp->mac, sizeof(pkt->arp->tha)) != 0) return;
    // MG_VERBOSE(("ARP resp from %M", mg_print_ip4, &pkt->arp->spa));
    if (pkt->arp->spa == ifp->gw) {
      // Got response for the GW ARP request. Set ifp->gwmac and IP -> READY
      memcpy(ifp->gwmac, pkt->arp->sha, sizeof(ifp->gwmac));
      ifp->gw_ready = true;
      if (ifp->state == MG_TCPIP_STATE_IP) {
        ifp->state = MG_TCPIP_STATE_READY;
        onstatechange(ifp);
      }
    } else {
      struct mg_connection *c = getpeer(ifp->mgr, pkt, false);
      if (c != NULL && c->is_arplooking) {
        struct connstate *s = (struct connstate *) (c + 1);
        memcpy(s->mac, pkt->arp->sha, sizeof(s->mac));
        MG_DEBUG(("%lu ARP resolved %M -> %M", c->id, mg_print_ip4,
                  &c->rem.addr.ip4, mg_print_mac, s->mac));
        c->is_arplooking = 0;
        l2addr_resolved(c);
      }
    }
  }
}

static void rx_icmp(struct mg_tcpip_if *ifp, struct pkt *pkt) {
  uint8_t *l2p = (uint8_t *) ifp->tx.buf;
  size_t plen = pkt->pay.len;
  if (!icmpcsum_ok(pkt->icmp, sizeof(struct icmp) + plen)) return;
  if (pkt->icmp->type == 8 && pkt->ip != NULL && pkt->ip->dst == ifp->ip) {
    size_t l2_max_overhead = ifp->framesize - ifp->mtu;
    size_t hlen = sizeof(struct ip) + sizeof(struct icmp);
    size_t room = ifp->tx.len - hlen - l2_max_overhead;
    uint8_t *l2addr;
    struct ip *ip;
    struct icmp *icmp;
    struct mg_addr ips;
    ips.addr.ip4 = pkt->ip->src;
    ips.is_ip6 = false;
    if ((l2addr = get_return_l2addr(ifp, &ips, false, pkt)) == NULL)
      return;  // safety net for lousy networks
    if (plen > room) plen = room;
    ip = tx_ip(ifp, l2addr, 1, ifp->ip, pkt->ip->src, sizeof(*icmp) + plen);
    icmp = (struct icmp *) (ip + 1);
    memset(icmp, 0, sizeof(*icmp));        // Set csum, type, code to 0
    memcpy(icmp + 1, pkt->pay.buf, plen);  // Copy RX payload to TX
    icmp->csum = ipcsum(icmp, sizeof(*icmp) + plen);
    driver_output(ifp, mg_l2_footer(ifp->l2type, hlen + plen, l2p));
  }
}

static void setdns4(struct mg_tcpip_if *ifp, uint32_t *ip);

static bool dhcp_opt_len_ok(uint8_t len, uint8_t *p, uint8_t *end) {
  return (len >= 4 && (len & 3) == 0 && p + 6 < end);
}

static void rx_dhcp_client(struct mg_tcpip_if *ifp, struct pkt *pkt) {
  uint32_t ip = 0, gw = 0, mask = 0, lease = 0, dns = 0, sntp = 0;
  uint8_t msgtype = 0, state = ifp->state;
  // perform size check first, then access fields
  uint8_t *p = pkt->dhcp->options,
          *end = (uint8_t *) &pkt->pay.buf[pkt->pay.len];
  if (end < p) return;  // options are optional, check min header length
  if (memcmp(&pkt->dhcp->xid, ifp->mac + 2, sizeof(pkt->dhcp->xid))) return;
  while (p + 1 < end && p[0] != 255) {  // Parse options, get #1; RFC-2132 9
    if (p[0] == 1 && p[1] == 4 && p + 6 < end) {  // Mask, 3.3
      memcpy(&mask, p + 2, sizeof(mask));
    } else if (p[0] == 3 && dhcp_opt_len_ok(p[1], p, end)) {  // GW, 3.5
      memcpy(&gw, p + 2, sizeof(gw));
      ip = pkt->dhcp->yiaddr;
    } else if (ifp->enable_req_dns && p[0] == 6 &&
               dhcp_opt_len_ok(p[1], p, end)) {  // DNS, 3.8
      memcpy(&dns, p + 2, sizeof(dns));
    } else if (ifp->enable_req_sntp && p[0] == 42 &&
               dhcp_opt_len_ok(p[1], p, end)) {  // SNTP, 8.3
      memcpy(&sntp, p + 2, sizeof(sntp));
    } else if (p[0] == 51 && p[1] == 4 && p + 6 < end) {  // Lease
      memcpy(&lease, p + 2, sizeof(lease));
      lease = mg_ntohl(lease);
    } else if (p[0] == 53 && p[1] == 1 && p + 6 < end) {  // Msg Type
      msgtype = p[2];
    }
    p += p[1] + 2;
  }
  // Process message type, RFC-1533 (9.4); RFC-2131 (3.1, 4)
  if (msgtype == 6 && ifp->ip == ip) {  // DHCPNACK, release IP
    ifp->state = MG_TCPIP_STATE_UP, ifp->ip = 0;
  } else if (msgtype == 2 && ifp->state == MG_TCPIP_STATE_UP && ip && gw &&
             lease) {  // DHCPOFFER
    // select IP, (4.4.1) (fallback to IP source addr on foul play)
    tx_dhcp_request_sel(ifp, ip,
                        pkt->dhcp->siaddr ? pkt->dhcp->siaddr : pkt->ip->src);
    ifp->state = MG_TCPIP_STATE_REQ;  // REQUESTING state
  } else if (msgtype == 5) {          // DHCPACK
    if (ifp->state == MG_TCPIP_STATE_REQ && ip && gw && lease) {  // got an IP
      uint64_t rand;
      ifp->lease_expire = ifp->now + lease * 1000;
      MG_INFO(("Lease: %u sec (%lld)", lease, ifp->lease_expire / 1000));
      // assume DHCP server = router until ARP resolves
      memcpy(ifp->gwmac, mg_l2_getaddr(ifp->l2type, pkt->l2),
             sizeof(ifp->gwmac));
      ifp->gw_ready = true;  // NOTE(): actual gw ARP won't retry now
      ifp->ip = ip, ifp->gw = gw, ifp->mask = mask;
      ifp->state = MG_TCPIP_STATE_IP;  // BOUND state
      mg_random(&rand, sizeof(rand));
      srand((unsigned int) (rand + mg_millis()));
      if (ifp->enable_req_dns && dns != 0) {
        setdns4(ifp, &dns);
        mg_tcpip_call(ifp, MG_TCPIP_EV_DHCP_DNS, &dns);
      }
      if (ifp->enable_req_sntp && sntp != 0)
        mg_tcpip_call(ifp, MG_TCPIP_EV_DHCP_SNTP, &sntp);
    } else if (ifp->state == MG_TCPIP_STATE_READY && ifp->ip == ip) {  // renew
      ifp->lease_expire = ifp->now + lease * 1000;
      MG_INFO(("Lease: %u sec (%lld)", lease, ifp->lease_expire / 1000));
    }  // TODO(): accept provided T1/T2 and store server IP for renewal (4.4)
  }
  if (ifp->state != state) onstatechange(ifp);
}

// Simple DHCP server that assigns a next IP address: ifp->ip + 1
static void rx_dhcp_server(struct mg_tcpip_if *ifp, struct pkt *pkt) {
  uint8_t *mac;
  uint8_t op = 0, *p = pkt->dhcp->options,
          *end = (uint8_t *) &pkt->pay.buf[pkt->pay.len];
  // NOTE(): assumes Ethernet: htype=1 hlen=6, copy 6 bytes
  struct dhcp res = {2, 1, 6, 0, 0, 0, 0, 0, 0, 0, 0, {0}, 0, {0}};
  if (end < p) return;  // options are optional, check min header length
  res.yiaddr = ifp->ip;
  ((uint8_t *) (&res.yiaddr))[3]++;                // Offer our IP + 1
  while (p + 1 < end && p[0] != 255) {             // Parse options
    if (p[0] == 53 && p[1] == 1 && p + 2 < end) {  // Message type
      op = p[2];
    }
    p += p[1] + 2;
  }
  if (op == 1 || op == 3) {         // DHCP Discover or DHCP Request
    uint8_t msg = op == 1 ? 2 : 5;  // Message type: DHCP OFFER or DHCP ACK
    uint8_t opts[] = {
        53, 1, 0,                   // Message type
        1,  4, 0,   0,   0,   0,    // Subnet mask
        54, 4, 0,   0,   0,   0,    // Server ID
        12, 3, 'm', 'i', 'p',       // Host name: "mip"
        51, 4, 255, 255, 255, 255,  // Lease time
        255                         // End of options
    };
    opts[2] = msg;
    memcpy(&res.hwaddr, pkt->dhcp->hwaddr, 6);
    memcpy(opts + 5, &ifp->mask, sizeof(ifp->mask));
    memcpy(opts + 11, &ifp->ip, sizeof(ifp->ip));
    memcpy(&res.options, opts, sizeof(opts));
    res.magic = pkt->dhcp->magic;
    res.xid = pkt->dhcp->xid;
    mac = mg_l2_getaddr(ifp->l2type, pkt->l2);
    if (ifp->enable_get_gateway) {
      ifp->gw = res.yiaddr;  // set gw IP, best-effort gwmac as DHCP server's
      memcpy(ifp->gwmac, mac, sizeof(ifp->gwmac));
    }
    tx_udp4(ifp, mac, ifp->ip, mg_htons(67), op == 1 ? ~0U : res.yiaddr,
            mg_htons(68), &res, sizeof(res));
  }
}

#if MG_ENABLE_IPV6
static struct ip6 *tx_ip6(struct mg_tcpip_if *ifp, uint8_t *l2_dst,
                          uint8_t next, uint64_t *ip_src, uint64_t *ip_dst,
                          size_t plen) {
  // ifp->tx.buf is 8-bit aligned, keep other headers as pointers, see pkt
  uint8_t *l2p = (uint8_t *) ifp->tx.buf;
  struct ip6 *ip6 = (struct ip6 *) mg_l2_header(
      ifp->l2type, MG_TCPIP_L2PROTO_IPV6, ifp->mac, l2_dst, l2p);
  memset(ip6, 0, sizeof(*ip6));
  ip6->ver = 0x60;  // Version 6, traffic class 0
  ip6->plen = mg_htons((uint16_t) plen);
  ip6->next = next;
  ip6->hops = 255;  // NDP requires max
  ip6->src[0] = *ip_src++;
  ip6->src[1] = *ip_src;
  ip6->dst[0] = *ip_dst++;
  ip6->dst[1] = *ip_dst;
  return ip6;
}

static void tx_icmp6(struct mg_tcpip_if *ifp, uint8_t *l2_dst, uint64_t *ip_src,
                     uint64_t *ip_dst, uint8_t type, uint8_t code,
                     const void *buf, size_t len) {
  uint8_t *l2p = (uint8_t *) ifp->tx.buf;
  struct ip6 *ip6;
  struct icmp6 *icmp6;
  ip6 = tx_ip6(ifp, l2_dst, 58, ip_src, ip_dst, sizeof(*icmp6) + len);
  icmp6 = (struct icmp6 *) (ip6 + 1);
  memset(icmp6, 0, sizeof(*icmp6));  // Set csum to 0
  icmp6->type = type;
  icmp6->code = code;
  memcpy(icmp6 + 1, buf, len);  // Copy payload
  icmp6->csum = 0;              // RFC-4443 2.3, RFC-8200 8.1
  icmp6->csum = p6csum(ip6, icmp6, sizeof(*icmp6) + len);
  driver_output(
      ifp, mg_l2_footer(ifp->l2type, sizeof(*ip6) + sizeof(*icmp6) + len, l2p));
}

// Neighbor Discovery Protocol, RFC-4861
// Neighbor Advertisement, 4.4
static void tx_ndp_na(struct mg_tcpip_if *ifp, uint8_t *l2_dst,
                      uint64_t *ip_src, uint64_t *ip_dst, bool solicited,
                      uint8_t *l2) {
  uint8_t data[20 + 16];  // NOTE(): optional len upto 2 hw addr
  memset(data, 0, sizeof(data));
  data[0] = solicited ? 0x60 : 0x20;                    // O + S
  memcpy(data + 4, ip_src, 16);                         // Target address
  data[20] = 2;                                         // 4.6.1, target hwaddr
  data[21] = mg_l2_ip6put(ifp->l2type, l2, data + 22);  // option length / 8
  tx_icmp6(ifp, l2_dst, ip_src, ip_dst, 136, 0, data,
           20 + (size_t) (8 * data[21]));
}

static void onstate6change(struct mg_tcpip_if *ifp);

static void rx_ndp_na(struct mg_tcpip_if *ifp, struct pkt *pkt) {
  struct ndp_na *na = (struct ndp_na *) (pkt->icmp6 + 1);
  uint8_t *opts = (uint8_t *) (na + 1);
  if ((na->res[0] & 0x40) == 0) return;  // not "solicited"
  if (*opts++ != 2) return;              // no target hwaddr
  MG_VERBOSE(("NDP NA resp from %M", mg_print_ip6, (char *) &na->addr));
  if (MG_IP6MATCH(na->addr, ifp->gw6)) {
    // Got response for the GW NS request. Set ifp->gw6mac and IP6 -> READY
    uint8_t len = *opts++;  // check valid hwaddr and get it
    if (!mg_l2_ip6get(ifp->l2type, ifp->gw6mac, opts, len)) return;
    ifp->gw6_ready = true;
    if (ifp->state6 == MG_TCPIP_STATE_IP) {
      ifp->state6 = MG_TCPIP_STATE_READY;
      onstate6change(ifp);
    }
  } else {
    struct mg_connection *c = getpeer(ifp->mgr, pkt, false);
    if (c != NULL && c->is_arplooking) {
      struct connstate *s = (struct connstate *) (c + 1);
      uint8_t len = *opts++;  // check valid hwaddr and get it
      if (!mg_l2_ip6get(ifp->l2type, s->mac, opts, len)) return;
      MG_DEBUG(("%lu NDP resolved %M -> %M", c->id, mg_print_ip6,
                &c->rem.addr.ip6, mg_print_mac, ifp->l2type, s->mac));
      c->is_arplooking = 0;
      l2addr_resolved(c);
    }
  }
}

// Neighbor Solicitation, 4.3
static void rx_ndp_ns(struct mg_tcpip_if *ifp, struct pkt *pkt) {
  uint64_t target[2];
  if (pkt->pay.len < sizeof(target)) return;
  memcpy(target, pkt->pay.buf + 4, sizeof(target));
  if (MG_IP6MATCH(target, ifp->ip6ll) || MG_IP6MATCH(target, ifp->ip6)) {
    uint64_t req[2];  // requester address
    uint8_t l2[sizeof(struct mg_l2addr)];
    uint8_t len, *opts = (uint8_t *) pkt->pay.buf + 20;
    if (*opts++ != 1) return;  // no requester hwaddr (source)
    len = *opts++;             // check valid hwaddr and get it
    if (!mg_l2_ip6get(ifp->l2type, l2, opts, len)) return;
    req[0] = pkt->ip6->src[0], req[1] = pkt->ip6->src[1];  // align to 64-bit
    tx_ndp_na(ifp, l2, target, req, true, ifp->mac);
  }
}

// - use solicited node multicast to resolve a l2 address (l2_addr = NULL)
// - use unicast to verify presence (l2_addr = neighbor l2 address)
static void tx_ndp_ns(struct mg_tcpip_if *ifp, uint64_t *ip_dst,
                      uint8_t *l2_addr) {
  uint8_t payload[4 + 16 + 16];  // NOTE(): 16 --> optional len upto 2 hw addr
  uint64_t ip_unspec[2] = {0, 0};
  size_t payload_len = 20;
  bool mcast = (l2_addr == NULL);
  uint64_t ip_mcast[2] = {0, 0};
  uint8_t *l2 = l2_addr;

  memset(payload, 0, sizeof(payload));
  memcpy(payload + 4, ip_dst, 16);
  if (mcast) {
    struct mg_addr ipd;
    ip6sn(ip_dst, ip_mcast);
    ipd.addr.ip6[0] = ip_mcast[0], ipd.addr.ip6[1] = ip_mcast[1],
    ipd.is_ip6 = true;
    l2 = mg_l2_mapip(ifp->l2type, MG_TCPIP_L2ADDR_MCAST6, &ipd);
  }
  payload_len = 20;
  // TODO(robertc2000): using only link-local IP addr for now
  // We might consider to add an option to use either link-local or global IP
  if (!MG_IP6MATCH(ifp->ip6ll, ip_unspec)) {
    payload[20] = 1;  // 4.6.1, source hwaddr; option length in 8-byte units
    payload[21] = mg_l2_ip6put(ifp->l2type, ifp->mac, payload + 22);
    payload_len += 8 * payload[21];
  }
  tx_icmp6(ifp, l2, ifp->ip6ll, mcast ? ip_mcast : ip_dst, 135, 0, payload,
           payload_len);
}

// Router Solicitation, 4.1
static void tx_ndp_rs(struct mg_tcpip_if *ifp) {
  uint8_t payload[4 + 16];  // reserved + optional len upto 2 hw addr NOTE()
  size_t payload_len = 4;
  uint64_t ip_unspec[2] = {0, 0};

  memset(payload, 0, sizeof(payload));

  if (!MG_IP6MATCH(ifp->ip6ll, ip_unspec)) {
    payload[4] = 1;  // 4.6.1, source hwaddr; option length in 8-byte units
    payload[5] = mg_l2_ip6put(ifp->l2type, ifp->mac, payload + 6);
    payload_len += 8 * payload[5];
  }
  tx_icmp6(ifp,
           mg_l2_mapip(ifp->l2type, MG_TCPIP_L2ADDR_MCAST6,
                       (struct mg_addr *) &ip6_allrouters),
           ifp->ip6ll, (uint64_t *) ip6_allrouters.addr.ip6, 133, 0, payload,
           payload_len);
  MG_DEBUG(("NDP Router Solicitation sent"));
}

static void fill_prefix(uint8_t *dst, uint8_t *src, uint8_t len) {
  uint8_t full = len / 8;
  uint8_t rem = len % 8;
  if (full > 0) memcpy(dst, src, full);
  if (rem > 0) {
    uint8_t mask = (uint8_t) (0xFF << (8 - rem));
    dst[full] |= src[full] & mask;  // mg_l2_genip6() zeroes dst
  }
}

static bool match_prefix(uint8_t *newp, uint8_t *curp, uint8_t len) {
  uint8_t full = len / 8;
  uint8_t rem = len % 8;
  if (full > 0 && memcmp(curp, newp, full) != 0) return false;
  if (rem > 0) {
    uint8_t mask = (uint8_t) (0xFF << (8 - rem));
    if (curp[full] != (newp[full] & mask)) return false;
  }
  return true;
}

static bool fill_global(struct mg_tcpip_if *ifp, uint8_t *prefix,
                        uint8_t prefix_len) {
  if (!mg_l2_genip6(ifp->l2type, ifp->ip6, prefix_len, ifp->mac)) return false;
  fill_prefix((uint8_t *) ifp->ip6, prefix, prefix_len);
  fill_prefix(ifp->prefix, prefix, prefix_len);
  ifp->prefix_len = prefix_len;
  return true;
}

// Router Advertisement, 4.2
static void rx_ndp_ra(struct mg_tcpip_if *ifp, struct pkt *pkt) {
  if (pkt->pay.len < 12) return;
  struct ndp_ra *ra = (struct ndp_ra *) (pkt->icmp6 + 1);
  uint8_t *opts = (uint8_t *) (ra + 1);
  size_t opt_left = pkt->pay.len - 12;
  bool gotl2addr = false, gotprefix = false;
  uint8_t l2[sizeof(struct mg_l2addr)];
  uint32_t mtu = 0;
  uint8_t *prefix, prefix_len;

  if (ifp->state6 == MG_TCPIP_STATE_UP) {
    MG_DEBUG(("Received NDP RA"));  // fill gw6 address
    // parse options
    while (opt_left >= 2) {
      uint8_t type = opts[0], len = opts[1];
      size_t length = (size_t) len * 8;
      if (length == 0 || length > opt_left) break;  // malformed
      if (type == 1 && length >= 8) {
        // Received router's L2 address
        if (!mg_l2_ip6get(ifp->l2type, l2, opts + 2, len)) break;
        gotl2addr = true;
      } else if (type == 5 && length >= 8) {
        // process MTU if available
        mtu = mg_ntohl(*(uint32_t *) (opts + 4));
      } else if (type == 3 && length >= 32) {
        // process prefix, 4.6.2
        uint8_t pfx_flags = opts[3];  // L=0x80, A=0x40
        uint32_t valid = mg_ntohl(*(uint32_t *) (opts + 4));
        uint32_t pref_lifetime = mg_ntohl(*(uint32_t *) (opts + 8));
        prefix_len = opts[2];
        prefix = opts + 16;

        // TODO (robertc2000): handle prefix options if necessary
        (void) pfx_flags;
        (void) valid;
        (void) pref_lifetime;

        gotprefix = true;
      }
      opts += length;
      opt_left -= length;
    }

    // fill prefix and global
    if (gotprefix && !fill_global(ifp, prefix, prefix_len)) return;
    ifp->gw6[0] = pkt->ip6->src[0], ifp->gw6[1] = pkt->ip6->src[1];
    if (gotl2addr) {
      memcpy(ifp->gw6mac, l2, sizeof(ifp->gw6mac));
      ifp->state6 = MG_TCPIP_STATE_READY;
      ifp->gw6_ready = true;
    }
    if (mtu != 0 && ifp->mtu != mtu) {
      MG_ERROR(
          ("got an MTU: %u, that differs from the configured one. "
           "All devices in an IPv6 network should have the same MTU, "
           "using the router's instead...",
           mtu));
      ifp->mtu = (uint16_t) mtu;
    }
    if (ifp->state6 != MG_TCPIP_STATE_READY) {
      tx_ndp_ns(ifp, ifp->gw6, NULL);  // unsolicited GW hwaddr resolution
      ifp->state6 = MG_TCPIP_STATE_IP;
    }
    onstate6change(ifp);
  }
}

static void rx_icmp6(struct mg_tcpip_if *ifp, struct pkt *pkt) {
  if (!icmp6csum_ok(pkt->ip6, pkt->icmp6)) return;
  switch (pkt->icmp6->type) {
    case 128: {  // Echo Request, RFC-4443 4.1
      uint64_t target[2];
      target[0] = pkt->ip6->dst[0], target[1] = pkt->ip6->dst[1];
      if (MG_IP6MATCH(target, ifp->ip6ll) || MG_IP6MATCH(target, ifp->ip6)) {
        size_t l2_max_overhead = ifp->framesize - ifp->mtu;
        size_t hlen = sizeof(struct ip6) + sizeof(struct icmp6);
        size_t room = ifp->tx.len - hlen - l2_max_overhead, plen = pkt->pay.len;
        struct mg_addr ips;
        uint8_t *l2addr;

        ips.addr.ip6[0] = pkt->ip6->src[0], ips.addr.ip6[1] = pkt->ip6->src[1];
        ips.is_ip6 = true;
        if ((l2addr = get_return_l2addr(ifp, &ips, false, pkt)) == NULL)
          return;                      // safety net for lousy networks
        if (plen > room) plen = room;  // Copy (truncated) RX payload to TX
        // Echo Reply, 4.2
        tx_icmp6(ifp, l2addr, target, ips.addr.ip6, 129, 0, pkt->pay.buf, plen);
      }
    } break;
    case 134:  // Router Advertisement
      rx_ndp_ra(ifp, pkt);
      break;
    case 135:  // Neighbor Solicitation
      rx_ndp_ns(ifp, pkt);
      break;
    case 136:  // Neighbor Advertisement
      rx_ndp_na(ifp, pkt);
      break;
  }
}

static void onstate6change(struct mg_tcpip_if *ifp) {
  if (ifp->state6 == MG_TCPIP_STATE_READY) {
    MG_INFO(("READY, IP: %M", mg_print_ip6, &ifp->ip6));
    MG_INFO(("       GW: %M", mg_print_ip6, &ifp->gw6));
    if (ifp->l2type == MG_TCPIP_L2_ETH)  // TODO(): print other l2
      MG_INFO(("      MAC: %M", mg_print_mac, &ifp->mac));
  } else if (ifp->state6 == MG_TCPIP_STATE_IP) {
    if (ifp->gw6[0] != 0 || ifp->gw6[1] != 0)
      tx_ndp_ns(ifp, ifp->gw6, NULL);  // unsolicited GW hwaddr resolution
  } else if (ifp->state6 == MG_TCPIP_STATE_UP) {
    MG_INFO(("IP: %M", mg_print_ip6, &ifp->ip6ll));
  }
  if (ifp->state6 != MG_TCPIP_STATE_UP && ifp->state6 != MG_TCPIP_STATE_DOWN)
    mg_tcpip_call(ifp, MG_TCPIP_EV_ST6_CHG, &ifp->state6);
}
#endif

static uint8_t *tcpip_mapip(struct mg_tcpip_if *ifp, struct mg_addr *ip) {
#if MG_ENABLE_IPV6
  if (ip->is_ip6) {
    if (MG_IP6MATCH(ip->addr.ip6, ip6_allnodes.addr.ip6))  // local broadcast
      return mg_l2_mapip(ifp->l2type, MG_TCPIP_L2ADDR_MCAST6,
                         (struct mg_addr *) &ip6_allnodes);
    if (*ip->addr.ip == 0xFF)  // multicast
      return mg_l2_mapip(ifp->l2type, MG_TCPIP_L2ADDR_MCAST6, ip);
  } else
#endif
  {  // global/local broadcast
    if (ip->addr.ip4 == 0xffffffff || ip->addr.ip4 == (ifp->ip | ~ifp->mask))
      return mg_l2_mapip(ifp->l2type, MG_TCPIP_L2ADDR_BCAST, NULL);
    if ((*ip->addr.ip & 0xE0) == 0xE0)  // 224 ~ 239 = E0 ~ EF, multicast
      return mg_l2_mapip(ifp->l2type, MG_TCPIP_L2ADDR_MCAST, ip);
  }
  return NULL;
}

static uint8_t *get_return_l2addr(struct mg_tcpip_if *ifp, struct mg_addr *rem,
                                  bool is_udp, struct pkt *pkt) {
  uint8_t *l2addr;
  if (is_udp && (l2addr = tcpip_mapip(ifp, rem)) != NULL)
    return l2addr;  // broadcast or multicast
#if MG_ENABLE_IPV6
  if (rem->is_ip6) {
    if (rem->addr.ip6[0] == ifp->ip6ll[0] ||
        match_prefix((uint8_t *) rem->addr.ip6, ifp->prefix, ifp->prefix_len))
      return mg_l2_getaddr(ifp->l2type, pkt->l2);  // same LAN, get from frame
    if (ifp->gw6_ready)                            // use the router
      return ifp->gw6mac;  // ignore source address in frame
  } else
#endif
  {
    if (ifp->ip != 0 && ((rem->addr.ip4 & ifp->mask) == (ifp->ip & ifp->mask)))
      return mg_l2_getaddr(ifp->l2type, pkt->l2);  // same LAN, get from frame
    if (ifp->gw_ready)                             // use the router
      return ifp->gwmac;  // ignore source address in frame
  }
  MG_ERROR(("%M %s: No way back, can't respond", mg_print_ip_port, rem,
            is_udp ? "UDP" : "TCP"));
  return NULL;
}

static bool rx_udp(struct mg_tcpip_if *ifp, struct pkt *pkt) {
  struct mg_connection *c = getpeer(ifp->mgr, pkt, true);
  struct connstate *s;
  uint8_t *l2addr;
  if (c == NULL) return false;  // No UDP listener on this port
  s = (struct connstate *) (c + 1);
  c->rem.port = pkt->udp->sport;
#if MG_ENABLE_IPV6
  if (c->loc.is_ip6) {  // matching of v4/v6 to dest is done bt getpeer()
    if (!udp6csum_ok(pkt->ip6, pkt->udp)) return false;
    c->rem.addr.ip6[0] = pkt->ip6->src[0],
    c->rem.addr.ip6[1] = pkt->ip6->src[1], c->rem.is_ip6 = true;
  } else
#endif
  {
    if (!udpcsum_ok(pkt->ip, pkt->udp)) return false;
    c->rem.addr.ip4 = pkt->ip->src;
  }
  if ((l2addr = get_return_l2addr(ifp, &c->rem, true, pkt)) == NULL)
    return false;  // safety net for lousy networks
  memcpy(s->mac, l2addr, sizeof(s->mac));
  if (c->recv.len >= MG_MAX_RECV_SIZE) {
    mg_error(c, "max_recv_buf_size reached");
  } else if (c->recv.size - c->recv.len < pkt->pay.len &&
             !mg_iobuf_resize(&c->recv, c->recv.len + pkt->pay.len)) {
    mg_error(c, "oom");
  } else {
    memcpy(&c->recv.buf[c->recv.len], pkt->pay.buf, pkt->pay.len);
    c->recv.len += pkt->pay.len;
    mg_call(c, MG_EV_READ, &pkt->pay.len);
  }
  return true;
}

static size_t tx_tcp(struct mg_tcpip_if *ifp, uint8_t *l2_dst,
                     struct mg_addr *ip_src, struct mg_addr *ip_dst,
                     uint8_t flags, uint32_t seq, uint32_t ack, const void *buf,
                     size_t len) {
  uint8_t *l2p = (uint8_t *) ifp->tx.buf;
  struct ip *ip = NULL;
  struct tcp *tcp;
  uint16_t opts[4 / 2];
  size_t hlen = sizeof(*tcp);
#if MG_ENABLE_IPV6
  struct ip6 *ip6 = NULL;
#endif

  // Handle any options first, here, to determine header size
  if (flags & TH_SYN) {  // Send MSS
    uint16_t mss;
#if MG_ENABLE_IPV6  // RFC-9293 3.7.1; RFC-6691 2
    mss = (uint16_t) (ifp->mtu - 60);
#else
    mss = (uint16_t) (ifp->mtu - 40);
#endif
    opts[0] = mg_htons(0x0204);  // RFC-9293 3.2
    opts[1] = mg_htons(mss);
    hlen += sizeof(opts);  // always whole number of 32-bit words
  }

#if MG_ENABLE_IPV6
  if (ip_dst->is_ip6) {
    ip6 =
        tx_ip6(ifp, l2_dst, 6, ip_src->addr.ip6, ip_dst->addr.ip6, hlen + len);
    tcp = (struct tcp *) (ip6 + 1);
  } else
#endif
  {
    ip = tx_ip(ifp, l2_dst, 6, ip_src->addr.ip4, ip_dst->addr.ip4, hlen + len);
    tcp = (struct tcp *) (ip + 1);
  }
  memset(tcp, 0, sizeof(*tcp));
  memmove(tcp + 1, opts, hlen - sizeof(*tcp));  // copy opts if any
  if (buf != NULL && len) memmove((uint8_t *) tcp + hlen, buf, len);
  tcp->sport = ip_src->port;
  tcp->dport = ip_dst->port;
  tcp->seq = seq;
  tcp->ack = ack;
  tcp->flags = flags;
  tcp->win = mg_htons(MG_TCPIP_WIN);
  tcp->off = (uint8_t) (hlen / 4 << 4);
#if MG_ENABLE_IPV6
  if (ip_dst->is_ip6) {
    tcp->csum = p6csum(ip6, tcp, hlen + len);
  } else
#endif
  {
    tcp->csum = pcsum(ip, tcp, hlen + len);
  }
  MG_VERBOSE(("TCP %M -> %M fl %x len %u", mg_print_ip_port, ip_src,
              mg_print_ip_port, ip_dst, tcp->flags, len));
  return driver_output(
      ifp, mg_l2_footer(ifp->l2type, PDIFF(l2p, tcp) + hlen + len, l2p));
}

static size_t tx_tcp_ctrlresp(struct mg_tcpip_if *ifp, struct pkt *pkt,
                              uint8_t flags, uint32_t seqno) {
  uint32_t ackno = mg_htonl(mg_ntohl(pkt->tcp->seq) + (uint32_t) pkt->pay.len +
                            ((pkt->tcp->flags & (TH_SYN | TH_FIN)) ? 1 : 0));
  struct mg_addr ips, ipd;
  uint8_t *l2addr;
  memset(&ips, 0, sizeof(ips));
  memset(&ipd, 0, sizeof(ipd));
  if (pkt->ip != NULL) {
    ips.addr.ip4 = pkt->ip->dst;
    ipd.addr.ip4 = pkt->ip->src;
  } else {
    ips.addr.ip6[0] = pkt->ip6->dst[0], ips.addr.ip6[1] = pkt->ip6->dst[1];
    ipd.addr.ip6[0] = pkt->ip6->src[0], ipd.addr.ip6[1] = pkt->ip6->src[1];
    ips.is_ip6 = true;
    ipd.is_ip6 = true;
  }
  ips.port = pkt->tcp->dport;
  ipd.port = pkt->tcp->sport;
  if ((l2addr = get_return_l2addr(ifp, &ipd, false, pkt)) == NULL)
    return 0;  // safety net for lousy networks
  return tx_tcp(ifp, l2addr, &ips, &ipd, flags, seqno, ackno, NULL, 0);
}

static size_t tx_tcp_rst(struct mg_tcpip_if *ifp, struct pkt *pkt, bool toack) {
  return tx_tcp_ctrlresp(ifp, pkt, toack ? TH_RST : (TH_RST | TH_ACK),
                         toack ? pkt->tcp->ack : 0);
}

static struct mg_connection *accept_conn(struct mg_connection *lsn,
                                         struct pkt *pkt, uint16_t mss) {
  struct connstate *s;
  uint8_t *l2addr;
  struct mg_connection *c = mg_alloc_conn(lsn->mgr);
  if (c == NULL) {
    MG_ERROR(("OOM"));
    return NULL;
  }
  s = (struct connstate *) (c + 1);
  s->dmss = mss;  // from options in client SYN
  s->seq = mg_ntohl(pkt->tcp->ack), s->ack = mg_ntohl(pkt->tcp->seq);
#if MG_ENABLE_IPV6
  if (lsn->loc.is_ip6) {
    c->rem.addr.ip6[0] = pkt->ip6->src[0],
    c->rem.addr.ip6[1] = pkt->ip6->src[1], c->rem.is_ip6 = true;
    c->loc.addr.ip6[0] = c->mgr->ifp->ip6[0],
    c->loc.addr.ip6[1] = c->mgr->ifp->ip6[1], c->loc.is_ip6 = true;
    // TODO(): compare lsn to link-local, or rem as link-local: use ll instead
  } else
#endif
  {
    c->rem.addr.ip4 = pkt->ip->src;
    c->loc.addr.ip4 = c->mgr->ifp->ip;
  }
  c->rem.port = pkt->tcp->sport;
  c->loc.port = lsn->loc.port;
  if ((l2addr = get_return_l2addr(lsn->mgr->ifp, &c->rem, false, pkt)) ==
      NULL) {
    free(c);      // safety net for lousy networks, not actually needed
    return NULL;  // as path has already been checked at SYN (sending SYN+ACK)
  }
  memcpy(s->mac, l2addr, sizeof(s->mac));
  settmout(c, MIP_TTYPE_KEEPALIVE);
  MG_DEBUG(("%lu accepted %M", c->id, mg_print_ip_port, &c->rem));
  LIST_ADD_HEAD(struct mg_connection, &lsn->mgr->conns, c);
  c->is_accepted = 1;
  c->is_hexdumping = lsn->is_hexdumping;
  c->pfn = lsn->pfn;
  c->pfn_data = lsn->pfn_data;
  c->fn = lsn->fn;
  c->fn_data = lsn->fn_data;
  c->is_tls = lsn->is_tls;
  mg_call(c, MG_EV_OPEN, NULL);
  mg_call(c, MG_EV_ACCEPT, NULL);
  if (!c->is_tls_hs) c->is_tls = 0;  // user did not call mg_tls_init()
  return c;
}

static size_t trim_len(struct mg_connection *c, size_t len) {
  struct mg_tcpip_if *ifp = c->mgr->ifp;
  size_t l2_max_overhead = ifp->framesize - ifp->mtu;
  size_t ip_max_h_len = c->rem.is_ip6 ? 40 : 24;  // we don't send options
  size_t tcp_max_h_len = 60 /* RFC-9293 3.7.1; RFC-6691 2 */, udp_h_len = 8;
  size_t max_headers_len =
      ip_max_h_len + (c->is_udp ? udp_h_len : tcp_max_h_len);
  size_t min_mtu = c->rem.is_ip6 ? 1280 /* RFC-8200, IPv6 minimum */
                   : c->is_udp   ? 68   /* RFC-791, IP minimum */
                                 : max_headers_len /* fit full TCP header */;
  // NOTE(): We are effectively reducing transmitted TCP segment length by 20,
  // accounting for possible options; though we currently don't send options
  // except for SYN.

  // If the frame exceeds the available buffer, trim the length.
  if (len + max_headers_len + l2_max_overhead > ifp->tx.len)
    len = ifp->tx.len - max_headers_len - l2_max_overhead;
  // Ensure the MTU isn't lower than the minimum allowed value
  if (ifp->mtu < min_mtu) {
    MG_ERROR(("MTU is lower than minimum, raising to %lu", min_mtu));
    ifp->mtu = (uint16_t) min_mtu;
  }
  // If the total packet size exceeds the MTU, trim the length
  if (len + max_headers_len > ifp->mtu) {
    len = ifp->mtu - max_headers_len;
    if (c->is_udp) MG_ERROR(("UDP datagram exceeds MTU. Truncating it."));
  }

  return len;
}

static bool udp_send(struct mg_connection *c, const void *buf, size_t len) {
  struct mg_tcpip_if *ifp = c->mgr->ifp;
  struct connstate *s = (struct connstate *) (c + 1);
  struct mg_addr ips;
  memset(&ips, 0, sizeof(ips));
#if MG_ENABLE_IPV6
  if (c->loc.is_ip6) {
    ips.addr.ip6[0] = ifp->ip6[0], ips.addr.ip6[1] = ifp->ip6[1],
    ips.is_ip6 = true;
    // TODO(): detect link-local (c->rem) and use it
  } else
#endif
  {
    ips.addr.ip4 = ifp->ip;
  }
  ips.port = c->loc.port;
  return tx_udp(ifp, s->mac, &ips, &c->rem, buf, len);
}

long mg_io_send(struct mg_connection *c, const void *buf, size_t len) {
  struct connstate *s = (struct connstate *) (c + 1);
  len = trim_len(c, len);
  if (c->is_udp) {
    if (!udp_send(c, buf, len)) return MG_IO_WAIT;
  } else {  // TCP, cap to peer's MSS
    struct mg_tcpip_if *ifp = c->mgr->ifp;
    size_t sent;
    if (len > s->dmss) len = s->dmss;  // RFC-6691: reduce if sending opts
    sent = tx_tcp(ifp, s->mac, &c->loc, &c->rem, TH_PUSH | TH_ACK,
                  mg_htonl(s->seq), mg_htonl(s->ack), buf, len);
    if (sent == 0) {
      return MG_IO_WAIT;
    } else if (sent == (size_t) -1) {
      return MG_IO_ERR;
    } else {
      s->seq += (uint32_t) len;
      if (s->ttype == MIP_TTYPE_ACK) settmout(c, MIP_TTYPE_KEEPALIVE);
    }
  }
  return (long) len;
}

static void handle_tls_recv(struct mg_connection *c) {
  size_t avail = mg_tls_pending(c);
  size_t min = avail > MG_MAX_RECV_SIZE ? MG_MAX_RECV_SIZE : avail;
  struct mg_iobuf *io = &c->recv;
  if (io->size - io->len < min && !mg_iobuf_resize(io, io->len + min)) {
    mg_error(c, "oom");
  } else {
    // Decrypt data directly into c->recv
    long n = mg_tls_recv(c, io->buf != NULL ? &io->buf[io->len] : io->buf,
                         io->size - io->len);
    if (n == MG_IO_ERR) {
      mg_error(c, "TLS recv error");
    } else if (n > 0) {
      // Decrypted successfully - trigger MG_EV_READ
      io->len += (size_t) n;
      mg_call(c, MG_EV_READ, &n);
    }  // else n < 0: outstanding data to be moved to c->recv
  }
}

static void read_conn(struct mg_connection *c, struct pkt *pkt) {
  struct connstate *s = (struct connstate *) (c + 1);
  struct mg_iobuf *io = c->is_tls ? &c->rtls : &c->recv;
  uint32_t seq = mg_ntohl(pkt->tcp->seq);
  if (pkt->tcp->flags & TH_FIN) {
    uint8_t flags = TH_ACK;
    if (mg_ntohl(pkt->tcp->seq) != s->ack) {
      MG_VERBOSE(("ignoring FIN, %x != %x", mg_ntohl(pkt->tcp->seq), s->ack));
      tx_tcp(c->mgr->ifp, s->mac, &c->loc, &c->rem, TH_ACK, mg_htonl(s->seq),
             mg_htonl(s->ack), "", 0);
      return;
    }
    // If we initiated the closure, we reply with ACK upon receiving FIN
    // If we didn't initiate it, we reply with FIN as part of the normal TCP
    // closure process
    s->ack = (uint32_t) (mg_htonl(pkt->tcp->seq) + pkt->pay.len + 1);
    s->fin_rcvd = true;
    if (c->is_draining && s->ttype == MIP_TTYPE_FIN) {
      if (s->seq == mg_htonl(pkt->tcp->ack)) {  // Simultaneous closure ?
        s->seq++;                               // Yes. Increment our SEQ
      } else {                                  // Otherwise,
        s->seq = mg_htonl(pkt->tcp->ack);       // Set to peer's ACK
      }
      s->twclosure = true;
    } else {
      flags |= TH_FIN;
      c->is_draining = 1;
      settmout(c, MIP_TTYPE_FIN);
    }
    tx_tcp(c->mgr->ifp, s->mac, &c->loc, &c->rem, flags, mg_htonl(s->seq),
           mg_htonl(s->ack), "", 0);
    if (pkt->pay.len == 0) return;  // if no data, we're done
  } else if (pkt->pay.len <= 1 && mg_ntohl(pkt->tcp->seq) == s->ack - 1) {
    // Keep-Alive (RFC-9293 3.8.4, allow erroneous implementations)
    MG_VERBOSE(("%lu keepalive ACK", c->id));
    tx_tcp(c->mgr->ifp, s->mac, &c->loc, &c->rem, TH_ACK, mg_htonl(s->seq),
           mg_htonl(s->ack), NULL, 0);
    return;                        // no data to process
  } else if (pkt->pay.len == 0) {  // this is an ACK
    if (s->fin_rcvd && s->ttype == MIP_TTYPE_FIN) s->twclosure = true;
    return;  // no data to process
  } else if (seq != s->ack) {
    uint32_t ack = (uint32_t) (mg_htonl(pkt->tcp->seq) + pkt->pay.len);
    if (s->ack == ack) {
      MG_VERBOSE(("ignoring duplicate pkt"));
    } else {
      MG_VERBOSE(("SEQ != ACK: %x %x %x", seq, s->ack, ack));
      tx_tcp(c->mgr->ifp, s->mac, &c->loc, &c->rem, TH_ACK, mg_htonl(s->seq),
             mg_htonl(s->ack), "", 0);
    }
    return;  // drop it
  } else if (io->size - io->len < pkt->pay.len &&
             !mg_iobuf_resize(io, io->len + pkt->pay.len)) {
    mg_error(c, "oom");
    return;  // drop it
  }
  // Copy TCP payload into the IO buffer. If the connection is plain text,
  // we copy to c->recv. If the connection is TLS, this data is encrypted,
  // therefore we copy that encrypted data to the c->rtls iobuffer instead,
  // and then call mg_tls_recv() to decrypt it. NOTE: mg_tls_recv() will
  // call back mg_io_recv() which grabs raw data from c->rtls
  memcpy(&io->buf[io->len], pkt->pay.buf, pkt->pay.len);
  io->len += pkt->pay.len;
  MG_VERBOSE(("%lu SEQ %x -> %x", c->id, mg_htonl(pkt->tcp->seq), s->ack));
  // Advance ACK counter
  s->ack = (uint32_t) (mg_htonl(pkt->tcp->seq) + pkt->pay.len);
  s->unacked += pkt->pay.len;
  // size_t diff = s->acked <= s->ack ? s->ack - s->acked : s->ack;
  if (s->unacked > MG_TCPIP_WIN / 2 && s->acked != s->ack) {
    // Send ACK immediately
    MG_VERBOSE(("%lu imm ACK %lu", c->id, s->acked));
    tx_tcp(c->mgr->ifp, s->mac, &c->loc, &c->rem, TH_ACK, mg_htonl(s->seq),
           mg_htonl(s->ack), NULL, 0);
    s->unacked = 0;
    s->acked = s->ack;
    if (s->ttype != MIP_TTYPE_KEEPALIVE) settmout(c, MIP_TTYPE_KEEPALIVE);
  } else {
    // if not already running, setup a timer to send an ACK later
    if (s->ttype != MIP_TTYPE_ACK) settmout(c, MIP_TTYPE_ACK);
  }
  if (c->is_tls) {
    c->is_tls_hs ? mg_tls_handshake(c) : handle_tls_recv(c);
  } else {
    // Plain text connection, data is already in c->recv, trigger MG_EV_READ
    mg_call(c, MG_EV_READ, &pkt->pay.len);
  }
}

// TCP backlog
struct mg_backlog {
  uint16_t port, mss;  // use port=0 for available entries
  uint8_t age;
};

static int backlog_insert(struct mg_connection *c, uint16_t port,
                          uint16_t mss) {
  struct mg_backlog *p = (struct mg_backlog *) c->data;
  size_t i;
  for (i = 0; i < sizeof(c->data) / sizeof(*p); i++) {
    if (p[i].port != 0) continue;
    p[i].age = 2;  // remove after two calls, average 1.5 call rate
    p[i].port = port, p[i].mss = mss;
    return (int) i;
  }
  return -1;
}

static struct mg_backlog *backlog_retrieve(struct mg_connection *c,
                                           uint16_t key, uint16_t port) {
  struct mg_backlog *p = (struct mg_backlog *) c->data;
  if (key >= sizeof(c->data) / sizeof(*p)) return NULL;
  if (p[key].port != port) return NULL;
  p += key;
  return p;
}

static void backlog_remove(struct mg_connection *c, uint16_t key) {
  struct mg_backlog *p = (struct mg_backlog *) c->data;
  p[key].port = 0;
}

static void backlog_maintain(struct mg_connection *c) {
  struct mg_backlog *p = (struct mg_backlog *) c->data;
  size_t i;  // dec age and remove those where it reaches 0
  for (i = 0; i < sizeof(c->data) / sizeof(*p); i++) {
    if (p[i].port == 0) continue;
    if (p[i].age != 0) --p[i].age;
    if (p[i].age == 0) p[i].port = 0;
  }
}

static void backlog_poll(struct mg_mgr *mgr) {
  struct mg_connection *c = NULL;
  for (c = mgr->conns; c != NULL; c = c->next) {
    if (!c->is_udp && c->is_listening) backlog_maintain(c);
  }
}

// process options (MSS)
static bool handle_opt(struct connstate *s, struct tcp *tcp, bool ip6) {
  uint8_t *opts = (uint8_t *) (tcp + 1);
  int len = 4 * ((int) (tcp->off >> 4) - ((int) sizeof(*tcp) / 4));
  s->dmss = ip6 ? 1220 : 536;  // assume default, RFC-9293 3.7.1
  while (len > 0) {            // RFC-9293 3.1 3.2
    uint8_t kind = opts[0], optlen = 1;
    if (kind != 1) {         // No-Operation
      if (kind == 0) break;  // End of Option List
      if (len < 2 || opts[1] == 0) return false; // Malformed options
      optlen = opts[1];
      if (kind == 2 && optlen == 4)  // set received MSS
        s->dmss = (uint16_t) (((uint16_t) opts[2] << 8) + opts[3]);
    }
    MG_VERBOSE(("kind: %u, optlen: %u, len: %d\n", kind, optlen, len));
    opts += optlen;
    len -= optlen;
  }
  return true;
}

static void rx_tcp(struct mg_tcpip_if *ifp, struct pkt *pkt) {
  struct mg_connection *c = getpeer(ifp->mgr, pkt, false);
  struct connstate *s = c == NULL ? NULL : (struct connstate *) (c + 1);
#if MG_ENABLE_IPV6  // matching of v4/v6 to dest is done by getpeer()
  if (pkt->ip6 != NULL && !tcp6csum_ok(pkt->ip6, pkt->tcp)) return;
#endif
  if (pkt->ip != NULL && !tcpcsum_ok(pkt->ip, pkt->tcp)) return;
  pkt->tcp->flags &= TH_STDFLAGS;  // tolerate creative usage (ECN, ?)
  // Order is VERY important; RFC-9293 3.5.2
  // - check clients (Group 1) and established connections (Group 3)
  if (c != NULL && c->is_connecting && pkt->tcp->flags == (TH_SYN | TH_ACK)) {
    // client got a server connection accept
    if (!handle_opt(s, pkt->tcp, pkt->ip6 != NULL)) return;  // process options (MSS)
    s->seq = mg_ntohl(pkt->tcp->ack), s->ack = mg_ntohl(pkt->tcp->seq) + 1;
    tx_tcp_ctrlresp(ifp, pkt, TH_ACK, pkt->tcp->ack);
    c->is_connecting = 0;  // Client connected
    settmout(c, MIP_TTYPE_KEEPALIVE);
    mg_call(c, MG_EV_CONNECT, NULL);  // Let user know
    if (c->is_tls_hs) mg_tls_handshake(c);
    if (!c->is_tls_hs) c->is_tls = 0;  // user did not call mg_tls_init()
  } else if (c != NULL && c->is_connecting && pkt->tcp->flags != TH_ACK) {
    mg_error(c, "connection refused");
  } else if (c != NULL && pkt->tcp->flags & TH_RST) {
    uint32_t seqno = mg_ntohl(pkt->tcp->seq);
    if (seqno >= s->ack && seqno < (s->ack + MG_TCPIP_WIN))  // RFC-9293 3.5.3
      mg_error(c, "peer RST");  // RFC-1122 4.2.2.13
  } else if (c != NULL) {
    // process segment
    s->tmiss = 0;                         // Reset missed keep-alive counter
    if (s->ttype == MIP_TTYPE_KEEPALIVE)  // Advance keep-alive timer
      settmout(c,
               MIP_TTYPE_KEEPALIVE);  // unless a former ACK timeout is pending
    read_conn(c, pkt);  // Override timer with ACK timeout if needed
  } else
    // - we don't listen on that port; RFC-9293 3.5.2 Group 1
    // - check listening connections; RFC-9293 3.5.2 Group 2
    if ((c = getpeer(ifp->mgr, pkt, true)) == NULL) {
      // not listening on that port
      if (!(pkt->tcp->flags & TH_RST)) {
        tx_tcp_rst(ifp, pkt, pkt->tcp->flags & TH_ACK);
      }  // else silently discard
    } else if (pkt->tcp->flags == TH_SYN) {
      // listener receives a connection request
      struct connstate cs;  // At this point, s = NULL, there is no connection
      int key;
      uint32_t isn;
      if (pkt->tcp->sport != 0) {
        if (!handle_opt(&cs, pkt->tcp, pkt->ip6 != NULL)) return;  // process options (MSS)
        key = backlog_insert(c, pkt->tcp->sport,
                             cs.dmss);  // backlog options (MSS)
        if (key < 0) return;  // no room in backlog, discard SYN, client retries
        // Use peer's src port and bl key as ISN, to later identify the
        // handshake
        isn = (mg_htonl(((uint32_t) key << 16) | mg_ntohs(pkt->tcp->sport)));
        if (tx_tcp_ctrlresp(ifp, pkt, TH_SYN | TH_ACK, isn) == 0)
          backlog_remove(c, (uint16_t) key);  // safety net for lousy networks
      }  // what should we do when port=0 ? Linux takes port 0 as any other
         // port
    } else if (pkt->tcp->flags == TH_ACK) {
      // listener receives an ACK
      struct mg_backlog *b = NULL;
      if ((uint16_t) (mg_htonl(pkt->tcp->ack) - 1) ==
          mg_htons(pkt->tcp->sport)) {
        uint16_t key = (uint16_t) ((mg_htonl(pkt->tcp->ack) - 1) >> 16);
        b = backlog_retrieve(c, key, pkt->tcp->sport);
        if (b != NULL) {                // ACK is a response to a SYN+ACK
          accept_conn(c, pkt, b->mss);  // pass options
          backlog_remove(c, key);
        }  // else not an actual match, reset
      }
      if (b == NULL) tx_tcp_rst(ifp, pkt, true);
    } else if (pkt->tcp->flags & TH_RST) {
      // silently discard
    } else if (pkt->tcp->flags & TH_ACK) {  // ACK + something else != RST
      tx_tcp_rst(ifp, pkt, true);
    } else if (pkt->tcp->flags & TH_SYN) {  // SYN + something else != ACK
      tx_tcp_rst(ifp, pkt, false);
    }  // else  silently discard
}

static void rx_ip(struct mg_tcpip_if *ifp, struct pkt *pkt) {
  uint8_t ihl;
  uint16_t frag, len;
  if (pkt->pay.len < sizeof(*pkt->ip)) return;  // Truncated
  if ((pkt->ip->ver >> 4) != 4) return;         // Not IP
  ihl = pkt->ip->ver & 0x0F;
  if (ihl < 5) return;                              // bad IHL
  if (pkt->pay.len < (uint16_t) (ihl * 4)) return;  // Truncated / malformed
  // There can be link padding, take length from IP header
  len = mg_ntohs(pkt->ip->len);  // IP datagram length
  if (len < (uint16_t) (ihl * 4) || len > pkt->pay.len) return;  // malformed
  pkt->pay.len = len;                      // strip padding
  mkpay(pkt, (uint32_t *) pkt->ip + ihl);  // account for opts
  if (!ipcsum_ok(pkt->ip)) return;
  frag = mg_ntohs(pkt->ip->frag);
  if (frag & IP_MORE_FRAGS_MSK || frag & IP_FRAG_OFFSET_MSK) {
    struct mg_connection *c;
    if (pkt->ip->proto == 17) pkt->udp = (struct udp *) (pkt->pay.buf);
    if (pkt->ip->proto == 6) pkt->tcp = (struct tcp *) (pkt->pay.buf);
    c = getpeer(ifp->mgr, pkt, false);
    if (c) mg_error(c, "Received fragmented packet");
  } else if (pkt->ip->proto == 1) {
    pkt->icmp = (struct icmp *) (pkt->pay.buf);
    if (pkt->pay.len < sizeof(*pkt->icmp)) return;
    mkpay(pkt, pkt->icmp + 1);
    rx_icmp(ifp, pkt);
  } else if (pkt->ip->proto == 17) {
    pkt->udp = (struct udp *) (pkt->pay.buf);
    if (pkt->pay.len < sizeof(*pkt->udp)) return;  // truncated
    // Take length from UDP header
    len = mg_ntohs(pkt->udp->len);  // UDP datagram length
    if (len < sizeof(*pkt->udp) || len > pkt->pay.len) return;  // malformed
    pkt->pay.len = len;  // strip excess data
    mkpay(pkt, pkt->udp + 1);
    MG_VERBOSE(("UDP %M:%hu -> %M:%hu len %u", mg_print_ip4, &pkt->ip->src,
                mg_ntohs(pkt->udp->sport), mg_print_ip4, &pkt->ip->dst,
                mg_ntohs(pkt->udp->dport), (int) pkt->pay.len));
    if (ifp->enable_dhcp_client && pkt->udp->dport == mg_htons(68)) {
      pkt->dhcp = (struct dhcp *) (pkt->udp + 1);
      mkpay(pkt, &pkt->dhcp->options);
      rx_dhcp_client(ifp, pkt);
    } else if (ifp->enable_dhcp_server && pkt->udp->dport == mg_htons(67)) {
      pkt->dhcp = (struct dhcp *) (pkt->udp + 1);
      mkpay(pkt, &pkt->dhcp->options);
      rx_dhcp_server(ifp, pkt);
    } else if (!rx_udp(ifp, pkt)) {
      // Should send ICMP Destination Unreachable for unicasts, but keep
      // silent
    }
  } else if (pkt->ip->proto == 6) {
    uint8_t off;
    pkt->tcp = (struct tcp *) (pkt->pay.buf);
    if (pkt->pay.len < sizeof(*pkt->tcp)) return;
    off = pkt->tcp->off >> 4;  // account for opts
    if (pkt->pay.len < (uint16_t) (4 * off)) return;
    mkpay(pkt, (uint32_t *) pkt->tcp + off);
    MG_VERBOSE(("TCP %M:%hu -> %M:%hu len %u", mg_print_ip4, &pkt->ip->src,
                mg_ntohs(pkt->tcp->sport), mg_print_ip4, &pkt->ip->dst,
                mg_ntohs(pkt->tcp->dport), (int) pkt->pay.len));
    rx_tcp(ifp, pkt);
  } else {
    MG_DEBUG(("Unknown IP proto %x", (int) pkt->ip->proto));
    if (mg_log_level >= MG_LL_VERBOSE)
      mg_hexdump(pkt->ip, pkt->pay.len >= 32 ? 32 : pkt->pay.len);
  }
}

#if MG_ENABLE_IPV6
static void rx_ip6(struct mg_tcpip_if *ifp, struct pkt *pkt) {
  uint16_t len = 0, plen;
  uint8_t next, *nhdr;
  bool loop = true;
  if (pkt->pay.len < sizeof(*pkt->ip6)) return;  // Truncated
  if ((pkt->ip6->ver >> 4) != 0x6) return;       // Not IPv6
  plen = mg_ntohs(pkt->ip6->plen);
  if (plen > (pkt->pay.len - sizeof(*pkt->ip6))) return;  // malformed
  next = pkt->ip6->next;
  nhdr = (uint8_t *) (pkt->ip6 + 1);
  while (loop) {
    switch (next) {
      case 0:   // Hop-by-Hop 4.3
      case 43:  // Routing 4.4
      case 60:  // Destination Options 4.6
      case 51:  // Authentication RFC-4302
        MG_INFO(("IPv6 extension header %d", (int) next));
        next = nhdr[0];
        len += (uint16_t) (8 * (nhdr[1] + 1));
        nhdr += 8 * (nhdr[1] + 1);
        break;
      case 44:  // Fragment 4.5
      {
        struct mg_connection *c;
        if (nhdr[0] == 17) pkt->udp = (struct udp *) (pkt->pay.buf);
        if (nhdr[0] == 6) pkt->tcp = (struct tcp *) (pkt->pay.buf);
        c = getpeer(ifp->mgr, pkt, false);
        if (c) mg_error(c, "Received fragmented packet");
      }
        return;
      case 59:  // No Next Header 4.7
        return;
      case 50:  // IPsec ESP RFC-4303, unsupported
      default:
        loop = false;
        break;
    }
  }
  if (len >= plen) return;
  // There can be link padding, take payload length from IPv6 header - options
  pkt->pay.buf = (char *) nhdr;
  pkt->pay.len = plen - len;
  if (next == 58) {
    pkt->icmp6 = (struct icmp6 *) (pkt->pay.buf);
    if (pkt->pay.len < sizeof(*pkt->icmp6)) return;
    mkpay(pkt, pkt->icmp6 + 1);
    MG_DEBUG(("ICMPv6 %M -> %M len %u", mg_print_ip6, &pkt->ip6->src,
              mg_print_ip6, &pkt->ip6->dst, (int) pkt->pay.len));
    rx_icmp6(ifp, pkt);
  } else if (next == 17) {
    pkt->udp = (struct udp *) (pkt->pay.buf);
    if (pkt->pay.len < sizeof(*pkt->udp)) return;
    // Take length from UDP header
    len = mg_ntohs(pkt->udp->len);  // UDP datagram length
    if (len < sizeof(*pkt->udp) || len > pkt->pay.len) return;  // malformed
    pkt->pay.len = len;  // strip excess data
    mkpay(pkt, pkt->udp + 1);
    MG_DEBUG(("UDP %M:%hu -> %M:%hu len %u", mg_print_ip6, &pkt->ip6->src,
              mg_ntohs(pkt->udp->sport), mg_print_ip6, &pkt->ip6->dst,
              mg_ntohs(pkt->udp->dport), (int) pkt->pay.len));
    if (ifp->enable_dhcp6_client && pkt->udp->dport == mg_htons(546)) {
      pkt->dhcp6 = (struct dhcp6 *) (pkt->udp + 1);
      mkpay(pkt, pkt->dhcp6 + 1);
      // rx_dhcp6_client(ifp, pkt);
#if 0
    } else if (ifp->enable_dhcp_server && pkt->udp->dport == mg_htons(547)) {
      pkt->dhcp6 = (struct dhcp6 *) (pkt->udp + 1);
      mkpay(pkt, pkt->dhcp6 + 1);
      rx_dhcp6_server(ifp, pkt);
#endif
    } else if (!rx_udp(ifp, pkt)) {
      // Should send ICMPv6 Destination Unreachable for unicasts, keep silent
    }
  } else if (next == 6) {
    uint8_t off;
    pkt->tcp = (struct tcp *) (pkt->pay.buf);
    if (pkt->pay.len < sizeof(*pkt->tcp)) return;
    off = pkt->tcp->off >> 4;  // account for opts
    if (pkt->pay.len < (uint16_t) (4 * off)) return;
    mkpay(pkt, (uint32_t *) pkt->tcp + off);
    MG_DEBUG(("TCP %M:%hu -> %M:%hu len %u", mg_print_ip6, &pkt->ip6->src,
              mg_ntohs(pkt->tcp->sport), mg_print_ip6, &pkt->ip6->dst,
              mg_ntohs(pkt->tcp->dport), (int) pkt->pay.len));
    rx_tcp(ifp, pkt);
  } else {
    MG_DEBUG(("Unknown IPv6 next hdr %x", (int) next));
    if (mg_log_level >= MG_LL_VERBOSE)
      mg_hexdump(pkt->ip6, pkt->pay.len >= 32 ? 32 : pkt->pay.len);
  }
}
#else
#define rx_ip6(x, y)
#endif

static void mg_tcpip_rx(struct mg_tcpip_if *ifp, void *buf, size_t len) {
  struct pkt pkt;
  enum mg_l2proto proto;
  memset(&pkt, 0, sizeof(pkt));
  pkt.raw.buf = (char *) buf;
  pkt.raw.len = len;
  pkt.l2 = (uint8_t *) pkt.raw.buf;
  if (!mg_l2_rx(ifp, &proto, &pkt.pay, &pkt.raw)) return;
  if (proto == MG_TCPIP_L2PROTO_ARP) {
    pkt.arp = (struct arp *) (pkt.pay.buf);
    if (pkt.pay.len < sizeof(*pkt.arp)) return;  // Truncated
    mg_tcpip_call(ifp, MG_TCPIP_EV_ARP, &pkt.raw);
    rx_arp(ifp, &pkt);
  } else if (proto == MG_TCPIP_L2PROTO_IPV6) {
    pkt.ip6 = (struct ip6 *) (pkt.pay.buf);
    rx_ip6(ifp, &pkt);
  } else if (proto == MG_TCPIP_L2PROTO_IPV4) {
    pkt.ip = (struct ip *) (pkt.pay.buf);
    rx_ip(ifp, &pkt);
  }
}

static void mg_ip_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (ifp->state == MG_TCPIP_STATE_DOWN) return;
  // DHCP RFC-2131 (4.4)
  if (ifp->enable_dhcp_client && s1) {
    if (ifp->state == MG_TCPIP_STATE_UP) {
      tx_dhcp_discover(ifp);  // INIT (4.4.1)
    } else if (ifp->state == MG_TCPIP_STATE_READY &&
               ifp->lease_expire > 0) {  // BOUND / RENEWING / REBINDING
      if (ifp->now >= ifp->lease_expire) {
        ifp->state = MG_TCPIP_STATE_UP, ifp->ip = 0;  // expired, release IP
        onstatechange(ifp);
      } else if (ifp->now + 30UL * 60UL * 1000UL > ifp->lease_expire &&
                 ((ifp->now / 1000) % 60) == 0) {
        // hack: 30 min before deadline, try to rebind (4.3.6) every min
        tx_dhcp_request_re(
            ifp, mg_l2_mapip(ifp->l2type, MG_TCPIP_L2ADDR_BCAST, NULL), ifp->ip,
            0xffffffff);
      }  // TODO(): Handle T1 (RENEWING) and T2 (REBINDING) (4.4.5)
    }
  }
}
static void mg_ip_link(struct mg_tcpip_if *ifp, bool up) {
  bool current = ifp->state != MG_TCPIP_STATE_DOWN;
  if (!up && ifp->enable_dhcp_client) ifp->ip = 0;
  if (up != current) {  // link state has changed
    ifp->state = up == false                               ? MG_TCPIP_STATE_DOWN
                 : ifp->enable_dhcp_client || ifp->ip == 0 ? MG_TCPIP_STATE_UP
                                                           : MG_TCPIP_STATE_IP;
    onstatechange(ifp);
  } else if (!ifp->enable_dhcp_client && ifp->state == MG_TCPIP_STATE_UP &&
             ifp->ip) {
    ifp->state = MG_TCPIP_STATE_IP;  // ifp->fn has set an IP
    onstatechange(ifp);
  }
}

#if MG_ENABLE_IPV6
static void mg_ip6_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (ifp->state6 == MG_TCPIP_STATE_DOWN) return;
  if (ifp->enable_slaac && s1 && ifp->state6 == MG_TCPIP_STATE_UP)
    tx_ndp_rs(ifp);
}
static void mg_ip6_link(struct mg_tcpip_if *ifp, bool up) {
  bool current = ifp->state6 != MG_TCPIP_STATE_DOWN;
  if (!up && ifp->enable_slaac) ifp->ip6[0] = ifp->ip6[1] = 0;
  if (up != current) {  // link state has changed
    ifp->state6 = !up                                     ? MG_TCPIP_STATE_DOWN
                  : ifp->enable_slaac || ifp->ip6[0] == 0 ? MG_TCPIP_STATE_UP
                                                          : MG_TCPIP_STATE_IP;
    onstate6change(ifp);
  } else if (!ifp->enable_slaac && ifp->state6 == MG_TCPIP_STATE_UP &&
             ifp->ip6[0]) {
    ifp->state6 = MG_TCPIP_STATE_IP;  // ifp->fn has set an IP
    onstate6change(ifp);
  }
}
#else
#define mg_ip6_poll(x, y)
#define mg_ip6_link(x, y)
#endif

static void mg_tcpip_poll(struct mg_tcpip_if *ifp, uint64_t now) {
  struct mg_connection *c;
  bool expired_1000ms = mg_timer_expired(&ifp->timer_1000ms, 1000, now);
  ifp->now = now;

  if (expired_1000ms) {
#if MG_ENABLE_TCPIP_PRINT_DEBUG_STATS
    const char *names[] = {"down", "up", "req", "ip", "ready"};
    size_t max = sizeof(names) / sizeof(char *);
    unsigned int state = ifp->state >= max ? max - 1 : ifp->state;
    MG_INFO(("Status: %s, IP: %M, rx:%u, tx:%u, dr:%u, er:%u", names[state],
             mg_print_ip4, &ifp->ip, ifp->nrecv, ifp->nsent, ifp->ndrop,
             ifp->nerr));
#if MG_ENABLE_IPV6
    state = ifp->state6 >= max ? max - 1 : ifp->state6;
    if (state > MG_TCPIP_STATE_UP)
      MG_INFO(("Status: %s, IPv6: %M", names[state], mg_print_ip6, &ifp->ip6));
#endif
#endif
    backlog_poll(ifp->mgr);
  }
  // Handle gw ARP request timeout, order is important
  if (expired_1000ms && ifp->state == MG_TCPIP_STATE_IP) {
    ifp->state = MG_TCPIP_STATE_READY;  // keep best-effort MAC or poison mark
    onstatechange(ifp);
  }
  if (expired_1000ms && ifp->state == MG_TCPIP_STATE_READY && !ifp->gw_ready &&
      ifp->gw != 0)
    mg_tcpip_arp_request(ifp, ifp->gw, NULL);  // retry GW ARP request
#if MG_ENABLE_IPV6
  // Handle gw NS/NA req/resp timeout, order is important
  if (expired_1000ms && ifp->state6 == MG_TCPIP_STATE_IP) {
    ifp->state6 = MG_TCPIP_STATE_READY;  // keep best-effort MAC or poison mark
    onstate6change(ifp);
  }
  if (expired_1000ms && ifp->state == MG_TCPIP_STATE_READY && !ifp->gw6_ready &&
      (ifp->gw6[0] != 0 || ifp->gw6[1] != 0))
    tx_ndp_ns(ifp, ifp->gw6, NULL);  // retry GW hwaddr resolution
#endif

  // poll driver
  if (ifp->driver->poll) {
    bool up = ifp->driver->poll(ifp, expired_1000ms);
    // Handle physical interface up/down status, ifp->state rules over state6
    if (expired_1000ms) {
      mg_ip_link(ifp, up);   // Handle IPv4
      mg_ip6_link(ifp, up);  // Handle IPv6
      if (ifp->state == MG_TCPIP_STATE_DOWN) MG_ERROR(("Network is down"));
      mg_tcpip_call(ifp, MG_TCPIP_EV_TIMER_1S, NULL);
    }
  }

  mg_ip_poll(ifp, expired_1000ms);   // Handle IPv4
  mg_ip6_poll(ifp, expired_1000ms);  // Handle IPv6

  if (ifp->state == MG_TCPIP_STATE_DOWN) return;
  // Read data from the network
  if (ifp->driver->rx != NULL) {  // Simple polling driver, returns one frame
    size_t len =
        ifp->driver->rx(ifp->recv_queue.buf, ifp->recv_queue.size, ifp);
    if (len > 0) {
      ifp->nrecv++;
      mg_tcpip_rx(ifp, ifp->recv_queue.buf, len);
    }
  } else {  // Complex poll / Interrupt-based driver. Queues recvd frames
    char *buf;
    size_t len, cnt = 7;  // Max 7 packets to fetch
    while (cnt-- > 0 && (len = mg_queue_next(&ifp->recv_queue, &buf)) > 0) {
      mg_tcpip_rx(ifp, buf, len);
      mg_queue_del(&ifp->recv_queue, len);
    }
  }

  // Process timeouts
  for (c = ifp->mgr->conns; c != NULL; c = c->next) {
    struct connstate *s = (struct connstate *) (c + 1);
    if ((c->is_udp && !c->is_arplooking) || c->is_listening || c->is_resolving)
      continue;
    if (ifp->now > s->timer) {
      if (s->ttype == MIP_TTYPE_ARP) {
        mg_error(c, "ARP timeout");
      } else if (c->is_udp) {
        continue;
      } else if (s->ttype == MIP_TTYPE_ACK && s->acked != s->ack) {
        MG_VERBOSE(("%lu ack %x %x", c->id, s->seq, s->ack));
        tx_tcp(ifp, s->mac, &c->loc, &c->rem, TH_ACK, mg_htonl(s->seq),
               mg_htonl(s->ack), NULL, 0);
        s->acked = s->ack;
      } else if (s->ttype == MIP_TTYPE_SYN) {
        mg_error(c, "Connection timeout");
      } else if (s->ttype == MIP_TTYPE_FIN) {
        c->is_closing = 1;
        continue;
      } else {
        if (s->tmiss++ > 2) {
          mg_error(c, "keepalive");
        } else {
          MG_VERBOSE(("%lu keepalive", c->id));
          tx_tcp(ifp, s->mac, &c->loc, &c->rem, TH_ACK, mg_htonl(s->seq - 1),
                 mg_htonl(s->ack), NULL, 0);
        }
      }

      settmout(c, MIP_TTYPE_KEEPALIVE);
    }
  }
}

// This function executes in interrupt context, thus it should copy data
// somewhere fast. Note that newlib's malloc is not thread safe, thus use
// our lock-free queue with preallocated buffer to copy data and return asap
void mg_tcpip_qwrite(void *buf, size_t len, struct mg_tcpip_if *ifp) {
  char *p;
  if (mg_queue_book(&ifp->recv_queue, &p, len) >= len) {
    memcpy(p, buf, len);
    mg_queue_add(&ifp->recv_queue, len);
    ifp->nrecv++;
  } else {
    ifp->ndrop++;
  }
}

void mg_tcpip_init(struct mg_mgr *mgr, struct mg_tcpip_if *ifp) {
  // If L2 address is not set, make a random one; fill MTU
  mg_l2_init(ifp->l2type, ifp->mac, &ifp->mtu, &ifp->framesize);

  if (ifp->dhcp_name[0] == '\0')  // If DHCP name is not set, use "mip"
    memcpy(ifp->dhcp_name, "mip", 4);
  ifp->dhcp_name[sizeof(ifp->dhcp_name) - 1] = '\0';  // Just in case

  if (ifp->driver->init && !ifp->driver->init(ifp)) {
    MG_ERROR(("driver init failed"));
  } else {
    ifp->tx.buf = (char *) mg_calloc(1, ifp->framesize),
    ifp->tx.len = ifp->framesize;
    if (ifp->recv_queue.size == 0)
      ifp->recv_queue.size = ifp->driver->rx ? ifp->framesize : 8192;
    ifp->recv_queue.buf = (char *) mg_calloc(1, ifp->recv_queue.size);
    ifp->timer_1000ms = mg_millis();
    mgr->ifp = ifp;
    ifp->mgr = mgr;
    mgr->extraconnsize = sizeof(struct connstate);
    if (ifp->ip == 0) ifp->enable_dhcp_client = true;
    mg_random(&ifp->eport, sizeof(ifp->eport));  // Random from 0 to 65535
    ifp->eport |= MG_EPHEMERAL_PORT_BASE;        // Random from
                                           // MG_EPHEMERAL_PORT_BASE to 65535
#if MG_ENABLE_IPV6
    if (ifp->ip6ll[0] == 0 && ifp->ip6ll[1] == 0) {    // gen link-local address
      uint8_t px[8] = {0xfe, 0x80, 0, 0, 0, 0, 0, 0};  // RFC-4291 2.5.6
      mg_l2_genip6(ifp->l2type, ifp->ip6ll, 64, ifp->mac);
      memcpy(ifp->ip6ll, px, 8);  // RFC-4291 2.5.4
    }  // just got our link local address if we didn't.
    // If static configuration is used, global addresses,
    // prefix length, and gw are already filled at this point.
    if (ifp->ip6[0] == 0 && ifp->ip6[1] == 0) ifp->enable_slaac = true;
#endif
    if (ifp->tx.buf == NULL || ifp->recv_queue.buf == NULL) MG_ERROR(("OOM"));
  }
}

void mg_tcpip_free(struct mg_tcpip_if *ifp) {
  mg_free(ifp->recv_queue.buf);
  mg_free(ifp->tx.buf);
  mg_free(ifp->dns4_url);
}

static void send_syn(struct mg_connection *c) {
  struct connstate *s = (struct connstate *) (c + 1);
  uint32_t isn = mg_htonl((uint32_t) mg_ntohs(c->loc.port));
  tx_tcp(c->mgr->ifp, s->mac, &c->loc, &c->rem, TH_SYN, isn, 0, NULL, 0);
}

static void l2addr_resolved(struct mg_connection *c) {
  if (c->is_udp) {
    c->is_connecting = 0;
    mg_call(c, MG_EV_CONNECT, NULL);
  } else {
    send_syn(c);
    settmout(c, MIP_TTYPE_SYN);
  }
}

void mg_connect_resolved(struct mg_connection *c) {
  struct mg_tcpip_if *ifp = c->mgr->ifp;
  uint8_t *l2addr;
  c->is_resolving = 0;
  if (ifp->eport < MG_EPHEMERAL_PORT_BASE) ifp->eport = MG_EPHEMERAL_PORT_BASE;
  c->loc.port = mg_htons(ifp->eport++);
#if MG_ENABLE_IPV6
  if (c->rem.is_ip6) {
    c->loc.addr.ip6[0] = ifp->ip6[0], c->loc.addr.ip6[1] = ifp->ip6[1],
    c->loc.is_ip6 = true;
  } else
#endif
  {
    c->loc.addr.ip4 = ifp->ip;
  }
  MG_DEBUG(("%lu %M -> %M", c->id, mg_print_ip_port, &c->loc, mg_print_ip_port,
            &c->rem));
  mg_call(c, MG_EV_RESOLVE, NULL);
  c->is_connecting = 1;
  if (c->is_udp && (l2addr = tcpip_mapip(ifp, &c->rem)) != NULL) {
    struct connstate *s = (struct connstate *) (c + 1);
    memcpy(s->mac, l2addr, sizeof(s->mac));
    l2addr_resolved(c);  // broadcast or multicast
#if MG_ENABLE_IPV6
  } else if (c->rem.is_ip6) {
    if (match_prefix((uint8_t *) c->rem.addr.ip6, ifp->prefix,
                     ifp->prefix_len)                       // same global LAN
        || (c->rem.addr.ip6[0] == ifp->ip6ll[0]             // same local LAN
            && !MG_IP6MATCH(c->rem.addr.ip6, ifp->gw6))) {  // and not gw
      // If we're in the same LAN, fire a Neighbor Solicitation
      MG_DEBUG(("%lu NS lookup...", c->id));
      tx_ndp_ns(ifp, c->rem.addr.ip6, NULL);  // RFC-4861 4.3, requesting
      settmout(c, MIP_TTYPE_ARP);
      c->is_arplooking = 1;
    } else if (ifp->gw6_ready) {
      struct connstate *s = (struct connstate *) (c + 1);
      memcpy(s->mac, ifp->gw6mac, sizeof(s->mac));
      l2addr_resolved(c);
    } else {
      MG_ERROR(("No IPv6 gateway, can't connect"));
    }
#endif
  } else {
    uint32_t rem_ip = c->rem.addr.ip4;
    if (ifp->ip && ((rem_ip & ifp->mask) == (ifp->ip & ifp->mask)) &&
        rem_ip != ifp->gw) {  // skip if gw (onstatechange -> ARP)
      // If we're in the same LAN, fire an ARP lookup.
      MG_DEBUG(("%lu ARP lookup...", c->id));
      mg_tcpip_arp_request(ifp, rem_ip, NULL);
      settmout(c, MIP_TTYPE_ARP);
      c->is_arplooking = 1;
    } else if (ifp->gw_ready) {
      struct connstate *s = (struct connstate *) (c + 1);
      memcpy(s->mac, ifp->gwmac, sizeof(s->mac));
      l2addr_resolved(c);
    } else {
      MG_ERROR(("No gateway, can't connect"));
    }
  }
}

bool mg_open_listener(struct mg_connection *c, const char *url) {
  c->loc.port = mg_htons(mg_url_port(url));
  if (!mg_aton(mg_url_host(url), &c->loc)) {
    MG_ERROR(("invalid listening URL: %s", url));
    return false;
  }
  return true;
}

static void write_conn(struct mg_connection *c) {
  long len = c->is_tls ? mg_tls_send(c, c->send.buf, c->send.len)
                       : mg_io_send(c, c->send.buf, c->send.len);
  // TODO(): mg_tls_send() may return 0 forever on steady OOM
  if (len == MG_IO_ERR) {
    mg_error(c, "tx err");
  } else if (len > 0) {
    mg_iobuf_del(&c->send, 0, (size_t) len);
    mg_call(c, MG_EV_WRITE, &len);
  }
}

static void init_closure(struct mg_connection *c) {
  struct connstate *s = (struct connstate *) (c + 1);
  if (c->is_udp == false && c->is_listening == false &&
      c->is_connecting == false) {  // For TCP conns,
    tx_tcp(c->mgr->ifp, s->mac, &c->loc, &c->rem, TH_FIN | TH_ACK,
           mg_htonl(s->seq), mg_htonl(s->ack), NULL, 0);
    settmout(c, MIP_TTYPE_FIN);
  }
}

static void close_conn(struct mg_connection *c) {
  struct connstate *s = (struct connstate *) (c + 1);
  mg_iobuf_free(&s->raw);  // For TLS connections, release raw data
  mg_close_conn(c);
}

static bool can_write(struct mg_connection *c) {
  return c->is_connecting == 0 && c->is_resolving == 0 && c->send.len > 0 &&
         c->is_tls_hs == 0 && c->is_arplooking == 0;
}

void mg_mgr_poll(struct mg_mgr *mgr, int ms) {
  struct mg_connection *c, *tmp;
  uint64_t now = mg_millis();
  mg_timer_poll(&mgr->timers, now);
  if (mgr->ifp == NULL || mgr->ifp->driver == NULL) return;
  mg_tcpip_poll(mgr->ifp, now);
  for (c = mgr->conns; c != NULL; c = tmp) {
    struct connstate *s = (struct connstate *) (c + 1);
    bool is_tls = c->is_tls && !c->is_resolving && !c->is_arplooking &&
                  !c->is_listening && !c->is_connecting;
    tmp = c->next;
    mg_call(c, MG_EV_POLL, &now);
    MG_VERBOSE(("%lu .. %c%c%c%c%c %lu %lu", c->id, c->is_tls ? 'T' : 't',
                c->is_connecting ? 'C' : 'c', c->is_tls_hs ? 'H' : 'h',
                c->is_resolving ? 'R' : 'r', c->is_closing ? 'C' : 'c',
                mg_tls_pending(c), c->rtls.len));
    // order is important, TLS conn close with > 1 record in buffer (below)
    if (is_tls && (c->rtls.len > 0 || mg_tls_pending(c) > 0))
      c->is_tls_hs ? mg_tls_handshake(c) : handle_tls_recv(c);
    if (can_write(c)) write_conn(c);
    if (is_tls && c->send.len == 0) mg_tls_flush(c);
    if (c->is_draining && c->send.len == 0 && s->ttype != MIP_TTYPE_FIN)
      init_closure(c);
    // For non-TLS, close immediately upon completing the 3-way closure
    // For TLS, handle any pending data (above) until MIP_TTYPE_FIN expires
    if (s->twclosure &&
        (!c->is_tls || (c->rtls.len == 0 && mg_tls_pending(c) == 0)))
      c->is_closing = 1;
    if (c->is_closing) close_conn(c);
  }
  (void) ms;
}

bool mg_send(struct mg_connection *c, const void *buf, size_t len) {
  struct mg_tcpip_if *ifp = c->mgr->ifp;
  bool res = false;
  if (!c->loc.is_ip6 && (ifp->ip == 0 || ifp->state != MG_TCPIP_STATE_READY)) {
    mg_error(c, "net down");
#if MG_ENABLE_IPV6
  } else if (c->loc.is_ip6 && ifp->state6 != MG_TCPIP_STATE_READY) {
    mg_error(c, "net down");
#endif
  } else if (c->is_udp && (c->is_arplooking || c->is_resolving)) {
    // Fail to send, no target MAC or IP
    MG_VERBOSE(("still resolving..."));
  } else if (c->is_udp) {
    len = trim_len(c, len);  // Trimming length if necessary
    res = udp_send(c, buf, len);
  } else {
    res = len == 0 || mg_iobuf_add(&c->send, c->send.len, buf, len) > 0;
    // returning 0 means an OOM condition (iobuf couldn't resize), yet this is
    // so far recoverable, let the caller decide
  }
  return res;
}

uint8_t mcast_addr[6] = {0x01, 0x00, 0x5e, 0x00, 0x00, 0xfb};
void mg_multicast_add(struct mg_connection *c, char *ip) {
  (void) ip;  // ip4/6_mcastmac(mcast_mac, &ip); ipv6 param
  // TODO(): actual IP -> MAC; check database, update
  c->mgr->ifp->update_mac_hash_table = true;  // mark dirty
}

bool mg_dnsc_init(struct mg_mgr *mgr, struct mg_dns *dnsc);

static void setdns4(struct mg_tcpip_if *ifp, uint32_t *ip) {
  struct mg_dns *dnsc;
  mg_free(ifp->dns4_url);
  ifp->dns4_url = mg_mprintf("udp://%M:53", mg_print_ip4, ip);
  dnsc = &ifp->mgr->dns4;
  dnsc->url = (const char *) ifp->dns4_url;
  MG_DEBUG(("Set DNS URL to %s", dnsc->url));
  if (ifp->mgr->use_dns6) return;
  if (dnsc->c != NULL) mg_close_conn(dnsc->c);
  if (!mg_dnsc_init(ifp->mgr, dnsc))  // create DNS connection
    MG_ERROR(("DNS connection creation failed"));
}

void mg_tcpip_mapip(struct mg_connection *c, struct mg_addr *ip) {
  struct connstate *s = (struct connstate *) (c + 1);
  uint8_t *l2addr = tcpip_mapip(c->mgr->ifp, ip);
  if (l2addr == NULL) return;
  memcpy(s->mac, l2addr, sizeof(s->mac));
}

#endif  // MG_ENABLE_TCPIP

#ifdef MG_ENABLE_LINES
#line 1 "src/ota_ch32v307.c"
#endif




#if MG_OTA == MG_OTA_CH32V307
// RM: https://www.wch-ic.com/downloads/CH32FV2x_V3xRM_PDF.html

static bool mg_ch32v307_write(void *, const void *, size_t);
static bool mg_ch32v307_swap(void);

static struct mg_flash s_mg_flash_ch32v307 = {
    (void *) 0x08000000,  // Start
    480 * 1024,           // Size, first 320k is 0-wait
    4 * 1024,             // Sector size, 4k
    4,                    // Align, 32 bit
    mg_ch32v307_write,
    mg_ch32v307_swap,
};

#define FLASH_BASE 0x40022000
#define FLASH_ACTLR (FLASH_BASE + 0)
#define FLASH_KEYR (FLASH_BASE + 4)
#define FLASH_OBKEYR (FLASH_BASE + 8)
#define FLASH_STATR (FLASH_BASE + 12)
#define FLASH_CTLR (FLASH_BASE + 16)
#define FLASH_ADDR (FLASH_BASE + 20)
#define FLASH_OBR (FLASH_BASE + 28)
#define FLASH_WPR (FLASH_BASE + 32)

MG_IRAM static void flash_unlock(void) {
  static bool unlocked;
  if (unlocked == false) {
    MG_REG(FLASH_KEYR) = 0x45670123;
    MG_REG(FLASH_KEYR) = 0xcdef89ab;
    unlocked = true;
  }
}

MG_IRAM static void flash_wait(void) {
  while (MG_REG(FLASH_STATR) & MG_BIT(0)) (void) 0;
}

MG_IRAM static void mg_ch32v307_erase(void *addr) {
  // MG_INFO(("%p", addr));
  flash_unlock();
  flash_wait();
  MG_REG(FLASH_ADDR) = (uint32_t) addr;
  MG_REG(FLASH_CTLR) |= MG_BIT(1) | MG_BIT(6);  // PER | STRT;
  flash_wait();
}

MG_IRAM static bool is_page_boundary(const void *addr) {
  uint32_t val = (uint32_t) addr;
  return (val & (s_mg_flash_ch32v307.secsz - 1)) == 0;
}

MG_IRAM static bool mg_ch32v307_write(void *addr, const void *buf, size_t len) {
  // MG_INFO(("%p %p %lu", addr, buf, len));
  // mg_hexdump(buf, len);
  flash_unlock();
  const uint16_t *src = (uint16_t *) buf, *end = &src[len / 2];
  uint16_t *dst = (uint16_t *) addr;
  MG_REG(FLASH_CTLR) |= MG_BIT(0);  // Set PG
  // MG_INFO(("CTLR: %#lx", MG_REG(FLASH_CTLR)));
  while (src < end) {
    if (is_page_boundary(dst)) mg_ch32v307_erase(dst);
    *dst++ = *src++;
    flash_wait();
  }
  MG_REG(FLASH_CTLR) &= ~MG_BIT(0);  // Clear PG
  return true;
}

MG_IRAM bool mg_ch32v307_swap(void) {
  return true;
}

// just overwrite instead of swap
MG_IRAM static void single_bank_swap(char *p1, char *p2, size_t s, size_t ss) {
  // no stdlib calls here
  for (size_t ofs = 0; ofs < s; ofs += ss) {
    mg_ch32v307_write(p1 + ofs, p2 + ofs, ss);
  }
  *((volatile uint32_t *) 0xbeef0000) |= 1U << 7;  // NVIC_SystemReset()
}

bool mg_ota_begin(size_t new_firmware_size) {
  return mg_ota_flash_begin(new_firmware_size, &s_mg_flash_ch32v307);
}

bool mg_ota_write(const void *buf, size_t len) {
  return mg_ota_flash_write(buf, len, &s_mg_flash_ch32v307);
}

bool mg_ota_end(void) {
  if (mg_ota_flash_end(&s_mg_flash_ch32v307)) {
    // Swap partitions. Pray power does not go away
    MG_INFO(("Swapping partitions, size %u (%u sectors)",
             s_mg_flash_ch32v307.size,
             s_mg_flash_ch32v307.size / s_mg_flash_ch32v307.secsz));
    MG_INFO(("Do NOT power off..."));
    mg_log_level = MG_LL_NONE;
    // TODO() disable IRQ, s_flash_irq_disabled = true;
    // Runs in RAM, will reset when finished
    single_bank_swap(
        (char *) s_mg_flash_ch32v307.start,
        (char *) s_mg_flash_ch32v307.start + s_mg_flash_ch32v307.size / 2,
        s_mg_flash_ch32v307.size / 2, s_mg_flash_ch32v307.secsz);
  }
  return false;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ota_dummy.c"
#endif



#if MG_OTA == MG_OTA_NONE
bool mg_ota_begin(size_t new_firmware_size) {
  (void) new_firmware_size;
  return true;
}
bool mg_ota_write(const void *buf, size_t len) {
  (void) buf, (void) len;
  return true;
}
bool mg_ota_end(void) {
  return true;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ota_esp32.c"
#endif


#if MG_ARCH == MG_ARCH_ESP32 && MG_OTA == MG_OTA_ESP32

static const esp_partition_t *s_ota_update_partition;
static esp_ota_handle_t s_ota_update_handle;
static bool s_ota_success;

// Those empty macros do nothing, but mark places in the code which could
// potentially trigger a watchdog reboot due to the log flash erase operation
#define disable_wdt()
#define enable_wdt()

bool mg_ota_begin(size_t new_firmware_size) {
  if (s_ota_update_partition != NULL) {
    MG_ERROR(("Update in progress. Call mg_ota_end() ?"));
    return false;
  } else {
    s_ota_success = false;
    disable_wdt();
    s_ota_update_partition = esp_ota_get_next_update_partition(NULL);
    esp_err_t err = esp_ota_begin(s_ota_update_partition, new_firmware_size,
                                  &s_ota_update_handle);
    enable_wdt();
    MG_DEBUG(("esp_ota_begin(): %d", err));
    s_ota_success = (err == ESP_OK);
  }
  return s_ota_success;
}

bool mg_ota_write(const void *buf, size_t len) {
  disable_wdt();
  esp_err_t err = esp_ota_write(s_ota_update_handle, buf, len);
  enable_wdt();
  MG_INFO(("esp_ota_write(): %d", err));
  s_ota_success = err == ESP_OK;
  return s_ota_success;
}

bool mg_ota_end(void) {
  esp_err_t err = esp_ota_end(s_ota_update_handle);
  MG_DEBUG(("esp_ota_end(%p): %d", s_ota_update_handle, err));
  if (s_ota_success && err == ESP_OK) {
    err = esp_ota_set_boot_partition(s_ota_update_partition);
    s_ota_success = (err == ESP_OK);
  }
  MG_DEBUG(("Finished ESP32 OTA, success: %d", s_ota_success));
  s_ota_update_partition = NULL;
  return s_ota_success;
}

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ota_imxrt.c"
#endif




#if MG_OTA >= MG_OTA_RT1020 && MG_OTA <= MG_OTA_RT1170

static bool mg_imxrt_write(void *, const void *, size_t);
static bool mg_imxrt_swap(void);

#if MG_OTA <= MG_OTA_RT1060
#define MG_IMXRT_FLASH_START 0x60000000
#define FLEXSPI_NOR_INSTANCE 0
#elif MG_OTA == MG_OTA_RT1064
#define MG_IMXRT_FLASH_START 0x70000000
#define FLEXSPI_NOR_INSTANCE 1
#else  // RT1170
#define MG_IMXRT_FLASH_START 0x30000000
#define FLEXSPI_NOR_INSTANCE 1
#endif

#if MG_OTA == MG_OTA_RT1050
#define MG_IMXRT_SECTOR_SIZE (256 * 1024)
#define MG_IMXRT_PAGE_SIZE 512
#else
#define MG_IMXRT_SECTOR_SIZE (4 * 1024)
#define MG_IMXRT_PAGE_SIZE 256
#endif

// TODO(): fill at init, support more devices in a dynamic way
// TODO(): then, check alignment is <= 256, see Wizard's #251
static struct mg_flash s_mg_flash_imxrt = {
    (void *) MG_IMXRT_FLASH_START,  // Start,
    4 * 1024 * 1024,                // Size, 4mb
    MG_IMXRT_SECTOR_SIZE,           // Sector size
    MG_IMXRT_PAGE_SIZE,             // Align
    mg_imxrt_write,
    mg_imxrt_swap,
};

struct mg_flexspi_lut_seq {
  uint8_t seqNum;
  uint8_t seqId;
  uint16_t reserved;
};

struct mg_flexspi_mem_config {
  uint32_t tag;
  uint32_t version;
  uint32_t reserved0;
  uint8_t readSampleClkSrc;
  uint8_t csHoldTime;
  uint8_t csSetupTime;
  uint8_t columnAddressWidth;
  uint8_t deviceModeCfgEnable;
  uint8_t deviceModeType;
  uint16_t waitTimeCfgCommands;
  struct mg_flexspi_lut_seq deviceModeSeq;
  uint32_t deviceModeArg;
  uint8_t configCmdEnable;
  uint8_t configModeType[3];
  struct mg_flexspi_lut_seq configCmdSeqs[3];
  uint32_t reserved1;
  uint32_t configCmdArgs[3];
  uint32_t reserved2;
  uint32_t controllerMiscOption;
  uint8_t deviceType;
  uint8_t sflashPadType;
  uint8_t serialClkFreq;
  uint8_t lutCustomSeqEnable;
  uint32_t reserved3[2];
  uint32_t sflashA1Size;
  uint32_t sflashA2Size;
  uint32_t sflashB1Size;
  uint32_t sflashB2Size;
  uint32_t csPadSettingOverride;
  uint32_t sclkPadSettingOverride;
  uint32_t dataPadSettingOverride;
  uint32_t dqsPadSettingOverride;
  uint32_t timeoutInMs;
  uint32_t commandInterval;
  uint16_t dataValidTime[2];
  uint16_t busyOffset;
  uint16_t busyBitPolarity;
  uint32_t lookupTable[64];
  struct mg_flexspi_lut_seq lutCustomSeq[12];
  uint32_t reserved4[4];
};

struct mg_flexspi_nor_config {
  struct mg_flexspi_mem_config memConfig;
  uint32_t pageSize;
  uint32_t sectorSize;
  uint8_t ipcmdSerialClkFreq;
  uint8_t isUniformBlockSize;
  uint8_t reserved0[2];
  uint8_t serialNorType;
  uint8_t needExitNoCmdMode;
  uint8_t halfClkForNonReadCmd;
  uint8_t needRestoreNoCmdMode;
  uint32_t blockSize;
  uint32_t reserve2[11];
};

/* FLEXSPI memory config block related defintions */
#define MG_FLEXSPI_CFG_BLK_TAG (0x42464346UL)      // ascii "FCFB" Big Endian
#define MG_FLEXSPI_CFG_BLK_VERSION (0x56010400UL)  // V1.4.0

#define MG_FLEXSPI_LUT_SEQ(cmd0, pad0, op0, cmd1, pad1, op1)       \
  (MG_FLEXSPI_LUT_OPERAND0(op0) | MG_FLEXSPI_LUT_NUM_PADS0(pad0) | \
   MG_FLEXSPI_LUT_OPCODE0(cmd0) | MG_FLEXSPI_LUT_OPERAND1(op1) |   \
   MG_FLEXSPI_LUT_NUM_PADS1(pad1) | MG_FLEXSPI_LUT_OPCODE1(cmd1))

#define MG_CMD_SDR 0x01
#define MG_CMD_DDR 0x21
#define MG_DUMMY_SDR 0x0C
#define MG_DUMMY_DDR 0x2C
#define MG_DUMMY_RWDS_DDR 0x2D
#define MG_RADDR_SDR 0x02
#define MG_RADDR_DDR 0x22
#define MG_CADDR_DDR 0x23
#define MG_READ_SDR 0x09
#define MG_READ_DDR 0x29
#define MG_WRITE_SDR 0x08
#define MG_WRITE_DDR 0x28
#define MG_STOP 0

#define MG_FLEXSPI_1PAD 0
#define MG_FLEXSPI_2PAD 1
#define MG_FLEXSPI_4PAD 2
#define MG_FLEXSPI_8PAD 3

#define MG_FLEXSPI_QSPI_LUT                                                    \
  {                                                                            \
    [0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0xEB, MG_RADDR_SDR,  \
                             MG_FLEXSPI_4PAD, 0x18),                           \
    [1] = MG_FLEXSPI_LUT_SEQ(MG_DUMMY_SDR, MG_FLEXSPI_4PAD, 0x06, MG_READ_SDR, \
                             MG_FLEXSPI_4PAD, 0x04),                           \
    [4 * 1 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0x05,        \
                                     MG_READ_SDR, MG_FLEXSPI_1PAD, 0x04),      \
    [4 * 3 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0x06,        \
                                     MG_STOP, MG_FLEXSPI_1PAD, 0x0),           \
    [4 * 5 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0x20,        \
                                     MG_RADDR_SDR, MG_FLEXSPI_1PAD, 0x18),     \
    [4 * 8 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0xD8,        \
                                     MG_RADDR_SDR, MG_FLEXSPI_1PAD, 0x18),     \
    [4 * 9 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0x02,        \
                                     MG_RADDR_SDR, MG_FLEXSPI_1PAD, 0x18),     \
    [4 * 9 + 1] = MG_FLEXSPI_LUT_SEQ(MG_WRITE_SDR, MG_FLEXSPI_1PAD, 0x04,      \
                                     MG_STOP, MG_FLEXSPI_1PAD, 0x0),           \
    [4 * 11 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0x60,       \
                                      MG_STOP, MG_FLEXSPI_1PAD, 0x0),          \
  }

#define MG_FLEXSPI_HYPER_LUT                                                  \
  {                                                                           \
    [0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xA0, MG_RADDR_DDR, \
                             MG_FLEXSPI_8PAD, 0x18),                          \
    [1] = MG_FLEXSPI_LUT_SEQ(MG_CADDR_DDR, MG_FLEXSPI_8PAD, 0x10,             \
                             MG_DUMMY_DDR, MG_FLEXSPI_8PAD, 0x0C),            \
    [2] = MG_FLEXSPI_LUT_SEQ(MG_READ_DDR, MG_FLEXSPI_8PAD, 0x04, MG_STOP,     \
                             MG_FLEXSPI_1PAD, 0x0),                           \
    [4 * 1 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),       \
    [4 * 1 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),      \
    [4 * 1 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x05),      \
    [4 * 1 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x70),      \
    [4 * 2 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xA0,       \
                                     MG_RADDR_DDR, MG_FLEXSPI_8PAD, 0x18),    \
    [4 * 2 + 1] =                                                             \
        MG_FLEXSPI_LUT_SEQ(MG_CADDR_DDR, MG_FLEXSPI_8PAD, 0x10,               \
                           MG_DUMMY_RWDS_DDR, MG_FLEXSPI_8PAD, 0x0B),         \
    [4 * 2 + 2] = MG_FLEXSPI_LUT_SEQ(MG_READ_DDR, MG_FLEXSPI_8PAD, 0x4,       \
                                     MG_STOP, MG_FLEXSPI_1PAD, 0x0),          \
    [4 * 3 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),       \
    [4 * 3 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),      \
    [4 * 3 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x05),      \
    [4 * 3 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),      \
    [4 * 4 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),       \
    [4 * 4 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x55),      \
    [4 * 4 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x02),      \
    [4 * 4 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x55),      \
    [4 * 5 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),       \
    [4 * 5 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),      \
    [4 * 5 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x05),      \
    [4 * 5 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x80),      \
    [4 * 6 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),       \
    [4 * 6 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),      \
    [4 * 6 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x05),      \
    [4 * 6 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),      \
    [4 * 7 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),       \
    [4 * 7 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x55),      \
    [4 * 7 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x02),      \
    [4 * 7 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x55),      \
    [4 * 8 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_RADDR_DDR, MG_FLEXSPI_8PAD, 0x18),    \
    [4 * 8 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CADDR_DDR, MG_FLEXSPI_8PAD, 0x10,     \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),       \
    [4 * 8 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x30,       \
                                     MG_STOP, MG_FLEXSPI_1PAD, 0x0),          \
    [4 * 9 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),       \
    [4 * 9 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),      \
    [4 * 9 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x05),      \
    [4 * 9 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,        \
                                     MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xA0),      \
    [4 * 10 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_RADDR_DDR, MG_FLEXSPI_8PAD, 0x18),   \
    [4 * 10 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CADDR_DDR, MG_FLEXSPI_8PAD, 0x10,    \
                                      MG_WRITE_DDR, MG_FLEXSPI_8PAD, 0x80),   \
    [4 * 11 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),      \
    [4 * 11 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),     \
    [4 * 11 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x05),     \
    [4 * 11 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x80),     \
    [4 * 12 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),      \
    [4 * 12 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),     \
    [4 * 12 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x05),     \
    [4 * 12 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),     \
    [4 * 13 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),      \
    [4 * 13 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x55),     \
    [4 * 13 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x02),     \
    [4 * 13 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x55),     \
    [4 * 14 + 0] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0),      \
    [4 * 14 + 1] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0xAA),     \
    [4 * 14 + 2] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x05),     \
    [4 * 14 + 3] = MG_FLEXSPI_LUT_SEQ(MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x0,       \
                                      MG_CMD_DDR, MG_FLEXSPI_8PAD, 0x10),     \
  }

#define MG_LUT_CUSTOM_SEQ                          \
  {                                                \
    {.seqNum = 0, .seqId = 0, .reserved = 0},      \
        {.seqNum = 2, .seqId = 1, .reserved = 0},  \
        {.seqNum = 2, .seqId = 3, .reserved = 0},  \
        {.seqNum = 4, .seqId = 5, .reserved = 0},  \
        {.seqNum = 2, .seqId = 9, .reserved = 0},  \
        {.seqNum = 4, .seqId = 11, .reserved = 0}, \
  }

#define MG_FLEXSPI_LUT_OPERAND0(x) (((uint32_t) (((uint32_t) (x)))) & 0xFFU)
#define MG_FLEXSPI_LUT_NUM_PADS0(x) \
  (((uint32_t) (((uint32_t) (x)) << 8U)) & 0x300U)
#define MG_FLEXSPI_LUT_OPCODE0(x) \
  (((uint32_t) (((uint32_t) (x)) << 10U)) & 0xFC00U)
#define MG_FLEXSPI_LUT_OPERAND1(x) \
  (((uint32_t) (((uint32_t) (x)) << 16U)) & 0xFF0000U)
#define MG_FLEXSPI_LUT_NUM_PADS1(x) \
  (((uint32_t) (((uint32_t) (x)) << 24U)) & 0x3000000U)
#define MG_FLEXSPI_LUT_OPCODE1(x) \
  (((uint32_t) (((uint32_t) (x)) << 26U)) & 0xFC000000U)

#if MG_OTA == MG_OTA_RT1020 || MG_OTA == MG_OTA_RT1050
// RT102X and RT105x boards support ROM API version 1.4
struct mg_flexspi_nor_driver_interface {
  uint32_t version;
  int (*init)(uint32_t instance, struct mg_flexspi_nor_config *config);
  int (*program)(uint32_t instance, struct mg_flexspi_nor_config *config,
                 uint32_t dst_addr, const uint32_t *src);
  uint32_t reserved;
  int (*erase)(uint32_t instance, struct mg_flexspi_nor_config *config,
               uint32_t start, uint32_t lengthInBytes);
  uint32_t reserved2;
  int (*update_lut)(uint32_t instance, uint32_t seqIndex,
                    const uint32_t *lutBase, uint32_t seqNumber);
  int (*xfer)(uint32_t instance, char *xfer);
  void (*clear_cache)(uint32_t instance);
};
#elif MG_OTA <= MG_OTA_RT1064
// RT104x and RT106x support ROM API version 1.5
struct mg_flexspi_nor_driver_interface {
  uint32_t version;
  int (*init)(uint32_t instance, struct mg_flexspi_nor_config *config);
  int (*program)(uint32_t instance, struct mg_flexspi_nor_config *config,
                 uint32_t dst_addr, const uint32_t *src);
  int (*erase_all)(uint32_t instance, struct mg_flexspi_nor_config *config);
  int (*erase)(uint32_t instance, struct mg_flexspi_nor_config *config,
               uint32_t start, uint32_t lengthInBytes);
  int (*read)(uint32_t instance, struct mg_flexspi_nor_config *config,
              uint32_t *dst, uint32_t addr, uint32_t lengthInBytes);
  void (*clear_cache)(uint32_t instance);
  int (*xfer)(uint32_t instance, char *xfer);
  int (*update_lut)(uint32_t instance, uint32_t seqIndex,
                    const uint32_t *lutBase, uint32_t seqNumber);
  int (*get_config)(uint32_t instance, struct mg_flexspi_nor_config *config,
                    uint32_t *option);
};
#else
// RT117x support ROM API version 1.7
struct mg_flexspi_nor_driver_interface {
  uint32_t version;
  int (*init)(uint32_t instance, struct mg_flexspi_nor_config *config);
  int (*program)(uint32_t instance, struct mg_flexspi_nor_config *config,
                 uint32_t dst_addr, const uint32_t *src);
  int (*erase_all)(uint32_t instance, struct mg_flexspi_nor_config *config);
  int (*erase)(uint32_t instance, struct mg_flexspi_nor_config *config,
               uint32_t start, uint32_t lengthInBytes);
  int (*read)(uint32_t instance, struct mg_flexspi_nor_config *config,
              uint32_t *dst, uint32_t addr, uint32_t lengthInBytes);
  uint32_t reserved;
  int (*xfer)(uint32_t instance, char *xfer);
  int (*update_lut)(uint32_t instance, uint32_t seqIndex,
                    const uint32_t *lutBase, uint32_t seqNumber);
  int (*get_config)(uint32_t instance, struct mg_flexspi_nor_config *config,
                    uint32_t *option);
  int (*erase_sector)(uint32_t instance, struct mg_flexspi_nor_config *config,
                      uint32_t address);
  int (*erase_block)(uint32_t instance, struct mg_flexspi_nor_config *config,
                     uint32_t address);
  void (*hw_reset)(uint32_t instance, uint32_t resetLogic);
  int (*wait_busy)(uint32_t instance, struct mg_flexspi_nor_config *config,
                   bool isParallelMode, uint32_t address);
  int (*set_clock_source)(uint32_t instance, uint32_t clockSrc);
  void (*config_clock)(uint32_t instance, uint32_t freqOption,
                       uint32_t sampleClkMode);
};
#endif

#if MG_OTA <= MG_OTA_RT1064
#define MG_FLEXSPI_BASE 0x402A8000
#define flexspi_nor                                                          \
  (*((struct mg_flexspi_nor_driver_interface **) (*(uint32_t *) 0x0020001c + \
                                                  16)))
#else
#define MG_FLEXSPI_BASE 0x400CC000
#define flexspi_nor                                                          \
  (*((struct mg_flexspi_nor_driver_interface **) (*(uint32_t *) 0x0021001c + \
                                                  12)))
#endif

static bool s_flash_irq_disabled;

MG_IRAM static bool flash_page_start(volatile uint32_t *dst) {
  char *base = (char *) s_mg_flash_imxrt.start,
       *end = base + s_mg_flash_imxrt.size;
  volatile char *p = (char *) dst;
  return p >= base && p < end && ((p - base) % s_mg_flash_imxrt.secsz) == 0;
}

#if MG_OTA == MG_OTA_RT1050
// Configuration for Hyper flash memory
static struct mg_flexspi_nor_config default_config = {
    .memConfig =
        {
            .tag = MG_FLEXSPI_CFG_BLK_TAG,
            .version = MG_FLEXSPI_CFG_BLK_VERSION,
            .readSampleClkSrc = 3,  // ReadSampleClk_LoopbackFromDqsPad
            .csHoldTime = 3,
            .csSetupTime = 3,
            .columnAddressWidth = 3u,
            .controllerMiscOption =
                MG_BIT(6) | MG_BIT(4) | MG_BIT(3) | MG_BIT(0),
            .deviceType = 1,  // serial NOR
            .sflashPadType = 8,
            .serialClkFreq = 7,  // 133MHz
            .sflashA1Size = 64 * 1024 * 1024,
            .dataValidTime = {15, 0},
            .busyOffset = 15,
            .busyBitPolarity = 1,
            .lutCustomSeqEnable = 0x1,
            .lookupTable = MG_FLEXSPI_HYPER_LUT,
            .lutCustomSeq = MG_LUT_CUSTOM_SEQ,
        },
    .pageSize = 512,
    .sectorSize = 256 * 1024,
    .ipcmdSerialClkFreq = 1,
    .serialNorType = 1u,
    .blockSize = 256 * 1024,
    .isUniformBlockSize = true};
#else
// Note: this QSPI configuration works for RTs supporting QSPI
// Configuration for QSPI memory
static struct mg_flexspi_nor_config default_config = {
    .memConfig = {.tag = MG_FLEXSPI_CFG_BLK_TAG,
                  .version = MG_FLEXSPI_CFG_BLK_VERSION,
                  .readSampleClkSrc = 1,  // ReadSampleClk_LoopbackFromDqsPad
                  .csHoldTime = 3,
                  .csSetupTime = 3,
                  .controllerMiscOption = MG_BIT(4),
                  .deviceType = 1,  // serial NOR
                  .sflashPadType = 4,
                  .serialClkFreq = 7,  // 133MHz
                  .sflashA1Size = 8 * 1024 * 1024,
                  .lookupTable = MG_FLEXSPI_QSPI_LUT},
    .pageSize = 256,
    .sectorSize = 4 * 1024,
    .ipcmdSerialClkFreq = 1,
    .blockSize = 64 * 1024,
    .isUniformBlockSize = false};
#endif

// must reside in RAM, as flash will be erased
MG_IRAM static int flexspi_nor_get_config(
    struct mg_flexspi_nor_config **config) {
  *config = &default_config;
  return 0;
}

#if 0
// ROM API get_config call (ROM version >= 1.5)
MG_IRAM static int flexspi_nor_get_config(
    struct mg_flexspi_nor_config **config) {
  uint32_t options[] = {0xc0000000, 0x00};

  MG_ARM_DISABLE_IRQ();
  uint32_t status =
      flexspi_nor->get_config(FLEXSPI_NOR_INSTANCE, *config, options);
  if (!s_flash_irq_disabled) {
    MG_ARM_ENABLE_IRQ();
  }
  if (status) {
    MG_ERROR(("Failed to extract flash configuration: status %u", status));
  }
  return status;
}
#endif

MG_IRAM static void mg_spin(volatile uint32_t count) {
  while (count--) (void) 0;
}

MG_IRAM static void flash_wait(void) {
  while ((*((volatile uint32_t *) (MG_FLEXSPI_BASE + 0xE0)) & MG_BIT(1)) == 0)
    mg_spin(1);
}

MG_IRAM static bool flash_erase(struct mg_flexspi_nor_config *config,
                                void *addr) {
  if (flash_page_start(addr) == false) {
    MG_ERROR(("%p is not on a sector boundary", addr));
    return false;
  }

  void *dst = (void *) ((char *) addr - (char *) s_mg_flash_imxrt.start);

  bool ok = (flexspi_nor->erase(FLEXSPI_NOR_INSTANCE, config, (uint32_t) dst,
                                s_mg_flash_imxrt.secsz) == 0);
  MG_DEBUG(("Sector starting at %p erasure: %s", addr, ok ? "ok" : "fail"));
  return ok;
}

#if 0
// standalone erase call
MG_IRAM static bool mg_imxrt_erase(void *addr) {
  struct mg_flexspi_nor_config config, *config_ptr = &config;
  bool ret;
  // Interrupts must be disabled before calls to ROM API in RT1020 and 1060
  MG_ARM_DISABLE_IRQ();
  ret = (flexspi_nor_get_config(&config_ptr) == 0);
  if (ret) ret = flash_erase(config_ptr, addr);
  MG_ARM_ENABLE_IRQ();
  return ret;
}
#endif

MG_IRAM bool mg_imxrt_swap(void) {
  return true;
}

MG_IRAM static bool mg_imxrt_write(void *addr, const void *buf, size_t len) {
  struct mg_flexspi_nor_config config, *config_ptr = &config;
  bool ok = false;
  // Interrupts must be disabled before calls to ROM API in RT1020 and 1060
  MG_ARM_DISABLE_IRQ();
  if (flexspi_nor_get_config(&config_ptr) != 0) goto fwxit;
  if ((len % s_mg_flash_imxrt.align) != 0) {
    MG_ERROR(("%lu is not aligned to %lu", len, s_mg_flash_imxrt.align));
    goto fwxit;
  }
  if ((char *) addr < (char *) s_mg_flash_imxrt.start) {
    MG_ERROR(("Invalid flash write address: %p", addr));
    goto fwxit;
  }

  uint32_t *dst = (uint32_t *) addr;
  uint32_t *src = (uint32_t *) buf;
  uint32_t *end = (uint32_t *) ((char *) buf + len);
  ok = true;

  while (ok && src < end) {
    if (flash_page_start(dst) && flash_erase(config_ptr, dst) == false) {
      ok = false;
      break;
    }
    uint32_t status;
    uint32_t dst_ofs = (uint32_t) dst - (uint32_t) s_mg_flash_imxrt.start;
    if ((char *) buf >= (char *) s_mg_flash_imxrt.start) {
      // If we copy from FLASH to FLASH, then we first need to copy the source
      // to RAM
      size_t tmp_buf_size = s_mg_flash_imxrt.align / sizeof(uint32_t);
      uint32_t tmp[tmp_buf_size];

      for (size_t i = 0; i < tmp_buf_size; i++) {
        flash_wait();
        tmp[i] = src[i];
      }
      status = flexspi_nor->program(FLEXSPI_NOR_INSTANCE, config_ptr,
                                    (uint32_t) dst_ofs, tmp);
    } else {
      status = flexspi_nor->program(FLEXSPI_NOR_INSTANCE, config_ptr,
                                    (uint32_t) dst_ofs, src);
    }
    src = (uint32_t *) ((char *) src + s_mg_flash_imxrt.align);
    dst = (uint32_t *) ((char *) dst + s_mg_flash_imxrt.align);
    if (status != 0) {
      ok = false;
    }
  }
  MG_DEBUG(("Flash write %lu bytes @ %p: %s.", len, dst, ok ? "ok" : "fail"));
fwxit:
  if (!s_flash_irq_disabled) MG_ARM_ENABLE_IRQ();
  return ok;
}

// just overwrite instead of swap
MG_IRAM static void single_bank_swap(char *p1, char *p2, size_t s, size_t ss) {
  // no stdlib calls here
  for (size_t ofs = 0; ofs < s; ofs += ss) {
    mg_imxrt_write(p1 + ofs, p2 + ofs, ss);
  }
  *(volatile unsigned long *) 0xe000ed0c = 0x5fa0004;
}

bool mg_ota_begin(size_t new_firmware_size) {
  return mg_ota_flash_begin(new_firmware_size, &s_mg_flash_imxrt);
}

bool mg_ota_write(const void *buf, size_t len) {
  return mg_ota_flash_write(buf, len, &s_mg_flash_imxrt);
}

bool mg_ota_end(void) {
  if (mg_ota_flash_end(&s_mg_flash_imxrt)) {
    if (0) {  // is_dualbank()
      // TODO(): no devices so far
      *(volatile unsigned long *) 0xe000ed0c = 0x5fa0004;
    } else {
      // Swap partitions. Pray power does not go away
      MG_INFO(("Swapping partitions, size %u (%u sectors)",
               s_mg_flash_imxrt.size,
               s_mg_flash_imxrt.size / s_mg_flash_imxrt.secsz));
      MG_INFO(("Do NOT power off..."));
      mg_log_level = MG_LL_NONE;
      s_flash_irq_disabled = true;
      // Runs in RAM, will reset when finished
      single_bank_swap(
          (char *) s_mg_flash_imxrt.start,
          (char *) s_mg_flash_imxrt.start + s_mg_flash_imxrt.size / 2,
          s_mg_flash_imxrt.size / 2, s_mg_flash_imxrt.secsz);
    }
  }
  return false;
}

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ota_mcxn.c"
#endif




#if MG_OTA == MG_OTA_MCXN

// - Flash phrase: 16 bytes; smallest portion programmed in one operation.
// - Flash page: 128 bytes; largest portion programmed in one operation.
// - Flash sector: 8 KB; smallest portion that can be erased in one operation.
// - Flash API mg_flash_driver->program: "start" and "len" must be page-size
// aligned; to use 'phrase', FMU register access is needed. Using ROM

static bool mg_mcxn_write(void *, const void *, size_t);
static bool mg_mcxn_swap(void);

static struct mg_flash s_mg_flash_mcxn = {
    (void *) 0,  // Start, filled at init
    0,           // Size, filled at init
    0,           // Sector size, filled at init
    0,           // Align, filled at init
    mg_mcxn_write,
    mg_mcxn_swap,
};

struct mg_flash_config {
  uint32_t addr;
  uint32_t size;
  uint32_t blocks;
  uint32_t page_size;
  uint32_t sector_size;
  uint32_t ffr[6];
  uint32_t reserved0[5];
  uint32_t *bootctx;
  bool useahb;
};

struct mg_flash_driver_interface {
  uint32_t version;
  uint32_t (*init)(struct mg_flash_config *);
  uint32_t (*erase)(struct mg_flash_config *, uint32_t start, uint32_t len,
                    uint32_t key);
  uint32_t (*program)(struct mg_flash_config *, uint32_t start, uint8_t *src,
                      uint32_t len);
  uint32_t (*verify_erase)(struct mg_flash_config *, uint32_t start,
                           uint32_t len);
  uint32_t (*verify_program)(struct mg_flash_config *, uint32_t start,
                             uint32_t len, const uint8_t *expected,
                             uint32_t *addr, uint32_t *failed);
  uint32_t reserved1[12];
  uint32_t (*read)(struct mg_flash_config *, uint32_t start, uint8_t *dest,
                   uint32_t len);
  uint32_t reserved2[4];
  uint32_t (*deinit)(struct mg_flash_config *);
};
#define mg_flash_driver \
  ((struct mg_flash_driver_interface *) (*((uint32_t *) 0x1303fc00 + 4)))
#define MG_MCXN_FLASK_KEY (('k' << 24) | ('e' << 16) | ('f' << 8) | 'l')

MG_IRAM static bool flash_sector_start(volatile uint32_t *dst) {
  char *base = (char *) s_mg_flash_mcxn.start,
       *end = base + s_mg_flash_mcxn.size;
  volatile char *p = (char *) dst;
  return p >= base && p < end && ((p - base) % s_mg_flash_mcxn.secsz) == 0;
}

MG_IRAM static bool flash_erase(struct mg_flash_config *config, void *addr) {
  if (flash_sector_start(addr) == false) {
    MG_ERROR(("%p is not on a sector boundary", addr));
    return false;
  }
  uint32_t dst =
      (uint32_t) addr - (uint32_t) s_mg_flash_mcxn.start;  // future-proof
  uint32_t status = mg_flash_driver->erase(config, dst, s_mg_flash_mcxn.secsz,
                                           MG_MCXN_FLASK_KEY);
  bool ok = (status == 0);
  if (!ok) MG_ERROR(("Flash write error: %lu", status));
  MG_DEBUG(("Sector starting at %p erasure: %s", addr, ok ? "ok" : "fail"));
  return ok;
}

#if 0
// read-while-write, no need to disable IRQs for standalone usage
MG_IRAM static bool mg_mcxn_erase(void *addr) {
  uint32_t status;
  struct mg_flash_config config;
  if ((status = mg_flash_driver->init(&config)) != 0) {
    MG_ERROR(("Flash driver init error: %lu", status));
    return false;
  }
  bool ok = flash_erase(&config, addr);
  mg_flash_driver->deinit(&config);
  return ok;
}
#endif

MG_IRAM static bool mg_mcxn_swap(void) {
  // TODO(): no devices so far
  return true;
}

static bool s_flash_irq_disabled;

MG_IRAM static bool mg_mcxn_write(void *addr, const void *buf, size_t len) {
  bool ok = false;
  uint32_t status;
  struct mg_flash_config config;
  if ((status = mg_flash_driver->init(&config)) != 0) {
    MG_ERROR(("Flash driver init error: %lu", status));
    return false;
  }
  if ((len % s_mg_flash_mcxn.align) != 0) {
    MG_ERROR(("%lu is not aligned to %lu", len, s_mg_flash_mcxn.align));
    goto fwxit;
  }
  if ((((size_t) addr - (size_t) s_mg_flash_mcxn.start) %
       s_mg_flash_mcxn.align) != 0) {
    MG_ERROR(("%p is not on a page boundary", addr));
    goto fwxit;
  }

  uint32_t *dst = (uint32_t *) addr;
  uint32_t *src = (uint32_t *) buf;
  uint32_t *end = (uint32_t *) ((char *) buf + len);
  ok = true;

  MG_ARM_DISABLE_IRQ();
  while (ok && src < end) {
    if (flash_sector_start(dst) && flash_erase(&config, dst) == false) {
      ok = false;
      break;
    }
    uint32_t dst_ofs = (uint32_t) dst - (uint32_t) s_mg_flash_mcxn.start;
    // assume source is in RAM or in a different bank or read-while-write
    status = mg_flash_driver->program(&config, dst_ofs, (uint8_t *) src,
                                      s_mg_flash_mcxn.align);
    src = (uint32_t *) ((char *) src + s_mg_flash_mcxn.align);
    dst = (uint32_t *) ((char *) dst + s_mg_flash_mcxn.align);
    if (status != 0) {
      MG_ERROR(("Flash write error: %lu", status));
      ok = false;
    }
  }
  if (!s_flash_irq_disabled) MG_ARM_ENABLE_IRQ();
  MG_DEBUG(("Flash write %lu bytes @ %p: %s.", len, dst, ok ? "ok" : "fail"));

fwxit:
  mg_flash_driver->deinit(&config);
  return ok;
}

// try to swap (honor dual image), otherwise just overwrite
MG_IRAM static void single_bank_swap(char *p1, char *p2, size_t s, size_t ss) {
  char *tmp = mg_calloc(1, ss);
  // no stdlib calls here
  for (size_t ofs = 0; ofs < s; ofs += ss) {
    if (tmp != NULL)
      for (size_t i = 0; i < ss; i++) tmp[i] = p1[ofs + i];
    mg_mcxn_write(p1 + ofs, p2 + ofs, ss);
    if (tmp != NULL) mg_mcxn_write(p2 + ofs, tmp, ss);
  }
  *(volatile unsigned long *) 0xe000ed0c = 0x5fa0004;
}

bool mg_ota_begin(size_t new_firmware_size) {
  uint32_t status;
  struct mg_flash_config config;
  if ((status = mg_flash_driver->init(&config)) != 0) {
    MG_ERROR(("Flash driver init error: %lu", status));
    return false;
  }
  s_mg_flash_mcxn.start = (void *) config.addr;
  s_mg_flash_mcxn.size = config.size;
  s_mg_flash_mcxn.secsz = config.sector_size;
  s_mg_flash_mcxn.align = config.page_size;
  mg_flash_driver->deinit(&config);
  MG_DEBUG(
      ("%lu-byte flash @%p, using %lu-byte sectors with %lu-byte-aligned pages",
       s_mg_flash_mcxn.size, s_mg_flash_mcxn.start, s_mg_flash_mcxn.secsz,
       s_mg_flash_mcxn.align));
  return mg_ota_flash_begin(new_firmware_size, &s_mg_flash_mcxn);
}

bool mg_ota_write(const void *buf, size_t len) {
  return mg_ota_flash_write(buf, len, &s_mg_flash_mcxn);
}

bool mg_ota_end(void) {
  if (mg_ota_flash_end(&s_mg_flash_mcxn)) {
    if (0) {  // is_dualbank()
      // TODO(): no devices so far
      *(volatile unsigned long *) 0xe000ed0c = 0x5fa0004;
    } else {
      // Swap partitions. Pray power does not go away
      MG_INFO(("Swapping partitions, size %u (%u sectors)",
               s_mg_flash_mcxn.size,
               s_mg_flash_mcxn.size / s_mg_flash_mcxn.secsz));
      MG_INFO(("Do NOT power off..."));
      mg_log_level = MG_LL_NONE;
      s_flash_irq_disabled = true;
      // Runs in RAM, will reset when finished
      single_bank_swap(
          (char *) s_mg_flash_mcxn.start,
          (char *) s_mg_flash_mcxn.start + s_mg_flash_mcxn.size / 2,
          s_mg_flash_mcxn.size / 2, s_mg_flash_mcxn.secsz);
    }
  }
  return false;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ota_picosdk.c"
#endif




#if MG_OTA == MG_OTA_PICOSDK

// Both RP2040 and RP2350 have no flash, low-level flash access support in
// bootrom, and high-level support in Pico-SDK (2.0+ for the RP2350)
// - The RP2350 in RISC-V mode is not tested
// NOTE(): See OTA design notes

static bool mg_picosdk_write(void *, const void *, size_t);
static bool mg_picosdk_swap(void);

static struct mg_flash s_mg_flash_picosdk = {
    (void *) 0x10000000,  // Start; functions handle offset
#ifdef PICO_FLASH_SIZE_BYTES
    PICO_FLASH_SIZE_BYTES,  // Size, from board definitions
#else
    0x200000,  // Size, guess... is 2M enough ?
#endif
    FLASH_SECTOR_SIZE,  // Sector size, from hardware_flash
    FLASH_PAGE_SIZE,    // Align, from hardware_flash
    mg_picosdk_write,      mg_picosdk_swap,
};

#define MG_MODULO2(x, m) ((x) & ((m) -1))

static bool __no_inline_not_in_flash_func(flash_sector_start)(
    volatile uint32_t *dst) {
  char *base = (char *) s_mg_flash_picosdk.start,
       *end = base + s_mg_flash_picosdk.size;
  volatile char *p = (char *) dst;
  return p >= base && p < end &&
         MG_MODULO2(p - base, s_mg_flash_picosdk.secsz) == 0;
}

static bool __no_inline_not_in_flash_func(flash_erase)(void *addr) {
  if (flash_sector_start(addr) == false) {
    MG_ERROR(("%p is not on a sector boundary", addr));
    return false;
  }
  void *dst = (void *) ((char *) addr - (char *) s_mg_flash_picosdk.start);
  flash_range_erase((uint32_t) dst, s_mg_flash_picosdk.secsz);
  MG_DEBUG(("Sector starting at %p erasure", addr));
  return true;
}

static bool __no_inline_not_in_flash_func(mg_picosdk_swap)(void) {
  // TODO(): RP2350 might have some A/B functionality (DS 5.1)
  return true;
}

static bool s_flash_irq_disabled;

static bool __no_inline_not_in_flash_func(mg_picosdk_write)(void *addr,
                                                            const void *buf,
                                                            size_t len) {
  if ((len % s_mg_flash_picosdk.align) != 0) {
    MG_ERROR(("%lu is not aligned to %lu", len, s_mg_flash_picosdk.align));
    return false;
  }
  if ((((size_t) addr - (size_t) s_mg_flash_picosdk.start) %
       s_mg_flash_picosdk.align) != 0) {
    MG_ERROR(("%p is not on a page boundary", addr));
    return false;
  }

  uint32_t *dst = (uint32_t *) addr;
  uint32_t *src = (uint32_t *) buf;
  uint32_t *end = (uint32_t *) ((char *) buf + len);

#ifndef __riscv
  MG_ARM_DISABLE_IRQ();
#else
  asm volatile("csrrc zero, mstatus, %0" : : "i"(1 << 3) : "memory");
#endif
  while (src < end) {
    uint32_t dst_ofs = (uint32_t) dst - (uint32_t) s_mg_flash_picosdk.start;
    if (flash_sector_start(dst) && flash_erase(dst) == false) break;
    // flash_range_program() runs in RAM and handles writing up to
    // FLASH_PAGE_SIZE bytes. Source must not be in flash
    flash_range_program((uint32_t) dst_ofs, (uint8_t *) src,
                        s_mg_flash_picosdk.align);
    src = (uint32_t *) ((char *) src + s_mg_flash_picosdk.align);
    dst = (uint32_t *) ((char *) dst + s_mg_flash_picosdk.align);
  }
  if (!s_flash_irq_disabled) {
#ifndef __riscv
    MG_ARM_ENABLE_IRQ();
#else
    asm volatile("csrrs mstatus, %0" : : "i"(1 << 3) : "memory");
#endif
  }
  MG_DEBUG(("Flash write %lu bytes @ %p.", len, dst));
  return true;
}

// just overwrite instead of swap
static void __no_inline_not_in_flash_func(single_bank_swap)(char *p1, char *p2,
                                                            size_t s,
                                                            size_t ss) {
  char *tmp = mg_calloc(1, ss);
  if (tmp == NULL) return;
#if PICO_RP2040
  uint32_t xip[256 / sizeof(uint32_t)];
  void *dst = (void *) ((char *) p1 - (char *) s_mg_flash_picosdk.start);
  size_t count = MG_ROUND_UP(s, ss);
  // use SDK function calls to get BootROM function pointers
  rom_connect_internal_flash_fn connect = (rom_connect_internal_flash_fn) rom_func_lookup(ROM_FUNC_CONNECT_INTERNAL_FLASH);
  rom_flash_exit_xip_fn xit = (rom_flash_exit_xip_fn) rom_func_lookup(ROM_FUNC_FLASH_EXIT_XIP);
  rom_flash_range_program_fn program = (rom_flash_range_program_fn) rom_func_lookup(ROM_FUNC_FLASH_RANGE_PROGRAM);
  rom_flash_flush_cache_fn flush = (rom_flash_flush_cache_fn) rom_func_lookup(ROM_FUNC_FLASH_FLUSH_CACHE);
  // no stdlib calls here.
  MG_ARM_DISABLE_IRQ();
  // 2nd bootloader (XIP) is in flash, SDK functions copy it to RAM on entry
  for (size_t i = 0; i < 256 / sizeof(uint32_t); i++)
    xip[i] = ((uint32_t *) (s_mg_flash_picosdk.start))[i];
  flash_range_erase((uint32_t) dst, count);
  // flash has been erased, no XIP to copy. Only BootROM calls possible
  for (uint32_t ofs = 0; ofs < s; ofs += ss) {
    for (size_t i = 0; i < ss; i++) tmp[i] = p2[ofs + i];
    __compiler_memory_barrier();
    connect();
    xit();
    program((uint32_t) dst + ofs, tmp, ss);
    flush();
    ((void (*)(void))((intptr_t) xip + 1))(); // enter XIP again
  }
  *(volatile unsigned long *) 0xe000ed0c = 0x5fa0004;  // AIRCR = SYSRESETREQ
#else
  // RP2350 has BootRAM and copies second bootloader there, SDK uses that copy,
  // It might also be able to take advantage of partition swapping
  rom_reboot_fn reboot = (rom_reboot_fn) rom_func_lookup(ROM_FUNC_REBOOT);
  for (size_t ofs = 0; ofs < s; ofs += ss) {
    for (size_t i = 0; i < ss; i++) tmp[i] = p2[ofs + i];
    mg_picosdk_write(p1 + ofs, tmp, ss);
  }
  reboot(BOOT_TYPE_NORMAL | 0x100, 1, 0, 0); // 0x100: NO_RETURN_ON_SUCCESS
#endif
}

bool mg_ota_begin(size_t new_firmware_size) {
  return mg_ota_flash_begin(new_firmware_size, &s_mg_flash_picosdk);
}

bool mg_ota_write(const void *buf, size_t len) {
  return mg_ota_flash_write(buf, len, &s_mg_flash_picosdk);
}

bool mg_ota_end(void) {
  if (mg_ota_flash_end(&s_mg_flash_picosdk)) {
    // Swap partitions. Pray power does not go away
    MG_INFO(("Swapping partitions, size %u (%u sectors)",
             s_mg_flash_picosdk.size,
             s_mg_flash_picosdk.size / s_mg_flash_picosdk.secsz));
    MG_INFO(("Do NOT power off..."));
    mg_log_level = MG_LL_NONE;
    s_flash_irq_disabled = true;
    // Runs in RAM, will reset when finished or return on failure
    single_bank_swap(
        (char *) s_mg_flash_picosdk.start,
        (char *) s_mg_flash_picosdk.start + s_mg_flash_picosdk.size / 2,
        s_mg_flash_picosdk.size / 2, s_mg_flash_picosdk.secsz);
  }
  return false;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ota_rw612.c"
#endif




#if MG_OTA == MG_OTA_RW612

MG_IRAM static bool mg_frdm_write(void *, const void *, size_t);
static bool mg_frdm_swap(void);

static struct mg_flash s_mg_flash_frdm = {(void *) 0x08000000,  // Start,
                                          0x200000,             // Size
                                          0x1000,               // Sector size
                                          0x100,                // Align
                                          mg_frdm_write,
                                          mg_frdm_swap};

struct mg_flexspi_lut_seq {
  uint8_t seqNum;
  uint8_t seqId;
  uint16_t reserved;
};

struct mg_flexspi_mem_config {
  uint32_t tag;
  uint32_t version;
  uint32_t reserved0;
  uint8_t readSampleClkSrc;
  uint8_t csHoldTime;
  uint8_t csSetupTime;
  uint8_t columnAddressWidth;
  uint8_t deviceModeCfgEnable;
  uint8_t deviceModeType;
  uint16_t waitTimeCfgCommands;
  struct mg_flexspi_lut_seq deviceModeSeq;
  uint32_t deviceModeArg;
  uint8_t configCmdEnable;
  uint8_t configModeType[3];
  struct mg_flexspi_lut_seq configCmdSeqs[3];
  uint32_t reserved1;
  uint32_t configCmdArgs[3];
  uint32_t reserved2;
  uint32_t controllerMiscOption;
  uint8_t deviceType;
  uint8_t sflashPadType;
  uint8_t serialClkFreq;
  uint8_t lutCustomSeqEnable;
  uint32_t reserved3[2];
  uint32_t sflashA1Size;
  uint32_t sflashA2Size;
  uint32_t sflashB1Size;
  uint32_t sflashB2Size;
  uint32_t csPadSettingOverride;
  uint32_t sclkPadSettingOverride;
  uint32_t dataPadSettingOverride;
  uint32_t dqsPadSettingOverride;
  uint32_t timeoutInMs;
  uint32_t commandInterval;
  uint16_t dataValidTime[2];
  uint16_t busyOffset;
  uint16_t busyBitPolarity;
  uint32_t lookupTable[64];
  struct mg_flexspi_lut_seq lutCustomSeq[12];
  uint32_t reserved4[4];
};

struct mg_flexspi_nor_config {
  struct mg_flexspi_mem_config memConfig;
  uint32_t pageSize;
  uint32_t sectorSize;
  uint8_t ipcmdSerialClkFreq;
  uint8_t isUniformBlockSize;
  uint8_t isDataOrderSwapped;
  uint8_t reserved0[1];
  uint8_t serialNorType;
  uint8_t needExitNoCmdMode;
  uint8_t halfClkForNonReadCmd;
  uint8_t needRestoreNoCmdMode;
  uint32_t blockSize;
  uint32_t flashStateCtx;
  uint32_t reserve2[10];
};

struct mg_flexspi_nor_driver_interface {
  uint32_t version;
  uint32_t (*init)(uint32_t instance, struct mg_flexspi_nor_config *config);
  uint32_t (*wait_busy)(uint32_t instance, struct mg_flexspi_nor_config *config,
                        uint32_t address, bool keepState);
  uint32_t (*page_program)(uint32_t instance,
                           struct mg_flexspi_nor_config *config,
                           uint32_t dstAddr, const uint32_t *src,
                           bool keepState);
  uint32_t (*erase_all)(uint32_t instance,
                        struct mg_flexspi_nor_config *config);
  uint32_t (*erase)(uint32_t instance, struct mg_flexspi_nor_config *config,
                    uint32_t start, uint32_t length);
  uint32_t (*erase_sector)(uint32_t instance,
                           struct mg_flexspi_nor_config *config,
                           uint32_t address);
  uint32_t (*erase_block)(uint32_t instance,
                          struct mg_flexspi_nor_config *config,
                          uint32_t address);
  uint32_t (*read)(uint32_t instance, struct mg_flexspi_nor_config *config,
                   uint32_t *dst, uint32_t start, uint32_t bytes);
  void (*config_clock)(uint32_t instance, uint32_t freqOption,
                       uint32_t sampleClkMode);
  uint32_t (*set_clock_source)(uint32_t clockSrc);
  uint32_t (*get_config)(uint32_t instance,
                         struct mg_flexspi_nor_config *config,
                         uint32_t *option);
  void (*hw_reset)(uint32_t instance, uint32_t reset_logic);
  uint32_t (*xfer)(uint32_t instance, char *xfer);
  uint32_t (*update_lut)(uint32_t instance, uint32_t seqIndex,
                         const uint32_t *lutBase, uint32_t numberOfSeq);
  uint32_t (*partial_program)(uint32_t instance,
                              struct mg_flexspi_nor_config *config,
                              uint32_t dstAddr, const uint32_t *src,
                              uint32_t length, bool keepState);
};

#define MG_FLEXSPI_CFG_BLK_TAG (0x42464346UL)
#define MG_FLEXSPI_BASE 0x40134000UL

#define MG_CMD_SDR 0x01
#define MG_RADDR_SDR 0x02
#define MG_WRITE_SDR 0x08
#define MG_READ_SDR 0x09
#define MG_DUMMY_SDR 0x0C
#define MG_STOP_EXE 0

#define MG_FLEXSPI_1PAD 0
#define MG_FLEXSPI_4PAD 2

#define MG_FLEXSPI_LUT_OPERAND0(x) (((x) &0xFF) << 0)
#define MG_FLEXSPI_LUT_NUM_PADS0(x) (((x) &0x3) << 8)
#define MG_FLEXSPI_LUT_OPCODE0(x) (((x) &0x3F) << 10)
#define MG_FLEXSPI_LUT_OPERAND1(x) (((x) &0xFF) << 16)
#define MG_FLEXSPI_LUT_NUM_PADS1(x) (((x) &0x3) << 24)
#define MG_FLEXSPI_LUT_OPCODE1(x) (((x) &0x3F) << 26)

#define MG_FLEXSPI_LUT_SEQ(cmd0, pad0, op0, cmd1, pad1, op1)       \
  (MG_FLEXSPI_LUT_OPERAND0(op0) | MG_FLEXSPI_LUT_NUM_PADS0(pad0) | \
   MG_FLEXSPI_LUT_OPCODE0(cmd0) | MG_FLEXSPI_LUT_OPERAND1(op1) |   \
   MG_FLEXSPI_LUT_NUM_PADS1(pad1) | MG_FLEXSPI_LUT_OPCODE1(cmd1))

struct mg_flexspi_nor_config default_config = {
    .memConfig =
        {
            .tag = MG_FLEXSPI_CFG_BLK_TAG,
            .version = 0,
            .readSampleClkSrc = 1,
            .csHoldTime = 3,
            .csSetupTime = 3,
            .deviceModeCfgEnable = 1,
            .deviceModeSeq = {.seqNum = 1, .seqId = 2},
            .deviceModeArg = 0x0740,
            .configCmdEnable = 0,
            .deviceType = 0x1,
            .sflashPadType = 4,
            .serialClkFreq = 4,
            .sflashA1Size = 0x4000000U,
            .sflashA2Size = 0,
            .sflashB1Size = 0,
            .sflashB2Size = 0,
            .lookupTable =
                {
                    [0] =
                        MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0xEB,
                                           MG_RADDR_SDR, MG_FLEXSPI_4PAD, 0x18),
                    [1] =
                        MG_FLEXSPI_LUT_SEQ(MG_DUMMY_SDR, MG_FLEXSPI_4PAD, 0x06,
                                           MG_READ_SDR, MG_FLEXSPI_4PAD, 0x04),
                    [4 * 1 + 0] =
                        MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0x05,
                                           MG_READ_SDR, MG_FLEXSPI_1PAD, 0x04),
                    [4 * 2 + 0] =
                        MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0x01,
                                           MG_WRITE_SDR, MG_FLEXSPI_1PAD, 0x02),
                    [4 * 3 + 0] =
                        MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0x06,
                                           MG_STOP_EXE, MG_FLEXSPI_1PAD, 0x00),
                    [4 * 5 + 0] =
                        MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0x20,
                                           MG_RADDR_SDR, MG_FLEXSPI_1PAD, 0x18),
                    [4 * 8 + 0] =
                        MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0x52,
                                           MG_RADDR_SDR, MG_FLEXSPI_1PAD, 0x18),
                    [4 * 9 + 0] =
                        MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0x02,
                                           MG_RADDR_SDR, MG_FLEXSPI_1PAD, 0x18),
                    [4 * 9 + 1] =
                        MG_FLEXSPI_LUT_SEQ(MG_WRITE_SDR, MG_FLEXSPI_1PAD, 0x00,
                                           MG_STOP_EXE, MG_FLEXSPI_1PAD, 0x00),
                    [4 * 11 + 0] =
                        MG_FLEXSPI_LUT_SEQ(MG_CMD_SDR, MG_FLEXSPI_1PAD, 0x60,
                                           MG_STOP_EXE, MG_FLEXSPI_1PAD, 0x00),
                },
        },
    .pageSize = 0x100,
    .sectorSize = 0x1000,
    .ipcmdSerialClkFreq = 0,
    .blockSize = 0x8000,
};

#define MG_FLEXSPI_NOR_INSTANCE 0
#define MG_ROMAPI_ADDRESS 0x13030000U
#define flexspi_nor                              \
  ((struct mg_flexspi_nor_driver_interface *) (( \
      (uint32_t *) MG_ROMAPI_ADDRESS)[5]))

MG_IRAM static bool flash_page_start(volatile uint32_t *dst) {
  char *base = (char *) s_mg_flash_frdm.start,
       *end = base + s_mg_flash_frdm.size;
  volatile char *p = (char *) dst;
  return p >= base && p < end && ((p - base) % s_mg_flash_frdm.secsz) == 0;
}

MG_IRAM static int flexspi_nor_get_config(
    struct mg_flexspi_nor_config *config) {
  uint32_t option = 0xc0000004;
  return flexspi_nor->get_config(MG_FLEXSPI_NOR_INSTANCE, config, &option);
}

MG_IRAM static int flash_init(void) {
  static bool initialized = false;
  if (!initialized) {
    struct mg_flexspi_nor_config config;
    memset(&config, 0, sizeof(config));
    flexspi_nor->set_clock_source(0);
    flexspi_nor->config_clock(MG_FLEXSPI_NOR_INSTANCE, 1, 0);
    if (flexspi_nor->init(MG_FLEXSPI_NOR_INSTANCE, &default_config)) {
      return 1;
    }
    flexspi_nor_get_config(&config);
    if (flexspi_nor->init(MG_FLEXSPI_NOR_INSTANCE, &config)) {
      return 1;
    }
    initialized = true;
  }
  return 0;
}

MG_IRAM static bool flash_erase(struct mg_flexspi_nor_config *config,
                                void *addr) {
  if (flash_page_start(addr) == false) {
    MG_ERROR(("%p is not on a sector boundary", addr));
    return false;
  }

  void *dst = (void *) ((char *) addr - (char *) s_mg_flash_frdm.start);
  bool ok = (flexspi_nor->erase_sector(MG_FLEXSPI_NOR_INSTANCE, config,
                                       (uint32_t) dst) == 0);
  MG_INFO(("Sector starting at %p erasure: %s", addr, ok ? "ok" : "fail"));
  return ok;
}

MG_IRAM bool mg_frdm_swap(void) {
  return true;
}

MG_IRAM static void flash_wait(void) {
  while ((*((volatile uint32_t *) (MG_FLEXSPI_BASE + 0xE0)) & MG_BIT(1)) == 0)
    (void) 0;
}

static bool s_flash_irq_disabled;

MG_IRAM static bool mg_frdm_write(void *addr, const void *buf, size_t len) {
  struct mg_flexspi_nor_config config;
  bool ok = false;
  MG_ARM_DISABLE_IRQ();
  if (flash_init() != 0) goto fwxit;
  if (flexspi_nor_get_config(&config) != 0) goto fwxit;
  if ((len % s_mg_flash_frdm.align) != 0) {
    MG_ERROR(("%lu is not aligned to %lu", len, s_mg_flash_frdm.align));
    goto fwxit;
  }
  if ((char *) addr < (char *) s_mg_flash_frdm.start) {
    MG_ERROR(("Invalid flash write address: %p", addr));
    goto fwxit;
  }

  uint32_t *dst = (uint32_t *) addr;
  uint32_t *src = (uint32_t *) buf;
  uint32_t *end = (uint32_t *) ((char *) buf + len);
  ok = true;

  while (ok && src < end) {
    if (flash_page_start(dst) && flash_erase(&config, dst) == false) {
      ok = false;
      break;
    }
    uint32_t status;
    uint32_t dst_ofs = (uint32_t) dst - (uint32_t) s_mg_flash_frdm.start;
    if ((char *) buf >= (char *) s_mg_flash_frdm.start &&
        (char *) buf <
            (char *) (s_mg_flash_frdm.start + s_mg_flash_frdm.size)) {
      // If we copy from FLASH to FLASH, then we first need to copy the source
      // to RAM
      size_t tmp_buf_size = s_mg_flash_frdm.align / sizeof(uint32_t);
      uint32_t tmp[tmp_buf_size];

      for (size_t i = 0; i < tmp_buf_size; i++) {
        flash_wait();
        tmp[i] = src[i];
      }
      status = flexspi_nor->page_program(MG_FLEXSPI_NOR_INSTANCE, &config,
                                         (uint32_t) dst_ofs, tmp, false);
    } else {
      status = flexspi_nor->page_program(MG_FLEXSPI_NOR_INSTANCE, &config,
                                         (uint32_t) dst_ofs, src, false);
    }
    src = (uint32_t *) ((char *) src + s_mg_flash_frdm.align);
    dst = (uint32_t *) ((char *) dst + s_mg_flash_frdm.align);
    if (status != 0) {
      ok = false;
    }
  }
  MG_INFO(("Flash write %lu bytes @ %p: %s.", len, dst, ok ? "ok" : "fail"));
fwxit:
  if (!s_flash_irq_disabled) MG_ARM_ENABLE_IRQ();
  return ok;
}

// just overwrite instead of swap
MG_IRAM static void single_bank_swap(char *p1, char *p2, size_t s, size_t ss) {
  // no stdlib calls here
  for (size_t ofs = 0; ofs < s; ofs += ss) {
    mg_frdm_write(p1 + ofs, p2 + ofs, ss);
  }
  *(volatile unsigned long *) 0xe000ed0c = 0x5fa0004;
}

bool mg_ota_begin(size_t new_firmware_size) {
  return mg_ota_flash_begin(new_firmware_size, &s_mg_flash_frdm);
}

bool mg_ota_write(const void *buf, size_t len) {
  return mg_ota_flash_write(buf, len, &s_mg_flash_frdm);
}

bool mg_ota_end(void) {
  if (mg_ota_flash_end(&s_mg_flash_frdm)) {
    if (0) {  // is_dualbank()
      // TODO(): no devices so far
      *(volatile unsigned long *) 0xe000ed0c = 0x5fa0004;
    } else {
      // Swap partitions. Pray power does not go away
      MG_INFO(("Swapping partitions, size %u (%u sectors)",
               s_mg_flash_frdm.size,
               s_mg_flash_frdm.size / s_mg_flash_frdm.secsz));
      MG_INFO(("Do NOT power off..."));
      mg_log_level = MG_LL_NONE;
      s_flash_irq_disabled = true;
      // Runs in RAM, will reset when finished
      single_bank_swap(
          (char *) s_mg_flash_frdm.start,
          (char *) s_mg_flash_frdm.start + s_mg_flash_frdm.size / 2,
          s_mg_flash_frdm.size / 2, s_mg_flash_frdm.secsz);
    }
  }
  return false;
}

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ota_stm32f.c"
#endif




#if MG_OTA == MG_OTA_STM32F

static bool mg_stm32f_write(void *, const void *, size_t);
static bool mg_stm32f_swap(void);

static struct mg_flash s_mg_flash_stm32f = {
    (void *) 0x08000000,  // Start
    0,                    // Size, FLASH_SIZE_REG
    0,                    // Irregular sector size
    32,                   // Align, 256 bit
    mg_stm32f_write,
    mg_stm32f_swap,
};

#define MG_FLASH_BASE 0x40023c00
#define MG_FLASH_KEYR 0x04
#define MG_FLASH_SR 0x0c
#define MG_FLASH_CR 0x10
#define MG_FLASH_OPTCR 0x14
#define MG_FLASH_SIZE_REG_F7 0x1FF0F442
#define MG_FLASH_SIZE_REG_F4 0x1FFF7A22

#define STM_DBGMCU_IDCODE 0xE0042000
#define STM_DEV_ID (MG_REG(STM_DBGMCU_IDCODE) & (MG_BIT(12) - 1))
#define SYSCFG_MEMRMP 0x40013800

#define MG_FLASH_SIZE_REG_LOCATION \
  ((STM_DEV_ID >= 0x449) ? MG_FLASH_SIZE_REG_F7 : MG_FLASH_SIZE_REG_F4)

static size_t flash_size(void) {
  return (MG_REG(MG_FLASH_SIZE_REG_LOCATION) & 0xFFFF) * 1024;
}

MG_IRAM static int is_dualbank(void) {
  // only F42x/F43x series (0x419) support dual bank
  return STM_DEV_ID == 0x419;
}

MG_IRAM static void flash_unlock(void) {
  static bool unlocked = false;
  if (unlocked == false) {
    MG_REG(MG_FLASH_BASE + MG_FLASH_KEYR) = 0x45670123;
    MG_REG(MG_FLASH_BASE + MG_FLASH_KEYR) = 0xcdef89ab;
    unlocked = true;
  }
}

#define MG_FLASH_CONFIG_16_64_128 1   // used by STM32F7
#define MG_FLASH_CONFIG_32_128_256 2  // used by STM32F4 and F2

MG_IRAM static bool flash_page_start(volatile uint32_t *dst) {
  char *base = (char *) s_mg_flash_stm32f.start;
  char *end = base + s_mg_flash_stm32f.size;

  if (is_dualbank() && dst >= (uint32_t *) (base + (end - base) / 2)) {
    dst = (uint32_t *) ((uint32_t) dst - (end - base) / 2);
  }

  uint32_t flash_config = MG_FLASH_CONFIG_16_64_128;
  if (STM_DEV_ID >= 0x449) {
    flash_config = MG_FLASH_CONFIG_32_128_256;
  }

  volatile char *p = (char *) dst;
  if (p >= base && p < end) {
    if (p < base + 16 * 1024 * 4 * flash_config) {
      if ((p - base) % (16 * 1024 * flash_config) == 0) return true;
    } else if (p == base + 16 * 1024 * 4 * flash_config) {
      return true;
    } else if ((p - base) % (128 * 1024 * flash_config) == 0) {
      return true;
    }
  }
  return false;
}

MG_IRAM static int flash_sector(volatile uint32_t *addr) {
  char *base = (char *) s_mg_flash_stm32f.start;
  char *end = base + s_mg_flash_stm32f.size;
  bool addr_in_bank_2 = false;
  if (is_dualbank() && addr >= (uint32_t *) (base + (end - base) / 2)) {
    addr = (uint32_t *) ((uint32_t) addr - (end - base) / 2);
    addr_in_bank_2 = true;
  }
  volatile char *p = (char *) addr;
  uint32_t flash_config = MG_FLASH_CONFIG_16_64_128;
  if (STM_DEV_ID >= 0x449) {
    flash_config = MG_FLASH_CONFIG_32_128_256;
  }
  int sector = -1;
  if (p >= base && p < end) {
    if (p < base + 16 * 1024 * 4 * flash_config) {
      sector = (p - base) / (16 * 1024 * flash_config);
    } else if (p >= base + 64 * 1024 * flash_config &&
               p < base + 128 * 1024 * flash_config) {
      sector = 4;
    } else {
      sector = (p - base) / (128 * 1024 * flash_config) + 4;
    }
  }
  if (sector == -1) return -1;
  if (addr_in_bank_2) sector += 12;  // a bank has 12 sectors
  return sector;
}

MG_IRAM static bool flash_is_err(void) {
  return MG_REG(MG_FLASH_BASE + MG_FLASH_SR) & ((MG_BIT(7) - 1) << 1);
}

MG_IRAM static void flash_wait(void) {
  while (MG_REG(MG_FLASH_BASE + MG_FLASH_SR) & (MG_BIT(16))) (void) 0;
}

MG_IRAM static void flash_clear_err(void) {
  flash_wait();                                // Wait until ready
  MG_REG(MG_FLASH_BASE + MG_FLASH_SR) = 0xf2;  // Clear all errors
}

MG_IRAM static bool mg_stm32f_erase(void *addr) {
  bool ok = false;
  if (flash_page_start(addr) == false) {
    MG_ERROR(("%p is not on a sector boundary", addr));
  } else {
    int sector = flash_sector(addr);
    if (sector < 0) return false;
    uint32_t sector_reg = sector;
    if (is_dualbank() && sector >= 12) {
      // 3.9.8 Flash control register (FLASH_CR) for F42xxx and F43xxx
      // BITS[7:3]
      sector_reg -= 12;
      sector_reg |= MG_BIT(4);
    }
    flash_unlock();
    flash_wait();
    uint32_t cr = MG_BIT(1);       // SER
    cr |= MG_BIT(16);              // STRT
    cr |= (sector_reg & 31) << 3;  // sector
    MG_REG(MG_FLASH_BASE + MG_FLASH_CR) = cr;
    ok = !flash_is_err();
    MG_DEBUG(("Erase sector %lu @ %p %s. CR %#lx SR %#lx", sector, addr,
              ok ? "ok" : "fail", MG_REG(MG_FLASH_BASE + MG_FLASH_CR),
              MG_REG(MG_FLASH_BASE + MG_FLASH_SR)));
    // After we have erased the sector, set CR flags for programming
    // 2 << 8 is word write parallelism, bit(0) is PG. RM0385, section 3.7.5
    MG_REG(MG_FLASH_BASE + MG_FLASH_CR) = MG_BIT(0) | (2 << 8);
    flash_clear_err();
  }
  return ok;
}

MG_IRAM static bool mg_stm32f_swap(void) {
  // STM32 F42x/F43x support dual bank, however, the memory mapping
  // change will not be carried through a hard reset. Therefore, we will use
  // the single bank approach for this family as well.
  return true;
}

static bool s_flash_irq_disabled;

MG_IRAM static bool mg_stm32f_write(void *addr, const void *buf, size_t len) {
  if ((len % s_mg_flash_stm32f.align) != 0) {
    MG_ERROR(("%lu is not aligned to %lu", len, s_mg_flash_stm32f.align));
    return false;
  }
  uint32_t *dst = (uint32_t *) addr;
  uint32_t *src = (uint32_t *) buf;
  uint32_t *end = (uint32_t *) ((char *) buf + len);
  bool ok = true;
  MG_ARM_DISABLE_IRQ();
  flash_unlock();
  flash_clear_err();
  MG_REG(MG_FLASH_BASE + MG_FLASH_CR) = MG_BIT(0) | MG_BIT(9);  // PG, 32-bit
  flash_wait();
  MG_DEBUG(("Writing flash @ %p, %lu bytes", addr, len));
  while (ok && src < end) {
    if (flash_page_start(dst) && mg_stm32f_erase(dst) == false) break;
    *(volatile uint32_t *) dst++ = *src++;
    MG_DSB();  // ensure flash is written with no errors
    flash_wait();
    if (flash_is_err()) ok = false;
  }
  if (!s_flash_irq_disabled) MG_ARM_ENABLE_IRQ();
  MG_DEBUG(("Flash write %lu bytes @ %p: %s. CR %#lx SR %#lx", len, dst,
            ok ? "ok" : "fail", MG_REG(MG_FLASH_BASE + MG_FLASH_CR),
            MG_REG(MG_FLASH_BASE + MG_FLASH_SR)));
  MG_REG(MG_FLASH_BASE + MG_FLASH_CR) &= ~MG_BIT(0);  // Clear programming flag
  return ok;
}

// just overwrite instead of swap
MG_IRAM void single_bank_swap(char *p1, char *p2, size_t size) {
  // no stdlib calls here
  mg_stm32f_write(p1, p2, size);
  *(volatile unsigned long *) 0xe000ed0c = 0x5fa0004;
}

bool mg_ota_begin(size_t new_firmware_size) {
  s_mg_flash_stm32f.size = flash_size();
#ifdef __ZEPHYR__
  *((uint32_t *)0xE000ED94) = 0;
  MG_DEBUG(("Jailbreak %s", *((uint32_t *)0xE000ED94) == 0 ? "successful" : "failed"));
#endif
  return mg_ota_flash_begin(new_firmware_size, &s_mg_flash_stm32f);
}

bool mg_ota_write(const void *buf, size_t len) {
  return mg_ota_flash_write(buf, len, &s_mg_flash_stm32f);
}

bool mg_ota_end(void) {
  if (mg_ota_flash_end(&s_mg_flash_stm32f)) {
    // Swap partitions. Pray power does not go away
    MG_INFO(("Swapping partitions, size %u (%u sectors)",
             s_mg_flash_stm32f.size, STM_DEV_ID == 0x449 ? 8 : 12));
    MG_INFO(("Do NOT power off..."));
    mg_log_level = MG_LL_NONE;
    s_flash_irq_disabled = true;
    char *p1 = (char *) s_mg_flash_stm32f.start;
    char *p2 = p1 + s_mg_flash_stm32f.size / 2;
    size_t size = s_mg_flash_stm32f.size / 2;
    // Runs in RAM, will reset when finished
    single_bank_swap(p1, p2, size);
  }
  return false;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ota_stm32h5.c"
#endif




#if MG_OTA == MG_OTA_STM32H5

static bool mg_stm32h5_write(void *, const void *, size_t);
static bool mg_stm32h5_swap(void);

static struct mg_flash s_mg_flash_stm32h5 = {
    (void *) 0x08000000,  // Start
    2 * 1024 * 1024,      // Size, 2Mb
    8 * 1024,             // Sector size, 8k
    16,                   // Align, 128 bit
    mg_stm32h5_write,
    mg_stm32h5_swap,
};

#define MG_FLASH_BASE 0x40022000          // Base address of the flash controller
#define FLASH_KEYR (MG_FLASH_BASE + 0x4)  // See RM0481 7.11
#define FLASH_OPTKEYR (MG_FLASH_BASE + 0xc)
#define FLASH_OPTCR (MG_FLASH_BASE + 0x1c)
#define FLASH_NSSR (MG_FLASH_BASE + 0x20)
#define FLASH_NSCR (MG_FLASH_BASE + 0x28)
#define FLASH_NSCCR (MG_FLASH_BASE + 0x30)
#define FLASH_OPTSR_CUR (MG_FLASH_BASE + 0x50)
#define FLASH_OPTSR_PRG (MG_FLASH_BASE + 0x54)

static void flash_unlock(void) {
  static bool unlocked = false;
  if (unlocked == false) {
    MG_REG(FLASH_KEYR) = 0x45670123;
    MG_REG(FLASH_KEYR) = 0Xcdef89ab;
    MG_REG(FLASH_OPTKEYR) = 0x08192a3b;
    MG_REG(FLASH_OPTKEYR) = 0x4c5d6e7f;
    unlocked = true;
  }
}

static int flash_page_start(volatile uint32_t *dst) {
  char *base = (char *) s_mg_flash_stm32h5.start,
       *end = base + s_mg_flash_stm32h5.size;
  volatile char *p = (char *) dst;
  return p >= base && p < end && ((p - base) % s_mg_flash_stm32h5.secsz) == 0;
}

static bool flash_is_err(void) {
  return MG_REG(FLASH_NSSR) & ((MG_BIT(8) - 1) << 17);  // RM0481 7.11.9
}

static void flash_wait(void) {
  while ((MG_REG(FLASH_NSSR) & MG_BIT(0)) &&
         (MG_REG(FLASH_NSSR) & MG_BIT(16)) == 0) {
    (void) 0;
  }
}

static void flash_clear_err(void) {
  flash_wait();                                    // Wait until ready
  MG_REG(FLASH_NSCCR) = ((MG_BIT(9) - 1) << 16U);  // Clear all errors
}

static bool flash_bank_is_swapped(void) {
  return MG_REG(FLASH_OPTCR) & MG_BIT(31);  // RM0481 7.11.8
}

static bool mg_stm32h5_erase(void *location) {
  bool ok = false;
  if (flash_page_start(location) == false) {
    MG_ERROR(("%p is not on a sector boundary"));
  } else {
    uintptr_t diff = (char *) location - (char *) s_mg_flash_stm32h5.start;
    uint32_t sector = diff / s_mg_flash_stm32h5.secsz;
    uint32_t saved_cr = MG_REG(FLASH_NSCR);  // Save CR value
    flash_unlock();
    flash_clear_err();
    MG_REG(FLASH_NSCR) = 0;
    if ((sector < 128 && flash_bank_is_swapped()) ||
        (sector > 127 && !flash_bank_is_swapped())) {
      MG_REG(FLASH_NSCR) |= MG_BIT(31);  // Set FLASH_CR_BKSEL
    }
    if (sector > 127) sector -= 128;
    MG_REG(FLASH_NSCR) |= MG_BIT(2) | (sector << 6);  // Erase | sector_num
    MG_REG(FLASH_NSCR) |= MG_BIT(5);                  // Start erasing
    flash_wait();
    ok = !flash_is_err();
    MG_DEBUG(("Erase sector %lu @ %p: %s. CR %#lx SR %#lx", sector, location,
              ok ? "ok" : "fail", MG_REG(FLASH_NSCR), MG_REG(FLASH_NSSR)));
    // mg_hexdump(location, 32);
    MG_REG(FLASH_NSCR) = saved_cr;  // Restore saved CR
  }
  return ok;
}

static bool mg_stm32h5_swap(void) {
  uint32_t desired = flash_bank_is_swapped() ? 0 : MG_BIT(31);
  flash_unlock();
  flash_clear_err();
  // printf("OPTSR_PRG 1 %#lx\n", FLASH->OPTSR_PRG);
  MG_SET_BITS(MG_REG(FLASH_OPTSR_PRG), MG_BIT(31), desired);
  // printf("OPTSR_PRG 2 %#lx\n", FLASH->OPTSR_PRG);
  MG_REG(FLASH_OPTCR) |= MG_BIT(1);  // OPTSTART
  while ((MG_REG(FLASH_OPTSR_CUR) & MG_BIT(31)) != desired) (void) 0;
  return true;
}

static bool mg_stm32h5_write(void *addr, const void *buf, size_t len) {
  if ((len % s_mg_flash_stm32h5.align) != 0) {
    MG_ERROR(("%lu is not aligned to %lu", len, s_mg_flash_stm32h5.align));
    return false;
  }
  uint32_t *dst = (uint32_t *) addr;
  uint32_t *src = (uint32_t *) buf;
  uint32_t *end = (uint32_t *) ((char *) buf + len);
  bool ok = true;
  MG_ARM_DISABLE_IRQ();
  flash_unlock();
  flash_clear_err();
  MG_REG(FLASH_NSCR) = MG_BIT(1);  // Set programming flag
  while (ok && src < end) {
    if (flash_page_start(dst) && mg_stm32h5_erase(dst) == false) {
      ok = false;
      break;
    }
    *(volatile uint32_t *) dst++ = *src++;
    flash_wait();
    if (flash_is_err()) ok = false;
  }
  MG_ARM_ENABLE_IRQ();
  MG_DEBUG(("Flash write %lu bytes @ %p: %s. CR %#lx SR %#lx", len, dst,
            flash_is_err() ? "fail" : "ok", MG_REG(FLASH_NSCR),
            MG_REG(FLASH_NSSR)));
  MG_REG(FLASH_NSCR) = 0;  // Clear flags
  return ok;
}

bool mg_ota_begin(size_t new_firmware_size) {
#ifdef __ZEPHYR__
  *((uint32_t *)0xE000ED94) = 0;
  MG_DEBUG(("Jailbreak %s", *((uint32_t *)0xE000ED94) == 0 ? "successful" : "failed"));
#endif
  return mg_ota_flash_begin(new_firmware_size, &s_mg_flash_stm32h5);
}

bool mg_ota_write(const void *buf, size_t len) {
  return mg_ota_flash_write(buf, len, &s_mg_flash_stm32h5);
}

// Actual bank swap is deferred until reset, it is safe to execute in flash
bool mg_ota_end(void) {
  if(!mg_ota_flash_end(&s_mg_flash_stm32h5)) return false;
  *(volatile unsigned long *) 0xe000ed0c = 0x5fa0004;
  return true;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ota_stm32h7.c"
#endif




#if MG_OTA == MG_OTA_STM32H7 || MG_OTA == MG_OTA_STM32H7_DUAL_CORE

// - H723/735 RM 4.3.3: Note: The application can simultaneously request a read
// and a write operation through the AXI interface.
//   - We only need IRAM for partition swapping in the H723, however, all
//   related functions must reside in IRAM for this to be possible.
// - Linker files for other devices won't define a .iram section so there's no
// associated penalty

static bool mg_stm32h7_write(void *, const void *, size_t);
static bool mg_stm32h7_swap(void);

static struct mg_flash s_mg_flash_stm32h7 = {
    (void *) 0x08000000,  // Start
    0,                    // Size, FLASH_SIZE_REG
    128 * 1024,           // Sector size, 128k
    32,                   // Align, 256 bit
    mg_stm32h7_write,
    mg_stm32h7_swap,
};

#define FLASH_BASE1 0x52002000  // Base address for bank1
#define FLASH_BASE2 0x52002100  // Base address for bank2
#define FLASH_KEYR 0x04         // See RM0433 4.9.2
#define FLASH_OPTKEYR 0x08
#define FLASH_OPTCR 0x18
#define FLASH_SR 0x10
#define FLASH_CR 0x0c
#define FLASH_CCR 0x14
#define FLASH_OPTSR_CUR 0x1c
#define FLASH_OPTSR_PRG 0x20
#define FLASH_SIZE_REG 0x1ff1e880

#define IS_DUALCORE() (MG_OTA == MG_OTA_STM32H7_DUAL_CORE)

MG_IRAM static bool is_dualbank(void) {
  if (IS_DUALCORE()) {
    // H745/H755 and H747/H757 are running on dual core.
    // Using only the 1st bank (mapped to CM7), in order not to interfere
    // with the 2nd bank (CM4), possibly causing CM4 to boot unexpectedly.
    return false;
  }
  return (s_mg_flash_stm32h7.size < 2 * 1024 * 1024) ? false : true;
}

MG_IRAM static void flash_unlock(void) {
  static bool unlocked = false;
  if (unlocked == false) {
    MG_REG(FLASH_BASE1 + FLASH_KEYR) = 0x45670123;
    MG_REG(FLASH_BASE1 + FLASH_KEYR) = 0xcdef89ab;
    if (is_dualbank()) {
      MG_REG(FLASH_BASE2 + FLASH_KEYR) = 0x45670123;
      MG_REG(FLASH_BASE2 + FLASH_KEYR) = 0xcdef89ab;
    }
    MG_REG(FLASH_BASE1 + FLASH_OPTKEYR) = 0x08192a3b;  // opt reg is "shared"
    MG_REG(FLASH_BASE1 + FLASH_OPTKEYR) = 0x4c5d6e7f;  // thus unlock once
    unlocked = true;
  }
}

MG_IRAM static bool flash_page_start(volatile uint32_t *dst) {
  char *base = (char *) s_mg_flash_stm32h7.start,
       *end = base + s_mg_flash_stm32h7.size;
  volatile char *p = (char *) dst;
  return p >= base && p < end && ((p - base) % s_mg_flash_stm32h7.secsz) == 0;
}

MG_IRAM static bool flash_is_err(uint32_t bank) {
  return MG_REG(bank + FLASH_SR) & ((MG_BIT(11) - 1) << 17);  // RM0433 4.9.5
}

MG_IRAM static void flash_wait(uint32_t bank) {
  while (MG_REG(bank + FLASH_SR) & (MG_BIT(0) | MG_BIT(2))) (void) 0;
}

MG_IRAM static void flash_clear_err(uint32_t bank) {
  flash_wait(bank);                                      // Wait until ready
  MG_REG(bank + FLASH_CCR) = ((MG_BIT(11) - 1) << 16U);  // Clear all errors
}

MG_IRAM static bool flash_bank_is_swapped(uint32_t bank) {
  return MG_REG(bank + FLASH_OPTCR) & MG_BIT(31);  // RM0433 4.9.7
}

// Figure out flash bank based on the address
MG_IRAM static uint32_t flash_bank(void *addr) {
  size_t ofs = (char *) addr - (char *) s_mg_flash_stm32h7.start;
  if (!is_dualbank()) return FLASH_BASE1;
  return ofs < s_mg_flash_stm32h7.size / 2 ? FLASH_BASE1 : FLASH_BASE2;
}

// read-while-write, no need to disable IRQs for standalone usage
MG_IRAM static bool mg_stm32h7_erase(void *addr) {
  bool ok = false;
  if (flash_page_start(addr) == false) {
    MG_ERROR(("%p is not on a sector boundary", addr));
  } else {
    uintptr_t diff = (char *) addr - (char *) s_mg_flash_stm32h7.start;
    uint32_t sector = diff / s_mg_flash_stm32h7.secsz;
    uint32_t bank = flash_bank(addr);
    uint32_t saved_cr = MG_REG(bank + FLASH_CR);  // Save CR value

    flash_unlock();
    if (sector > 7) sector -= 8;

    flash_clear_err(bank);
    MG_REG(bank + FLASH_CR) = MG_BIT(5);             // 32-bit write parallelism
    MG_REG(bank + FLASH_CR) |= (sector & 7U) << 8U;  // Sector to erase
    MG_REG(bank + FLASH_CR) |= MG_BIT(2);            // Sector erase bit
    MG_REG(bank + FLASH_CR) |= MG_BIT(7);            // Start erasing
    ok = !flash_is_err(bank);
    MG_DEBUG(("Erase sector %lu @ %p %s. CR %#lx SR %#lx", sector, addr,
              ok ? "ok" : "fail", MG_REG(bank + FLASH_CR),
              MG_REG(bank + FLASH_SR)));
    MG_REG(bank + FLASH_CR) = saved_cr;  // Restore CR
  }
  return ok;
}

MG_IRAM static bool mg_stm32h7_swap(void) {
  if (!is_dualbank()) return true;
  uint32_t bank = FLASH_BASE1;
  uint32_t desired = flash_bank_is_swapped(bank) ? 0 : MG_BIT(31);
  flash_unlock();
  flash_clear_err(bank);
  // printf("OPTSR_PRG 1 %#lx\n", FLASH->OPTSR_PRG);
  MG_SET_BITS(MG_REG(bank + FLASH_OPTSR_PRG), MG_BIT(31), desired);
  // printf("OPTSR_PRG 2 %#lx\n", FLASH->OPTSR_PRG);
  MG_REG(bank + FLASH_OPTCR) |= MG_BIT(1);  // OPTSTART
  while ((MG_REG(bank + FLASH_OPTSR_CUR) & MG_BIT(31)) != desired) (void) 0;
  return true;
}

static bool s_flash_irq_disabled;

MG_IRAM static bool mg_stm32h7_write(void *addr, const void *buf, size_t len) {
  if ((len % s_mg_flash_stm32h7.align) != 0) {
    MG_ERROR(("%lu is not aligned to %lu", len, s_mg_flash_stm32h7.align));
    return false;
  }
  uint32_t bank = flash_bank(addr);
  uint32_t *dst = (uint32_t *) addr;
  uint32_t *src = (uint32_t *) buf;
  uint32_t *end = (uint32_t *) ((char *) buf + len);
  bool ok = true;
  MG_ARM_DISABLE_IRQ();
  flash_unlock();
  flash_clear_err(bank);
  MG_REG(bank + FLASH_CR) = MG_BIT(1);   // Set programming flag
  MG_REG(bank + FLASH_CR) |= MG_BIT(5);  // 32-bit write parallelism
  while (ok && src < end) {
    if (flash_page_start(dst) && mg_stm32h7_erase(dst) == false) {
      ok = false;
      break;
    }
    *(volatile uint32_t *) dst++ = *src++;
    flash_wait(bank);
    if (flash_is_err(bank)) ok = false;
  }
  if (!s_flash_irq_disabled) MG_ARM_ENABLE_IRQ();
  MG_DEBUG(("Flash write %lu bytes @ %p: %s. CR %#lx SR %#lx", len, dst,
            ok ? "ok" : "fail", MG_REG(bank + FLASH_CR),
            MG_REG(bank + FLASH_SR)));
  MG_REG(bank + FLASH_CR) &= ~MG_BIT(1);  // Clear programming flag
  return ok;
}

// just overwrite instead of swap
MG_IRAM static void single_bank_swap(char *p1, char *p2, size_t s, size_t ss) {
  // no stdlib calls here
  for (size_t ofs = 0; ofs < s; ofs += ss) {
    mg_stm32h7_write(p1 + ofs, p2 + ofs, ss);
  }
  *(volatile unsigned long *) 0xe000ed0c = 0x5fa0004;
}

bool mg_ota_begin(size_t new_firmware_size) {
  s_mg_flash_stm32h7.size = MG_REG(FLASH_SIZE_REG) * 1024;
  if (IS_DUALCORE()) {
    // Using only the 1st bank (mapped to CM7)
    s_mg_flash_stm32h7.size /= 2;
  }
#ifdef __ZEPHYR__
  *((uint32_t *)0xE000ED94) = 0;
  MG_DEBUG(("Jailbreak %s", *((uint32_t *)0xE000ED94) == 0 ? "successful" : "failed"));
#endif
  return mg_ota_flash_begin(new_firmware_size, &s_mg_flash_stm32h7);
}

bool mg_ota_write(const void *buf, size_t len) {
  return mg_ota_flash_write(buf, len, &s_mg_flash_stm32h7);
}

bool mg_ota_end(void) {
  if (mg_ota_flash_end(&s_mg_flash_stm32h7)) {
    if (is_dualbank()) {
      // Bank swap is deferred until reset, been executing in flash, reset
      *(volatile unsigned long *) 0xe000ed0c = 0x5fa0004;
    } else {
      // Swap partitions. Pray power does not go away
      MG_INFO(("Swapping partitions, size %u (%u sectors)",
               s_mg_flash_stm32h7.size,
               s_mg_flash_stm32h7.size / s_mg_flash_stm32h7.secsz));
      MG_INFO(("Do NOT power off..."));
      mg_log_level = MG_LL_NONE;
      s_flash_irq_disabled = true;
      // Runs in RAM, will reset when finished
      single_bank_swap(
          (char *) s_mg_flash_stm32h7.start,
          (char *) s_mg_flash_stm32h7.start + s_mg_flash_stm32h7.size / 2,
          s_mg_flash_stm32h7.size / 2, s_mg_flash_stm32h7.secsz);
    }
  }
  return false;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/printf.c"
#endif




size_t mg_queue_printf(struct mg_queue *q, const char *fmt, ...) {
  char *buf;
  size_t len;
  va_list ap1, ap2;
  va_start(ap1, fmt);
  len = mg_vsnprintf(NULL, 0, fmt, &ap1);
  va_end(ap1);
  if (len == 0 || mg_queue_book(q, &buf, len + 1) < len + 1)
    return 0;  // Nah. Not enough space
  va_start(ap2, fmt);
  len = mg_vsnprintf(buf, len + 1, fmt, &ap2);
  mg_queue_add(q, len);
  va_end(ap2);
  return len;
}

static void mg_pfn_iobuf_private(char ch, void *param, bool expand) {
  struct mg_iobuf *io = (struct mg_iobuf *) param;
  if (expand && io->len + 2 > io->size) mg_iobuf_resize(io, io->len + 2);
  if (io->len + 2 <= io->size) {
    io->buf[io->len++] = (uint8_t) ch;
    io->buf[io->len] = 0;
  } else if (io->len < io->size) {
    io->buf[io->len++] = 0;  // Guarantee to 0-terminate
  }
}

void mg_pfn_iobuf_noresize(char ch, void *param) {
  mg_pfn_iobuf_private(ch, param, false);
}

void mg_pfn_iobuf(char ch, void *param) {
  mg_pfn_iobuf_private(ch, param, true);
}

size_t mg_vsnprintf(char *buf, size_t len, const char *fmt, va_list *ap) {
  struct mg_iobuf io = {0, 0, 0, 0};
  size_t n;
  io.buf = (uint8_t *) buf, io.size = len;
  n = mg_vxprintf(mg_pfn_iobuf_noresize, &io, fmt, ap);
  if (n < len) buf[n] = '\0';
  return n;
}

size_t mg_snprintf(char *buf, size_t len, const char *fmt, ...) {
  va_list ap;
  size_t n;
  va_start(ap, fmt);
  n = mg_vsnprintf(buf, len, fmt, &ap);
  va_end(ap);
  return n;
}

char *mg_vmprintf(const char *fmt, va_list *ap) {
  struct mg_iobuf io = {0, 0, 0, 256};
  mg_vxprintf(mg_pfn_iobuf, &io, fmt, ap);
  return (char *) io.buf;
}

char *mg_mprintf(const char *fmt, ...) {
  char *s;
  va_list ap;
  va_start(ap, fmt);
  s = mg_vmprintf(fmt, &ap);
  va_end(ap);
  return s;
}

void mg_pfn_stdout(char c, void *param) {
  putchar(c);
  (void) param;
}

static size_t print_ip4(void (*out)(char, void *), void *arg, uint8_t *p) {
  return mg_xprintf(out, arg, "%d.%d.%d.%d", p[0], p[1], p[2], p[3]);
}

static size_t print_ip6(void (*out)(char, void *), void *arg, uint16_t *p) {
  return mg_xprintf(out, arg, "[%x:%x:%x:%x:%x:%x:%x:%x]", mg_ntohs(p[0]),
                    mg_ntohs(p[1]), mg_ntohs(p[2]), mg_ntohs(p[3]),
                    mg_ntohs(p[4]), mg_ntohs(p[5]), mg_ntohs(p[6]),
                    mg_ntohs(p[7]));
}

size_t mg_print_ip4(void (*out)(char, void *), void *arg, va_list *ap) {
  uint8_t *p = va_arg(*ap, uint8_t *);
  return print_ip4(out, arg, p);
}

size_t mg_print_ip6(void (*out)(char, void *), void *arg, va_list *ap) {
  uint16_t *p = va_arg(*ap, uint16_t *);
  return print_ip6(out, arg, p);
}

size_t mg_print_ip(void (*out)(char, void *), void *arg, va_list *ap) {
  struct mg_addr *addr = va_arg(*ap, struct mg_addr *);
  if (addr->is_ip6) return print_ip6(out, arg, (uint16_t *) addr->addr.ip);
  return print_ip4(out, arg, (uint8_t *) &addr->addr.ip);
}

size_t mg_print_ip_port(void (*out)(char, void *), void *arg, va_list *ap) {
  struct mg_addr *a = va_arg(*ap, struct mg_addr *);
  return mg_xprintf(out, arg, "%M:%hu", mg_print_ip, a, mg_ntohs(a->port));
}

static size_t print_mac(void (*out)(char, void *), void *arg, uint8_t *p) {
  return mg_xprintf(out, arg, "%02x:%02x:%02x:%02x:%02x:%02x", p[0], p[1], p[2],
                    p[3], p[4], p[5]);
}

size_t mg_print_mac(void (*out)(char, void *), void *arg, va_list *ap) {
  uint8_t *p = va_arg(*ap, uint8_t *);
  return print_mac(out, arg, p);
}

#if MG_ENABLE_TCPIP
size_t mg_print_l2addr(void (*out)(char, void *), void *arg, va_list *ap) {
  enum mg_l2type type = (enum mg_l2type) va_arg(*ap, int);
  if (type == MG_TCPIP_L2_ETH) {
    uint8_t *p = va_arg(*ap, uint8_t *);
    return print_mac(out, arg, p);
  }
  return 0;
}
#endif

static char mg_esc(int c, bool esc) {
  const char *p, *esc1 = "\b\f\n\r\t\\\"", *esc2 = "bfnrt\\\"";
  for (p = esc ? esc1 : esc2; *p != '\0'; p++) {
    if (*p == c) return esc ? esc2[p - esc1] : esc1[p - esc2];
  }
  return 0;
}

static char mg_escape(int c) {
  return mg_esc(c, true);
}

static size_t qcpy(void (*out)(char, void *), void *ptr, char *buf,
                   size_t len) {
  size_t i = 0, extra = 0;
  for (i = 0; i < len && buf[i] != '\0'; i++) {
    char c = mg_escape(buf[i]);
    if (c) {
      out('\\', ptr), out(c, ptr), extra++;
    } else {
      out(buf[i], ptr);
    }
  }
  return i + extra;
}

static size_t bcpy(void (*out)(char, void *), void *arg, uint8_t *buf,
                   size_t len) {
  size_t i, j, n = 0;
  const char *t =
      "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  for (i = 0; i < len; i += 3) {
    uint8_t c1 = buf[i], c2 = i + 1 < len ? buf[i + 1] : 0,
            c3 = i + 2 < len ? buf[i + 2] : 0;
    char tmp[4] = {0, 0, '=', '='};
    tmp[0] = t[c1 >> 2], tmp[1] = t[(c1 & 3) << 4 | (c2 >> 4)];
    if (i + 1 < len) tmp[2] = t[(c2 & 15) << 2 | (c3 >> 6)];
    if (i + 2 < len) tmp[3] = t[c3 & 63];
    for (j = 0; j < sizeof(tmp) && tmp[j] != '\0'; j++) out(tmp[j], arg);
    n += j;
  }
  return n;
}

size_t mg_print_hex(void (*out)(char, void *), void *arg, va_list *ap) {
  size_t bl = (size_t) va_arg(*ap, int);
  uint8_t *p = va_arg(*ap, uint8_t *);
  const char *hex = "0123456789abcdef";
  size_t j;
  for (j = 0; j < bl; j++) {
    out(hex[(p[j] >> 4) & 0x0F], arg);
    out(hex[p[j] & 0x0F], arg);
  }
  return 2 * bl;
}
size_t mg_print_base64(void (*out)(char, void *), void *arg, va_list *ap) {
  size_t len = (size_t) va_arg(*ap, int);
  uint8_t *buf = va_arg(*ap, uint8_t *);
  return bcpy(out, arg, buf, len);
}

size_t mg_print_esc(void (*out)(char, void *), void *arg, va_list *ap) {
  size_t len = (size_t) va_arg(*ap, int);
  char *p = va_arg(*ap, char *);
  if (len == 0) len = p == NULL ? 0 : strlen(p);
  return qcpy(out, arg, p, len);
}

#ifdef MG_ENABLE_LINES
#line 1 "src/queue.c"
#endif



#if (defined(__GNUC__) && (__GNUC__ > 4) ||                                \
     (defined(__GNUC_MINOR__) && __GNUC__ == 4 && __GNUC_MINOR__ >= 1)) || \
    defined(__clang__)
#define MG_MEMORY_BARRIER() __sync_synchronize()
#elif defined(_MSC_VER) && _MSC_VER >= 1700
#define MG_MEMORY_BARRIER() MemoryBarrier()
#elif !defined(MG_MEMORY_BARRIER)
#define MG_MEMORY_BARRIER()
#endif

// Every message in a queue is prepended by a 32-bit message length (ML).
// If ML is 0, then it is the end, and reader must wrap to the beginning.
//
//  Queue when q->tail <= q->head:
//  |----- free -----| ML | message1 | ML | message2 |  ----- free ------|
//  ^                ^                               ^                   ^
// buf              tail                            head                len
//
//  Queue when q->tail > q->head:
//  | ML | message2 |----- free ------| ML | message1 | 0 |---- free ----|
//  ^               ^                 ^                                  ^
// buf             head              tail                               len

void mg_queue_init(struct mg_queue *q, char *buf, size_t size) {
  q->size = size;
  q->buf = buf;
  q->head = q->tail = 0;
}

static size_t mg_queue_read_len(struct mg_queue *q) {
  uint32_t n = 0;
  MG_MEMORY_BARRIER();
  memcpy(&n, q->buf + q->tail, sizeof(n));
  assert(q->tail + n + sizeof(n) <= q->size);
  return n;
}

static void mg_queue_write_len(struct mg_queue *q, size_t len) {
  uint32_t n = (uint32_t) len;
  memcpy(q->buf + q->head, &n, sizeof(n));
  MG_MEMORY_BARRIER();
}

size_t mg_queue_book(struct mg_queue *q, char **buf, size_t len) {
  size_t space = 0, hs = sizeof(uint32_t) * 2;  // *2 is for the 0 marker
  if (q->head >= q->tail && q->head + len + hs <= q->size) {
    space = q->size - q->head - hs;  // There is enough space
  } else if (q->head >= q->tail && q->tail > hs) {
    mg_queue_write_len(q, 0);  // Not enough space ahead
    q->head = 0;               // Wrap head to the beginning
  }
  if (q->head + hs + len < q->tail) space = q->tail - q->head - hs;
  if (buf != NULL) *buf = q->buf + q->head + sizeof(uint32_t);
  return space;
}

size_t mg_queue_next(struct mg_queue *q, char **buf) {
  size_t len = 0;
  if (q->tail != q->head) {
    len = mg_queue_read_len(q);
    if (len == 0) {  // Zero (head wrapped) ?
      q->tail = 0;   // Reset tail to the start
      if (q->head > q->tail) len = mg_queue_read_len(q);  // Read again
    }
  }
  if (buf != NULL) *buf = q->buf + q->tail + sizeof(uint32_t);
  assert(q->tail + len <= q->size);
  return len;
}

void mg_queue_add(struct mg_queue *q, size_t len) {
  assert(len > 0);
  mg_queue_write_len(q, len);
  assert(q->head + sizeof(uint32_t) * 2 + len <= q->size);
  q->head += len + sizeof(uint32_t);
}

void mg_queue_del(struct mg_queue *q, size_t len) {
  q->tail += len + sizeof(uint32_t);
  assert(q->tail + sizeof(uint32_t) <= q->size);
}

#ifdef MG_ENABLE_LINES
#line 1 "src/rpc.c"
#endif




void mg_rpc_add(struct mg_rpc **head, struct mg_str method,
                void (*fn)(struct mg_rpc_req *), void *fn_data) {
  struct mg_rpc *rpc = (struct mg_rpc *) mg_calloc(1, sizeof(*rpc));
  if (rpc != NULL) {
    rpc->method = mg_strdup(method);
    rpc->fn = fn;
    rpc->fn_data = fn_data;
    rpc->next = *head, *head = rpc;
  }
}

void mg_rpc_del(struct mg_rpc **head, void (*fn)(struct mg_rpc_req *)) {
  struct mg_rpc *r;
  while ((r = *head) != NULL) {
    if (r->fn == fn || fn == NULL) {
      *head = r->next;
      mg_free((void *) r->method.buf);
      mg_free(r);
    } else {
      head = &(*head)->next;
    }
  }
}

static void mg_rpc_call(struct mg_rpc_req *r, struct mg_str method) {
  struct mg_rpc *h = r->head == NULL ? NULL : *r->head;
  while (h != NULL && !mg_match(method, h->method, NULL)) h = h->next;
  if (h != NULL) {
    r->rpc = h;
    h->fn(r);
  } else {
    mg_rpc_err(r, -32601, "\"%.*s not found\"", (int) method.len, method.buf);
  }
}

void mg_rpc_process(struct mg_rpc_req *r) {
  int len, off = mg_json_get(r->frame, "$.method", &len);
  if (off > 0 && r->frame.buf[off] == '"') {
    struct mg_str method = mg_str_n(&r->frame.buf[off + 1], (size_t) len - 2);
    mg_rpc_call(r, method);
  } else if ((off = mg_json_get(r->frame, "$.result", &len)) > 0 ||
             (off = mg_json_get(r->frame, "$.error", &len)) > 0) {
    mg_rpc_call(r, mg_str(""));  // JSON response! call "" method handler
  } else {
    mg_rpc_err(r, -32700, "%m", mg_print_esc, (int) r->frame.len,
               r->frame.buf);  // Invalid
  }
}

void mg_rpc_vok(struct mg_rpc_req *r, const char *fmt, va_list *ap) {
  int len, off = mg_json_get(r->frame, "$.id", &len);
  if (off > 0) {
    mg_xprintf(r->pfn, r->pfn_data, "{%m:%.*s,%m:", mg_print_esc, 0, "id", len,
               &r->frame.buf[off], mg_print_esc, 0, "result");
    mg_vxprintf(r->pfn, r->pfn_data, fmt == NULL ? "null" : fmt, ap);
    mg_xprintf(r->pfn, r->pfn_data, "}");
  }
}

void mg_rpc_ok(struct mg_rpc_req *r, const char *fmt, ...) {
  va_list ap;
  va_start(ap, fmt);
  mg_rpc_vok(r, fmt, &ap);
  va_end(ap);
}

void mg_rpc_verr(struct mg_rpc_req *r, int code, const char *fmt, va_list *ap) {
  int len, off = mg_json_get(r->frame, "$.id", &len);
  mg_xprintf(r->pfn, r->pfn_data, "{");
  if (off > 0) {
    mg_xprintf(r->pfn, r->pfn_data, "%m:%.*s,", mg_print_esc, 0, "id", len,
               &r->frame.buf[off]);
  }
  mg_xprintf(r->pfn, r->pfn_data, "%m:{%m:%d,%m:", mg_print_esc, 0, "error",
             mg_print_esc, 0, "code", code, mg_print_esc, 0, "message");
  mg_vxprintf(r->pfn, r->pfn_data, fmt == NULL ? "null" : fmt, ap);
  mg_xprintf(r->pfn, r->pfn_data, "}}");
}

void mg_rpc_err(struct mg_rpc_req *r, int code, const char *fmt, ...) {
  va_list ap;
  va_start(ap, fmt);
  mg_rpc_verr(r, code, fmt, &ap);
  va_end(ap);
}

static size_t print_methods(mg_pfn_t pfn, void *pfn_data, va_list *ap) {
  struct mg_rpc *h, **head = (struct mg_rpc **) va_arg(*ap, void **);
  size_t len = 0;
  for (h = *head; h != NULL; h = h->next) {
    if (h->method.len == 0) continue;  // Ignore response handler
    len += mg_xprintf(pfn, pfn_data, "%s%m", h == *head ? "" : ",",
                      mg_print_esc, (int) h->method.len, h->method.buf);
  }
  return len;
}

void mg_rpc_list(struct mg_rpc_req *r) {
  mg_rpc_ok(r, "[%M]", print_methods, r->head);
}

#ifdef MG_ENABLE_LINES
#line 1 "src/sha1.c"
#endif
/* Copyright(c) By Steve Reid <steve@edmweb.com> */
/* 100% Public Domain */



union char64long16 {
  unsigned char c[64];
  uint32_t l[16];
};

#define rol(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))

static uint32_t blk0(union char64long16 *block, int i) {
  if (MG_BIG_ENDIAN) {
  } else {
    block->l[i] = (rol(block->l[i], 24) & 0xFF00FF00) |
                  (rol(block->l[i], 8) & 0x00FF00FF);
  }
  return block->l[i];
}

/* Avoid redefine warning (ARM /usr/include/sys/ucontext.h define R0~R4) */
#undef blk
#undef R0
#undef R1
#undef R2
#undef R3
#undef R4

#define blk(i)                                                               \
  (block->l[i & 15] = rol(block->l[(i + 13) & 15] ^ block->l[(i + 8) & 15] ^ \
                              block->l[(i + 2) & 15] ^ block->l[i & 15],     \
                          1))
#define R0(v, w, x, y, z, i)                                          \
  z += ((w & (x ^ y)) ^ y) + blk0(block, i) + 0x5A827999 + rol(v, 5); \
  w = rol(w, 30);
#define R1(v, w, x, y, z, i)                                  \
  z += ((w & (x ^ y)) ^ y) + blk(i) + 0x5A827999 + rol(v, 5); \
  w = rol(w, 30);
#define R2(v, w, x, y, z, i)                          \
  z += (w ^ x ^ y) + blk(i) + 0x6ED9EBA1 + rol(v, 5); \
  w = rol(w, 30);
#define R3(v, w, x, y, z, i)                                        \
  z += (((w | x) & y) | (w & x)) + blk(i) + 0x8F1BBCDC + rol(v, 5); \
  w = rol(w, 30);
#define R4(v, w, x, y, z, i)                          \
  z += (w ^ x ^ y) + blk(i) + 0xCA62C1D6 + rol(v, 5); \
  w = rol(w, 30);

static void mg_sha1_transform(uint32_t state[5],
                              const unsigned char *buffer) {
  uint32_t a, b, c, d, e;
  union char64long16 block[1];

  memcpy(block, buffer, 64);
  a = state[0];
  b = state[1];
  c = state[2];
  d = state[3];
  e = state[4];
  R0(a, b, c, d, e, 0);
  R0(e, a, b, c, d, 1);
  R0(d, e, a, b, c, 2);
  R0(c, d, e, a, b, 3);
  R0(b, c, d, e, a, 4);
  R0(a, b, c, d, e, 5);
  R0(e, a, b, c, d, 6);
  R0(d, e, a, b, c, 7);
  R0(c, d, e, a, b, 8);
  R0(b, c, d, e, a, 9);
  R0(a, b, c, d, e, 10);
  R0(e, a, b, c, d, 11);
  R0(d, e, a, b, c, 12);
  R0(c, d, e, a, b, 13);
  R0(b, c, d, e, a, 14);
  R0(a, b, c, d, e, 15);
  R1(e, a, b, c, d, 16);
  R1(d, e, a, b, c, 17);
  R1(c, d, e, a, b, 18);
  R1(b, c, d, e, a, 19);
  R2(a, b, c, d, e, 20);
  R2(e, a, b, c, d, 21);
  R2(d, e, a, b, c, 22);
  R2(c, d, e, a, b, 23);
  R2(b, c, d, e, a, 24);
  R2(a, b, c, d, e, 25);
  R2(e, a, b, c, d, 26);
  R2(d, e, a, b, c, 27);
  R2(c, d, e, a, b, 28);
  R2(b, c, d, e, a, 29);
  R2(a, b, c, d, e, 30);
  R2(e, a, b, c, d, 31);
  R2(d, e, a, b, c, 32);
  R2(c, d, e, a, b, 33);
  R2(b, c, d, e, a, 34);
  R2(a, b, c, d, e, 35);
  R2(e, a, b, c, d, 36);
  R2(d, e, a, b, c, 37);
  R2(c, d, e, a, b, 38);
  R2(b, c, d, e, a, 39);
  R3(a, b, c, d, e, 40);
  R3(e, a, b, c, d, 41);
  R3(d, e, a, b, c, 42);
  R3(c, d, e, a, b, 43);
  R3(b, c, d, e, a, 44);
  R3(a, b, c, d, e, 45);
  R3(e, a, b, c, d, 46);
  R3(d, e, a, b, c, 47);
  R3(c, d, e, a, b, 48);
  R3(b, c, d, e, a, 49);
  R3(a, b, c, d, e, 50);
  R3(e, a, b, c, d, 51);
  R3(d, e, a, b, c, 52);
  R3(c, d, e, a, b, 53);
  R3(b, c, d, e, a, 54);
  R3(a, b, c, d, e, 55);
  R3(e, a, b, c, d, 56);
  R3(d, e, a, b, c, 57);
  R3(c, d, e, a, b, 58);
  R3(b, c, d, e, a, 59);
  R4(a, b, c, d, e, 60);
  R4(e, a, b, c, d, 61);
  R4(d, e, a, b, c, 62);
  R4(c, d, e, a, b, 63);
  R4(b, c, d, e, a, 64);
  R4(a, b, c, d, e, 65);
  R4(e, a, b, c, d, 66);
  R4(d, e, a, b, c, 67);
  R4(c, d, e, a, b, 68);
  R4(b, c, d, e, a, 69);
  R4(a, b, c, d, e, 70);
  R4(e, a, b, c, d, 71);
  R4(d, e, a, b, c, 72);
  R4(c, d, e, a, b, 73);
  R4(b, c, d, e, a, 74);
  R4(a, b, c, d, e, 75);
  R4(e, a, b, c, d, 76);
  R4(d, e, a, b, c, 77);
  R4(c, d, e, a, b, 78);
  R4(b, c, d, e, a, 79);
  state[0] += a;
  state[1] += b;
  state[2] += c;
  state[3] += d;
  state[4] += e;
  /* Erase working structures. The order of operations is important,
   * used to ensure that compiler doesn't optimize those out. */
  memset(block, 0, sizeof(block));
  a = b = c = d = e = 0;
  (void) a;
  (void) b;
  (void) c;
  (void) d;
  (void) e;
}

void mg_sha1_init(mg_sha1_ctx *context) {
  context->state[0] = 0x67452301;
  context->state[1] = 0xEFCDAB89;
  context->state[2] = 0x98BADCFE;
  context->state[3] = 0x10325476;
  context->state[4] = 0xC3D2E1F0;
  context->count[0] = context->count[1] = 0;
}

void mg_sha1_update(mg_sha1_ctx *context, const unsigned char *data,
                    size_t len) {
  size_t i, j;

  j = context->count[0];
  if ((context->count[0] += (uint32_t) len << 3) < j) context->count[1]++;
  context->count[1] += (uint32_t) (len >> 29);
  j = (j >> 3) & 63;
  if ((j + len) > 63) {
    memcpy(&context->buffer[j], data, (i = 64 - j));
    mg_sha1_transform(context->state, context->buffer);
    for (; i + 63 < len; i += 64) {
      mg_sha1_transform(context->state, &data[i]);
    }
    j = 0;
  } else
    i = 0;
  memcpy(&context->buffer[j], &data[i], len - i);
}

void mg_sha1_final(unsigned char digest[20], mg_sha1_ctx *context) {
  unsigned i;
  unsigned char finalcount[8], c;

  for (i = 0; i < 8; i++) {
    finalcount[i] = (unsigned char) ((context->count[(i >= 4 ? 0 : 1)] >>
                                      ((3 - (i & 3)) * 8)) &
                                     255);
  }
  c = 0200;
  mg_sha1_update(context, &c, 1);
  while ((context->count[0] & 504) != 448) {
    c = 0000;
    mg_sha1_update(context, &c, 1);
  }
  mg_sha1_update(context, finalcount, 8);
  for (i = 0; i < 20; i++) {
    digest[i] =
        (unsigned char) ((context->state[i >> 2] >> ((3 - (i & 3)) * 8)) & 255);
  }
  memset(context, '\0', sizeof(*context));
  memset(&finalcount, '\0', sizeof(finalcount));
}

#ifdef MG_ENABLE_LINES
#line 1 "src/sha256.c"
#endif
// https://github.com/B-Con/crypto-algorithms
// Author:     Brad Conte (brad AT bradconte.com)
// Disclaimer: This code is presented "as is" without any guarantees.
// Details:    Defines the API for the corresponding SHA1 implementation.
// Copyright:  public domain



#define ror(x, n) (((x) >> (n)) | ((x) << (32 - (n))))
#define ch(x, y, z) (((x) & (y)) ^ (~(x) & (z)))
#define maj(x, y, z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))
#define ep0(x) (ror(x, 2) ^ ror(x, 13) ^ ror(x, 22))
#define ep1(x) (ror(x, 6) ^ ror(x, 11) ^ ror(x, 25))
#define sig0(x) (ror(x, 7) ^ ror(x, 18) ^ ((x) >> 3))
#define sig1(x) (ror(x, 17) ^ ror(x, 19) ^ ((x) >> 10))

static const uint32_t mg_sha256_k[64] = {
    0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1,
    0x923f82a4, 0xab1c5ed5, 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
    0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786,
    0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
    0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147,
    0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
    0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b,
    0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
    0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a,
    0x5b9cca4f, 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
    0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2};

void mg_sha256_init(mg_sha256_ctx *ctx) {
  ctx->len = 0;
  ctx->bits = 0;
  ctx->state[0] = 0x6a09e667;
  ctx->state[1] = 0xbb67ae85;
  ctx->state[2] = 0x3c6ef372;
  ctx->state[3] = 0xa54ff53a;
  ctx->state[4] = 0x510e527f;
  ctx->state[5] = 0x9b05688c;
  ctx->state[6] = 0x1f83d9ab;
  ctx->state[7] = 0x5be0cd19;
}

static void mg_sha256_chunk(mg_sha256_ctx *ctx) {
  int i, j;
  uint32_t a, b, c, d, e, f, g, h;
  uint32_t m[64];
  for (i = 0, j = 0; i < 16; ++i, j += 4)
    m[i] = (uint32_t) (((uint32_t) ctx->buffer[j] << 24) |
                       ((uint32_t) ctx->buffer[j + 1] << 16) |
                       ((uint32_t) ctx->buffer[j + 2] << 8) |
                       ((uint32_t) ctx->buffer[j + 3]));
  for (; i < 64; ++i)
    m[i] = sig1(m[i - 2]) + m[i - 7] + sig0(m[i - 15]) + m[i - 16];

  a = ctx->state[0];
  b = ctx->state[1];
  c = ctx->state[2];
  d = ctx->state[3];
  e = ctx->state[4];
  f = ctx->state[5];
  g = ctx->state[6];
  h = ctx->state[7];

  for (i = 0; i < 64; ++i) {
    uint32_t t1 = h + ep1(e) + ch(e, f, g) + mg_sha256_k[i] + m[i];
    uint32_t t2 = ep0(a) + maj(a, b, c);
    h = g;
    g = f;
    f = e;
    e = d + t1;
    d = c;
    c = b;
    b = a;
    a = t1 + t2;
  }

  ctx->state[0] += a;
  ctx->state[1] += b;
  ctx->state[2] += c;
  ctx->state[3] += d;
  ctx->state[4] += e;
  ctx->state[5] += f;
  ctx->state[6] += g;
  ctx->state[7] += h;
}

void mg_sha256_update(mg_sha256_ctx *ctx, const unsigned char *data,
                      size_t len) {
  size_t i;
  for (i = 0; i < len; i++) {
    ctx->buffer[ctx->len] = data[i];
    if ((++ctx->len) == 64) {
      mg_sha256_chunk(ctx);
      ctx->bits += 512;
      ctx->len = 0;
    }
  }
}

// TODO: make final reusable (remove side effects)
void mg_sha256_final(unsigned char digest[32], mg_sha256_ctx *ctx) {
  uint32_t i = ctx->len;
  if (i < 56) {
    ctx->buffer[i++] = 0x80;
    while (i < 56) {
      ctx->buffer[i++] = 0x00;
    }
  } else {
    ctx->buffer[i++] = 0x80;
    while (i < 64) {
      ctx->buffer[i++] = 0x00;
    }
    mg_sha256_chunk(ctx);
    memset(ctx->buffer, 0, 56);
  }

  ctx->bits += ctx->len * 8;
  ctx->buffer[63] = (uint8_t) ((ctx->bits) & 0xff);
  ctx->buffer[62] = (uint8_t) ((ctx->bits >> 8) & 0xff);
  ctx->buffer[61] = (uint8_t) ((ctx->bits >> 16) & 0xff);
  ctx->buffer[60] = (uint8_t) ((ctx->bits >> 24) & 0xff);
  ctx->buffer[59] = (uint8_t) ((ctx->bits >> 32) & 0xff);
  ctx->buffer[58] = (uint8_t) ((ctx->bits >> 40) & 0xff);
  ctx->buffer[57] = (uint8_t) ((ctx->bits >> 48) & 0xff);
  ctx->buffer[56] = (uint8_t) ((ctx->bits >> 56) & 0xff);
  mg_sha256_chunk(ctx);

  for (i = 0; i < 4; ++i) {
    digest[i] = (uint8_t) ((ctx->state[0] >> (24 - i * 8)) & 0xff);
    digest[i + 4] = (uint8_t) ((ctx->state[1] >> (24 - i * 8)) & 0xff);
    digest[i + 8] = (uint8_t) ((ctx->state[2] >> (24 - i * 8)) & 0xff);
    digest[i + 12] = (uint8_t) ((ctx->state[3] >> (24 - i * 8)) & 0xff);
    digest[i + 16] = (uint8_t) ((ctx->state[4] >> (24 - i * 8)) & 0xff);
    digest[i + 20] = (uint8_t) ((ctx->state[5] >> (24 - i * 8)) & 0xff);
    digest[i + 24] = (uint8_t) ((ctx->state[6] >> (24 - i * 8)) & 0xff);
    digest[i + 28] = (uint8_t) ((ctx->state[7] >> (24 - i * 8)) & 0xff);
  }
}

void mg_sha256(uint8_t dst[32], uint8_t *data, size_t datasz) {
  mg_sha256_ctx ctx;
  mg_sha256_init(&ctx);
  mg_sha256_update(&ctx, data, datasz);
  mg_sha256_final(dst, &ctx);
}

void mg_hmac_sha256(uint8_t dst[32], uint8_t *key, size_t keysz, uint8_t *data,
                    size_t datasz) {
  mg_sha256_ctx ctx;
  uint8_t k[64] = {0};
  uint8_t o_pad[64], i_pad[64];
  unsigned int i;
  memset(i_pad, 0x36, sizeof(i_pad));
  memset(o_pad, 0x5c, sizeof(o_pad));
  if (keysz < 64) {
    if (keysz > 0) memmove(k, key, keysz);
  } else {
    mg_sha256_init(&ctx);
    mg_sha256_update(&ctx, key, keysz);
    mg_sha256_final(k, &ctx);
  }
  for (i = 0; i < sizeof(k); i++) {
    i_pad[i] ^= k[i];
    o_pad[i] ^= k[i];
  }
  mg_sha256_init(&ctx);
  mg_sha256_update(&ctx, i_pad, sizeof(i_pad));
  mg_sha256_update(&ctx, data, datasz);
  mg_sha256_final(dst, &ctx);
  mg_sha256_init(&ctx);
  mg_sha256_update(&ctx, o_pad, sizeof(o_pad));
  mg_sha256_update(&ctx, dst, 32);
  mg_sha256_final(dst, &ctx);
}

#define rotr64(x, n) (((x) >> (n)) | ((x) << (64 - (n))))
#define ep064(x) (rotr64(x, 28) ^ rotr64(x, 34) ^ rotr64(x, 39))
#define ep164(x) (rotr64(x, 14) ^ rotr64(x, 18) ^ rotr64(x, 41))
#define sig064(x) (rotr64(x, 1) ^ rotr64(x, 8) ^ ((x) >> 7))
#define sig164(x) (rotr64(x, 19) ^ rotr64(x, 61) ^ ((x) >> 6))

static const uint64_t mg_sha256_k2[80] = {
#if defined(__DCC__)
    0x428a2f98d728ae22ull, 0x7137449123ef65cdull, 0xb5c0fbcfec4d3b2full,
    0xe9b5dba58189dbbcull, 0x3956c25bf348b538ull, 0x59f111f1b605d019ull,
    0x923f82a4af194f9bull, 0xab1c5ed5da6d8118ull, 0xd807aa98a3030242ull,
    0x12835b0145706fbeull, 0x243185be4ee4b28cull, 0x550c7dc3d5ffb4e2ull,
    0x72be5d74f27b896full, 0x80deb1fe3b1696b1ull, 0x9bdc06a725c71235ull,
    0xc19bf174cf692694ull, 0xe49b69c19ef14ad2ull, 0xefbe4786384f25e3ull,
    0x0fc19dc68b8cd5b5ull, 0x240ca1cc77ac9c65ull, 0x2de92c6f592b0275ull,
    0x4a7484aa6ea6e483ull, 0x5cb0a9dcbd41fbd4ull, 0x76f988da831153b5ull,
    0x983e5152ee66dfabull, 0xa831c66d2db43210ull, 0xb00327c898fb213full,
    0xbf597fc7beef0ee4ull, 0xc6e00bf33da88fc2ull, 0xd5a79147930aa725ull,
    0x06ca6351e003826full, 0x142929670a0e6e70ull, 0x27b70a8546d22ffcull,
    0x2e1b21385c26c926ull, 0x4d2c6dfc5ac42aedull, 0x53380d139d95b3dfull,
    0x650a73548baf63deull, 0x766a0abb3c77b2a8ull, 0x81c2c92e47edaee6ull,
    0x92722c851482353bull, 0xa2bfe8a14cf10364ull, 0xa81a664bbc423001ull,
    0xc24b8b70d0f89791ull, 0xc76c51a30654be30ull, 0xd192e819d6ef5218ull,
    0xd69906245565a910ull, 0xf40e35855771202aull, 0x106aa07032bbd1b8ull,
    0x19a4c116b8d2d0c8ull, 0x1e376c085141ab53ull, 0x2748774cdf8eeb99ull,
    0x34b0bcb5e19b48a8ull, 0x391c0cb3c5c95a63ull, 0x4ed8aa4ae3418acbull,
    0x5b9cca4f7763e373ull, 0x682e6ff3d6b2b8a3ull, 0x748f82ee5defb2fcull,
    0x78a5636f43172f60ull, 0x84c87814a1f0ab72ull, 0x8cc702081a6439ecull,
    0x90befffa23631e28ull, 0xa4506cebde82bde9ull, 0xbef9a3f7b2c67915ull,
    0xc67178f2e372532bull, 0xca273eceea26619cull, 0xd186b8c721c0c207ull,
    0xeada7dd6cde0eb1eull, 0xf57d4f7fee6ed178ull, 0x06f067aa72176fbaull,
    0x0a637dc5a2c898a6ull, 0x113f9804bef90daeull, 0x1b710b35131c471bull,
    0x28db77f523047d84ull, 0x32caab7b40c72493ull, 0x3c9ebe0a15c9bebcull,
    0x431d67c49c100d4cull, 0x4cc5d4becb3e42b6ull, 0x597f299cfc657e2aull,
    0x5fcb6fab3ad6faecull, 0x6c44198c4a475817ull
#else
    0x428a2f98d728ae22, 0x7137449123ef65cd, 0xb5c0fbcfec4d3b2f,
    0xe9b5dba58189dbbc, 0x3956c25bf348b538, 0x59f111f1b605d019,
    0x923f82a4af194f9b, 0xab1c5ed5da6d8118, 0xd807aa98a3030242,
    0x12835b0145706fbe, 0x243185be4ee4b28c, 0x550c7dc3d5ffb4e2,
    0x72be5d74f27b896f, 0x80deb1fe3b1696b1, 0x9bdc06a725c71235,
    0xc19bf174cf692694, 0xe49b69c19ef14ad2, 0xefbe4786384f25e3,
    0x0fc19dc68b8cd5b5, 0x240ca1cc77ac9c65, 0x2de92c6f592b0275,
    0x4a7484aa6ea6e483, 0x5cb0a9dcbd41fbd4, 0x76f988da831153b5,
    0x983e5152ee66dfab, 0xa831c66d2db43210, 0xb00327c898fb213f,
    0xbf597fc7beef0ee4, 0xc6e00bf33da88fc2, 0xd5a79147930aa725,
    0x06ca6351e003826f, 0x142929670a0e6e70, 0x27b70a8546d22ffc,
    0x2e1b21385c26c926, 0x4d2c6dfc5ac42aed, 0x53380d139d95b3df,
    0x650a73548baf63de, 0x766a0abb3c77b2a8, 0x81c2c92e47edaee6,
    0x92722c851482353b, 0xa2bfe8a14cf10364, 0xa81a664bbc423001,
    0xc24b8b70d0f89791, 0xc76c51a30654be30, 0xd192e819d6ef5218,
    0xd69906245565a910, 0xf40e35855771202a, 0x106aa07032bbd1b8,
    0x19a4c116b8d2d0c8, 0x1e376c085141ab53, 0x2748774cdf8eeb99,
    0x34b0bcb5e19b48a8, 0x391c0cb3c5c95a63, 0x4ed8aa4ae3418acb,
    0x5b9cca4f7763e373, 0x682e6ff3d6b2b8a3, 0x748f82ee5defb2fc,
    0x78a5636f43172f60, 0x84c87814a1f0ab72, 0x8cc702081a6439ec,
    0x90befffa23631e28, 0xa4506cebde82bde9, 0xbef9a3f7b2c67915,
    0xc67178f2e372532b, 0xca273eceea26619c, 0xd186b8c721c0c207,
    0xeada7dd6cde0eb1e, 0xf57d4f7fee6ed178, 0x06f067aa72176fba,
    0x0a637dc5a2c898a6, 0x113f9804bef90dae, 0x1b710b35131c471b,
    0x28db77f523047d84, 0x32caab7b40c72493, 0x3c9ebe0a15c9bebc,
    0x431d67c49c100d4c, 0x4cc5d4becb3e42b6, 0x597f299cfc657e2a,
    0x5fcb6fab3ad6faec, 0x6c44198c4a475817
#endif
};

static void mg_sha384_transform(mg_sha384_ctx *ctx, const uint8_t data[]) {
  uint64_t m[80];
  uint64_t a, b, c, d, e, f, g, h;
  int i, j;

  for (i = 0, j = 0; i < 16; ++i, j += 8)
    m[i] = ((uint64_t) data[j] << 56) | ((uint64_t) data[j + 1] << 48) |
           ((uint64_t) data[j + 2] << 40) | ((uint64_t) data[j + 3] << 32) |
           ((uint64_t) data[j + 4] << 24) | ((uint64_t) data[j + 5] << 16) |
           ((uint64_t) data[j + 6] << 8) | ((uint64_t) data[j + 7]);
  for (; i < 80; ++i)
    m[i] = sig164(m[i - 2]) + m[i - 7] + sig064(m[i - 15]) + m[i - 16];

  a = ctx->state[0];
  b = ctx->state[1];
  c = ctx->state[2];
  d = ctx->state[3];
  e = ctx->state[4];
  f = ctx->state[5];
  g = ctx->state[6];
  h = ctx->state[7];

  for (i = 0; i < 80; ++i) {
    uint64_t t1 = h + ep164(e) + ch(e, f, g) + mg_sha256_k2[i] + m[i];
    uint64_t t2 = ep064(a) + maj(a, b, c);
    h = g;
    g = f;
    f = e;
    e = d + t1;
    d = c;
    c = b;
    b = a;
    a = t1 + t2;
  }

  ctx->state[0] += a;
  ctx->state[1] += b;
  ctx->state[2] += c;
  ctx->state[3] += d;
  ctx->state[4] += e;
  ctx->state[5] += f;
  ctx->state[6] += g;
  ctx->state[7] += h;
}

void mg_sha384_init(mg_sha384_ctx *ctx) {
  ctx->datalen = 0;
  ctx->bitlen[0] = 0;
  ctx->bitlen[1] = 0;
#if defined(__DCC__)
  ctx->state[0] = 0xcbbb9d5dc1059ed8ull;
  ctx->state[1] = 0x629a292a367cd507ull;
  ctx->state[2] = 0x9159015a3070dd17ull;
  ctx->state[3] = 0x152fecd8f70e5939ull;
  ctx->state[4] = 0x67332667ffc00b31ull;
  ctx->state[5] = 0x8eb44a8768581511ull;
  ctx->state[6] = 0xdb0c2e0d64f98fa7ull;
  ctx->state[7] = 0x47b5481dbefa4fa4ull;
#else
  ctx->state[0] = 0xcbbb9d5dc1059ed8;
  ctx->state[1] = 0x629a292a367cd507;
  ctx->state[2] = 0x9159015a3070dd17;
  ctx->state[3] = 0x152fecd8f70e5939;
  ctx->state[4] = 0x67332667ffc00b31;
  ctx->state[5] = 0x8eb44a8768581511;
  ctx->state[6] = 0xdb0c2e0d64f98fa7;
  ctx->state[7] = 0x47b5481dbefa4fa4;
#endif
}

void mg_sha384_update(mg_sha384_ctx *ctx, const uint8_t *data, size_t len) {
  size_t i;
  for (i = 0; i < len; ++i) {
    ctx->buffer[ctx->datalen] = data[i];
    ctx->datalen++;
    if (ctx->datalen == 128) {
      mg_sha384_transform(ctx, ctx->buffer);
      ctx->bitlen[1] += 1024;
      if (ctx->bitlen[1] < 1024) ctx->bitlen[0]++;
      ctx->datalen = 0;
    }
  }
}

void mg_sha384_final(uint8_t hash[48], mg_sha384_ctx *ctx) {
  size_t i = ctx->datalen;

  if (ctx->datalen < 112) {
    ctx->buffer[i++] = 0x80;
    while (i < 112) ctx->buffer[i++] = 0x00;
  } else {
    ctx->buffer[i++] = 0x80;
    while (i < 128) ctx->buffer[i++] = 0x00;
    mg_sha384_transform(ctx, ctx->buffer);
    memset(ctx->buffer, 0, 112);
  }

  ctx->bitlen[1] += ctx->datalen * 8;
  if (ctx->bitlen[1] < ctx->datalen * 8) ctx->bitlen[0]++;
  ctx->buffer[127] = (uint8_t) (ctx->bitlen[1]);
  ctx->buffer[126] = (uint8_t) (ctx->bitlen[1] >> 8);
  ctx->buffer[125] = (uint8_t) (ctx->bitlen[1] >> 16);
  ctx->buffer[124] = (uint8_t) (ctx->bitlen[1] >> 24);
  ctx->buffer[123] = (uint8_t) (ctx->bitlen[1] >> 32);
  ctx->buffer[122] = (uint8_t) (ctx->bitlen[1] >> 40);
  ctx->buffer[121] = (uint8_t) (ctx->bitlen[1] >> 48);
  ctx->buffer[120] = (uint8_t) (ctx->bitlen[1] >> 56);
  ctx->buffer[119] = (uint8_t) (ctx->bitlen[0]);
  ctx->buffer[118] = (uint8_t) (ctx->bitlen[0] >> 8);
  ctx->buffer[117] = (uint8_t) (ctx->bitlen[0] >> 16);
  ctx->buffer[116] = (uint8_t) (ctx->bitlen[0] >> 24);
  ctx->buffer[115] = (uint8_t) (ctx->bitlen[0] >> 32);
  ctx->buffer[114] = (uint8_t) (ctx->bitlen[0] >> 40);
  ctx->buffer[113] = (uint8_t) (ctx->bitlen[0] >> 48);
  ctx->buffer[112] = (uint8_t) (ctx->bitlen[0] >> 56);
  mg_sha384_transform(ctx, ctx->buffer);

  for (i = 0; i < 6; ++i) {
    hash[i * 8] = (uint8_t) ((ctx->state[i] >> 56) & 0xff);
    hash[i * 8 + 1] = (uint8_t) ((ctx->state[i] >> 48) & 0xff);
    hash[i * 8 + 2] = (uint8_t) ((ctx->state[i] >> 40) & 0xff);
    hash[i * 8 + 3] = (uint8_t) ((ctx->state[i] >> 32) & 0xff);
    hash[i * 8 + 4] = (uint8_t) ((ctx->state[i] >> 24) & 0xff);
    hash[i * 8 + 5] = (uint8_t) ((ctx->state[i] >> 16) & 0xff);
    hash[i * 8 + 6] = (uint8_t) ((ctx->state[i] >> 8) & 0xff);
    hash[i * 8 + 7] = (uint8_t) (ctx->state[i] & 0xff);
  }
}

void mg_sha384(uint8_t dst[48], uint8_t *data, size_t datasz) {
  mg_sha384_ctx ctx;
  mg_sha384_init(&ctx);
  mg_sha384_update(&ctx, data, datasz);
  mg_sha384_final(dst, &ctx);
}

#ifdef MG_ENABLE_LINES
#line 1 "src/sntp.c"
#endif






#define SNTP_TIME_OFFSET 2208988800U  // (1970 - 1900) in seconds
#define SNTP_MAX_FRAC 4294967295.0    // 2 ** 32 - 1

static uint64_t s_boot_timestamp = 0;  // Updated by SNTP

uint64_t mg_now(void) {
  return mg_millis() + s_boot_timestamp;
}

static int64_t gettimestamp(const uint32_t *data) {
  uint32_t sec = mg_ntohl(data[0]), frac = mg_ntohl(data[1]);
  if (sec) sec -= SNTP_TIME_OFFSET;
  return ((int64_t) sec) * 1000 + (int64_t) (frac / SNTP_MAX_FRAC * 1000.0);
}

int64_t mg_sntp_parse(const unsigned char *buf, size_t len) {
  int64_t epoch_milliseconds = -1;
  int mode = len > 0 ? buf[0] & 7 : 0;
  int version = len > 0 ? (buf[0] >> 3) & 7 : 0;
  if (len < 48) {
    MG_ERROR(("%s", "corrupt packet"));
  } else if (mode != 4 && mode != 5) {
    MG_ERROR(("%s", "not a server reply"));
  } else if (buf[1] == 0) {
    MG_ERROR(("%s", "server sent a kiss of death"));
  } else if (version == 4 || version == 3) {
    // int64_t ref = gettimestamp((uint32_t *) &buf[16]);
    int64_t origin_time = gettimestamp((uint32_t *) &buf[24]);
    int64_t receive_time = gettimestamp((uint32_t *) &buf[32]);
    int64_t transmit_time = gettimestamp((uint32_t *) &buf[40]);
    int64_t now = (int64_t) mg_millis();
    int64_t latency = (now - origin_time) - (transmit_time - receive_time);
    epoch_milliseconds = transmit_time + latency / 2;
    s_boot_timestamp = (uint64_t) (epoch_milliseconds - now);
  } else {
    MG_ERROR(("unexpected version: %d", version));
  }
  return epoch_milliseconds;
}

static void sntp_cb(struct mg_connection *c, int ev, void *ev_data) {
  uint64_t *expiration_time = (uint64_t *) c->data;
  if (ev == MG_EV_OPEN) {
    *expiration_time = mg_millis() + 3000;  // Store expiration time in 3s
  } else if (ev == MG_EV_CONNECT) {
    mg_sntp_request(c);
  } else if (ev == MG_EV_READ) {
    int64_t milliseconds = mg_sntp_parse(c->recv.buf, c->recv.len);
    if (milliseconds > 0) {
      s_boot_timestamp = (uint64_t) milliseconds - mg_millis();
      mg_call(c, MG_EV_SNTP_TIME, (uint64_t *) &milliseconds);
      MG_DEBUG(("%lu got time: %lld ms from epoch", c->id, milliseconds));
    }
    // mg_iobuf_del(&c->recv, 0, c->recv.len);  // Free receive buffer
    c->is_closing = 1;
  } else if (ev == MG_EV_POLL) {
    if (mg_millis() > *expiration_time) c->is_closing = 1;
  } else if (ev == MG_EV_CLOSE) {
  }
  (void) ev_data;
}

void mg_sntp_request(struct mg_connection *c) {
  if (c->is_resolving) {
    MG_ERROR(("%lu wait until resolved", c->id));
  } else {
    int64_t now = (int64_t) mg_millis();  // Use int64_t, for vc98
    uint8_t buf[48] = {0};
    uint32_t *t = (uint32_t *) &buf[40];
    double frac = ((double) (now % 1000)) / 1000.0 * SNTP_MAX_FRAC;
    buf[0] = (0 << 6) | (4 << 3) | 3;
    t[0] = mg_htonl((uint32_t) (now / 1000) + SNTP_TIME_OFFSET);
    t[1] = mg_htonl((uint32_t) frac);
    mg_send(c, buf, sizeof(buf));
  }
}

struct mg_connection *mg_sntp_connect(struct mg_mgr *mgr, const char *url,
                                      mg_event_handler_t fn, void *fn_data) {
  if (url == NULL) url = "udp://time.google.com:123";
  return mg_connect_svc(mgr, url, fn, fn_data, sntp_cb, NULL);
}

#ifdef MG_ENABLE_LINES
#line 1 "src/sock.c"
#endif











#if MG_ENABLE_SOCKET

#ifndef closesocket
#define closesocket(x) close(x)
#endif

#define FD(c_) ((MG_SOCKET_TYPE) (size_t) (c_)->fd)
#define S2PTR(s_) ((void *) (size_t) (s_))

#ifndef MSG_NONBLOCKING
#define MSG_NONBLOCKING 0
#endif

#ifndef AF_INET6
#define AF_INET6 10
#endif

#ifndef MG_SOCK_ERR
#define MG_SOCK_ERR(errcode) ((errcode) < 0 ? errno : 0)
#endif

#ifndef MG_SOCK_INTR
#define MG_SOCK_INTR(fd) (fd == MG_INVALID_SOCKET && MG_SOCK_ERR(-1) == EINTR)
#endif

#ifndef MG_SOCK_PENDING
#define MG_SOCK_PENDING(errcode) \
  (((errcode) < 0) && (errno == EINPROGRESS || errno == EWOULDBLOCK))
#endif

#ifndef MG_SOCK_RESET
#define MG_SOCK_RESET(errcode) \
  (((errcode) < 0) && (errno == EPIPE || errno == ECONNRESET))
#endif

union usa {
  struct sockaddr sa;
  struct sockaddr_in sin;
#if MG_ENABLE_IPV6
  struct sockaddr_in6 sin6;
#endif
};

static socklen_t tousa(struct mg_addr *a, union usa *usa) {
  socklen_t len = sizeof(usa->sin);
  memset(usa, 0, sizeof(*usa));
  usa->sin.sin_family = AF_INET;
  usa->sin.sin_port = a->port;
  memcpy(&usa->sin.sin_addr, a->addr.ip, sizeof(uint32_t));
#if MG_ENABLE_IPV6
  if (a->is_ip6) {
    usa->sin.sin_family = AF_INET6;
    usa->sin6.sin6_port = a->port;
    usa->sin6.sin6_scope_id = a->scope_id;
    memcpy(&usa->sin6.sin6_addr, a->addr.ip, sizeof(a->addr.ip));
    len = sizeof(usa->sin6);
  }
#endif
  return len;
}

static void tomgaddr(union usa *usa, struct mg_addr *a, bool is_ip6) {
  a->is_ip6 = is_ip6;
#if MG_ENABLE_IPV6
  if (is_ip6) {
    memcpy(a->addr.ip, &usa->sin6.sin6_addr, sizeof(a->addr.ip));
    a->port = usa->sin6.sin6_port;
    a->scope_id = (uint8_t) usa->sin6.sin6_scope_id;
  } else
#endif
  {
    a->port = usa->sin.sin_port;
    memcpy(&a->addr.ip, &usa->sin.sin_addr, sizeof(uint32_t));
  }
}

static void setlocaddr(MG_SOCKET_TYPE fd, struct mg_addr *addr) {
  union usa usa;
  socklen_t n = sizeof(usa);
  if (getsockname(fd, &usa.sa, &n) == 0) {
    tomgaddr(&usa, addr, n != sizeof(usa.sin));
  }
}

// Get the local 'addr' the stack will use to connect to 'to'
void mg_getlocaddr(struct mg_connection *c, struct mg_addr *to, struct mg_addr *addr);
void mg_getlocaddr(struct mg_connection *c, struct mg_addr *to, struct mg_addr *addr) {
  union usa usa;
  socklen_t slen;
  MG_SOCKET_TYPE fd;
  int rc, af = to->is_ip6 ? AF_INET6 : AF_INET;
  fd = socket(af, SOCK_DGRAM, IPPROTO_UDP);
  if (fd == MG_INVALID_SOCKET) {
    mg_error(c, "socket(): %d", MG_SOCK_ERR(-1));
    return;
  }
  // NOTE(): TI-RTOS NDK may require binding
  slen = tousa(to, &usa);
  if ((rc = connect(fd, &usa.sa, slen)) != 0) {
    mg_error(c, "connect: %d", MG_SOCK_ERR(rc));
    return;
  }
  setlocaddr(fd, addr);
  closesocket(fd);
}


static void iolog(struct mg_connection *c, char *buf, long n, bool r) {
  if (n == MG_IO_WAIT) {
    // Do nothing
  } else if (n <= 0) {
    c->is_closing = 1;  // Termination. Don't call mg_error(): #1529
  } else if (n > 0) {
    if (c->is_hexdumping) {
      MG_INFO(("\n-- %lu %M %s %M %ld", c->id, mg_print_ip_port, &c->loc,
               r ? "<-" : "->", mg_print_ip_port, &c->rem, n));
      mg_hexdump(buf, (size_t) n);
    }
    if (r) {
      c->recv.len += (size_t) n;
      mg_call(c, MG_EV_READ, &n);
    } else {
      mg_iobuf_del(&c->send, 0, (size_t) n);
      // if (c->send.len == 0) mg_iobuf_resize(&c->send, 0);
      if (c->send.len == 0) {
        MG_EPOLL_MOD(c, 0);
      }
      mg_call(c, MG_EV_WRITE, &n);
    }
  }
}

long mg_io_send(struct mg_connection *c, const void *buf, size_t len) {
  long n;
  if (c->is_udp) {
    union usa usa;
    socklen_t slen = tousa(&c->rem, &usa);
    n = sendto(FD(c), (char *) buf, len, 0, &usa.sa, slen);
    if (n > 0) setlocaddr(FD(c), &c->loc);
  } else {
    n = send(FD(c), (char *) buf, len, MSG_NONBLOCKING);
  }
  MG_VERBOSE(("%lu %ld %d", c->id, n, MG_SOCK_ERR(n)));
  if (MG_SOCK_PENDING(n)) return MG_IO_WAIT;
  if (MG_SOCK_RESET(n)) return MG_IO_RESET;  // MbedTLS, see #1507
  if (n <= 0) return MG_IO_ERR;
  return n;
}

bool mg_send(struct mg_connection *c, const void *buf, size_t len) {
  if (c->is_udp) {
    long n = mg_io_send(c, buf, len);
    MG_DEBUG(("%lu %ld %lu:%lu:%lu %ld err %d", c->id, c->fd, c->send.len,
              c->recv.len, c->rtls.len, n, MG_SOCK_ERR(n)));
    iolog(c, (char *) buf, n, false);
    return n > 0;
  } else {
    return len == 0 || mg_iobuf_add(&c->send, c->send.len, buf, len) > 0;
    // returning 0 means an OOM condition (iobuf couldn't resize), yet this is
    // so far recoverable, let the caller decide
  }
}

static void mg_set_non_blocking_mode(MG_SOCKET_TYPE fd) {
#if defined(MG_CUSTOM_NONBLOCK)
  MG_CUSTOM_NONBLOCK(fd);
#elif MG_ARCH == MG_ARCH_WIN32 && MG_ENABLE_WINSOCK
  unsigned long on = 1;
  ioctlsocket(fd, FIONBIO, &on);
#elif MG_ENABLE_RL
  unsigned long on = 1;
  ioctlsocket(fd, FIONBIO, &on);
#elif MG_ENABLE_FREERTOS_TCP
  const BaseType_t off = 0;
  if (setsockopt(fd, 0, FREERTOS_SO_RCVTIMEO, &off, sizeof(off)) != 0) (void) 0;
  if (setsockopt(fd, 0, FREERTOS_SO_SNDTIMEO, &off, sizeof(off)) != 0) (void) 0;
#elif MG_ENABLE_LWIP
  lwip_fcntl(fd, F_SETFL, O_NONBLOCK);
#elif MG_ARCH == MG_ARCH_THREADX
  // NetxDuo fails to send large blocks of data to the non-blocking sockets
  (void) fd;
  // fcntl(fd, F_SETFL, O_NONBLOCK);
#elif MG_ARCH == MG_ARCH_TIRTOS
  int val = 0;
  setsockopt(fd, SOL_SOCKET, SO_BLOCKING, &val, sizeof(val));
  // SPRU524J section 3.3.3 page 63, SO_SNDLOWAT
  int sz = sizeof(val);
  getsockopt(fd, SOL_SOCKET, SO_SNDBUF, &val, &sz);
  val /= 2;  // set send low-water mark at half send buffer size
  setsockopt(fd, SOL_SOCKET, SO_SNDLOWAT, &val, sizeof(val));
#else
  fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) | O_NONBLOCK);  // Non-blocking mode
  fcntl(fd, F_SETFD, FD_CLOEXEC);                          // Set close-on-exec
#endif
}

void mg_multicast_add(struct mg_connection *c, char *ip);
void mg_multicast_add(struct mg_connection *c, char *ip) {
#if MG_ENABLE_RL
  MG_ERROR(("unsupported"));
#elif MG_ENABLE_FREERTOS_TCP
  // TODO(): prvAllowIPPacketIPv4()
#else
  // lwIP, Unix, Windows, Zephyr 4+(, AzureRTOS ?)
#if MG_ENABLE_LWIP && !LWIP_IGMP
  MG_ERROR(("LWIP_IGMP not defined, no multicast support"));
#else
#if defined(__ZEPHYR__) && ZEPHYR_VERSION_CODE < 0x40000
  MG_ERROR(("struct ip_mreq not defined"));
#else
  struct ip_mreq mreq;
  mreq.imr_multiaddr.s_addr = inet_addr(ip);
  mreq.imr_interface.s_addr = mg_htonl(INADDR_ANY);
  setsockopt(FD(c), IPPROTO_IP, IP_ADD_MEMBERSHIP, (char *) &mreq,
             sizeof(mreq));
#endif  // !Zephyr
#endif  // !lwIP
#endif
}

bool mg_open_listener(struct mg_connection *c, const char *url) {
  MG_SOCKET_TYPE fd = MG_INVALID_SOCKET;
  bool success = false;
  c->loc.port = mg_htons(mg_url_port(url));
  if (!mg_aton(mg_url_host(url), &c->loc)) {
    MG_ERROR(("invalid listening URL: %s", url));
  } else {
    union usa usa;
    socklen_t slen = tousa(&c->loc, &usa);
    int rc, on = 1, af = c->loc.is_ip6 ? AF_INET6 : AF_INET;
    int type = strncmp(url, "udp:", 4) == 0 ? SOCK_DGRAM : SOCK_STREAM;
    int proto = type == SOCK_DGRAM ? IPPROTO_UDP : IPPROTO_TCP;
    (void) on;

    if ((fd = socket(af, type, proto)) == MG_INVALID_SOCKET) {
      MG_ERROR(("socket: %d", MG_SOCK_ERR(-1)));
#if defined(SO_EXCLUSIVEADDRUSE)
    } else if ((rc = setsockopt(fd, SOL_SOCKET, SO_EXCLUSIVEADDRUSE,
                                (char *) &on, sizeof(on))) != 0) {
      // "Using SO_REUSEADDR and SO_EXCLUSIVEADDRUSE"
      MG_ERROR(("setsockopt(SO_EXCLUSIVEADDRUSE): %d %d", on, MG_SOCK_ERR(rc)));
#elif defined(SO_REUSEADDR) && (!defined(LWIP_SOCKET) || SO_REUSE)
    } else if ((rc = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, (char *) &on,
                                sizeof(on))) != 0) {
      // 1. SO_REUSEADDR semantics on UNIX and Windows is different.  On
      // Windows, SO_REUSEADDR allows to bind a socket to a port without error
      // even if the port is already open by another program. This is not the
      // behavior SO_REUSEADDR was designed for, and leads to hard-to-track
      // failure scenarios.
      //
      // 2. For LWIP, SO_REUSEADDR should be explicitly enabled by defining
      // SO_REUSE = 1 in lwipopts.h, otherwise the code below will compile but
      // won't work! (setsockopt will return EINVAL)
      MG_ERROR(("setsockopt(SO_REUSEADDR): %d", MG_SOCK_ERR(rc)));
#endif
#if MG_IPV6_V6ONLY
      // Bind only to the V6 address, not V4 address on this port
    } else if (c->loc.is_ip6 &&
               (rc = setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, (char *) &on,
                                sizeof(on))) != 0) {
      // See #2089. Allow to bind v4 and v6 sockets on the same port
      MG_ERROR(("setsockopt(IPV6_V6ONLY): %d", MG_SOCK_ERR(rc)));
#endif
    } else if ((rc = bind(fd, &usa.sa, slen)) != 0) {
      MG_ERROR(("bind: %d", MG_SOCK_ERR(rc)));
    } else if ((type == SOCK_STREAM &&
                (rc = listen(fd, MG_SOCK_LISTEN_BACKLOG_SIZE)) != 0)) {
      // NOTE(lsm): FreeRTOS uses backlog value as a connection limit
      // In case port was set to 0, get the real port number
      MG_ERROR(("listen: %d", MG_SOCK_ERR(rc)));
    } else {
      setlocaddr(fd, &c->loc);
      mg_set_non_blocking_mode(fd);
      c->fd = S2PTR(fd);
      MG_EPOLL_ADD(c);
      success = true;
    }
  }
  if (success == false && fd != MG_INVALID_SOCKET) closesocket(fd);
  return success;
}

static long recv_raw(struct mg_connection *c, void *buf, size_t len) {
  long n = 0;
  if (c->is_udp) {
    union usa usa;
    socklen_t slen = tousa(&c->rem, &usa);
    n = recvfrom(FD(c), (char *) buf, len, 0, &usa.sa, &slen);
    if (n > 0) tomgaddr(&usa, &c->rem, slen != sizeof(usa.sin));
  } else {
    n = recv(FD(c), (char *) buf, len, MSG_NONBLOCKING);
  }
  MG_VERBOSE(("%lu %ld %d", c->id, n, MG_SOCK_ERR(n)));
  if (MG_SOCK_PENDING(n)) return MG_IO_WAIT;
  if (MG_SOCK_RESET(n)) return MG_IO_RESET;  // MbedTLS, see #1507
  if (n <= 0) return MG_IO_ERR;
  return n;
}

static bool ioalloc(struct mg_connection *c, struct mg_iobuf *io) {
  bool res = false;
  if (io->len >= MG_MAX_RECV_SIZE) {
    mg_error(c, "MG_MAX_RECV_SIZE");
  } else if (io->size <= io->len &&
             !mg_iobuf_resize(io, io->size + MG_IO_SIZE)) {
    mg_error(c, "OOM");
  } else {
    res = true;
  }
  return res;
}

// NOTE(lsm): do only one iteration of reads, cause some systems
// (e.g. FreeRTOS stack) return 0 instead of -1/EWOULDBLOCK when no data
static void read_conn(struct mg_connection *c) {
  if (ioalloc(c, &c->recv)) {
    char *buf = (char *) &c->recv.buf[c->recv.len];
    size_t len = c->recv.size - c->recv.len;
    long n = -1;
    if (c->is_tls) {
      // Do not read to the raw TLS buffer if it already has enough.
      // This is to prevent overflowing c->rtls if our reads are slow
      long m;
      if (c->rtls.len < 16 * 1024 + 40) {  // TLS record, header, MAC, padding
        if (!ioalloc(c, &c->rtls)) return;
        n = recv_raw(c, (char *) &c->rtls.buf[c->rtls.len],
                     c->rtls.size - c->rtls.len);
        if (n > 0) c->rtls.len += (size_t) n;
      }
      // there can still be > 16K from last iteration, always mg_tls_recv()
      m = c->is_tls_hs ? (long) MG_IO_WAIT : mg_tls_recv(c, buf, len);
      if (n == MG_IO_ERR || n == MG_IO_RESET) {  // Windows, see #3031
        if (c->rtls.len == 0 || m < 0) {
          // Close only when we have fully drained both rtls and TLS buffers
          c->is_closing = 1;         // or there's nothing we can do about it.
          if (m < 0) m = MG_IO_ERR;  // but return last record data, see #3104
        } else {                     // see #2885
          // TLS buffer is capped to max record size, even though, there can
          // be more than one record, give TLS a chance to process them.
        }
      } else if (c->is_tls_hs) {
        mg_tls_handshake(c);
      }
      n = m;
    } else {
      n = recv_raw(c, buf, len);
    }
    MG_DEBUG(("%lu %ld %lu:%lu:%lu %ld err %d", c->id, c->fd, c->send.len,
              c->recv.len, c->rtls.len, n, MG_SOCK_ERR(n)));
    iolog(c, buf, n, true);
  }
}

static void write_conn(struct mg_connection *c) {
  char *buf = (char *) c->send.buf;
  size_t len = c->send.len;
  long n = c->is_tls ? mg_tls_send(c, buf, len) : mg_io_send(c, buf, len);
  // TODO(): mg_tls_send() may return 0 forever on steady OOM
  MG_DEBUG(("%lu %ld snd %ld/%ld rcv %ld/%ld n=%ld err=%d", c->id, c->fd,
            (long) c->send.len, (long) c->send.size, (long) c->recv.len,
            (long) c->recv.size, n, MG_SOCK_ERR(n)));
  iolog(c, buf, n, false);
}

static void close_conn(struct mg_connection *c) {
  if (FD(c) != MG_INVALID_SOCKET) {
#if MG_ENABLE_EPOLL
    epoll_ctl(c->mgr->epoll_fd, EPOLL_CTL_DEL, FD(c), NULL);
#endif
    closesocket(FD(c));
#if MG_ENABLE_FREERTOS_TCP
    FreeRTOS_FD_CLR(c->fd, c->mgr->ss, eSELECT_ALL);
#endif
  }
  mg_close_conn(c);
}

static void connect_conn(struct mg_connection *c) {
  union usa usa;
  socklen_t n = sizeof(usa);
  // Use getpeername() to test whether we have connected
  if (getpeername(FD(c), &usa.sa, &n) == 0) {
    c->is_connecting = 0;
    setlocaddr(FD(c), &c->loc);
    mg_call(c, MG_EV_CONNECT, NULL);
    MG_EPOLL_MOD(c, 0);
    if (c->is_tls_hs) mg_tls_handshake(c);
    if (!c->is_tls_hs) c->is_tls = 0;  // user did not call mg_tls_init()
  } else {
    mg_error(c, "socket error");
  }
}

static void setsockopts(struct mg_connection *c) {
#if MG_ENABLE_FREERTOS_TCP || MG_ARCH == MG_ARCH_THREADX || \
    MG_ARCH == MG_ARCH_TIRTOS
  (void) c;
#else
  int on = 1;
#if !defined(SOL_TCP)
#define SOL_TCP IPPROTO_TCP
#endif
  if (setsockopt(FD(c), SOL_TCP, TCP_NODELAY, (char *) &on, sizeof(on)) != 0)
    (void) 0;
  if (setsockopt(FD(c), SOL_SOCKET, SO_KEEPALIVE, (char *) &on, sizeof(on)) !=
      0)
    (void) 0;
#endif
}

void mg_connect_resolved(struct mg_connection *c) {
  int type = c->is_udp ? SOCK_DGRAM : SOCK_STREAM;
  int proto = type == SOCK_DGRAM ? IPPROTO_UDP : IPPROTO_TCP;
  int rc, af = c->rem.is_ip6 ? AF_INET6 : AF_INET;  // c->rem has resolved IP
  c->fd = S2PTR(socket(af, type, proto));           // Create outbound socket
  c->is_resolving = 0;                              // Clear resolving flag
  if (FD(c) == MG_INVALID_SOCKET) {
    mg_error(c, "socket(): %d", MG_SOCK_ERR(-1));
  } else if (c->is_udp) {
    MG_EPOLL_ADD(c);
#if MG_ARCH == MG_ARCH_TIRTOS
    union usa usa;  // TI-RTOS NDK requires binding to receive on UDP sockets
    socklen_t slen = tousa(&c->loc, &usa);
    if ((rc = bind(c->fd, &usa.sa, slen)) != 0)
      MG_ERROR(("bind: %d", MG_SOCK_ERR(rc)));
#endif
    setlocaddr(FD(c), &c->loc);
    mg_call(c, MG_EV_RESOLVE, NULL);
    mg_call(c, MG_EV_CONNECT, NULL);
  } else {
    union usa usa;
    socklen_t slen = tousa(&c->rem, &usa);
    mg_set_non_blocking_mode(FD(c));
    setsockopts(c);
    MG_EPOLL_ADD(c);
    mg_call(c, MG_EV_RESOLVE, NULL);
    rc = connect(FD(c), &usa.sa, slen);  // Attempt to connect
    if (rc == 0) {                       // Success
      setlocaddr(FD(c), &c->loc);
      mg_call(c, MG_EV_CONNECT, NULL);   // Send MG_EV_CONNECT to the user
      if (!c->is_tls_hs) c->is_tls = 0;  // user did not call mg_tls_init()
    } else if (MG_SOCK_PENDING(rc)) {    // Need to wait for TCP handshake
      MG_DEBUG(("%lu %ld -> %M pend", c->id, c->fd, mg_print_ip_port, &c->rem));
      c->is_connecting = 1;
    } else {
      mg_error(c, "connect: %d", MG_SOCK_ERR(rc));
    }
  }
}

static MG_SOCKET_TYPE raccept(MG_SOCKET_TYPE sock, union usa *usa,
                              socklen_t *len) {
  MG_SOCKET_TYPE fd = MG_INVALID_SOCKET;
  do {
    memset(usa, 0, sizeof(*usa));
    fd = accept(sock, &usa->sa, len);
  } while (MG_SOCK_INTR(fd));
  return fd;
}

static void accept_conn(struct mg_mgr *mgr, struct mg_connection *lsn) {
  struct mg_connection *c = NULL;
  union usa usa;
  socklen_t sa_len = sizeof(usa);
  MG_SOCKET_TYPE fd = raccept(FD(lsn), &usa, &sa_len);
  if (fd == MG_INVALID_SOCKET) {
#if MG_ARCH == MG_ARCH_THREADX || defined(__ECOS)
    // NetxDuo, in non-block socket mode can mark listening socket readable
    // even it is not. See comment for 'select' func implementation in
    // nx_bsd.c That's not an error, just should try later
    if (errno != EAGAIN)
#endif
      MG_ERROR(("%lu accept failed, errno %d", lsn->id, MG_SOCK_ERR(-1)));
#if (MG_ARCH != MG_ARCH_WIN32) && !MG_ENABLE_FREERTOS_TCP && \
    (MG_ARCH != MG_ARCH_TIRTOS) && !MG_ENABLE_POLL && !MG_ENABLE_EPOLL
  } else if ((long) fd >= FD_SETSIZE) {
    MG_ERROR(("%ld > %ld", (long) fd, (long) FD_SETSIZE));
    closesocket(fd);
#endif
  } else if ((c = mg_alloc_conn(mgr)) == NULL) {
    MG_ERROR(("%lu OOM", lsn->id));
    closesocket(fd);
  } else {
    tomgaddr(&usa, &c->rem, sa_len != sizeof(usa.sin));
    LIST_ADD_HEAD(struct mg_connection, &mgr->conns, c);
    c->fd = S2PTR(fd);
    MG_EPOLL_ADD(c);
    mg_set_non_blocking_mode(FD(c));
    setsockopts(c);
    c->is_accepted = 1;
    c->is_hexdumping = lsn->is_hexdumping;
    setlocaddr(fd, &c->loc); // set local addr to where the client connected to
    c->pfn = lsn->pfn;
    c->pfn_data = lsn->pfn_data;
    c->fn = lsn->fn;
    c->fn_data = lsn->fn_data;
    c->is_tls = lsn->is_tls;
    MG_DEBUG(("%lu %ld accepted %M -> %M", c->id, c->fd, mg_print_ip_port,
              &c->rem, mg_print_ip_port, &c->loc));
    mg_call(c, MG_EV_OPEN, NULL);
    mg_call(c, MG_EV_ACCEPT, NULL);
    if (!c->is_tls_hs) c->is_tls = 0;  // user did not call mg_tls_init()
  }
}

static bool can_read(const struct mg_connection *c) {
  return c->is_full == false;
}

static bool can_write(const struct mg_connection *c) {
  return c->is_connecting || (c->send.len > 0 && c->is_tls_hs == 0);
}

static bool skip_iotest(const struct mg_connection *c) {
  return (c->is_closing || c->is_resolving || FD(c) == MG_INVALID_SOCKET) ||
         (can_read(c) == false && can_write(c) == false);
}

static void mg_iotest(struct mg_mgr *mgr, int ms) {
#if MG_ENABLE_FREERTOS_TCP
  struct mg_connection *c;
  for (c = mgr->conns; c != NULL; c = c->next) {
    c->is_readable = c->is_writable = 0;
    if (skip_iotest(c)) continue;
    if (can_read(c))
      FreeRTOS_FD_SET(c->fd, mgr->ss, eSELECT_READ | eSELECT_EXCEPT);
    if (can_write(c)) FreeRTOS_FD_SET(c->fd, mgr->ss, eSELECT_WRITE);
    if (c->is_closing) ms = 1;
  }
  FreeRTOS_select(mgr->ss, pdMS_TO_TICKS(ms));
  for (c = mgr->conns; c != NULL; c = c->next) {
    EventBits_t bits = FreeRTOS_FD_ISSET(c->fd, mgr->ss);
    c->is_readable = bits & (eSELECT_READ | eSELECT_EXCEPT) ? 1U : 0;
    c->is_writable = bits & eSELECT_WRITE ? 1U : 0;
    if (c->fd != MG_INVALID_SOCKET)
      FreeRTOS_FD_CLR(c->fd, mgr->ss,
                      eSELECT_READ | eSELECT_EXCEPT | eSELECT_WRITE);
  }
#elif MG_ENABLE_EPOLL
  size_t max = 1;
  for (struct mg_connection *c = mgr->conns; c != NULL; c = c->next) {
    c->is_readable = c->is_writable = 0;
    if (c->rtls.len > 0 || mg_tls_pending(c) > 0) ms = 1, c->is_readable = 1;
    if (can_write(c)) MG_EPOLL_MOD(c, 1);
    if (c->is_closing) ms = 1;
    max++;
  }
  struct epoll_event *evs = (struct epoll_event *) alloca(max * sizeof(evs[0]));
  int n = epoll_wait(mgr->epoll_fd, evs, (int) max, ms);
  for (int i = 0; i < n; i++) {
    struct mg_connection *c = (struct mg_connection *) evs[i].data.ptr;
    if (evs[i].events & EPOLLERR) {
      mg_error(c, "socket error");
    } else if (c->is_readable == 0) {
      bool rd = evs[i].events & (EPOLLIN | EPOLLHUP);
      bool wr = evs[i].events & EPOLLOUT;
      c->is_readable = can_read(c) && rd ? 1U : 0;
      c->is_writable = can_write(c) && wr ? 1U : 0;
      if (c->rtls.len > 0 || mg_tls_pending(c) > 0) c->is_readable = 1;
    }
  }
  (void) skip_iotest;
#elif MG_ENABLE_POLL
  nfds_t n = 0;
  for (struct mg_connection *c = mgr->conns; c != NULL; c = c->next) n++;
  struct pollfd *fds = (struct pollfd *) alloca(n * sizeof(fds[0]));
  memset(fds, 0, n * sizeof(fds[0]));
  n = 0;
  for (struct mg_connection *c = mgr->conns; c != NULL; c = c->next) {
    c->is_readable = c->is_writable = 0;
    if (c->is_closing) ms = 1;
    if (skip_iotest(c)) {
      // Socket not valid, ignore
    } else {
      // Don't wait if TLS is ready
      if (c->rtls.len > 0 || mg_tls_pending(c) > 0) ms = 1;
      fds[n].fd = FD(c);
      if (can_read(c)) fds[n].events |= POLLIN;
      if (can_write(c)) fds[n].events |= POLLOUT;
      n++;
    }
  }

  // MG_INFO(("poll n=%d ms=%d", (int) n, ms));
  if (poll(fds, n, ms) < 0) {
#if MG_ARCH == MG_ARCH_WIN32
    if (n == 0) Sleep(ms);  // On Windows, poll fails if no sockets
#endif
    memset(fds, 0, n * sizeof(fds[0]));
  }
  n = 0;
  for (struct mg_connection *c = mgr->conns; c != NULL; c = c->next) {
    if (skip_iotest(c)) {
      // Socket not valid, ignore
    } else {
      if (fds[n].revents & POLLERR) {
        mg_error(c, "socket error");
      } else {
        c->is_readable =
            (unsigned) (fds[n].revents & (POLLIN | POLLHUP) ? 1 : 0);
        c->is_writable = (unsigned) (fds[n].revents & POLLOUT ? 1 : 0);
        if (c->rtls.len > 0 || mg_tls_pending(c) > 0) c->is_readable = 1;
      }
      n++;
    }
  }
#else
  struct timeval tv = {ms / 1000, (ms % 1000) * 1000}, tv_1ms = {0, 1000}, *tvp;
  struct mg_connection *c;
  fd_set rset, wset, eset;
  MG_SOCKET_TYPE maxfd = 0;
  int rc;

  FD_ZERO(&rset);
  FD_ZERO(&wset);
  FD_ZERO(&eset);
  tvp = ms < 0 ? NULL : &tv;
  for (c = mgr->conns; c != NULL; c = c->next) {
    c->is_readable = c->is_writable = 0;
    if (skip_iotest(c)) continue;
    FD_SET(FD(c), &eset);
    if (can_read(c)) FD_SET(FD(c), &rset);
    if (can_write(c)) FD_SET(FD(c), &wset);
    if (c->rtls.len > 0 || mg_tls_pending(c) > 0) tvp = &tv_1ms;
    if (FD(c) > maxfd) maxfd = FD(c);
    if (c->is_closing) tvp = &tv_1ms;
  }

  if ((rc = select((int) maxfd + 1, &rset, &wset, &eset, tvp)) <= 0) {
#if MG_ARCH == MG_ARCH_WIN32
    if (maxfd == 0) Sleep(ms);  // On Windows, select fails if no sockets
#else
    if (rc < 0) MG_ERROR(("select: %d %d", rc, MG_SOCK_ERR(rc)));
#endif
    FD_ZERO(&rset);
    FD_ZERO(&wset);
    FD_ZERO(&eset);
  }

  for (c = mgr->conns; c != NULL; c = c->next) {
    if (FD(c) != MG_INVALID_SOCKET && FD_ISSET(FD(c), &eset)) {
#if MG_ARCH == MG_ARCH_THREADX
      // NetxDuo stack returns exceptions for listening connection after accept
      if (c->is_listening == 0) mg_error(c, "socket error");
#else
      mg_error(c, "socket error");
#endif
    } else {
      c->is_readable = FD(c) != MG_INVALID_SOCKET && FD_ISSET(FD(c), &rset);
      c->is_writable = FD(c) != MG_INVALID_SOCKET && FD_ISSET(FD(c), &wset);
      if (c->rtls.len > 0 || mg_tls_pending(c) > 0) c->is_readable = 1;
    }
  }
#endif
}

static bool mg_socketpair(MG_SOCKET_TYPE sp[2], union usa usa[2]) {
  socklen_t n = sizeof(usa[0].sin);
  bool success = false;

  sp[0] = sp[1] = MG_INVALID_SOCKET;
  (void) memset(&usa[0], 0, sizeof(usa[0]));
  usa[0].sin.sin_family = AF_INET;
  *(uint32_t *) &usa->sin.sin_addr = mg_htonl(0x7f000001U);  // 127.0.0.1
  usa[1] = usa[0];

  if ((sp[0] = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) != MG_INVALID_SOCKET &&
      (sp[1] = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) != MG_INVALID_SOCKET &&
      bind(sp[0], &usa[0].sa, n) == 0 &&          //
      bind(sp[1], &usa[1].sa, n) == 0 &&          //
      getsockname(sp[0], &usa[0].sa, &n) == 0 &&  //
      getsockname(sp[1], &usa[1].sa, &n) == 0 &&  //
      connect(sp[0], &usa[1].sa, n) == 0 &&       //
      connect(sp[1], &usa[0].sa, n) == 0) {       //
    success = true;
  }
  if (!success) {
    if (sp[0] != MG_INVALID_SOCKET) closesocket(sp[0]);
    if (sp[1] != MG_INVALID_SOCKET) closesocket(sp[1]);
    sp[0] = sp[1] = MG_INVALID_SOCKET;
  }
  return success;
}

// mg_wakeup() event handler
static void wufn(struct mg_connection *c, int ev, void *ev_data) {
  if (ev == MG_EV_READ) {
    unsigned long *id = (unsigned long *) c->recv.buf;
    // MG_INFO(("Got data"));
    // mg_hexdump(c->recv.buf, c->recv.len);
    if (c->recv.len >= sizeof(*id)) {
      struct mg_connection *t;
      for (t = c->mgr->conns; t != NULL; t = t->next) {
        if (t->id == *id) {
          struct mg_str data = mg_str_n((char *) c->recv.buf + sizeof(*id),
                                        c->recv.len - sizeof(*id));
          mg_call(t, MG_EV_WAKEUP, &data);
        }
      }
    }
    c->recv.len = 0;  // Consume received data
  } else if (ev == MG_EV_CLOSE) {
    closesocket(c->mgr->pipe);         // When we're closing, close the other
    c->mgr->pipe = MG_INVALID_SOCKET;  // side of the socketpair, too
  }
  (void) ev_data;
}

bool mg_wakeup_init(struct mg_mgr *mgr) {
  bool ok = false;
  if (mgr->pipe == MG_INVALID_SOCKET) {
    union usa usa[2];
    MG_SOCKET_TYPE sp[2] = {MG_INVALID_SOCKET, MG_INVALID_SOCKET};
    struct mg_connection *c = NULL;
    if (!mg_socketpair(sp, usa)) {
      MG_ERROR(("Cannot create socket pair"));
    } else if ((c = mg_wrapfd(mgr, (int) sp[1], wufn, NULL)) == NULL) {
      closesocket(sp[0]);
      closesocket(sp[1]);
      sp[0] = sp[1] = MG_INVALID_SOCKET;
    } else {
      tomgaddr(&usa[0], &c->rem, false);
      MG_DEBUG(("%lu %p pipe %lu", c->id, c->fd, (unsigned long) sp[0]));
      mgr->pipe = sp[0];
      ok = true;
    }
  }
  return ok;
}

bool mg_wakeup(struct mg_mgr *mgr, unsigned long conn_id, const void *buf,
               size_t len) {
  if (mgr->pipe != MG_INVALID_SOCKET && conn_id > 0) {
    char *extended_buf = (char *) alloca(len + sizeof(conn_id));
    memcpy(extended_buf, &conn_id, sizeof(conn_id));
    memcpy(extended_buf + sizeof(conn_id), buf, len);
    send(mgr->pipe, extended_buf, len + sizeof(conn_id), MSG_NONBLOCKING);
    return true;
  }
  return false;
}

void mg_mgr_poll(struct mg_mgr *mgr, int ms) {
  struct mg_connection *c, *tmp;
  uint64_t now;

  mg_iotest(mgr, ms);
  now = mg_millis();
  mg_timer_poll(&mgr->timers, now);

  for (c = mgr->conns; c != NULL; c = tmp) {
    bool is_resp = c->is_resp;
    tmp = c->next;
    mg_call(c, MG_EV_POLL, &now);
    if (is_resp && !c->is_resp) {
      long n = 0;
      mg_call(c, MG_EV_READ, &n);
    }
    MG_VERBOSE(("%lu %c%c %c%c%c%c%c %lu %lu", c->id,
                c->is_readable ? 'r' : '-', c->is_writable ? 'w' : '-',
                c->is_tls ? 'T' : 't', c->is_connecting ? 'C' : 'c',
                c->is_tls_hs ? 'H' : 'h', c->is_resolving ? 'R' : 'r',
                c->is_closing ? 'C' : 'c', mg_tls_pending(c), c->rtls.len));
    if (c->is_resolving || c->is_closing) {
      // Do nothing
    } else if (c->is_listening && c->is_udp == 0) {
      if (c->is_readable) accept_conn(mgr, c);
    } else if (c->is_connecting) {
      if (c->is_readable || c->is_writable) connect_conn(c);
    } else {
      if (c->is_readable) read_conn(c);
      if (c->is_writable) write_conn(c);
      if (c->is_tls && !c->is_tls_hs && c->send.len == 0) mg_tls_flush(c);
    }

    if (c->is_draining && c->send.len == 0) c->is_closing = 1;
    if (c->is_closing) close_conn(c);
  }
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ssi.c"
#endif





#ifndef MG_MAX_SSI_DEPTH
#define MG_MAX_SSI_DEPTH 5
#endif

#ifndef MG_SSI_BUFSIZ
#define MG_SSI_BUFSIZ 1024
#endif

#if MG_ENABLE_SSI
static char *mg_ssi(const char *path, const char *root, int depth) {
  struct mg_iobuf b = {NULL, 0, 0, MG_IO_SIZE};
  FILE *fp = fopen(path, "rb");
  if (fp != NULL) {
    char buf[MG_SSI_BUFSIZ], arg[sizeof(buf)];
    int ch, intag = 0;
    size_t len = 0;
    buf[0] = arg[0] = '\0';
    while ((ch = fgetc(fp)) != EOF) {
      if (intag && ch == '>' && buf[len - 1] == '-' && buf[len - 2] == '-') {
        buf[len++] = (char) (ch & 0xff);
        buf[len] = '\0';
        if (sscanf(buf, "<!--#include file=\"%[^\"]", arg) > 0) {
          char tmp[MG_PATH_MAX + MG_SSI_BUFSIZ + 10],
              *p = (char *) path + strlen(path), *data;
          while (p > path && p[-1] != MG_DIRSEP && p[-1] != '/') p--;
          mg_snprintf(tmp, sizeof(tmp), "%.*s%s", (int) (p - path), path, arg);
          if (depth < MG_MAX_SSI_DEPTH &&
              (data = mg_ssi(tmp, root, depth + 1)) != NULL) {
            size_t datalen = strlen(data);
            size_t ret = mg_iobuf_add(&b, b.len, data, datalen);
            mg_free(data);
            if (datalen > 0 && ret == 0) goto fail;
          } else {
            MG_ERROR(("%s: file=%s error or too deep", path, arg));
          } // TODO(): or OOM at recursive call
        } else if (sscanf(buf, "<!--#include virtual=\"%[^\"]", arg) > 0) {
          char tmp[MG_PATH_MAX + MG_SSI_BUFSIZ + 10], *data;
          mg_snprintf(tmp, sizeof(tmp), "%s%s", root, arg);
          if (depth < MG_MAX_SSI_DEPTH &&
              (data = mg_ssi(tmp, root, depth + 1)) != NULL) {
            size_t datalen = strlen(data);
            size_t ret = mg_iobuf_add(&b, b.len, data, datalen);
            mg_free(data);
            if (datalen > 0 && ret == 0) goto fail;
          } else {
            MG_ERROR(("%s: virtual=%s error or too deep", path, arg));
          } // TODO(): or OOM at recursive call
        } else {
          // Unknown SSI tag
          MG_ERROR(("Unknown SSI tag: %.*s", (int) len, buf));
          if (len > 0 && mg_iobuf_add(&b, b.len, buf, len) == 0) goto fail;
        }
        intag = 0;
        len = 0;
      } else if (ch == '<') {
        intag = 1;
        if (len > 0 && mg_iobuf_add(&b, b.len, buf, len) == 0) goto fail;
        len = 0;
        buf[len++] = (char) (ch & 0xff);
      } else if (intag) {
        if (len == 5 && strncmp(buf, "<!--#", 5) != 0) {
          intag = 0;
        } else if (len >= sizeof(buf) - 2) {
          MG_ERROR(("%s: SSI tag is too large", path));
          len = 0;
        }
        buf[len++] = (char) (ch & 0xff);
      } else {
        buf[len++] = (char) (ch & 0xff);
        if (len >= sizeof(buf)) {
          if (mg_iobuf_add(&b, b.len, buf, len) == 0) goto fail;
          len = 0;
        }
      }
    }
    if (len > 0 && mg_iobuf_add(&b, b.len, buf, len) == 0) goto fail;
    if (b.len > 0 && mg_iobuf_add(&b, b.len, "", 1) == 0)  // nul-terminate
      goto fail;
    fclose(fp);
  }
  (void) depth;
  (void) root;
  return (char *) b.buf;

fail:
  fclose(fp);
  return NULL;
}

void mg_http_serve_ssi(struct mg_connection *c, const char *root,
                       const char *fullpath) {
  const char *headers = "Content-Type: text/html; charset=utf-8\r\n";
  char *data = mg_ssi(fullpath, root, 0);
  if (data == NULL) {
    mg_error(c, "OOM");
    return;
  }
  mg_http_reply(c, 200, headers, "%s", data == NULL ? "" : data);
  mg_free(data);
}
#else
void mg_http_serve_ssi(struct mg_connection *c, const char *root,
                       const char *fullpath) {
  mg_http_reply(c, 501, NULL, "SSI not enabled");
  (void) root, (void) fullpath;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/str.c"
#endif



struct mg_str mg_str_s(const char *s) {
  struct mg_str str;
  str.buf = (char *) s, str.len = (s == NULL) ? 0 : strlen(s);
  return str;
}

struct mg_str mg_str_n(const char *s, size_t n) {
  struct mg_str str;
  str.buf = (char *) s, str.len = n;
  return str;
}

static int mg_tolc(char c) {
  return (c >= 'A' && c <= 'Z') ? c + 'a' - 'A' : c;
}

int mg_casecmp(const char *s1, const char *s2) {
  int diff = 0;
  do {
    int c = mg_tolc(*s1++), d = mg_tolc(*s2++);
    diff = c - d;
  } while (diff == 0 && s1[-1] != '\0');
  return diff;
}

struct mg_str mg_strdup(const struct mg_str s) {
  struct mg_str r = {NULL, 0};
  if (s.len > 0 && s.buf != NULL) {
    char *sc = (char *) mg_calloc(1, s.len + 1);
    if (sc != NULL) {
      memcpy(sc, s.buf, s.len);
      sc[s.len] = '\0';
      r.buf = sc;
      r.len = s.len;
    }
  }
  return r;
}

int mg_strcmp(const struct mg_str str1, const struct mg_str str2) {
  size_t i = 0;
  while (i < str1.len && i < str2.len) {
    int c1 = str1.buf[i];
    int c2 = str2.buf[i];
    if (c1 < c2) return -1;
    if (c1 > c2) return 1;
    i++;
  }
  if (i < str1.len) return 1;
  if (i < str2.len) return -1;
  return 0;
}

int mg_strcasecmp(const struct mg_str str1, const struct mg_str str2) {
  size_t i = 0;
  while (i < str1.len && i < str2.len) {
    int c1 = mg_tolc(str1.buf[i]);
    int c2 = mg_tolc(str2.buf[i]);
    if (c1 < c2) return -1;
    if (c1 > c2) return 1;
    i++;
  }
  if (i < str1.len) return 1;
  if (i < str2.len) return -1;
  return 0;
}

bool mg_match(struct mg_str s, struct mg_str p, struct mg_str *caps) {
  size_t i = 0, j = 0, ni = 0, nj = 0;
  if (caps) caps->buf = NULL, caps->len = 0;
  while (i < p.len || j < s.len) {
    if (i < p.len && j < s.len &&
        (p.buf[i] == '?' ||
         (p.buf[i] != '*' && p.buf[i] != '#' && s.buf[j] == p.buf[i]))) {
      if (caps == NULL) {
      } else if (p.buf[i] == '?') {
        caps->buf = &s.buf[j], caps->len = 1;     // Finalize `?` cap
        caps++, caps->buf = NULL, caps->len = 0;  // Init next cap
      } else if (caps->buf != NULL && caps->len == 0) {
        caps->len = (size_t) (&s.buf[j] - caps->buf);  // Finalize current cap
        caps++, caps->len = 0, caps->buf = NULL;       // Init next cap
      }
      i++, j++;
    } else if (i < p.len && (p.buf[i] == '*' || p.buf[i] == '#')) {
      if (caps && !caps->buf) caps->len = 0, caps->buf = &s.buf[j];  // Init cap
      ni = i++, nj = j + 1;
    } else if (nj > 0 && nj <= s.len &&
               ((ni < p.len && p.buf[ni] == '#') ||
                (j < s.len && s.buf[j] != '/'))) {
      i = ni, j = nj;
      if (caps && caps->buf == NULL && caps->len == 0) {
        caps--, caps->len = 0;  // Restart previous cap
      }
    } else {
      return false;
    }
  }
  if (caps && caps->buf && caps->len == 0) {
    caps->len = (size_t) (&s.buf[j] - caps->buf);
  }
  return true;
}

bool mg_span(struct mg_str s, struct mg_str *a, struct mg_str *b, char sep) {
  if (s.len == 0 || s.buf == NULL) {
    return false;  // Empty string, nothing to span - fail
  } else {
    size_t len = 0;
    while (len < s.len && s.buf[len] != sep) len++;  // Find separator
    if (a) *a = mg_str_n(s.buf, len);                // Init a
    if (b) *b = mg_str_n(s.buf + len, s.len - len);  // Init b
    if (b && len < s.len) b->buf++, b->len--;        // Skip separator
    return true;
  }
}

bool mg_str_to_num(struct mg_str str, int base, void *val, size_t val_len) {
  size_t i = 0, ndigits = 0;
  uint64_t max = val_len == sizeof(uint8_t)    ? 0xFF
                 : val_len == sizeof(uint16_t) ? 0xFFFF
                 : val_len == sizeof(uint32_t) ? 0xFFFFFFFF
                                               : (uint64_t) ~0;
  uint64_t result = 0;
  if (max == (uint64_t) ~0 && val_len != sizeof(uint64_t)) return false;
  if (base == 0 && str.len >= 2) {
    if (str.buf[i] == '0') {
      i++;
      base = str.buf[i] == 'b' ? 2 : str.buf[i] == 'x' ? 16 : 10;
      if (base != 10) ++i;
    } else {
      base = 10;
    }
  }
  switch (base) {
    case 2:
      while (i < str.len && (str.buf[i] == '0' || str.buf[i] == '1')) {
        uint64_t digit = (uint64_t) (str.buf[i] - '0');
        if (result > max / 2) return false;  // Overflow
        result *= 2;
        if (result > max - digit) return false;  // Overflow
        result += digit;
        i++, ndigits++;
      }
      break;
    case 10:
      while (i < str.len && str.buf[i] >= '0' && str.buf[i] <= '9') {
        uint64_t digit = (uint64_t) (str.buf[i] - '0');
        if (result > max / 10) return false;  // Overflow
        result *= 10;
        if (result > max - digit) return false;  // Overflow
        result += digit;
        i++, ndigits++;
      }
      break;
    case 16:
      while (i < str.len) {
        char c = str.buf[i];
        uint64_t digit = (c >= '0' && c <= '9')   ? (uint64_t) (c - '0')
                         : (c >= 'A' && c <= 'F') ? (uint64_t) (c - '7')
                         : (c >= 'a' && c <= 'f') ? (uint64_t) (c - 'W')
                                                  : (uint64_t) ~0;
        if (digit == (uint64_t) ~0) break;
        if (result > max / 16) return false;  // Overflow
        result *= 16;
        if (result > max - digit) return false;  // Overflow
        result += digit;
        i++, ndigits++;
      }
      break;
    default: return false;
  }
  if (ndigits == 0) return false;
  if (i != str.len) return false;
  if (val_len == 1) {
    *((uint8_t *) val) = (uint8_t) result;
  } else if (val_len == 2) {
    *((uint16_t *) val) = (uint16_t) result;
  } else if (val_len == 4) {
    *((uint32_t *) val) = (uint32_t) result;
  } else {
    *((uint64_t *) val) = (uint64_t) result;
  }
  return true;
}

#ifdef MG_ENABLE_LINES
#line 1 "src/timer.c"
#endif




void mg_timer_init(struct mg_timer **head, struct mg_timer *t, uint64_t ms,
                   unsigned flags, void (*fn)(void *), void *arg) {
  t->period_ms = ms, t->expire = 0;
  t->flags = flags, t->fn = fn, t->arg = arg, t->next = *head;
  *head = t;
}

void mg_timer_free(struct mg_timer **head, struct mg_timer *t) {
  while (*head && *head != t) head = &(*head)->next;
  if (*head) *head = t->next;
}

// t: expiration time, prd: period, now: current time. Return true if expired
bool mg_timer_expired(uint64_t *t, uint64_t prd, uint64_t now) {
  if (now + prd < *t) *t = 0;                    // Time wrapped? Reset timer
  if (*t == 0) *t = now + prd;                   // Firt poll? Set expiration
  if (*t > now) return false;                    // Not expired yet, return
  *t = (now - *t) > prd ? now + prd : *t + prd;  // Next expiration time
  return true;                                   // Expired, return true
}

void mg_timer_poll(struct mg_timer **head, uint64_t now_ms) {
  struct mg_timer *t, *tmp;
  for (t = *head; t != NULL; t = tmp) {
    bool once = t->expire == 0 && (t->flags & MG_TIMER_RUN_NOW) &&
                !(t->flags & MG_TIMER_CALLED);  // Handle MG_TIMER_NOW only once
    bool expired = mg_timer_expired(&t->expire, t->period_ms, now_ms);
    tmp = t->next;
    if (!once && !expired) continue;
    if ((t->flags & MG_TIMER_REPEAT) || !(t->flags & MG_TIMER_CALLED)) {
      t->fn(t->arg);
    }
    t->flags |= MG_TIMER_CALLED;

    // If this timer is not repeating and marked AUTODELETE, remove it
    if (!(t->flags & MG_TIMER_REPEAT) && (t->flags & MG_TIMER_AUTODELETE)) {
      mg_timer_free(head, t);
      mg_free(t);
    }
  }
}

#ifdef MG_ENABLE_LINES
#line 1 "src/tls_aes128.c"
#endif
/******************************************************************************
 *
 * THIS SOURCE CODE IS HEREBY PLACED INTO THE PUBLIC DOMAIN FOR THE GOOD OF ALL
 *
 * This is a simple and straightforward implementation of the AES Rijndael
 * 128-bit block cipher designed by Vincent Rijmen and Joan Daemen. The focus
 * of this work was correctness & accuracy.  It is written in 'C' without any
 * particular focus upon optimization or speed. It should be endian (memory
 * byte order) neutral since the few places that care are handled explicitly.
 *
 * This implementation of Rijndael was created by Steven M. Gibson of GRC.com.
 *
 * It is intended for general purpose use, but was written in support of GRC's
 * reference implementation of the SQRL (Secure Quick Reliable Login) client.
 *
 * See:    http://csrc.nist.gov/archive/aes/rijndael/wsdindex.html
 *
 * NO COPYRIGHT IS CLAIMED IN THIS WORK, HOWEVER, NEITHER IS ANY WARRANTY MADE
 * REGARDING ITS FITNESS FOR ANY PARTICULAR PURPOSE. USE IT AT YOUR OWN RISK.
 *
 *******************************************************************************/



#if MG_TLS == MG_TLS_BUILTIN
/******************************************************************************/
#define AES_DECRYPTION 1  // whether AES decryption is supported
/******************************************************************************/

#define MG_ENCRYPT 1  // specify whether we're encrypting
#define MG_DECRYPT 0  // or decrypting



/******************************************************************************
 *  AES_INIT_KEYGEN_TABLES : MUST be called once before any AES use
 ******************************************************************************/
static void aes_init_keygen_tables(void);

/******************************************************************************
 *  AES_SETKEY : called to expand the key for encryption or decryption
 ******************************************************************************/
static int aes_setkey(
    aes_context *ctx,          // pointer to context
    int mode,                  // 1 or 0 for Encrypt/Decrypt
    const unsigned char *key,  // AES input key
    unsigned int keysize);     // size in bytes (must be 16, 24, 32 for
                               // 128, 192 or 256-bit keys respectively)
                               // returns 0 for success

/******************************************************************************
 *  AES_CIPHER : called to encrypt or decrypt ONE 128-bit block of data
 ******************************************************************************/
static int aes_cipher(
    aes_context *ctx,               // pointer to context
    const unsigned char input[16],  // 128-bit block to en/decipher
    unsigned char output[16]);      // 128-bit output result block
                                    // returns 0 for success

/******************************************************************************
 *  GCM_CONTEXT : GCM context / holds keytables, instance data, and AES ctx
 ******************************************************************************/
typedef struct {
  int mode;                     // cipher direction: encrypt/decrypt
  uint64_t len;                 // cipher data length processed so far
  uint64_t add_len;             // total add data length
  uint64_t HL[16];              // precalculated lo-half HTable
  uint64_t HH[16];              // precalculated hi-half HTable
  unsigned char base_ectr[16];  // first counter-mode cipher output for tag
  unsigned char y[16];          // the current cipher-input IV|Counter value
  unsigned char buf[16];        // buf working value
  aes_context aes_ctx;          // cipher context used
} gcm_context;

/******************************************************************************
 *  GCM_SETKEY : sets the GCM (and AES) keying material for use
 ******************************************************************************/
static int gcm_setkey(
    gcm_context *ctx,           // caller-provided context ptr
    const unsigned char *key,   // pointer to cipher key
    const unsigned int keysize  // size in bytes (must be 16, 24, 32 for
                                // 128, 192 or 256-bit keys respectively)
);                              // returns 0 for success

/******************************************************************************
 *
 *  GCM_CRYPT_AND_TAG
 *
 *  This either encrypts or decrypts the user-provided data and, either
 *  way, generates an authentication tag of the requested length. It must be
 *  called with a GCM context whose key has already been set with GCM_SETKEY.
 *
 *  The user would typically call this explicitly to ENCRYPT a buffer of data
 *  and optional associated data, and produce its an authentication tag.
 *
 *  To reverse the process the user would typically call the companion
 *  GCM_AUTH_DECRYPT function to decrypt data and verify a user-provided
 *  authentication tag.  The GCM_AUTH_DECRYPT function calls this function
 *  to perform its decryption and tag generation, which it then compares.
 *
 ******************************************************************************/
static int gcm_crypt_and_tag(
    gcm_context *ctx,  // gcm context with key already setup
    int mode,          // cipher direction: MG_ENCRYPT (1) or MG_DECRYPT (0)
    const unsigned char *iv,     // pointer to the 12-byte initialization vector
    size_t iv_len,               // byte length if the IV. should always be 12
    const unsigned char *add,    // pointer to the non-ciphered additional data
    size_t add_len,              // byte length of the additional AEAD data
    const unsigned char *input,  // pointer to the cipher data source
    unsigned char *output,       // pointer to the cipher data destination
    size_t length,               // byte length of the cipher data
    unsigned char *tag,          // pointer to the tag to be generated
    size_t tag_len);             // byte length of the tag to be generated

/******************************************************************************
 *
 *  GCM_START
 *
 *  Given a user-provided GCM context, this initializes it, sets the encryption
 *  mode, and preprocesses the initialization vector and additional AEAD data.
 *
 ******************************************************************************/
static int gcm_start(
    gcm_context *ctx,          // pointer to user-provided GCM context
    int mode,                  // MG_ENCRYPT (1) or MG_DECRYPT (0)
    const unsigned char *iv,   // pointer to initialization vector
    size_t iv_len,             // IV length in bytes (should == 12)
    const unsigned char *add,  // pointer to additional AEAD data (NULL if none)
    size_t add_len);           // length of additional AEAD data (bytes)

/******************************************************************************
 *
 *  GCM_UPDATE
 *
 *  This is called once or more to process bulk plaintext or ciphertext data.
 *  We give this some number of bytes of input and it returns the same number
 *  of output bytes. If called multiple times (which is fine) all but the final
 *  invocation MUST be called with length mod 16 == 0. (Only the final call can
 *  have a partial block length of < 128 bits.)
 *
 ******************************************************************************/
static int gcm_update(gcm_context *ctx,  // pointer to user-provided GCM context
                      size_t length,     // length, in bytes, of data to process
                      const unsigned char *input,  // pointer to source data
                      unsigned char *output);  // pointer to destination data

/******************************************************************************
 *
 *  GCM_FINISH
 *
 *  This is called once after all calls to GCM_UPDATE to finalize the GCM.
 *  It performs the final GHASH to produce the resulting authentication TAG.
 *
 ******************************************************************************/
static int gcm_finish(
    gcm_context *ctx,    // pointer to user-provided GCM context
    unsigned char *tag,  // ptr to tag buffer - NULL if tag_len = 0
    size_t tag_len);     // length, in bytes, of the tag-receiving buf

/******************************************************************************
 *
 *  GCM_ZERO_CTX
 *
 *  The GCM context contains both the GCM context and the AES context.
 *  This includes keying and key-related material which is security-
 *  sensitive, so it MUST be zeroed after use. This function does that.
 *
 ******************************************************************************/
static void gcm_zero_ctx(gcm_context *ctx);

/******************************************************************************
 *
 * THIS SOURCE CODE IS HEREBY PLACED INTO THE PUBLIC DOMAIN FOR THE GOOD OF ALL
 *
 * This is a simple and straightforward implementation of the AES Rijndael
 * 128-bit block cipher designed by Vincent Rijmen and Joan Daemen. The focus
 * of this work was correctness & accuracy.  It is written in 'C' without any
 * particular focus upon optimization or speed. It should be endian (memory
 * byte order) neutral since the few places that care are handled explicitly.
 *
 * This implementation of Rijndael was created by Steven M. Gibson of GRC.com.
 *
 * It is intended for general purpose use, but was written in support of GRC's
 * reference implementation of the SQRL (Secure Quick Reliable Login) client.
 *
 * See:    http://csrc.nist.gov/archive/aes/rijndael/wsdindex.html
 *
 * NO COPYRIGHT IS CLAIMED IN THIS WORK, HOWEVER, NEITHER IS ANY WARRANTY MADE
 * REGARDING ITS FITNESS FOR ANY PARTICULAR PURPOSE. USE IT AT YOUR OWN RISK.
 *
 *******************************************************************************/

static int aes_tables_inited = 0;  // run-once flag for performing key
                                   // expasion table generation (see below)
/*
 *  The following static local tables must be filled-in before the first use of
 *  the GCM or AES ciphers. They are used for the AES key expansion/scheduling
 *  and once built are read-only and thread safe. The "gcm_initialize" function
 *  must be called once during system initialization to populate these arrays
 *  for subsequent use by the AES key scheduler. If they have not been built
 *  before attempted use, an error will be returned to the caller.
 *
 *  NOTE: GCM Encryption/Decryption does NOT REQUIRE AES decryption. Since
 *  GCM uses AES in counter-mode, where the AES cipher output is XORed with
 *  the GCM input, we ONLY NEED AES encryption.  Thus, to save space AES
 *  decryption is typically disabled by setting AES_DECRYPTION to 0 in aes.h.
 */
// We always need our forward tables
static unsigned char FSb[256];  // Forward substitution box (FSb)
static uint32_t FT0[256];       // Forward key schedule assembly tables
static uint32_t FT1[256];
static uint32_t FT2[256];
static uint32_t FT3[256];

#if AES_DECRYPTION              // We ONLY need reverse for decryption
static unsigned char RSb[256];  // Reverse substitution box (RSb)
static uint32_t RT0[256];       // Reverse key schedule assembly tables
static uint32_t RT1[256];
static uint32_t RT2[256];
static uint32_t RT3[256];
#endif /* AES_DECRYPTION */

static uint32_t RCON[10];  // AES round constants

/*
 * Platform Endianness Neutralizing Load and Store Macro definitions
 * AES wants platform-neutral Little Endian (LE) byte ordering
 */
#define GET_UINT32_LE(n, b, i)                                               \
  {                                                                          \
    (n) = ((uint32_t) (b)[(i)]) | ((uint32_t) (b)[(i) + 1] << 8) |           \
          ((uint32_t) (b)[(i) + 2] << 16) | ((uint32_t) (b)[(i) + 3] << 24); \
  }

#define PUT_UINT32_LE(n, b, i)                  \
  {                                             \
    (b)[(i)] = (unsigned char) ((n));           \
    (b)[(i) + 1] = (unsigned char) ((n) >> 8);  \
    (b)[(i) + 2] = (unsigned char) ((n) >> 16); \
    (b)[(i) + 3] = (unsigned char) ((n) >> 24); \
  }

/*
 *  AES forward and reverse encryption round processing macros
 */
#define AES_FROUND(X0, X1, X2, X3, Y0, Y1, Y2, Y3)          \
  {                                                         \
    X0 = *RK++ ^ FT0[(Y0) & 0xFF] ^ FT1[(Y1 >> 8) & 0xFF] ^ \
         FT2[(Y2 >> 16) & 0xFF] ^ FT3[(Y3 >> 24) & 0xFF];   \
                                                            \
    X1 = *RK++ ^ FT0[(Y1) & 0xFF] ^ FT1[(Y2 >> 8) & 0xFF] ^ \
         FT2[(Y3 >> 16) & 0xFF] ^ FT3[(Y0 >> 24) & 0xFF];   \
                                                            \
    X2 = *RK++ ^ FT0[(Y2) & 0xFF] ^ FT1[(Y3 >> 8) & 0xFF] ^ \
         FT2[(Y0 >> 16) & 0xFF] ^ FT3[(Y1 >> 24) & 0xFF];   \
                                                            \
    X3 = *RK++ ^ FT0[(Y3) & 0xFF] ^ FT1[(Y0 >> 8) & 0xFF] ^ \
         FT2[(Y1 >> 16) & 0xFF] ^ FT3[(Y2 >> 24) & 0xFF];   \
  }

#define AES_RROUND(X0, X1, X2, X3, Y0, Y1, Y2, Y3)          \
  {                                                         \
    X0 = *RK++ ^ RT0[(Y0) & 0xFF] ^ RT1[(Y3 >> 8) & 0xFF] ^ \
         RT2[(Y2 >> 16) & 0xFF] ^ RT3[(Y1 >> 24) & 0xFF];   \
                                                            \
    X1 = *RK++ ^ RT0[(Y1) & 0xFF] ^ RT1[(Y0 >> 8) & 0xFF] ^ \
         RT2[(Y3 >> 16) & 0xFF] ^ RT3[(Y2 >> 24) & 0xFF];   \
                                                            \
    X2 = *RK++ ^ RT0[(Y2) & 0xFF] ^ RT1[(Y1 >> 8) & 0xFF] ^ \
         RT2[(Y0 >> 16) & 0xFF] ^ RT3[(Y3 >> 24) & 0xFF];   \
                                                            \
    X3 = *RK++ ^ RT0[(Y3) & 0xFF] ^ RT1[(Y2 >> 8) & 0xFF] ^ \
         RT2[(Y1 >> 16) & 0xFF] ^ RT3[(Y0 >> 24) & 0xFF];   \
  }

/*
 *  These macros improve the readability of the key
 *  generation initialization code by collapsing
 *  repetitive common operations into logical pieces.
 */
#define ROTL8(x) ((x << 8) & 0xFFFFFFFF) | (x >> 24)
#define XTIME(x) ((x << 1) ^ ((x & 0x80) ? 0x1B : 0x00))
#define MUL(x, y) ((x && y) ? pow[(log[x] + log[y]) % 255] : 0)
#define MIX(x, y)                     \
  {                                   \
    y = ((y << 1) | (y >> 7)) & 0xFF; \
    x ^= y;                           \
  }
#define CPY128     \
  {                \
    *RK++ = *SK++; \
    *RK++ = *SK++; \
    *RK++ = *SK++; \
    *RK++ = *SK++; \
  }

/******************************************************************************
 *
 *  AES_INIT_KEYGEN_TABLES
 *
 *  Fills the AES key expansion tables allocated above with their static
 *  data. This is not "per key" data, but static system-wide read-only
 *  table data. THIS FUNCTION IS NOT THREAD SAFE. It must be called once
 *  at system initialization to setup the tables for all subsequent use.
 *
 ******************************************************************************/
void aes_init_keygen_tables(void) {
  int i, x, y, z;  // general purpose iteration and computation locals
  int pow[256];
  int log[256];

  if (aes_tables_inited) return;

  // fill the 'pow' and 'log' tables over GF(2^8)
  for (i = 0, x = 1; i < 256; i++) {
    pow[i] = x;
    log[x] = i;
    x = (x ^ XTIME(x)) & 0xFF;
  }
  // compute the round constants
  for (i = 0, x = 1; i < 10; i++) {
    RCON[i] = (uint32_t) x;
    x = XTIME(x) & 0xFF;
  }
  // fill the forward and reverse substitution boxes
  FSb[0x00] = 0x63;
#if AES_DECRYPTION  // whether AES decryption is supported
  RSb[0x63] = 0x00;
#endif /* AES_DECRYPTION */

  for (i = 1; i < 256; i++) {
    x = y = pow[255 - log[i]];
    MIX(x, y);
    MIX(x, y);
    MIX(x, y);
    MIX(x, y);
    FSb[i] = (unsigned char) (x ^= 0x63);
#if AES_DECRYPTION  // whether AES decryption is supported
    RSb[x] = (unsigned char) i;
#endif /* AES_DECRYPTION */
  }
  // generate the forward and reverse key expansion tables
  for (i = 0; i < 256; i++) {
    x = FSb[i];
    y = XTIME(x) & 0xFF;
    z = (y ^ x) & 0xFF;

    FT0[i] = ((uint32_t) y) ^ ((uint32_t) x << 8) ^ ((uint32_t) x << 16) ^
             ((uint32_t) z << 24);

    FT1[i] = ROTL8(FT0[i]);
    FT2[i] = ROTL8(FT1[i]);
    FT3[i] = ROTL8(FT2[i]);

#if AES_DECRYPTION  // whether AES decryption is supported
    x = RSb[i];

    RT0[i] = ((uint32_t) MUL(0x0E, x)) ^ ((uint32_t) MUL(0x09, x) << 8) ^
             ((uint32_t) MUL(0x0D, x) << 16) ^ ((uint32_t) MUL(0x0B, x) << 24);

    RT1[i] = ROTL8(RT0[i]);
    RT2[i] = ROTL8(RT1[i]);
    RT3[i] = ROTL8(RT2[i]);
#endif /* AES_DECRYPTION */
  }
  aes_tables_inited = 1;  // flag that the tables have been generated
}  // to permit subsequent use of the AES cipher

/******************************************************************************
 *
 *  AES_SET_ENCRYPTION_KEY
 *
 *  This is called by 'aes_setkey' when we're establishing a key for
 *  subsequent encryption.  We give it a pointer to the encryption
 *  context, a pointer to the key, and the key's length in bytes.
 *  Valid lengths are: 16, 24 or 32 bytes (128, 192, 256 bits).
 *
 ******************************************************************************/
static int aes_set_encryption_key(aes_context *ctx, const unsigned char *key,
                                  unsigned int keysize) {
  unsigned int i;          // general purpose iteration local
  uint32_t *RK = ctx->rk;  // initialize our RoundKey buffer pointer

  for (i = 0; i < (keysize >> 2); i++) {
    GET_UINT32_LE(RK[i], key, i << 2);
  }

  switch (ctx->rounds) {
    case 10:
      for (i = 0; i < 10; i++, RK += 4) {
        RK[4] = RK[0] ^ RCON[i] ^ ((uint32_t) FSb[(RK[3] >> 8) & 0xFF]) ^
                ((uint32_t) FSb[(RK[3] >> 16) & 0xFF] << 8) ^
                ((uint32_t) FSb[(RK[3] >> 24) & 0xFF] << 16) ^
                ((uint32_t) FSb[(RK[3]) & 0xFF] << 24);

        RK[5] = RK[1] ^ RK[4];
        RK[6] = RK[2] ^ RK[5];
        RK[7] = RK[3] ^ RK[6];
      }
      break;

    case 12:
      for (i = 0; i < 8; i++, RK += 6) {
        RK[6] = RK[0] ^ RCON[i] ^ ((uint32_t) FSb[(RK[5] >> 8) & 0xFF]) ^
                ((uint32_t) FSb[(RK[5] >> 16) & 0xFF] << 8) ^
                ((uint32_t) FSb[(RK[5] >> 24) & 0xFF] << 16) ^
                ((uint32_t) FSb[(RK[5]) & 0xFF] << 24);

        RK[7] = RK[1] ^ RK[6];
        RK[8] = RK[2] ^ RK[7];
        RK[9] = RK[3] ^ RK[8];
        RK[10] = RK[4] ^ RK[9];
        RK[11] = RK[5] ^ RK[10];
      }
      break;

    case 14:
      for (i = 0; i < 7; i++, RK += 8) {
        RK[8] = RK[0] ^ RCON[i] ^ ((uint32_t) FSb[(RK[7] >> 8) & 0xFF]) ^
                ((uint32_t) FSb[(RK[7] >> 16) & 0xFF] << 8) ^
                ((uint32_t) FSb[(RK[7] >> 24) & 0xFF] << 16) ^
                ((uint32_t) FSb[(RK[7]) & 0xFF] << 24);

        RK[9] = RK[1] ^ RK[8];
        RK[10] = RK[2] ^ RK[9];
        RK[11] = RK[3] ^ RK[10];

        RK[12] = RK[4] ^ ((uint32_t) FSb[(RK[11]) & 0xFF]) ^
                 ((uint32_t) FSb[(RK[11] >> 8) & 0xFF] << 8) ^
                 ((uint32_t) FSb[(RK[11] >> 16) & 0xFF] << 16) ^
                 ((uint32_t) FSb[(RK[11] >> 24) & 0xFF] << 24);

        RK[13] = RK[5] ^ RK[12];
        RK[14] = RK[6] ^ RK[13];
        RK[15] = RK[7] ^ RK[14];
      }
      break;

    default:
      return -1;
  }
  return (0);
}

#if AES_DECRYPTION  // whether AES decryption is supported

/******************************************************************************
 *
 *  AES_SET_DECRYPTION_KEY
 *
 *  This is called by 'aes_setkey' when we're establishing a
 *  key for subsequent decryption.  We give it a pointer to
 *  the encryption context, a pointer to the key, and the key's
 *  length in bits. Valid lengths are: 128, 192, or 256 bits.
 *
 ******************************************************************************/
static int aes_set_decryption_key(aes_context *ctx, const unsigned char *key,
                                  unsigned int keysize) {
  int i, j;
  aes_context cty;         // a calling aes context for set_encryption_key
  uint32_t *RK = ctx->rk;  // initialize our RoundKey buffer pointer
  uint32_t *SK;
  int ret;

  cty.rounds = ctx->rounds;  // initialize our local aes context
  cty.rk = cty.buf;          // round count and key buf pointer

  if ((ret = aes_set_encryption_key(&cty, key, keysize)) != 0) return (ret);

  SK = cty.rk + cty.rounds * 4;

  CPY128  // copy a 128-bit block from *SK to *RK

      for (i = ctx->rounds - 1, SK -= 8; i > 0; i--, SK -= 8) {
    for (j = 0; j < 4; j++, SK++) {
      *RK++ = RT0[FSb[(*SK) & 0xFF]] ^ RT1[FSb[(*SK >> 8) & 0xFF]] ^
              RT2[FSb[(*SK >> 16) & 0xFF]] ^ RT3[FSb[(*SK >> 24) & 0xFF]];
    }
  }
  CPY128  // copy a 128-bit block from *SK to *RK
      memset(&cty, 0, sizeof(aes_context));  // clear local aes context
  return (0);
}

#endif /* AES_DECRYPTION */

/******************************************************************************
 *
 *  AES_SETKEY
 *
 *  Invoked to establish the key schedule for subsequent encryption/decryption
 *
 ******************************************************************************/
static int aes_setkey(aes_context *ctx,  // AES context provided by our caller
                      int mode,          // ENCRYPT or DECRYPT flag
                      const unsigned char *key,  // pointer to the key
                      unsigned int keysize)      // key length in bytes
{
  // since table initialization is not thread safe, we could either add
  // system-specific mutexes and init the AES key generation tables on
  // demand, or ask the developer to simply call "gcm_initialize" once during
  // application startup before threading begins. That's what we choose.
  if (!aes_tables_inited) return (-1);  // fail the call when not inited.

  ctx->mode = mode;    // capture the key type we're creating
  ctx->rk = ctx->buf;  // initialize our round key pointer

  switch (keysize)  // set the rounds count based upon the keysize
  {
    case 16:
      ctx->rounds = 10;
      break;  // 16-byte, 128-bit key
    case 24:
      ctx->rounds = 12;
      break;  // 24-byte, 192-bit key
    case 32:
      ctx->rounds = 14;
      break;  // 32-byte, 256-bit key
    default:
      return (-1);
  }

#if AES_DECRYPTION
  if (mode == MG_DECRYPT)  // expand our key for encryption or decryption
    return (aes_set_decryption_key(ctx, key, keysize));
  else /* MG_ENCRYPT */
#endif /* AES_DECRYPTION */
    return (aes_set_encryption_key(ctx, key, keysize));
}

/******************************************************************************
 *
 *  AES_CIPHER
 *
 *  Perform AES encryption and decryption.
 *  The AES context will have been setup with the encryption mode
 *  and all keying information appropriate for the task.
 *
 ******************************************************************************/
static int aes_cipher(aes_context *ctx, const unsigned char input[16],
                      unsigned char output[16]) {
  int i;
  uint32_t *RK, X0, X1, X2, X3, Y0, Y1, Y2, Y3;  // general purpose locals

  RK = ctx->rk;

  GET_UINT32_LE(X0, input, 0);
  X0 ^= *RK++;  // load our 128-bit
  GET_UINT32_LE(X1, input, 4);
  X1 ^= *RK++;  // input buffer in a storage
  GET_UINT32_LE(X2, input, 8);
  X2 ^= *RK++;  // memory endian-neutral way
  GET_UINT32_LE(X3, input, 12);
  X3 ^= *RK++;

#if AES_DECRYPTION  // whether AES decryption is supported

  if (ctx->mode == MG_DECRYPT) {
    for (i = (ctx->rounds >> 1) - 1; i > 0; i--) {
      AES_RROUND(Y0, Y1, Y2, Y3, X0, X1, X2, X3);
      AES_RROUND(X0, X1, X2, X3, Y0, Y1, Y2, Y3);
    }

    AES_RROUND(Y0, Y1, Y2, Y3, X0, X1, X2, X3);

    X0 = *RK++ ^ ((uint32_t) RSb[(Y0) & 0xFF]) ^
         ((uint32_t) RSb[(Y3 >> 8) & 0xFF] << 8) ^
         ((uint32_t) RSb[(Y2 >> 16) & 0xFF] << 16) ^
         ((uint32_t) RSb[(Y1 >> 24) & 0xFF] << 24);

    X1 = *RK++ ^ ((uint32_t) RSb[(Y1) & 0xFF]) ^
         ((uint32_t) RSb[(Y0 >> 8) & 0xFF] << 8) ^
         ((uint32_t) RSb[(Y3 >> 16) & 0xFF] << 16) ^
         ((uint32_t) RSb[(Y2 >> 24) & 0xFF] << 24);

    X2 = *RK++ ^ ((uint32_t) RSb[(Y2) & 0xFF]) ^
         ((uint32_t) RSb[(Y1 >> 8) & 0xFF] << 8) ^
         ((uint32_t) RSb[(Y0 >> 16) & 0xFF] << 16) ^
         ((uint32_t) RSb[(Y3 >> 24) & 0xFF] << 24);

    X3 = *RK++ ^ ((uint32_t) RSb[(Y3) & 0xFF]) ^
         ((uint32_t) RSb[(Y2 >> 8) & 0xFF] << 8) ^
         ((uint32_t) RSb[(Y1 >> 16) & 0xFF] << 16) ^
         ((uint32_t) RSb[(Y0 >> 24) & 0xFF] << 24);
  } else /* MG_ENCRYPT */
  {
#endif /* AES_DECRYPTION */

    for (i = (ctx->rounds >> 1) - 1; i > 0; i--) {
      AES_FROUND(Y0, Y1, Y2, Y3, X0, X1, X2, X3);
      AES_FROUND(X0, X1, X2, X3, Y0, Y1, Y2, Y3);
    }

    AES_FROUND(Y0, Y1, Y2, Y3, X0, X1, X2, X3);

    X0 = *RK++ ^ ((uint32_t) FSb[(Y0) & 0xFF]) ^
         ((uint32_t) FSb[(Y1 >> 8) & 0xFF] << 8) ^
         ((uint32_t) FSb[(Y2 >> 16) & 0xFF] << 16) ^
         ((uint32_t) FSb[(Y3 >> 24) & 0xFF] << 24);

    X1 = *RK++ ^ ((uint32_t) FSb[(Y1) & 0xFF]) ^
         ((uint32_t) FSb[(Y2 >> 8) & 0xFF] << 8) ^
         ((uint32_t) FSb[(Y3 >> 16) & 0xFF] << 16) ^
         ((uint32_t) FSb[(Y0 >> 24) & 0xFF] << 24);

    X2 = *RK++ ^ ((uint32_t) FSb[(Y2) & 0xFF]) ^
         ((uint32_t) FSb[(Y3 >> 8) & 0xFF] << 8) ^
         ((uint32_t) FSb[(Y0 >> 16) & 0xFF] << 16) ^
         ((uint32_t) FSb[(Y1 >> 24) & 0xFF] << 24);

    X3 = *RK++ ^ ((uint32_t) FSb[(Y3) & 0xFF]) ^
         ((uint32_t) FSb[(Y0 >> 8) & 0xFF] << 8) ^
         ((uint32_t) FSb[(Y1 >> 16) & 0xFF] << 16) ^
         ((uint32_t) FSb[(Y2 >> 24) & 0xFF] << 24);

#if AES_DECRYPTION  // whether AES decryption is supported
  }
#endif /* AES_DECRYPTION */

  PUT_UINT32_LE(X0, output, 0);
  PUT_UINT32_LE(X1, output, 4);
  PUT_UINT32_LE(X2, output, 8);
  PUT_UINT32_LE(X3, output, 12);

  return (0);
}
/* end of aes.c */
/******************************************************************************
 *
 * THIS SOURCE CODE IS HEREBY PLACED INTO THE PUBLIC DOMAIN FOR THE GOOD OF ALL
 *
 * This is a simple and straightforward implementation of AES-GCM authenticated
 * encryption. The focus of this work was correctness & accuracy. It is written
 * in straight 'C' without any particular focus upon optimization or speed. It
 * should be endian (memory byte order) neutral since the few places that care
 * are handled explicitly.
 *
 * This implementation of AES-GCM was created by Steven M. Gibson of GRC.com.
 *
 * It is intended for general purpose use, but was written in support of GRC's
 * reference implementation of the SQRL (Secure Quick Reliable Login) client.
 *
 * See:    http://csrc.nist.gov/publications/nistpubs/800-38D/SP-800-38D.pdf
 *         http://csrc.nist.gov/groups/ST/toolkit/BCM/documents/proposedmodes/
 *         gcm/gcm-revised-spec.pdf
 *
 * NO COPYRIGHT IS CLAIMED IN THIS WORK, HOWEVER, NEITHER IS ANY WARRANTY MADE
 * REGARDING ITS FITNESS FOR ANY PARTICULAR PURPOSE. USE IT AT YOUR OWN RISK.
 *
 *******************************************************************************/

/******************************************************************************
 *                      ==== IMPLEMENTATION WARNING ====
 *
 *  This code was developed for use within SQRL's fixed environmnent. Thus, it
 *  is somewhat less "general purpose" than it would be if it were designed as
 *  a general purpose AES-GCM library. Specifically, it bothers with almost NO
 *  error checking on parameter limits, buffer bounds, etc. It assumes that it
 *  is being invoked by its author or by someone who understands the values it
 *  expects to receive. Its behavior will be undefined otherwise.
 *
 *  All functions that might fail are defined to return 'ints' to indicate a
 *  problem. Most do not do so now. But this allows for error propagation out
 *  of internal functions if robust error checking should ever be desired.
 *
 ******************************************************************************/

/* Calculating the "GHASH"
 *
 * There are many ways of calculating the so-called GHASH in software, each with
 * a traditional size vs performance tradeoff.  The GHASH (Galois field hash) is
 * an intriguing construction which takes two 128-bit strings (also the cipher's
 * block size and the fundamental operation size for the system) and hashes them
 * into a third 128-bit result.
 *
 * Many implementation solutions have been worked out that use large precomputed
 * table lookups in place of more time consuming bit fiddling, and this approach
 * can be scaled easily upward or downward as needed to change the time/space
 * tradeoff. It's been studied extensively and there's a solid body of theory
 * and practice.  For example, without using any lookup tables an implementation
 * might obtain 119 cycles per byte throughput, whereas using a simple, though
 * large, key-specific 64 kbyte 8-bit lookup table the performance jumps to 13
 * cycles per byte.
 *
 * And Intel's processors have, since 2010, included an instruction which does
 * the entire 128x128->128 bit job in just several 64x64->128 bit pieces.
 *
 * Since SQRL is interactive, and only processing a few 128-bit blocks, I've
 * settled upon a relatively slower but appealing small-table compromise which
 * folds a bunch of not only time consuming but also bit twiddling into a simple
 * 16-entry table which is attributed to Victor Shoup's 1996 work while at
 * Bellcore: "On Fast and Provably Secure MessageAuthentication Based on
 * Universal Hashing."  See: http://www.shoup.net/papers/macs.pdf
 * See, also section 4.1 of the "gcm-revised-spec" cited above.
 */

/*
 *  This 16-entry table of pre-computed constants is used by the
 *  GHASH multiplier to improve over a strictly table-free but
 *  significantly slower 128x128 bit multiple within GF(2^128).
 */
static const uint64_t last4[16] = {
    0x0000, 0x1c20, 0x3840, 0x2460, 0x7080, 0x6ca0, 0x48c0, 0x54e0,
    0xe100, 0xfd20, 0xd940, 0xc560, 0x9180, 0x8da0, 0xa9c0, 0xb5e0};

/*
 * Platform Endianness Neutralizing Load and Store Macro definitions
 * GCM wants platform-neutral Big Endian (BE) byte ordering
 */
#define GET_UINT32_BE(n, b, i)                                            \
  {                                                                       \
    (n) = ((uint32_t) (b)[(i)] << 24) | ((uint32_t) (b)[(i) + 1] << 16) | \
          ((uint32_t) (b)[(i) + 2] << 8) | ((uint32_t) (b)[(i) + 3]);     \
  }

#define PUT_UINT32_BE(n, b, i)                  \
  {                                             \
    (b)[(i)] = (unsigned char) ((n) >> 24);     \
    (b)[(i) + 1] = (unsigned char) ((n) >> 16); \
    (b)[(i) + 2] = (unsigned char) ((n) >> 8);  \
    (b)[(i) + 3] = (unsigned char) ((n));       \
  }

/******************************************************************************
 *
 *  GCM_INITIALIZE
 *
 *  Must be called once to initialize the GCM library.
 *
 *  At present, this only calls the AES keygen table generator, which expands
 *  the AES keying tables for use. This is NOT A THREAD-SAFE function, so it
 *  MUST be called during system initialization before a multi-threading
 *  environment is running.
 *
 ******************************************************************************/
int mg_gcm_initialize(void) {
  aes_init_keygen_tables();
  return (0);
}

/******************************************************************************
 *
 *  GCM_MULT
 *
 *  Performs a GHASH operation on the 128-bit input vector 'x', setting
 *  the 128-bit output vector to 'x' times H using our precomputed tables.
 *  'x' and 'output' are seen as elements of GCM's GF(2^128) Galois field.
 *
 ******************************************************************************/
static void gcm_mult(
    gcm_context *ctx,           // pointer to established context
    const unsigned char x[16],  // pointer to 128-bit input vector
    unsigned char output[16])   // pointer to 128-bit output vector
{
  int i;
  unsigned char lo, hi, rem;
  uint64_t zh, zl;

  lo = (unsigned char) (x[15] & 0x0f);
  hi = (unsigned char) (x[15] >> 4);
  zh = ctx->HH[lo];
  zl = ctx->HL[lo];

  for (i = 15; i >= 0; i--) {
    lo = (unsigned char) (x[i] & 0x0f);
    hi = (unsigned char) (x[i] >> 4);

    if (i != 15) {
      rem = (unsigned char) (zl & 0x0f);
      zl = (zh << 60) | (zl >> 4);
      zh = (zh >> 4);
      zh ^= (uint64_t) last4[rem] << 48;
      zh ^= ctx->HH[lo];
      zl ^= ctx->HL[lo];
    }
    rem = (unsigned char) (zl & 0x0f);
    zl = (zh << 60) | (zl >> 4);
    zh = (zh >> 4);
    zh ^= (uint64_t) last4[rem] << 48;
    zh ^= ctx->HH[hi];
    zl ^= ctx->HL[hi];
  }
  PUT_UINT32_BE(zh >> 32, output, 0);
  PUT_UINT32_BE(zh, output, 4);
  PUT_UINT32_BE(zl >> 32, output, 8);
  PUT_UINT32_BE(zl, output, 12);
}

/******************************************************************************
 *
 *  GCM_SETKEY
 *
 *  This is called to set the AES-GCM key. It initializes the AES key
 *  and populates the gcm context's pre-calculated HTables.
 *
 ******************************************************************************/
static int gcm_setkey(
    gcm_context *ctx,            // pointer to caller-provided gcm context
    const unsigned char *key,    // pointer to the AES encryption key
    const unsigned int keysize)  // size in bytes (must be 16, 24, 32 for
                                 // 128, 192 or 256-bit keys respectively)
{
  int ret, i, j;
  uint64_t hi, lo;
  uint64_t vl, vh;
  unsigned char h[16];

  memset(ctx, 0, sizeof(gcm_context));  // zero caller-provided GCM context
  memset(h, 0, 16);                     // initialize the block to encrypt

  // encrypt the null 128-bit block to generate a key-based value
  // which is then used to initialize our GHASH lookup tables
  if ((ret = aes_setkey(&ctx->aes_ctx, MG_ENCRYPT, key, keysize)) != 0)
    return (ret);
  if ((ret = aes_cipher(&ctx->aes_ctx, h, h)) != 0) return (ret);

  GET_UINT32_BE(hi, h, 0);  // pack h as two 64-bit ints, big-endian
  GET_UINT32_BE(lo, h, 4);
  vh = (uint64_t) hi << 32 | lo;

  GET_UINT32_BE(hi, h, 8);
  GET_UINT32_BE(lo, h, 12);
  vl = (uint64_t) hi << 32 | lo;

  ctx->HL[8] = vl;  // 8 = 1000 corresponds to 1 in GF(2^128)
  ctx->HH[8] = vh;
  ctx->HH[0] = 0;  // 0 corresponds to 0 in GF(2^128)
  ctx->HL[0] = 0;

  for (i = 4; i > 0; i >>= 1) {
    uint32_t T = (uint32_t) (vl & 1) * 0xe1000000U;
    vl = (vh << 63) | (vl >> 1);
    vh = (vh >> 1) ^ ((uint64_t) T << 32);
    ctx->HL[i] = vl;
    ctx->HH[i] = vh;
  }
  for (i = 2; i < 16; i <<= 1) {
    uint64_t *HiL = ctx->HL + i, *HiH = ctx->HH + i;
    vh = *HiH;
    vl = *HiL;
    for (j = 1; j < i; j++) {
      HiH[j] = vh ^ ctx->HH[j];
      HiL[j] = vl ^ ctx->HL[j];
    }
  }
  return (0);
}

/******************************************************************************
 *
 *    GCM processing occurs four phases: SETKEY, START, UPDATE and FINISH.
 *
 *  SETKEY:
 *
 *   START: Sets the Encryption/Decryption mode.
 *          Accepts the initialization vector and additional data.
 *
 *  UPDATE: Encrypts or decrypts the plaintext or ciphertext.
 *
 *  FINISH: Performs a final GHASH to generate the authentication tag.
 *
 ******************************************************************************
 *
 *  GCM_START
 *
 *  Given a user-provided GCM context, this initializes it, sets the encryption
 *  mode, and preprocesses the initialization vector and additional AEAD data.
 *
 ******************************************************************************/
int gcm_start(
    gcm_context *ctx,          // pointer to user-provided GCM context
    int mode,                  // GCM_ENCRYPT or GCM_DECRYPT
    const unsigned char *iv,   // pointer to initialization vector
    size_t iv_len,             // IV length in bytes (should == 12)
    const unsigned char *add,  // ptr to additional AEAD data (NULL if none)
    size_t add_len)            // length of additional AEAD data (bytes)
{
  int ret;                     // our error return if the AES encrypt fails
  unsigned char work_buf[16];  // XOR source built from provided IV if len != 16
  const unsigned char *p;      // general purpose array pointer
  size_t use_len;              // byte count to process, up to 16 bytes
  size_t i;                    // local loop iterator

  // since the context might be reused under the same key
  // we zero the working buffers for this next new process
  memset(ctx->y, 0x00, sizeof(ctx->y));
  memset(ctx->buf, 0x00, sizeof(ctx->buf));
  ctx->len = 0;
  ctx->add_len = 0;

  ctx->mode = mode;                // set the GCM encryption/decryption mode
  ctx->aes_ctx.mode = MG_ENCRYPT;  // GCM *always* runs AES in ENCRYPTION mode

  if (iv_len == 12) {            // GCM natively uses a 12-byte, 96-bit IV
    memcpy(ctx->y, iv, iv_len);  // copy the IV to the top of the 'y' buff
    ctx->y[15] = 1;              // start "counting" from 1 (not 0)
  } else  // if we don't have a 12-byte IV, we GHASH whatever we've been given
  {
    memset(work_buf, 0x00, 16);               // clear the working buffer
    PUT_UINT32_BE(iv_len * 8, work_buf, 12);  // place the IV into buffer

    p = iv;
    while (iv_len > 0) {
      use_len = (iv_len < 16) ? iv_len : 16;
      for (i = 0; i < use_len; i++) ctx->y[i] ^= p[i];
      gcm_mult(ctx, ctx->y, ctx->y);
      iv_len -= use_len;
      p += use_len;
    }
    for (i = 0; i < 16; i++) ctx->y[i] ^= work_buf[i];
    gcm_mult(ctx, ctx->y, ctx->y);
  }
  if ((ret = aes_cipher(&ctx->aes_ctx, ctx->y, ctx->base_ectr)) != 0)
    return (ret);

  ctx->add_len = add_len;
  p = add;
  while (add_len > 0) {
    use_len = (add_len < 16) ? add_len : 16;
    for (i = 0; i < use_len; i++) ctx->buf[i] ^= p[i];
    gcm_mult(ctx, ctx->buf, ctx->buf);
    add_len -= use_len;
    p += use_len;
  }
  return (0);
}

/******************************************************************************
 *
 *  GCM_UPDATE
 *
 *  This is called once or more to process bulk plaintext or ciphertext data.
 *  We give this some number of bytes of input and it returns the same number
 *  of output bytes. If called multiple times (which is fine) all but the final
 *  invocation MUST be called with length mod 16 == 0. (Only the final call can
 *  have a partial block length of < 128 bits.)
 *
 ******************************************************************************/
int gcm_update(gcm_context *ctx,  // pointer to user-provided GCM context
               size_t length,     // length, in bytes, of data to process
               const unsigned char *input,  // pointer to source data
               unsigned char *output)       // pointer to destination data
{
  int ret;                 // our error return if the AES encrypt fails
  unsigned char ectr[16];  // counter-mode cipher output for XORing
  size_t use_len;          // byte count to process, up to 16 bytes
  size_t i;                // local loop iterator

  ctx->len += length;  // bump the GCM context's running length count

  while (length > 0) {
    // clamp the length to process at 16 bytes
    use_len = (length < 16) ? length : 16;

    // increment the context's 128-bit IV||Counter 'y' vector
    for (i = 16; i > 12; i--)
      if (++ctx->y[i - 1] != 0) break;

    // encrypt the context's 'y' vector under the established key
    if ((ret = aes_cipher(&ctx->aes_ctx, ctx->y, ectr)) != 0) return (ret);

    // encrypt or decrypt the input to the output
    if (ctx->mode == MG_ENCRYPT) {
      for (i = 0; i < use_len; i++) {
        // XOR the cipher's ouptut vector (ectr) with our input
        output[i] = (unsigned char) (ectr[i] ^ input[i]);
        // now we mix in our data into the authentication hash.
        // if we're ENcrypting we XOR in the post-XOR (output)
        // results, but if we're DEcrypting we XOR in the input
        // data
        ctx->buf[i] ^= output[i];
      }
    } else {
      for (i = 0; i < use_len; i++) {
        // but if we're DEcrypting we XOR in the input data first,
        // i.e. before saving to ouput data, otherwise if the input
        // and output buffer are the same (inplace decryption) we
        // would not get the correct auth tag

        ctx->buf[i] ^= input[i];

        // XOR the cipher's ouptut vector (ectr) with our input
        output[i] = (unsigned char) (ectr[i] ^ input[i]);
      }
    }
    gcm_mult(ctx, ctx->buf, ctx->buf);  // perform a GHASH operation

    length -= use_len;  // drop the remaining byte count to process
    input += use_len;   // bump our input pointer forward
    output += use_len;  // bump our output pointer forward
  }
  return (0);
}

/******************************************************************************
 *
 *  GCM_FINISH
 *
 *  This is called once after all calls to GCM_UPDATE to finalize the GCM.
 *  It performs the final GHASH to produce the resulting authentication TAG.
 *
 ******************************************************************************/
int gcm_finish(gcm_context *ctx,    // pointer to user-provided GCM context
               unsigned char *tag,  // pointer to buffer which receives the tag
               size_t tag_len)  // length, in bytes, of the tag-receiving buf
{
  unsigned char work_buf[16];
  uint64_t orig_len = ctx->len * 8;
  uint64_t orig_add_len = ctx->add_len * 8;
  size_t i;

  if (tag_len != 0) memcpy(tag, ctx->base_ectr, tag_len);

  if (orig_len || orig_add_len) {
    memset(work_buf, 0x00, 16);

    PUT_UINT32_BE((orig_add_len >> 32), work_buf, 0);
    PUT_UINT32_BE((orig_add_len), work_buf, 4);
    PUT_UINT32_BE((orig_len >> 32), work_buf, 8);
    PUT_UINT32_BE((orig_len), work_buf, 12);

    for (i = 0; i < 16; i++) ctx->buf[i] ^= work_buf[i];
    gcm_mult(ctx, ctx->buf, ctx->buf);
    for (i = 0; i < tag_len; i++) tag[i] ^= ctx->buf[i];
  }
  return (0);
}

/******************************************************************************
 *
 *  GCM_CRYPT_AND_TAG
 *
 *  This either encrypts or decrypts the user-provided data and, either
 *  way, generates an authentication tag of the requested length. It must be
 *  called with a GCM context whose key has already been set with GCM_SETKEY.
 *
 *  The user would typically call this explicitly to ENCRYPT a buffer of data
 *  and optional associated data, and produce its an authentication tag.
 *
 *  To reverse the process the user would typically call the companion
 *  GCM_AUTH_DECRYPT function to decrypt data and verify a user-provided
 *  authentication tag.  The GCM_AUTH_DECRYPT function calls this function
 *  to perform its decryption and tag generation, which it then compares.
 *
 ******************************************************************************/
int gcm_crypt_and_tag(
    gcm_context *ctx,            // gcm context with key already setup
    int mode,                    // cipher direction: GCM_ENCRYPT or GCM_DECRYPT
    const unsigned char *iv,     // pointer to the 12-byte initialization vector
    size_t iv_len,               // byte length if the IV. should always be 12
    const unsigned char *add,    // pointer to the non-ciphered additional data
    size_t add_len,              // byte length of the additional AEAD data
    const unsigned char *input,  // pointer to the cipher data source
    unsigned char *output,       // pointer to the cipher data destination
    size_t length,               // byte length of the cipher data
    unsigned char *tag,          // pointer to the tag to be generated
    size_t tag_len)              // byte length of the tag to be generated
{                                /*
                                    assuming that the caller has already invoked gcm_setkey to
                                    prepare the gcm context with the keying material, we simply
                                    invoke each of the three GCM sub-functions in turn...
                                 */
  gcm_start(ctx, mode, iv, iv_len, add, add_len);
  gcm_update(ctx, length, input, output);
  gcm_finish(ctx, tag, tag_len);
  return (0);
}

/******************************************************************************
 *
 *  GCM_ZERO_CTX
 *
 *  The GCM context contains both the GCM context and the AES context.
 *  This includes keying and key-related material which is security-
 *  sensitive, so it MUST be zeroed after use. This function does that.
 *
 ******************************************************************************/
void gcm_zero_ctx(gcm_context *ctx) {
  // zero the context originally provided to us
  memset(ctx, 0, sizeof(gcm_context));
}
//
//  aes-gcm.c
//  Pods
//
//  Created by Markus Kosmal on 20/11/14.
//
//

int mg_aes_gcm_encrypt(unsigned char *output,  //
                       const unsigned char *input, size_t input_length,
                       const unsigned char *key, const size_t key_len,
                       const unsigned char *iv, const size_t iv_len,
                       unsigned char *aead, size_t aead_len, unsigned char *tag,
                       const size_t tag_len) {
  int ret = 0;      // our return value
  gcm_context ctx;  // includes the AES context structure

  gcm_setkey(&ctx, key, (unsigned int) key_len);

  ret = gcm_crypt_and_tag(&ctx, MG_ENCRYPT, iv, iv_len, aead, aead_len, input,
                          output, input_length, tag, tag_len);

  gcm_zero_ctx(&ctx);

  return (ret);
}

int mg_aes_gcm_decrypt(unsigned char *output, const unsigned char *input,
                       size_t input_length, const unsigned char *key,
                       const size_t key_len, const unsigned char *iv,
                       const size_t iv_len, unsigned char *aead,
                       size_t aead_len, const unsigned char *tag,
                       const size_t tag_len) {
  int ret = 0;      // our return value
  gcm_context ctx;  // includes the AES context structure
  unsigned char computed_tag[16];
  size_t i;
  int diff = 0;

  if (tag_len > sizeof(computed_tag)) return -1;

  gcm_setkey(&ctx, key, (unsigned int) key_len);

  ret = gcm_crypt_and_tag(&ctx, MG_DECRYPT, iv, iv_len, aead, aead_len, input,
                          output, input_length, computed_tag, tag_len);

  gcm_zero_ctx(&ctx);

  // compare tags
  for (i = 0; i < tag_len; i++) diff |= computed_tag[i] ^ tag[i];
  if (diff != 0) ret = -1;

  return (ret);
}
#endif
// End of aes128 PD

#ifdef MG_ENABLE_LINES
#line 1 "src/tls_builtin.c"
#endif












#if MG_TLS == MG_TLS_BUILTIN

// PKCS#8 algorithm OIDs
static const uint8_t mg_rsa_oid[] = {
    0x2a, 0x86, 0x48, 0x86, 0xf7,
    0x0d, 0x01, 0x01, 0x01  // 1.2.840.113549.1.1.1 rsaEncryption
};
static const uint8_t mg_ec_public_key_oid[] = {
    0x2a, 0x86, 0x48, 0xce, 0x3d, 0x02, 0x01  // 1.2.840.10045.2.1 ecPublicKey
};
static const uint8_t mg_secp256r1_oid[] = {
    0x2a, 0x86, 0x48, 0xce,
    0x3d, 0x03, 0x01, 0x07  // 1.2.840.10045.3.1.7 secp256r1
};

/* TLS 1.3 Record Content Type (RFC8446 B.1) */
#define MG_TLS_CHANGE_CIPHER 20
#define MG_TLS_ALERT 21
#define MG_TLS_HANDSHAKE 22
#define MG_TLS_APP_DATA 23
#define MG_TLS_HEARTBEAT 24

/* TLS 1.3 Handshake Message Type (RFC8446 B.3) */
#define MG_TLS_CLIENT_HELLO 1
#define MG_TLS_SERVER_HELLO 2
#define MG_TLS_ENCRYPTED_EXTENSIONS 8
#define MG_TLS_CERTIFICATE 11
#define MG_TLS_CERTIFICATE_REQUEST 13
#define MG_TLS_CERTIFICATE_VERIFY 15
#define MG_TLS_FINISHED 20

#define MG_TLS_RSA_USE_CRT 1  // CRT instead of naive RSA

// handshake is re-entrant, so we need to keep track of its state state names
// refer to RFC8446#A.1
enum mg_tls_hs_state {
  // Client state machine:
  MG_TLS_STATE_CLIENT_START,        // Send ClientHello
  MG_TLS_STATE_CLIENT_WAIT_SH,      // Wait for ServerHello
  MG_TLS_STATE_CLIENT_WAIT_EE,      // Wait for EncryptedExtensions
  MG_TLS_STATE_CLIENT_WAIT_CERT,    // Wait for Certificate
  MG_TLS_STATE_CLIENT_WAIT_CV,      // Wait for CertificateVerify
  MG_TLS_STATE_CLIENT_WAIT_FINISH,  // Wait for Finish
  MG_TLS_STATE_CLIENT_CONNECTED,    // Done

  // Server state machine:
  MG_TLS_STATE_SERVER_START,       // Wait for ClientHello
  MG_TLS_STATE_SERVER_WAIT_CERT,   // Wait for Certificate
  MG_TLS_STATE_SERVER_WAIT_CV,     // Wait for CertificateVerify
  MG_TLS_STATE_SERVER_NEGOTIATED,  // Wait for Finish
  MG_TLS_STATE_SERVER_CONNECTED    // Done
};

// encryption keys for a TLS connection
struct tls_enc {
  uint32_t sseq;  // server sequence number, used in encryption
  uint32_t cseq;  // client sequence number, used in decryption
  // keys for AES encryption or ChaCha20
  uint8_t handshake_secret[32];
  uint8_t server_write_key[32];
  uint8_t server_write_iv[12];
  uint8_t server_finished_key[32];
  uint8_t client_write_key[32];
  uint8_t client_write_iv[12];
  uint8_t client_finished_key[32];
};

struct mg_rsa_key {
  struct mg_str n;     // modulus
  struct mg_str e;     // public exponent
  struct mg_str d;     // private exponent
  struct mg_str p;     // prime1
  struct mg_str q;     // prime2
  struct mg_str dP;    // exponent1 (d mod (p-1))
  struct mg_str dQ;    // exponent2 (d mod (q-1))
  struct mg_str qInv;  // coefficient ((inverse of q) mod p)
};

// per-connection TLS data
struct tls_data {
  enum mg_tls_hs_state state;  // keep track of connection handshake progress

  struct mg_iobuf send;  // For the receive path, we're reusing c->rtls
  size_t recv_offset;    // While c->rtls contains full records, reuse that
  size_t recv_len;       // buffer but point at individual decrypted messages

  uint8_t content_type;  // Last received record content type

  mg_sha256_ctx sha256;  // incremental SHA-256 hash for TLS handshake

  uint8_t random[32];      // client random from ClientHello
  uint8_t session_id[32];  // client session ID between the handshake states
  uint8_t x25519_cli[32];  // client X25519 key between the handshake states
  uint8_t x25519_sec[32];  // x25519 secret between the handshake states

  bool skip_verification;    // do not perform checks on server certificate
  bool cert_requested;       // client received a CertificateRequest
  bool is_twoway;            // server is configured to authenticate clients
  struct mg_str cert_der;    // certificate in DER format
  struct mg_str ca_der;      // CA certificate
  struct mg_str *chain_der;  // certificate chain (intermediate certs)
  size_t chain_len;          // number of certificates in chain
  uint8_t ec_key[32];        // EC private key
  struct mg_rsa_key rsa;
  struct mg_str rsa_key_der;  // RSA private key in DER format
  char hostname[254];         // matching hostname

  bool is_ec_pubkey;         // EC or RSA
  uint8_t pubkey[512 + 16];  // server EC (64) or RSA (512+exp) public key to
                             // verify cert
  size_t pubkeysz;           // size of the server public key
  uint8_t sighash[32];       // calculated signature verification hash

  struct tls_enc enc;       // actual keys in use at this time
  struct tls_enc app_keys;  // storage during two-way auth handshake
};

#define TLS_RECHDR_SIZE 5  // 1 byte type, 2 bytes version, 2 bytes length
#define TLS_MSGHDR_SIZE 4  // 1 byte type, 3 bytes length

#ifdef MG_TLS_SSLKEYLOGFILE
#include <stdio.h>
static void mg_ssl_key_log(const char *label, uint8_t client_random[32],
                           uint8_t *secret, size_t secretsz) {
  char *keylogfile = getenv("SSLKEYLOGFILE");
  size_t i;
  if (keylogfile != NULL) {
    MG_DEBUG(("Dumping key log into %s", keylogfile));
    FILE *f = fopen(keylogfile, "a");
    if (f != NULL) {
      fprintf(f, "%s ", label);
      for (i = 0; i < 32; i++) {
        fprintf(f, "%02x", client_random[i]);
      }
      fprintf(f, " ");
      for (i = 0; i < secretsz; i++) {
        fprintf(f, "%02x", secret[i]);
      }
      fprintf(f, "\n");
      fclose(f);
    } else {
      MG_ERROR(("Cannot open %s", keylogfile));
    }
  }
}
#endif

// for derived tls keys we need SHA256([0]*32)
static uint8_t zeros[32] = {0};
static uint8_t zeros_sha256_digest[32] = {
    0xe3, 0xb0, 0xc4, 0x42, 0x98, 0xfc, 0x1c, 0x14, 0x9a, 0xfb, 0xf4,
    0xc8, 0x99, 0x6f, 0xb9, 0x24, 0x27, 0xae, 0x41, 0xe4, 0x64, 0x9b,
    0x93, 0x4c, 0xa4, 0x95, 0x99, 0x1b, 0x78, 0x52, 0xb8, 0x55};

// helper to hexdump buffers inline
static void mg_tls_hexdump(const char *msg, uint8_t *buf, size_t bufsz) {
  MG_VERBOSE(("%s: %M", msg, mg_print_hex, bufsz, buf));
}

// helper utilities to parse ASN.1 DER
struct mg_der_tlv {
  uint8_t type;
  uint32_t len;
  uint8_t *value;
};

static int mg_der_parse(uint8_t *der, size_t dersz, struct mg_der_tlv *tlv) {
  size_t header_len = 2;
  uint32_t len = dersz < 2 ? 0 : der[1];
  if (dersz < 2) return -1;  // Invalid DER
  tlv->type = der[0];
  if (len > 0x7F) {  // long-form length
    uint8_t len_bytes = len & 0x7F, i;
    if (dersz < (size_t) (2 + len_bytes)) return -1;
    len = 0;
    for (i = 0; i < len_bytes; i++) {
      len = (len << 8) | der[2 + i];
    }
    header_len += len_bytes;
  }
  if (dersz < header_len + len) return -1;
  tlv->len = len;
  tlv->value = der + header_len;
  return (int) (header_len + len);
}

static int mg_der_next(struct mg_der_tlv *parent, struct mg_der_tlv *child) {
  int consumed;
  if (parent->len == 0) return 0;
  consumed = mg_der_parse(parent->value, parent->len, child);
  if (consumed < 0) return -1;
  parent->value += consumed;
  parent->len -= (uint32_t) consumed;
  return 1;
}

static int mg_der_find_oid(struct mg_der_tlv *tlv, const uint8_t *oid,
                           size_t oid_len, struct mg_der_tlv *found) {
  struct mg_der_tlv parent, child;
  parent = *tlv;
  while (mg_der_next(&parent, &child) > 0) {
    if (child.type == 0x06 && child.len == oid_len &&
        memcmp(child.value, oid, oid_len) == 0) {
      return mg_der_next(&parent, found);
    } else if (child.type & 0x20) {
      struct mg_der_tlv sub_parent = child;
      if (mg_der_find_oid(&sub_parent, oid, oid_len, found)) return 1;
    }
  }
  return 0;
}

#if 0
static void mg_der_debug(struct mg_der_tlv *tlv, int depth) {
  MG_DEBUG(("> %.*sd=%d Type: 0x%02X, Length: %u\n", depth * 4, " ", depth,
            tlv->type, tlv->len));

  if (tlv->type & 0x20) {  // Constructed: recurse into children
    struct mg_der_tlv child;
    struct mg_der_tlv parent = *tlv;
    while (mg_der_next(&parent, &child) > 0) {
      mg_der_debug(&child, depth + 1);
    }
  }
}
#endif

// parse DER into a TLV record
static int mg_der_to_tlv(uint8_t *der, size_t dersz, struct mg_der_tlv *tlv) {
  if (dersz < 2) {
    return -1;
  }
  tlv->type = der[0];
  tlv->len = der[1];
  tlv->value = der + 2;
  if (tlv->len > 0x7f) {
    uint32_t i, n = tlv->len - 0x80;
    tlv->len = 0;
    for (i = 0; i < n; i++) {
      tlv->len = (tlv->len << 8) | (der[2 + i]);
    }
    tlv->value = der + 2 + n;
  }
  if (der + dersz < tlv->value + tlv->len) {
    return -1;
  }
  return 0;
}

// Did we receive a full TLS record in the c->rtls buffer?
static bool mg_tls_got_record(struct mg_connection *c) {
  return c->rtls.len >= (size_t) TLS_RECHDR_SIZE &&
         c->rtls.len >=
             (size_t) (TLS_RECHDR_SIZE + MG_LOAD_BE16(c->rtls.buf + 3));
}

// Remove a single TLS record from the recv buffer
static void mg_tls_drop_record(struct mg_connection *c) {
  struct mg_iobuf *rio = &c->rtls;
  uint16_t n = MG_LOAD_BE16(rio->buf + 3) + TLS_RECHDR_SIZE;
  mg_iobuf_del(rio, 0, n);
}

// Remove a single TLS message from decrypted buffer, remove the wrapping
// record if it was the last message within a record
static void mg_tls_drop_message(struct mg_connection *c) {
  uint32_t len;
  struct tls_data *tls = (struct tls_data *) c->tls;
  unsigned char *recv_buf = &c->rtls.buf[tls->recv_offset];
  if (tls->recv_len == 0) return;
  len = MG_LOAD_BE24(recv_buf + 1) + TLS_MSGHDR_SIZE;
  if (tls->recv_len < len) {
    mg_error(c, "wrong size");
    return;
  }
  mg_sha256_update(&tls->sha256, recv_buf, len);
  tls->recv_offset += len;
  tls->recv_len -= len;
  if (tls->recv_len == 0) {
    mg_tls_drop_record(c);
  }
}

// TLS1.3 secret derivation based on the key label
static void mg_tls_derive_secret(const char *label, uint8_t *key, size_t keysz,
                                 uint8_t *data, size_t datasz, uint8_t *hash,
                                 size_t hashsz) {
  size_t labelsz = strlen(label);
  uint8_t secret[32];
  uint8_t packed[256] = {0, (uint8_t) hashsz, (uint8_t) labelsz};
  // TODO: assert lengths of label, key, data and hash
  if (labelsz > 0) memmove(packed + 3, label, labelsz);
  packed[3 + labelsz] = (uint8_t) datasz;
  if (datasz > 0) memmove(packed + labelsz + 4, data, datasz);
  packed[4 + labelsz + datasz] = 1;

  mg_hmac_sha256(secret, key, keysz, packed, 5 + labelsz + datasz);
  memmove(hash, secret, hashsz);
}

// at this point we have x25519 shared secret, we can generate a set of derived
// handshake encryption keys
static void mg_tls_generate_handshake_keys(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;

  mg_sha256_ctx sha256;
  uint8_t early_secret[32];
  uint8_t pre_extract_secret[32];
  uint8_t hello_hash[32];
  uint8_t server_hs_secret[32];
  uint8_t client_hs_secret[32];
#if MG_ENABLE_CHACHA20
  const size_t keysz = 32;
#else
  const size_t keysz = 16;
#endif

  mg_hmac_sha256(early_secret, NULL, 0, zeros, sizeof(zeros));
  mg_tls_derive_secret("tls13 derived", early_secret, 32, zeros_sha256_digest,
                       32, pre_extract_secret, 32);
  mg_hmac_sha256(tls->enc.handshake_secret, pre_extract_secret,
                 sizeof(pre_extract_secret), tls->x25519_sec,
                 sizeof(tls->x25519_sec));
  mg_tls_hexdump("hs secret", tls->enc.handshake_secret, 32);

  // mg_sha256_final is not idempotent, need to copy sha256 context to calculate
  // the digest
  memmove(&sha256, &tls->sha256, sizeof(mg_sha256_ctx));
  mg_sha256_final(hello_hash, &sha256);

  mg_tls_hexdump("hello hash", hello_hash, 32);
  // derive keys needed for the rest of the handshake
  mg_tls_derive_secret("tls13 s hs traffic", tls->enc.handshake_secret, 32,
                       hello_hash, 32, server_hs_secret, 32);
  mg_tls_derive_secret("tls13 c hs traffic", tls->enc.handshake_secret, 32,
                       hello_hash, 32, client_hs_secret, 32);

  mg_tls_derive_secret("tls13 key", server_hs_secret, 32, NULL, 0,
                       tls->enc.server_write_key, keysz);
  mg_tls_derive_secret("tls13 iv", server_hs_secret, 32, NULL, 0,
                       tls->enc.server_write_iv, 12);
  mg_tls_derive_secret("tls13 finished", server_hs_secret, 32, NULL, 0,
                       tls->enc.server_finished_key, 32);

  mg_tls_derive_secret("tls13 key", client_hs_secret, 32, NULL, 0,
                       tls->enc.client_write_key, keysz);
  mg_tls_derive_secret("tls13 iv", client_hs_secret, 32, NULL, 0,
                       tls->enc.client_write_iv, 12);
  mg_tls_derive_secret("tls13 finished", client_hs_secret, 32, NULL, 0,
                       tls->enc.client_finished_key, 32);

  mg_tls_hexdump("s hs traffic", server_hs_secret, 32);
  mg_tls_hexdump("s key", tls->enc.server_write_key, keysz);
  mg_tls_hexdump("s iv", tls->enc.server_write_iv, 12);
  mg_tls_hexdump("s finished", tls->enc.server_finished_key, 32);
  mg_tls_hexdump("c hs traffic", client_hs_secret, 32);
  mg_tls_hexdump("c key", tls->enc.client_write_key, keysz);
  mg_tls_hexdump("c iv", tls->enc.client_write_iv, 12);
  mg_tls_hexdump("c finished", tls->enc.client_finished_key, 32);

#ifdef MG_TLS_SSLKEYLOGFILE
  mg_ssl_key_log("SERVER_HANDSHAKE_TRAFFIC_SECRET", tls->random,
                 server_hs_secret, 32);
  mg_ssl_key_log("CLIENT_HANDSHAKE_TRAFFIC_SECRET", tls->random,
                 client_hs_secret, 32);
#endif
}

static void mg_tls_generate_application_keys(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  uint8_t hash[32];
  uint8_t premaster_secret[32];
  uint8_t master_secret[32];
  uint8_t server_secret[32];
  uint8_t client_secret[32];
#if MG_ENABLE_CHACHA20
  const size_t keysz = 32;
#else
  const size_t keysz = 16;
#endif

  mg_sha256_ctx sha256;
  memmove(&sha256, &tls->sha256, sizeof(mg_sha256_ctx));
  mg_sha256_final(hash, &sha256);

  mg_tls_derive_secret("tls13 derived", tls->enc.handshake_secret, 32,
                       zeros_sha256_digest, 32, premaster_secret, 32);
  mg_hmac_sha256(master_secret, premaster_secret, 32, zeros, 32);

  mg_tls_derive_secret("tls13 s ap traffic", master_secret, 32, hash, 32,
                       server_secret, 32);
  mg_tls_derive_secret("tls13 key", server_secret, 32, NULL, 0,
                       tls->enc.server_write_key, keysz);
  mg_tls_derive_secret("tls13 iv", server_secret, 32, NULL, 0,
                       tls->enc.server_write_iv, 12);
  mg_tls_derive_secret("tls13 c ap traffic", master_secret, 32, hash, 32,
                       client_secret, 32);
  mg_tls_derive_secret("tls13 key", client_secret, 32, NULL, 0,
                       tls->enc.client_write_key, keysz);
  mg_tls_derive_secret("tls13 iv", client_secret, 32, NULL, 0,
                       tls->enc.client_write_iv, 12);

  mg_tls_hexdump("s ap traffic", server_secret, 32);
  mg_tls_hexdump("s key", tls->enc.server_write_key, keysz);
  mg_tls_hexdump("s iv", tls->enc.server_write_iv, 12);
  mg_tls_hexdump("s finished", tls->enc.server_finished_key, 32);
  mg_tls_hexdump("c ap traffic", client_secret, 32);
  mg_tls_hexdump("c key", tls->enc.client_write_key, keysz);
  mg_tls_hexdump("c iv", tls->enc.client_write_iv, 12);
  mg_tls_hexdump("c finished", tls->enc.client_finished_key, 32);
  tls->enc.sseq = tls->enc.cseq = 0;

#ifdef MG_TLS_SSLKEYLOGFILE
  mg_ssl_key_log("SERVER_TRAFFIC_SECRET_0", tls->random, server_secret, 32);
  mg_ssl_key_log("CLIENT_TRAFFIC_SECRET_0", tls->random, client_secret, 32);
#endif
}

// AES GCM encryption of the message + put encoded data into the write buffer
static bool mg_tls_encrypt(struct mg_connection *c, const uint8_t *msg,
                           size_t msgsz, uint8_t msgtype) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  struct mg_iobuf *wio = &tls->send;
  uint8_t *outmsg;
  uint8_t *tag;
  size_t encsz = msgsz + 16 + 1;
  uint8_t hdr[5] = {MG_TLS_APP_DATA, 0x03, 0x03,
                    (uint8_t) ((encsz >> 8) & 0xff), (uint8_t) (encsz & 0xff)};
  uint8_t associated_data[5] = {MG_TLS_APP_DATA, 0x03, 0x03,
                                (uint8_t) ((encsz >> 8) & 0xff),
                                (uint8_t) (encsz & 0xff)};
  uint8_t nonce[12];

  uint32_t seq = c->is_client ? tls->enc.cseq : tls->enc.sseq;
  uint8_t *key =
      c->is_client ? tls->enc.client_write_key : tls->enc.server_write_key;
  uint8_t *iv =
      c->is_client ? tls->enc.client_write_iv : tls->enc.server_write_iv;

  if (msgsz > 16384) {
    MG_ERROR(("msg longer than recordsz"));
    return false;
  }

#if MG_ENABLE_CHACHA20
#else
  mg_gcm_initialize();
#endif

  memmove(nonce, iv, sizeof(nonce));
  nonce[8] ^= (uint8_t) ((seq >> 24) & 255U);
  nonce[9] ^= (uint8_t) ((seq >> 16) & 255U);
  nonce[10] ^= (uint8_t) ((seq >> 8) & 255U);
  nonce[11] ^= (uint8_t) ((seq) & 255U);

  if (mg_iobuf_add(wio, wio->len, hdr, sizeof(hdr)) == 0 ||
      !mg_iobuf_resize(wio, wio->len + encsz))
    return false;
  outmsg = wio->buf + wio->len;
  tag = wio->buf + wio->len + msgsz + 1;
  memmove(outmsg, msg, msgsz);
  outmsg[msgsz] = msgtype;
#if MG_ENABLE_CHACHA20
  (void) tag;  // tag is only used in aes gcm
  {
    size_t n;
    uint8_t *enc = (uint8_t *) mg_calloc(1, msgsz + 256 + 1);
    if (enc == NULL) return false;
    n = mg_chacha20_poly1305_encrypt(enc, key, nonce, associated_data,
                                     sizeof(associated_data), outmsg,
                                     msgsz + 1);
    memmove(outmsg, enc, n);
    mg_free(enc);
  }
#else
  mg_aes_gcm_encrypt(outmsg, outmsg, msgsz + 1, key, 16, nonce, sizeof(nonce),
                     associated_data, sizeof(associated_data), tag, 16);
#endif
  c->is_client ? tls->enc.cseq++ : tls->enc.sseq++;
  wio->len += encsz;
  return true;
}

// read an encrypted record, decrypt it in place
static int mg_tls_recv_record(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  struct mg_iobuf *rio = &c->rtls;
  uint16_t msgsz;
  uint8_t *msg;
  uint8_t nonce[12];
  int r;

  uint32_t seq = c->is_client ? tls->enc.sseq : tls->enc.cseq;
  uint8_t *key =
      c->is_client ? tls->enc.server_write_key : tls->enc.client_write_key;
  uint8_t *iv =
      c->is_client ? tls->enc.server_write_iv : tls->enc.client_write_iv;

  if (tls->recv_len > 0) {
    return 0; /* some data from previous record is still present */
  }
  for (;;) {
    if (!mg_tls_got_record(c)) {
      return MG_IO_WAIT;
    }
    if (rio->buf[0] == MG_TLS_APP_DATA) {
      break;
    } else if (rio->buf[0] == MG_TLS_CHANGE_CIPHER) {  // skip CCS
      mg_tls_drop_record(c);
    } else if (rio->buf[0] == MG_TLS_ALERT) {  // Skip Alerts
      if (rio->len >= 7) {
        uint8_t level = rio->buf[5], desc = rio->buf[6];
        MG_INFO(("TLS ALERT received: level=%d, desc=%d (%s)", level, desc,
                 desc == 0    ? "close_notify"
                 : desc == 10 ? "unexpected_message"
                 : desc == 20 ? "bad_record_mac"
                 : desc == 21 ? "decryption_failed"
                 : desc == 40 ? "handshake_failure"
                 : desc == 42 ? "bad_certificate"
                 : desc == 43 ? "unsupported_certificate"
                              : "unknown"));
      } else {
        MG_INFO(("TLS ALERT packet received (short)"));
      }
      mg_tls_drop_record(c);
    } else {
      mg_error(c, "unexpected packet");
      return -1;
    }
  }

  msgsz = MG_LOAD_BE16(rio->buf + 3);
  msg = rio->buf + 5;
  if (msgsz < 16) {
    mg_error(c, "wrong size");
    return -1;
  }

  memmove(nonce, iv, sizeof(nonce));
  nonce[8] ^= (uint8_t) ((seq >> 24) & 255U);
  nonce[9] ^= (uint8_t) ((seq >> 16) & 255U);
  nonce[10] ^= (uint8_t) ((seq >> 8) & 255U);
  nonce[11] ^= (uint8_t) ((seq) & 255U);
#if MG_ENABLE_CHACHA20
  {
    uint8_t associated_data[5] = {MG_TLS_APP_DATA, 0x03, 0x03,
                                  (uint8_t) ((msgsz >> 8) & 0xff),
                                  (uint8_t) (msgsz & 0xff)};
    uint8_t *dec = (uint8_t *) mg_calloc(1, msgsz);
    size_t n;
    if (dec == NULL) {
      mg_error(c, "TLS OOM");
      return -1;
    }
    n = mg_chacha20_poly1305_decrypt(dec, key, nonce, associated_data,
                                     sizeof(associated_data), msg, msgsz);
    if (n == (size_t) -1) {
      mg_free(dec);
      mg_error(c, "decryption error");
      return -1;
    }
    memmove(msg, dec, n);
    mg_free(dec);
  }
#else
  {
    uint8_t associated_data[5] = {MG_TLS_APP_DATA, 0x03, 0x03,
                                  (uint8_t) ((msgsz >> 8) & 0xff),
                                  (uint8_t) (msgsz & 0xff)};
    mg_gcm_initialize();
    if (mg_aes_gcm_decrypt(msg, msg, msgsz - 16, key, 16, nonce, sizeof(nonce),
                           associated_data, sizeof(associated_data),
                           msg + msgsz - 16, 16) != 0) {
      mg_error(c, "GCM tag verify failed");
      return -1;
    }
  }
#endif

  r = msgsz - 16 - 1;
  tls->content_type = msg[msgsz - 16 - 1];
  tls->recv_offset = (size_t) msg - (size_t) rio->buf;
  tls->recv_len = (size_t) msgsz - 16 - 1;
  c->is_client ? tls->enc.sseq++ : tls->enc.cseq++;
  return r;
}

static void mg_tls_calc_cert_verify_hash(struct mg_connection *c,
                                         uint8_t hash[32], bool is_client) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  uint8_t sig_content[130];
  mg_sha256_ctx sha256;

  memset(sig_content, 0x20, 64);
  if (is_client) {
    uint8_t client_context[34] = "TLS 1.3, client CertificateVerify";
    memcpy(sig_content + 64, client_context, sizeof(client_context));
  } else {
    uint8_t server_context[34] = "TLS 1.3, server CertificateVerify";
    memcpy(sig_content + 64, server_context, sizeof(server_context));
  }

  memmove(&sha256, &tls->sha256, sizeof(mg_sha256_ctx));
  mg_sha256_final(sig_content + 98, &sha256);

  mg_sha256_init(&sha256);
  mg_sha256_update(&sha256, sig_content, sizeof(sig_content));
  mg_sha256_final(hash, &sha256);
}

// read and parse ClientHello record
static int mg_tls_server_recv_hello(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  struct mg_iobuf *rio = &c->rtls;
  uint8_t session_id_len;
  uint16_t j;
  uint16_t cipher_suites_len;
  uint16_t ext_len;
  uint8_t *ext;
  uint16_t msgsz;

  if (!mg_tls_got_record(c)) {
    return MG_IO_WAIT;
  }
  if (rio->buf[0] != MG_TLS_HANDSHAKE || rio->buf[5] != MG_TLS_CLIENT_HELLO) {
    mg_error(c, "not a client hello packet");
    return -1;
  }
  if (rio->len < 50) goto fail;
  msgsz = MG_LOAD_BE16(rio->buf + 3);
  if (((uint32_t) msgsz + 4) > rio->len) goto fail;
  mg_sha256_update(&tls->sha256, rio->buf + 5, msgsz);
  // store client random
  memmove(tls->random, rio->buf + 11, sizeof(tls->random));
  // store session_id
  session_id_len = rio->buf[43];
  if (session_id_len == sizeof(tls->session_id)) {
    memmove(tls->session_id, rio->buf + 44, session_id_len);
  } else if (session_id_len != 0) {
    MG_INFO(("bad session id len"));
  }
  cipher_suites_len = MG_LOAD_BE16(rio->buf + 44 + session_id_len);
  if (((uint32_t) cipher_suites_len + 46 + session_id_len) > rio->len)
    goto fail;
  ext_len = MG_LOAD_BE16(rio->buf + 48 + session_id_len + cipher_suites_len);
  ext = rio->buf + 50 + session_id_len + cipher_suites_len;
  if (((unsigned char *) ext + ext_len) > (rio->buf + rio->len)) goto fail;
  for (j = 0; j < ext_len;) {
    uint16_t k;
    uint16_t key_exchange_len;
    uint8_t *key_exchange;
    uint16_t n = MG_LOAD_BE16(ext + j + 2);
    if (((uint32_t) n + j + 4) > ext_len) goto fail;
    if (MG_LOAD_BE16(ext + j) != 0x0033) {  // not a key share extension, ignore
      j += (uint16_t) (n + 4);
      continue;
    }
    key_exchange_len = MG_LOAD_BE16(ext + j + 4);
    key_exchange = ext + j + 6;
    if (((size_t) key_exchange_len +
         ((size_t) key_exchange - (size_t) rio->buf)) > rio->len)
      goto fail;
    for (k = 0; k < key_exchange_len;) {
      uint16_t m = MG_LOAD_BE16(key_exchange + k + 2);
      if (((uint32_t) m + k + 4) > key_exchange_len) goto fail;
      if (m == 32 && key_exchange[k] == 0x00 && key_exchange[k + 1] == 0x1d) {
        memmove(tls->x25519_cli, key_exchange + k + 4, m);
        mg_tls_drop_record(c);
        return 0;
      }
      k += (uint16_t) (m + 4);
    }
    j += (uint16_t) (n + 4);
  }
fail:
  mg_error(c, "bad client hello");
  return -1;
}

#define PLACEHOLDER_8B 'X', 'X', 'X', 'X', 'X', 'X', 'X', 'X'
#define PLACEHOLDER_16B PLACEHOLDER_8B, PLACEHOLDER_8B
#define PLACEHOLDER_32B PLACEHOLDER_16B, PLACEHOLDER_16B

// put ServerHello record into wio buffer
static bool mg_tls_server_send_hello(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  struct mg_iobuf *wio = &tls->send;

  // clang-format off
  uint8_t msg_server_hello[122] = {
      // server hello, tls 1.2
      0x02, 0x00, 0x00, 0x76, 0x03, 0x03,
      // random (32 bytes)
      PLACEHOLDER_32B,
      // session ID length + session ID (32 bytes)
      0x20, PLACEHOLDER_32B,
#if MG_ENABLE_CHACHA20
      // TLS_CHACHA20_POLY1305_SHA256 + no compression
      0x13, 0x03, 0x00,
#else
      // TLS_AES_128_GCM_SHA256 + no compression
      0x13, 0x01, 0x00,
#endif
      // extensions + keyshare
      0x00, 0x2e, 0x00, 0x33, 0x00, 0x24, 0x00, 0x1d, 0x00, 0x20,
      // x25519 keyshare
      PLACEHOLDER_32B,
      // supported versions (tls1.3 == 0x304)
      0x00, 0x2b, 0x00, 0x02, 0x03, 0x04};
  // clang-format on

  // calculate keyshare
  uint8_t x25519_pub[X25519_BYTES];
  uint8_t x25519_prv[X25519_BYTES];
  if (!mg_random(x25519_prv, sizeof(x25519_prv))) mg_error(c, "RNG");
  mg_tls_x25519(x25519_pub, x25519_prv, X25519_BASE_POINT, 1);
  mg_tls_x25519(tls->x25519_sec, x25519_prv, tls->x25519_cli, 1);
  mg_tls_hexdump("s x25519 sec", tls->x25519_sec, sizeof(tls->x25519_sec));

  // fill in the gaps: random + session ID + keyshare
  memmove(msg_server_hello + 6, tls->random, sizeof(tls->random));
  memmove(msg_server_hello + 39, tls->session_id, sizeof(tls->session_id));
  memmove(msg_server_hello + 84, x25519_pub, sizeof(x25519_pub));

  // server hello message
  if (mg_iobuf_add(wio, wio->len, "\x16\x03\x03\x00\x7a", 5) == 0 ||
      mg_iobuf_add(wio, wio->len, msg_server_hello, sizeof(msg_server_hello)) ==
          0)
    return false;
  mg_sha256_update(&tls->sha256, msg_server_hello, sizeof(msg_server_hello));

  // change cipher message
  if (mg_iobuf_add(wio, wio->len, "\x14\x03\x03\x00\x01\x01", 6) == 0)
    return false;
  return true;
}

static bool mg_tls_server_send_ext(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  // server extensions
  uint8_t ext[6] = {0x08, 0, 0, 2, 0, 0};
  mg_sha256_update(&tls->sha256, ext, sizeof(ext));
  return mg_tls_encrypt(c, ext, sizeof(ext), MG_TLS_HANDSHAKE);
}

// signature algorithms we actually support:
// rsa_pkcs1_sha256, rsa_pss_rsae_sha256 and ecdsa_secp256r1_sha256
static const uint8_t secp256r1_sig_algs[12] = {
    0x00, 0x0d, 0x00, 0x08, 0x00, 0x06, 0x04, 0x03, 0x08, 0x04, 0x04, 0x01};

static bool mg_tls_server_send_cert_request(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  uint8_t req[13 + sizeof(secp256r1_sig_algs)];
  req[0] = MG_TLS_CERTIFICATE_REQUEST;  // handshake header
  MG_STORE_BE24(req + 1, 9 + sizeof(secp256r1_sig_algs));
  req[4] = 0;                                              // context length
  MG_STORE_BE16(req + 5, 6 + sizeof(secp256r1_sig_algs));  // extensions length
  MG_STORE_BE16(req + 7, 13);  // "signature algorithms"
  MG_STORE_BE16(req + 9, 2 + sizeof(secp256r1_sig_algs));  // length
  MG_STORE_BE16(
      req + 11,
      sizeof(secp256r1_sig_algs));  // signature hash algorithms length
  memcpy(req + 13, (uint8_t *) secp256r1_sig_algs, sizeof(secp256r1_sig_algs));
  mg_sha256_update(&tls->sha256, req, sizeof(req));
  return mg_tls_encrypt(c, req, sizeof(req), MG_TLS_HANDSHAKE);
}

static bool mg_tls_send_cert(struct mg_connection *c, bool is_client) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  int send_ca = !is_client && tls->ca_der.len > 0;
  // DER certificate + CA (server optional)
  size_t i, offset, total_size = tls->cert_der.len + 5;
  uint8_t *cert;
  bool res = false;
  for (i = 1; i < tls->chain_len; i++) {
    total_size += tls->chain_der[i].len + 5;
  }
  if (send_ca) {
    total_size += tls->ca_der.len + 5;
  }
  cert = (uint8_t *) mg_calloc(1, 13 + total_size);
  if (cert == NULL) return res;
  cert[0] = MG_TLS_CERTIFICATE;  // handshake header
  MG_STORE_BE24(cert + 1, total_size + 4);
  cert[4] = 0;                          // request context
  MG_STORE_BE24(cert + 5, total_size);  // 3 bytes: cert (s) length
  offset = 8;
  MG_STORE_BE24(cert + offset, tls->cert_der.len);  // 3 bytes: first cert len
  offset += 3;
  // bytes 11+ are certificate in DER format
  memmove(cert + offset, tls->cert_der.buf, tls->cert_der.len);
  offset += tls->cert_der.len;
  MG_STORE_BE16(cert + offset, 0);  // certificate extensions (none)
  offset += 2;
  for (i = 1; i < tls->chain_len; i++) {
    MG_STORE_BE24(cert + offset, tls->chain_der[i].len);
    offset += 3;
    memmove(cert + offset, tls->chain_der[i].buf, tls->chain_der[i].len);
    offset += tls->chain_der[i].len;
    MG_STORE_BE16(cert + offset, 0);  // certificate extensions (none)
    offset += 2;
  }
  if (send_ca) {
    MG_STORE_BE24(cert + offset, tls->ca_der.len);  // 3 bytes: CA cert length
    offset += 3;
    memmove(cert + offset, tls->ca_der.buf,
            tls->ca_der.len);  // CA cert data
    offset += tls->ca_der.len;
    MG_STORE_BE16(cert + offset, 0);  // certificate extensions (none)
    offset += 2;
  }
  mg_sha256_update(&tls->sha256, cert, offset);
  res = mg_tls_encrypt(c, cert, offset, MG_TLS_HANDSHAKE);
  mg_free(cert);
  return res;
}

// type adapter between uECC hash context and our sha256 implementation
typedef struct SHA256_HashContext {
  MG_UECC_HashContext uECC;
  mg_sha256_ctx ctx;
} SHA256_HashContext;

static void init_SHA256(const MG_UECC_HashContext *base) {
  SHA256_HashContext *c = (SHA256_HashContext *) base;
  mg_sha256_init(&c->ctx);
}

static void update_SHA256(const MG_UECC_HashContext *base,
                          const uint8_t *message, unsigned message_size) {
  SHA256_HashContext *c = (SHA256_HashContext *) base;
  mg_sha256_update(&c->ctx, message, message_size);
}
static void finish_SHA256(const MG_UECC_HashContext *base,
                          uint8_t *hash_result) {
  SHA256_HashContext *c = (SHA256_HashContext *) base;
  mg_sha256_final(hash_result, &c->ctx);
}

static void mg_tls_mgf1(uint8_t *mask, size_t mask_len, const uint8_t *seed,
                        size_t seed_len) {
  uint32_t counter = 0;
  size_t chunk, chunk_len, generated = 0;
  while (generated < mask_len) {
    mg_sha256_ctx ctx;
    uint8_t digest[32];
    uint8_t ctr[4];
    ctr[0] = (uint8_t) (counter >> 24);
    ctr[1] = (uint8_t) (counter >> 16);
    ctr[2] = (uint8_t) (counter >> 8);
    ctr[3] = (uint8_t) counter;
    mg_sha256_init(&ctx);
    mg_sha256_update(&ctx, seed, seed_len);
    mg_sha256_update(&ctx, ctr, sizeof(ctr));
    mg_sha256_final(digest, &ctx);
    chunk_len = mask_len - generated;
    chunk = (chunk_len < sizeof(digest) ? chunk_len : sizeof(digest));
    memmove(mask + generated, digest, chunk);
    generated += chunk;
    counter++;
  }
}

static unsigned int mg_tls_rsa_bits(const struct mg_str *n) {
  size_t i = 0;
  unsigned int bits = 0;
  while (i < n->len && n->buf[i] == 0) i++;
  if (i == n->len) return 0;
  bits = (unsigned int) ((n->len - i) * 8);
  {
    uint8_t byte = (uint8_t) n->buf[i];
    while ((byte & 0x80U) == 0) {
      bits--;
      byte = (uint8_t) (byte << 1);
    }
  }
  return bits;
}

static bool mg_tls_pss_encode(const uint8_t *hash, size_t hashlen,
                              const struct mg_str *n, uint8_t *em) {
  size_t emlen = n->len, saltlen = hashlen, dblen, pslen, i;
  uint8_t salt[64];   // Max salt size for any reasonable hash
  uint8_t m[136];     // 8 + max hash (64) + max salt (64) = 136
  uint8_t H[64];      // Max hash size
  uint8_t DB[512];    // Max for 4096-bit RSA
  uint8_t mask[512];  // Max for 4096-bit RSA
  mg_sha256_ctx ctx;

  // Check bounds
  if (saltlen > sizeof(salt) || (8 + hashlen + saltlen) > sizeof(m) ||
      hashlen > sizeof(H) || emlen > sizeof(DB)) {
    MG_ERROR(("RSA key too large for static buffers"));
    return false;
  }
  if (emlen < hashlen + saltlen + 2) {
    return false;
  }
  if (!mg_random(salt, saltlen)) {
    return false;
  }
  MG_VERBOSE(("PSS salt: %M", mg_print_hex, saltlen, salt));

  // Build m = 8 zero bytes || hash || salt
  memset(m, 0, 8);
  memcpy(m + 8, hash, hashlen);
  memcpy(m + 8 + hashlen, salt, saltlen);
  mg_sha256_init(&ctx);
  mg_sha256_update(&ctx, m, 8 + hashlen + saltlen);
  mg_sha256_final(H, &ctx);
  MG_VERBOSE(("PSS H: %M", mg_print_hex, hashlen, H));

  dblen = emlen - hashlen - 1;
  pslen = emlen - hashlen - saltlen - 2;

  // Build DB = PS || 0x01 || salt
  memset(DB, 0, pslen);
  DB[pslen] = 0x01;
  memcpy(DB + pslen + 1, salt, saltlen);

  // Generate mask and apply to DB
  mg_tls_mgf1(mask, dblen, H, hashlen);
  for (i = 0; i < dblen; i++) DB[i] ^= mask[i];

  {
    // PSS standard: emBits = modulus_bit_length - 1
    unsigned rsa_bits = mg_tls_rsa_bits(n);
    unsigned embits = rsa_bits - 1;
    unsigned unused = (unsigned) (8 * emlen - embits);
    MG_VERBOSE(("RSA modulus bits: %u, emBits: %u, emlen: %zu, unused: %u",
                rsa_bits, embits, emlen, unused));
    if (unused > 0 && unused < 8) {
      uint8_t mask_byte = (uint8_t) (0xff >> unused);
      MG_VERBOSE(("Applying mask 0x%02x to first byte (was 0x%02x)", mask_byte,
                  DB[0]));
      DB[0] &= mask_byte;
      MG_VERBOSE(("First byte after mask: 0x%02x", DB[0]));
    }
  }

  // Build final em = maskedDB || H || 0xbc
  memcpy(em, DB, dblen);
  memcpy(em + dblen, H, hashlen);
  em[emlen - 1] = 0xbc;
  return true;
}

static bool mg_tls_rsa_sign(struct tls_data *tls, const uint8_t *em,
                            size_t emlen, uint8_t *sig) {
  size_t nlen;
  int crt_result;
#if MG_TLS_RSA_USE_CRT
  // RSA CRT (Chinese Remainder Theorem) optimization:
  // s1 = em^dP mod p
  // s2 = em^dQ mod q
  // h = qInv * (s1 - s2) mod p
  // s = s2 + h * q

  if (tls->rsa.p.len == 0 || tls->rsa.q.len == 0 || tls->rsa.dP.len == 0 ||
      tls->rsa.dQ.len == 0 || tls->rsa.qInv.len == 0) {
    MG_ERROR(("CRT parameters missing, cannot use CRT optimization"));
    return false;
  }

  MG_VERBOSE(("Using RSA-CRT optimization"));

  nlen = tls->rsa.n.len;

  crt_result = mg_rsa_crt_sign(
      em, emlen, (const uint8_t *) tls->rsa.dP.buf, tls->rsa.dP.len,
      (const uint8_t *) tls->rsa.dQ.buf, tls->rsa.dQ.len,
      (const uint8_t *) tls->rsa.p.buf, tls->rsa.p.len,
      (const uint8_t *) tls->rsa.q.buf, tls->rsa.q.len,
      (const uint8_t *) tls->rsa.qInv.buf, tls->rsa.qInv.len, sig, nlen);

  if (crt_result == 0) {
    MG_VERBOSE(("CRT signature successful (first 4 bytes): %02x %02x %02x %02x",
                sig[0], sig[1], sig[2], sig[3]));
    MG_VERBOSE(("CRT signature successful (last 4 bytes): %02x %02x %02x %02x",
                sig[nlen - 4], sig[nlen - 3], sig[nlen - 2], sig[nlen - 1]));
    return true;
  } else {
    MG_ERROR(("CRT signing failed"));
    return false;
  }
#else
  int ret;
  // Standard RSA: s = em^d mod n
  memset(sig, 0, tls->rsa.n.len);
  ret = mg_rsa_mod_pow((const uint8_t *) tls->rsa.n.buf, tls->rsa.n.len,
                       (const uint8_t *) tls->rsa.d.buf, tls->rsa.d.len, em,
                       emlen, sig, tls->rsa.n.len);
  if (ret == 0) {
    MG_VERBOSE(("RSA signature first 4 bytes: %02x %02x %02x %02x", sig[0],
                sig[1], sig[2], sig[3]));
    MG_VERBOSE(("RSA signature last 4 bytes: %02x %02x %02x %02x",
                sig[tls->rsa.n.len - 4], sig[tls->rsa.n.len - 3],
                sig[tls->rsa.n.len - 2], sig[tls->rsa.n.len - 1]));
  }
  return ret == 0;
#endif
}

static bool mg_tls_send_cert_verify(struct mg_connection *c, bool is_client) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  uint8_t hash[32] = {0};

  mg_tls_calc_cert_verify_hash(c, (uint8_t *) hash, is_client);

  if (tls->rsa.n.len > 0 && tls->rsa.d.len > 0) {
    // RSA certificate verify packet
    size_t emlen = tls->rsa.n.len;
    size_t verifysz = 8U + emlen;
    uint8_t em[512];      // Max for 4096-bit RSA
    uint8_t verify[520];  // 8 + 512 max

    // Check bounds
    if (emlen > sizeof(em) || verifysz > sizeof(verify)) {
      MG_ERROR(("RSA key too large for static buffers"));
      return false;
    }

    if (!mg_tls_pss_encode(hash, sizeof(hash), &tls->rsa.n, em)) {
      MG_ERROR(("Failed PSS encode"));
      return false;
    }

    // Validate PSS encoded message format
    if (em[emlen - 1] != 0xbc) {
      MG_ERROR(("Invalid PSS encoding: last byte is 0x%02x, expected 0xbc",
                em[emlen - 1]));
      return false;
    }

    // Build verify packet header, then sign directly into the packet
    verify[0] = 0x0f;
    MG_STORE_BE24(verify + 1, emlen + 4);
    MG_STORE_BE16(verify + 4, 0x0804);
    MG_STORE_BE16(verify + 6, emlen);

    // Sign directly into the verify buffer (verify + 8 = signature location)
    memset(verify + 8, 0, emlen);  // Initialize signature area
    if (!mg_tls_rsa_sign(tls, em, emlen, verify + 8)) {
      MG_ERROR(("Failed RSA sign"));
      return false;
    }

    MG_VERBOSE(
        ("PSS EM first 4: %02x %02x %02x %02x", em[0], em[1], em[2], em[3]));
    MG_VERBOSE(("PSS EM last 4: %02x %02x %02x %02x", em[emlen - 4],
                em[emlen - 3], em[emlen - 2], em[emlen - 1]));

    mg_sha256_update(&tls->sha256, verify, verifysz);
    return mg_tls_encrypt(c, verify, verifysz, MG_TLS_HANDSHAKE);
  } else {
    // EC certificate verify packet
    uint8_t verify[82] = {0x0f, 0x00, 0x00, 0x00, 0x04, 0x03, 0x00, 0x00};
    uint8_t tmp[2 * 32 + 64] = {0};
    struct SHA256_HashContext ctx = {
        {&init_SHA256, &update_SHA256, &finish_SHA256, 64, 32, tmp},
        {{0}, 0, 0, {0}}};
    size_t sigsz, verifysz = 0;
    int neg1, neg2;
    uint8_t sig[64] = {0};
    mg_uecc_sign_deterministic(tls->ec_key, hash, sizeof(hash), &ctx.uECC, sig,
                               mg_uecc_secp256r1());

    neg1 = !!(sig[0] & 0x80);
    neg2 = !!(sig[32] & 0x80);
    verify[8] = 0x30;  // ASN.1 SEQUENCE
    verify[9] = (uint8_t) (68 + neg1 + neg2);
    verify[10] = 0x02;  // ASN.1 INTEGER
    verify[11] = (uint8_t) (32 + neg1);
    memmove(verify + 12 + neg1, sig, 32);
    verify[12 + 32 + neg1] = 0x02;  // ASN.1 INTEGER
    verify[13 + 32 + neg1] = (uint8_t) (32 + neg2);
    memmove(verify + 14 + 32 + neg1 + neg2, sig + 32, 32);

    sigsz = (size_t) (70 + neg1 + neg2);
    verifysz = 8U + sigsz;
    verify[3] = (uint8_t) (sigsz + 4);
    verify[7] = (uint8_t) sigsz;

    mg_sha256_update(&tls->sha256, verify, verifysz);
    return mg_tls_encrypt(c, verify, verifysz, MG_TLS_HANDSHAKE);
  }
}

static bool mg_tls_server_send_finish(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  mg_sha256_ctx sha256;
  uint8_t hash[32];
  uint8_t finish[36] = {0x14, 0, 0, 32};
  memmove(&sha256, &tls->sha256, sizeof(mg_sha256_ctx));
  mg_sha256_final(hash, &sha256);
  mg_hmac_sha256(finish + 4, tls->enc.server_finished_key, 32, hash, 32);
  if (!mg_tls_encrypt(c, finish, sizeof(finish), MG_TLS_HANDSHAKE))
    return false;
  mg_sha256_update(&tls->sha256, finish, sizeof(finish));
  return true;
}

static int mg_tls_server_recv_finish(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  unsigned char *recv_buf;
  // we have to backup sha256 value to restore it later, since Finished record
  // is exceptional and is not supposed to be added to the rolling hash
  // calculation.
  mg_sha256_ctx sha256 = tls->sha256;
  if (mg_tls_recv_record(c) < 0) {
    return -1;
  }
  recv_buf = &c->rtls.buf[tls->recv_offset];
  if (recv_buf[0] != MG_TLS_FINISHED) {
    mg_error(c, "expected Finish but got msg 0x%02x", recv_buf[0]);
    return -1;
  }
  mg_tls_drop_message(c);

  // restore hash
  tls->sha256 = sha256;
  return 0;
}

static bool mg_tls_client_send_hello(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  struct mg_iobuf *wio = &tls->send;

  uint8_t x25519_pub[X25519_BYTES];

  // - "signature algorithms we actually support", see above
  //   uint8_t secp256r1_sig_algs[]
  // - all popular signature algorithms (if we don't care about verification)
  uint8_t all_sig_algs[34] = {
      0x00, 0x0d, 0x00, 0x1e, 0x00, 0x1c, 0x04, 0x03, 0x05, 0x03, 0x06, 0x03,
      0x08, 0x07, 0x08, 0x08, 0x08, 0x09, 0x08, 0x0a, 0x08, 0x0b, 0x08, 0x04,
      0x08, 0x05, 0x08, 0x06, 0x04, 0x01, 0x05, 0x01, 0x06, 0x01};
  uint8_t server_name_ext[9] = {0x00, 0x00, 0x00, 0xfe, 0x00,
                                0xfe, 0x00, 0x00, 0xfe};

  // clang-format off
  uint8_t msg_client_hello[145] = {
      // TLS Client Hello header reported as TLS1.2 (5)
      0x16, 0x03, 0x03, 0x00, 0xfe,
      // client hello, tls 1.2 (6)
      0x01, 0x00, 0x00, 0x8c, 0x03, 0x03,
      // random (32 bytes)
      PLACEHOLDER_32B,
      // session ID length + session ID (32 bytes)
      0x20, PLACEHOLDER_32B, 0x00,
      0x02,  // size = 2 bytes
#if MG_ENABLE_CHACHA20
      // TLS_CHACHA20_POLY1305_SHA256
      0x13, 0x03,
#else
      // TLS_AES_128_GCM_SHA256
      0x13, 0x01,
#endif
      // no compression
      0x01, 0x00,
      // extensions + keyshare
      0x00, 0xfe,
      // x25519 keyshare
      0x00, 0x33, 0x00, 0x26, 0x00, 0x24, 0x00, 0x1d, 0x00, 0x20,
      PLACEHOLDER_32B,
      // supported groups (x25519)
      0x00, 0x0a, 0x00, 0x04, 0x00, 0x02, 0x00, 0x1d,
      // supported versions (tls1.3 == 0x304)
      0x00, 0x2b, 0x00, 0x03, 0x02, 0x03, 0x04,
      // session ticket (none)
      0x00, 0x23, 0x00, 0x00, // 144 bytes till here
	};
  // clang-format on
  const char *hostname = tls->hostname;
  size_t hostnamesz = strlen(tls->hostname);
  size_t hostname_extsz = hostnamesz ? hostnamesz + 9 : 0;
  uint8_t *sig_alg =
      tls->skip_verification ? all_sig_algs : (uint8_t *) secp256r1_sig_algs;
  size_t sig_alg_sz = tls->skip_verification ? sizeof(all_sig_algs)
                                             : sizeof(secp256r1_sig_algs);

  // patch ClientHello with correct hostname ext length (if any)
  MG_STORE_BE16(msg_client_hello + 3,
                hostname_extsz + 183 - 9 - 34 + sig_alg_sz);
  MG_STORE_BE16(msg_client_hello + 7,
                hostname_extsz + 179 - 9 - 34 + sig_alg_sz);
  MG_STORE_BE16(msg_client_hello + 82,
                hostname_extsz + 104 - 9 - 34 + sig_alg_sz);

  if (hostnamesz > 0) {
    MG_STORE_BE16(server_name_ext + 2, hostnamesz + 5);
    MG_STORE_BE16(server_name_ext + 4, hostnamesz + 3);
    MG_STORE_BE16(server_name_ext + 7, hostnamesz);
  }

  // calculate keyshare
  if (!mg_random(tls->x25519_cli, sizeof(tls->x25519_cli))) mg_error(c, "RNG");
  mg_tls_x25519(x25519_pub, tls->x25519_cli, X25519_BASE_POINT, 1);

  // fill in the gaps: random + session ID + keyshare
  if (!mg_random(tls->session_id, sizeof(tls->session_id))) mg_error(c, "RNG");
  if (!mg_random(tls->random, sizeof(tls->random))) mg_error(c, "RNG");
  memmove(msg_client_hello + 11, tls->random, sizeof(tls->random));
  memmove(msg_client_hello + 44, tls->session_id, sizeof(tls->session_id));
  memmove(msg_client_hello + 94, x25519_pub, sizeof(x25519_pub));

  // client hello message
  if (mg_iobuf_add(wio, wio->len, msg_client_hello, sizeof(msg_client_hello)) ==
      0)
    return false;
  mg_sha256_update(&tls->sha256, msg_client_hello + 5,
                   sizeof(msg_client_hello) - 5);
  if (mg_iobuf_add(wio, wio->len, sig_alg, sig_alg_sz) == 0) return false;
  mg_sha256_update(&tls->sha256, sig_alg, sig_alg_sz);
  if (hostnamesz > 0) {
    if (mg_iobuf_add(wio, wio->len, server_name_ext, sizeof(server_name_ext)) ==
            0 ||
        mg_iobuf_add(wio, wio->len, hostname, hostnamesz) == 0)
      return false;
    mg_sha256_update(&tls->sha256, server_name_ext, sizeof(server_name_ext));
    mg_sha256_update(&tls->sha256, (uint8_t *) hostname, hostnamesz);
  }

  // change cipher message
  if (mg_iobuf_add(wio, wio->len, (const char *) "\x14\x03\x03\x00\x01\x01",
                   6) == 0)
    return false;
  return true;
}

static int mg_tls_client_recv_hello(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  struct mg_iobuf *rio = &c->rtls;
  uint16_t msgsz;
  uint8_t *ext;
  uint16_t ext_len;
  int j;

  if (!mg_tls_got_record(c)) {
    return MG_IO_WAIT;
  }
  if (rio->buf[0] != MG_TLS_HANDSHAKE || rio->buf[5] != MG_TLS_SERVER_HELLO) {
    if (rio->buf[0] == MG_TLS_ALERT && rio->len >= 7) {
      mg_error(c, "tls alert %d", rio->buf[6]);
      return -1;
    }
    MG_INFO(("got packet type 0x%02x/0x%02x", rio->buf[0], rio->buf[5]));
    mg_error(c, "not a server hello packet");
    return -1;
  }

  msgsz = MG_LOAD_BE16(rio->buf + 3);
  mg_sha256_update(&tls->sha256, rio->buf + 5, msgsz);

  ext_len = MG_LOAD_BE16(rio->buf + 5 + 39 + 32 + 3);
  ext = rio->buf + 5 + 39 + 32 + 3 + 2;
  if (ext_len > (rio->len - (5 + 39 + 32 + 3 + 2))) goto fail;

  for (j = 0; j < ext_len;) {
    uint16_t ext_type = MG_LOAD_BE16(ext + j);
    uint16_t ext_len2 = MG_LOAD_BE16(ext + j + 2);
    uint16_t group;
    uint8_t *key_exchange;
    uint16_t key_exchange_len;
    if (ext_len2 > (ext_len - j - 4)) goto fail;
    if (ext_type != 0x0033) {  // not a key share extension, ignore
      j += (uint16_t) (ext_len2 + 4);
      continue;
    }
    group = MG_LOAD_BE16(ext + j + 4);
    if (group != 0x001d) {
      mg_error(c, "bad key exchange group");
      return -1;
    }
    key_exchange_len = MG_LOAD_BE16(ext + j + 6);
    key_exchange = ext + j + 8;
    if (key_exchange_len != 32) {
      mg_error(c, "bad key exchange length");
      return -1;
    }
    mg_tls_x25519(tls->x25519_sec, tls->x25519_cli, key_exchange, 1);
    mg_tls_hexdump("c x25519 sec", tls->x25519_sec, 32);
    mg_tls_drop_record(c);
    /* generate handshake keys */
    mg_tls_generate_handshake_keys(c);
    return 0;
  }
fail:
  mg_error(c, "bad server hello");
  return -1;
}

static int mg_tls_client_recv_ext(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  unsigned char *recv_buf;
  if (mg_tls_recv_record(c) < 0) {
    return -1;
  }
  recv_buf = &c->rtls.buf[tls->recv_offset];
  if (recv_buf[0] != MG_TLS_ENCRYPTED_EXTENSIONS) {
    mg_error(c, "expected server extensions but got msg 0x%02x", recv_buf[0]);
    return -1;
  }
  mg_tls_drop_message(c);
  return 0;
}

struct mg_tls_cert {
  int is_ec_pubkey;
  struct mg_str sn;
  struct mg_str pubkey;
  struct mg_der_tlv subj;
  struct mg_str sig;    // signature
  uint8_t tbshash[48];  // 32b for sha256/secp256, 48b for sha384/secp384
  size_t tbshashsz;     // actual TBS hash size
};

static void mg_der_debug_cert_name(const char *name, struct mg_der_tlv *tlv) {
  struct mg_der_tlv v;
  struct mg_str cn, c, o, ou;
  cn = c = o = ou = mg_str("");
  if (mg_der_find_oid(tlv, (uint8_t *) "\x55\x04\x03", 3, &v))
    cn = mg_str_n((const char *) v.value, v.len);
  if (mg_der_find_oid(tlv, (uint8_t *) "\x55\x04\x06", 3, &v))
    c = mg_str_n((const char *) v.value, v.len);
  if (mg_der_find_oid(tlv, (uint8_t *) "\x55\x04\x0a", 3, &v))
    o = mg_str_n((const char *) v.value, v.len);
  if (mg_der_find_oid(tlv, (uint8_t *) "\x55\x04\x0b", 3, &v))
    ou = mg_str_n((const char *) v.value, v.len);
  MG_VERBOSE(("%s: CN=%.*s, C=%.*s, O=%.*s, OU=%.*s", name, cn.len, cn.buf,
              c.len, c.buf, o.len, o.buf, ou.len, ou.buf));
}

static int mg_tls_parse_cert_der(void *buf, size_t dersz,
                                 struct mg_tls_cert *cert) {
  uint8_t *tbs, *der = (uint8_t *) buf;
  size_t tbssz;
  struct mg_der_tlv root, tbs_cert, field, algo;  // pubkey, signature;
  struct mg_der_tlv pki, pki_algo, pki_key, pki_curve, raw_sig;

  // Parse outermost SEQUENCE
  if (mg_der_parse(der, dersz, &root) <= 0 || root.type != 0x30) return -1;

  // Parse TBSCertificate SEQUENCE
  tbs = root.value;
  if (mg_der_next(&root, &tbs_cert) <= 0 || tbs_cert.type != 0x30) return -1;
  tbssz = (size_t) (tbs_cert.value + tbs_cert.len - tbs);

  // Parse Version (optional field)
  if (mg_der_next(&tbs_cert, &field) <= 0) return -1;
  if (field.type == 0xa0) {  // v3
    if (mg_der_parse(field.value, field.len, &field) <= 0 || field.len != 1 ||
        field.value[0] != 2)
      return -1;
    if (mg_der_next(&tbs_cert, &field) <= 0) return -1;
  }

  // Parse Serial Number
  if (field.type != 2) return -1;
  cert->sn = mg_str_n((char *) field.value, field.len);
  MG_VERBOSE(("cert s/n: %M", mg_print_hex, cert->sn.len, cert->sn.buf));

  // Parse signature algorithm (first occurrence)
  if (mg_der_next(&tbs_cert, &field) <= 0 || field.type != 0x30) return -1;
  if (mg_der_next(&field, &algo) <= 0 || algo.type != 0x06) return -1;

  MG_VERBOSE(("sig algo (oid): %M", mg_print_hex, algo.len, algo.value));
  // Signature algorithm OID mapping
  if (algo.len == 8 &&
      memcmp(algo.value, "\x2A\x86\x48\xCE\x3D\x04\x03\x02", 8) == 0) {
    MG_VERBOSE(("sig algo: ECDSA with SHA256"));
    mg_sha256(cert->tbshash, tbs, tbssz);
    cert->tbshashsz = 32;
  } else if (algo.len == 9 &&
             memcmp(algo.value, "\x2A\x86\x48\x86\xF7\x0D\x01\x01\x0B", 9) ==
                 0) {
    MG_VERBOSE(("sig algo: RSA with SHA256"));
    mg_sha256(cert->tbshash, tbs, tbssz);
    cert->tbshashsz = 32;
  } else if (algo.len == 8 &&
             memcmp(algo.value, "\x2A\x86\x48\xCE\x3D\x04\x03\x03", 8) == 0) {
    MG_VERBOSE(("sig algo: ECDSA with SHA384"));
    mg_sha384(cert->tbshash, tbs, tbssz);
    cert->tbshashsz = 48;
  } else if (algo.len == 9 &&
             memcmp(algo.value, "\x2A\x86\x48\x86\xF7\x0D\x01\x01\x0C", 9) ==
                 0) {
    MG_VERBOSE(("sig algo: RSA with SHA384"));
    mg_sha384(cert->tbshash, tbs, tbssz);
    cert->tbshashsz = 48;
  } else {
    MG_ERROR(
        ("sig algo: unsupported OID: %M", mg_print_hex, algo.len, algo.value));
    return -1;
  }
  MG_VERBOSE(("tbs hash: %M", mg_print_hex, cert->tbshashsz, cert->tbshash));

  // issuer
  if (mg_der_next(&tbs_cert, &field) <= 0 || field.type != 0x30) return -1;
  mg_der_debug_cert_name("issuer", &field);

  // validity dates (before/after)
  if (mg_der_next(&tbs_cert, &field) <= 0 || field.type != 0x30) return -1;
  if (1) {
    struct mg_der_tlv before, after;
    mg_der_next(&field, &before);
    mg_der_next(&field, &after);
    if (after.len == 13 && memcmp(after.value, "250101000000Z", 13) < 0) {
      MG_ERROR(("invalid validity dates: before=%M after=%M", mg_print_hex,
                before.len, before.value, mg_print_hex, after.len,
                after.value));
      return -1;
    }
  }

  // subject
  if (mg_der_next(&tbs_cert, &field) <= 0 || field.type != 0x30) return -1;
  cert->subj = field;
  mg_der_debug_cert_name("subject", &field);

  // subject public key info
  if (mg_der_next(&tbs_cert, &field) <= 0 || field.type != 0x30) return -1;

  if (mg_der_next(&field, &pki) <= 0 || pki.type != 0x30) return -1;
  if (mg_der_next(&pki, &pki_algo) <= 0 || pki_algo.type != 0x06) return -1;

  // public key algorithm
  MG_VERBOSE(("pk algo (oid): %M", mg_print_hex, pki_algo.len, pki_algo.value));
  if (pki_algo.len == 8 &&
      memcmp(pki_algo.value, "\x2A\x86\x48\xCE\x3D\x03\x01\x07", 8) == 0) {
    cert->is_ec_pubkey = 1;
    MG_VERBOSE(("pk algo: ECDSA secp256r1"));
  } else if (pki_algo.len == 8 &&
             memcmp(pki_algo.value, "\x2A\x86\x48\xCE\x3D\x03\x01\x08", 8) ==
                 0) {
    cert->is_ec_pubkey = 1;
    MG_VERBOSE(("pk algo: ECDSA secp384r1"));
  } else if (pki_algo.len == 7 &&
             memcmp(pki_algo.value, "\x2A\x86\x48\xCE\x3D\x02\x01", 7) == 0) {
    cert->is_ec_pubkey = 1;
    MG_VERBOSE(("pk algo: EC public key"));
  } else if (pki_algo.len == 9 &&
             memcmp(pki_algo.value, "\x2A\x86\x48\x86\xF7\x0D\x01\x01\x01",
                    9) == 0) {
    cert->is_ec_pubkey = 0;
    MG_VERBOSE(("pk algo: RSA"));
  } else {
    MG_ERROR(("unsupported pk algo: %M", mg_print_hex, pki_algo.len,
              pki_algo.value));
    return -1;
  }

  // Parse public key
  if (cert->is_ec_pubkey) {
    if (mg_der_next(&pki, &pki_curve) <= 0 || pki_curve.type != 0x06) return -1;
  }
  if (mg_der_next(&field, &pki_key) <= 0 || pki_key.type != 0x03) return -1;

  if (cert->is_ec_pubkey) {  // Skip leading 0x00 and 0x04 (=uncompressed)
    cert->pubkey = mg_str_n((char *) pki_key.value + 2, pki_key.len - 2);
  } else {  // Skip leading 0x00 byte
    cert->pubkey = mg_str_n((char *) pki_key.value + 1, pki_key.len - 1);
  }

  // Parse signature
  if (mg_der_next(&root, &field) <= 0 || field.type != 0x30) return -1;
  if (mg_der_next(&root, &raw_sig) <= 0 || raw_sig.type != 0x03) return -1;
  if (raw_sig.len < 1 || raw_sig.value[0] != 0x00) return -1;

  cert->sig = mg_str_n((char *) raw_sig.value + 1, raw_sig.len - 1);
  MG_VERBOSE(("sig: %M", mg_print_hex, cert->sig.len, cert->sig.buf));

  return 0;
}

static int mg_tls_verify_cert_san(const uint8_t *der, size_t dersz,
                                  const char *server_name,
                                  struct mg_addr *server_ip) {
  struct mg_der_tlv root, field, name;
  if (mg_der_parse((uint8_t *) der, dersz, &root) < 0) {
    MG_ERROR(("failed to parse certificate"));
    return -1;
  }
  if (mg_der_find_oid(&root, (uint8_t *) "\x55\x1d\x11", 3, &field) <= 0) {
    MG_ERROR(("failed to extract SAN"));
    return -1;
  }
  if (mg_der_parse(field.value, field.len, &field) < 0) {
    MG_ERROR(("SAN is not a constructed object"));
    return -1;
  }
  while (mg_der_next(&field, &name) > 0) {
    if (name.type == 0x87 && name.len == 4) {  // this is an IPv4 address
      MG_VERBOSE(("Found SAN, IP: %M", mg_print_ip4, name.value));
      if (!server_ip->is_ip6 &&
          *((uint32_t *) name.value) == server_ip->addr.ip4)
        return 1;  // and matches the one we're connected to
    } else {       // this is a text SAN
      MG_VERBOSE(("Found SAN, (%u): %.*s", name.type, name.len, name.value));
      if (mg_match(mg_str(server_name), mg_str_n((char *) name.value, name.len),
                   NULL))
        return 1;  // and matches the host name
    }  // TODO(): add IPv6 comparison, more items ?
  }
  return -1;
}

static int mg_tls_verify_cert_signature(const struct mg_tls_cert *cert,
                                        const struct mg_tls_cert *issuer) {
  if (issuer->is_ec_pubkey) {
    uint8_t sig[128];
    struct mg_der_tlv seq = {0, 0, 0}, a = {0, 0, 0}, b = {0, 0, 0};
    mg_der_parse((uint8_t *) cert->sig.buf, cert->sig.len, &seq);
    mg_der_next(&seq, &a);
    mg_der_next(&seq, &b);
    if (a.len == 0 || b.len == 0) {
      MG_ERROR(("cert verification error"));
      return 0;
    }
    if (issuer->pubkey.len == 64) {
      const uint32_t N = 32;
      if (a.len > N) a.value += (a.len - N), a.len = N;
      if (b.len > N) b.value += (b.len - N), b.len = N;
      memmove(sig, a.value, N);
      memmove(sig + N, b.value, N);
      return mg_uecc_verify((uint8_t *) issuer->pubkey.buf, cert->tbshash,
                            (unsigned) cert->tbshashsz, sig,
                            mg_uecc_secp256r1());
    } else if (issuer->pubkey.len == 96) {
      MG_ERROR(("reject secp386 for now"));
      return 0;
    } else {
      MG_ERROR(("unsupported public key length: %d", issuer->pubkey.len));
      return 0;
    }
  } else {
    int r;
    uint8_t sig2[256];  // 2048 bits
    struct mg_der_tlv seq, modulus, exponent;
    if (mg_der_parse((uint8_t *) issuer->pubkey.buf, issuer->pubkey.len,
                     &seq) <= 0 ||
        mg_der_next(&seq, &modulus) <= 0 || modulus.type != 2 ||
        mg_der_next(&seq, &exponent) <= 0 || exponent.type != 2) {
      return -1;
    }
    mg_rsa_mod_pow(modulus.value, modulus.len, exponent.value, exponent.len,
                   (uint8_t *) cert->sig.buf, cert->sig.len, sig2,
                   sizeof(sig2));

    r = memcmp(sig2 + sizeof(sig2) - cert->tbshashsz, cert->tbshash,
               cert->tbshashsz);
    return r == 0;
  }
}

static int mg_tls_verify_cert_cn(struct mg_der_tlv *subj, const char *host) {
  struct mg_der_tlv v;
  int matched = 0;
  if (mg_der_find_oid(subj, (uint8_t *) "\x55\x04\x03", 3, &v) > 0) {
    MG_VERBOSE(("using CN: %.*s <-> %s", v.len, v.value, host));
    matched = mg_match(mg_str(host), mg_str_n((char *) v.value, v.len), NULL);
  }
  return matched;
}

static int mg_tls_recv_cert(struct mg_connection *c, bool is_client) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  unsigned char *recv_buf;

  if (mg_tls_recv_record(c) < 0) {
    return -1;
  }

  recv_buf = &c->rtls.buf[tls->recv_offset];

  if (recv_buf[0] == MG_TLS_CERTIFICATE_REQUEST) {
    MG_VERBOSE(("got certificate request"));
    mg_tls_drop_message(c);
    tls->cert_requested = 1;
    return -1;
  }

  if (recv_buf[0] != MG_TLS_CERTIFICATE) {
    mg_error(c, "expected %s certificate but got msg 0x%02x",
             is_client ? "server" : "client", recv_buf[0]);
    return -1;
  }

  if (tls->recv_len < 11) {
    mg_error(c, "certificate list too short");
    return -1;
  }

  {
    // Normally, there are 2-3 certs in a chain (when is_client)
    struct mg_tls_cert certs[8];
    int certnum = 0;
    uint32_t full_cert_chain_len = MG_LOAD_BE24(recv_buf + 1);
    uint32_t cert_chain_len = MG_LOAD_BE24(recv_buf + 5);
    uint8_t *p = recv_buf + 8;
    uint8_t *endp = recv_buf + cert_chain_len;
    bool found_ca = false;
    struct mg_tls_cert ca;

    if (cert_chain_len != full_cert_chain_len - 4) {
      MG_ERROR(("full chain length: %d, chain length: %d", full_cert_chain_len,
                cert_chain_len));
      mg_error(c, "certificate chain length mismatch");
      return -1;
    }

    memset(certs, 0, sizeof(certs));
    memset(&ca, 0, sizeof(ca));

    if (tls->ca_der.len > 0) {
      if (mg_tls_parse_cert_der(tls->ca_der.buf, tls->ca_der.len, &ca) < 0) {
        mg_error(c, "failed to parse CA certificate");
        return -1;
      }
      MG_VERBOSE(("CA serial: %M", mg_print_hex, ca.sn.len, ca.sn.buf));
    }

    while (p < endp) {
      struct mg_tls_cert *ci = &certs[certnum++];
      uint32_t certsz = MG_LOAD_BE24(p);
      uint8_t *cert = p + 3;
      uint16_t certext = MG_LOAD_BE16(cert + certsz);
      if (certext != 0) {
        mg_error(c, "certificate extensions are not supported");
        return -1;
      }
      p = cert + certsz + 2;

      if (mg_tls_parse_cert_der(cert, certsz, ci) < 0) {
        mg_error(c, "failed to parse certificate");
        return -1;
      }

      if (ci == certs) {
        // First certificate in the chain is peer cert, check SAN if requested,
        // and store public key for further CertVerify step
        if (tls->hostname[0] != '\0' &&
            mg_tls_verify_cert_san(cert, certsz, tls->hostname, &c->rem) <= 0 &&
            mg_tls_verify_cert_cn(&ci->subj, tls->hostname) <= 0) {
          mg_error(c, "failed to verify hostname");
          return -1;
        }
        if (ci->pubkey.len > sizeof(tls->pubkey)) {
          mg_error(c, "invalid certificate length");
          return -1;
        }
        if (ci->pubkey.len > sizeof(tls->pubkey)) {
          mg_error(c, "peer public key too large");
          return -1;
        }
        memmove(tls->pubkey, ci->pubkey.buf, ci->pubkey.len);
        tls->pubkeysz = ci->pubkey.len;
      } else {
        if (!mg_tls_verify_cert_signature(ci - 1, ci)) {
          mg_error(c, "failed to verify certificate chain");
          return -1;
        }
      }

      if (ca.pubkey.len == ci->pubkey.len &&
          memcmp(ca.pubkey.buf, ci->pubkey.buf, ca.pubkey.len) == 0) {
        found_ca = true;
        break;
      }

      if (certnum == sizeof(certs) / sizeof(certs[0]) - 1) {
        mg_error(c, "too many certificates in the chain");
        return -1;
      }
    }

    if (!found_ca && tls->ca_der.len > 0) {
      if (certnum < 1 ||
          !mg_tls_verify_cert_signature(&certs[certnum - 1], &ca)) {
        mg_error(c, "failed to verify CA");
        return -1;
      } else if (is_client) {
        MG_VERBOSE(
            ("CA was not in the chain, but verification with builtin CA "
             "passed"));
      }
    }
  }
  mg_tls_drop_message(c);
  mg_tls_calc_cert_verify_hash(c, tls->sighash, !is_client);
  return 0;
}

static int mg_tls_recv_cert_verify(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  unsigned char *recv_buf;
  if (mg_tls_recv_record(c) < 0) {
    return -1;
  }
  recv_buf = &c->rtls.buf[tls->recv_offset];
  if (recv_buf[0] != MG_TLS_CERTIFICATE_VERIFY) {
    mg_error(c, "expected %s certificate verify but got msg 0x%02x",
             c->is_client ? "server" : "client", recv_buf[0]);
    return -1;
  }
  if (tls->recv_len < 8) {
    mg_error(c, "server certificate verify is too short: %d bytes",
             tls->recv_len);
    return -1;
  }

  // Ignore CertificateVerify if strict checks are not required
  if (tls->skip_verification) {
    mg_tls_drop_message(c);
    return 0;
  }

  {
    uint16_t sigalg = MG_LOAD_BE16(recv_buf + 4);
    uint16_t siglen = MG_LOAD_BE16(recv_buf + 6);
    uint8_t *sigbuf = recv_buf + 8;
    if (siglen > tls->recv_len - 8) {
      mg_error(c, "invalid certverify signature length: %d, expected %d",
               siglen, tls->recv_len - 8);
      return -1;
    }
    MG_VERBOSE(
        ("certificate verification, algo=%04x, siglen=%d", sigalg, siglen));

    if (sigalg == 0x0804) {  // rsa_pss_rsae_sha256
      uint8_t sig2[512];     // 2048 or 4096 bits
      struct mg_der_tlv seq, modulus, exponent;

      if (mg_der_parse(tls->pubkey, tls->pubkeysz, &seq) <= 0 ||
          mg_der_next(&seq, &modulus) <= 0 || modulus.type != 2 ||
          mg_der_next(&seq, &exponent) <= 0 || exponent.type != 2) {
        mg_error(c, "invalid public key");
        return -1;
      }

      mg_rsa_mod_pow(modulus.value, modulus.len, exponent.value, exponent.len,
                     sigbuf, siglen, sig2, sizeof(sig2));

      if (sig2[sizeof(sig2) - 1] != 0xbc) {
        mg_error(c, "failed to verify RSA certificate (certverify)");
        return -1;
      }
      MG_VERBOSE(("certificate verification successful (RSA)"));
    } else if (sigalg == 0x0403) {  // ecdsa_secp256r1_sha256
      // Extract certificate signature and verify it using pubkey and sighash
      uint8_t sig[64];
      struct mg_der_tlv seq, r, s;
      memset(sig, 0, 64);
      if (mg_der_to_tlv(sigbuf, siglen, &seq) < 0) {
        mg_error(c, "verification message is not an ASN.1 DER sequence");
        return -1;
      }
      if (mg_der_to_tlv(seq.value, seq.len, &r) < 0) {
        mg_error(c, "missing first part of the signature");
        return -1;
      }
      if (mg_der_to_tlv(r.value + r.len, seq.len - r.len, &s) < 0) {
        mg_error(c, "missing second part of the signature");
        return -1;
      }
      // Integers may be padded with zeroes
      if (r.len > 32) r.value = r.value + (r.len - 32), r.len = 32;
      if (s.len > 32) s.value = s.value + (s.len - 32), s.len = 32;

      // r or s may be shorter than 32 bytes, "right-justify" (network order)
      memmove(sig + (32 - r.len), r.value, r.len);
      memmove(sig + 32 + (32 - s.len), s.value, s.len);

      if (mg_uecc_verify(tls->pubkey, tls->sighash, sizeof(tls->sighash), sig,
                         mg_uecc_secp256r1()) != 1) {
        mg_error(c, "failed to verify EC certificate (certverify)");
        return -1;
      }
      MG_VERBOSE(("certificate verification successful (EC)"));
    } else {
      // From
      // https://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml:
      //   0805 = rsa_pss_rsae_sha384
      //   0806 = rsa_pss_rsae_sha512
      //   0807 = ed25519
      //   0808 = ed448
      //   0809 = rsa_pss_pss_sha256
      //   080A = rsa_pss_pss_sha384
      //   080B = rsa_pss_pss_sha512
      MG_ERROR(("unsupported certverify signature scheme: %x of %d bytes",
                sigalg, siglen));
      return -1;
    }
  }
  mg_tls_drop_message(c);
  return 0;
}

static int mg_tls_client_recv_finish(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  unsigned char *recv_buf;
  if (mg_tls_recv_record(c) < 0) {
    return -1;
  }
  recv_buf = &c->rtls.buf[tls->recv_offset];
  if (recv_buf[0] != MG_TLS_FINISHED) {
    mg_error(c, "expected server finished but got msg 0x%02x", recv_buf[0]);
    return -1;
  }
  mg_tls_drop_message(c);
  return 0;
}

static bool mg_tls_client_send_finish(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  mg_sha256_ctx sha256;
  uint8_t hash[32];
  uint8_t finish[36] = {0x14, 0, 0, 32};
  memmove(&sha256, &tls->sha256, sizeof(mg_sha256_ctx));
  mg_sha256_final(hash, &sha256);
  mg_hmac_sha256(finish + 4, tls->enc.client_finished_key, 32, hash, 32);
  return mg_tls_encrypt(c, finish, sizeof(finish), MG_TLS_HANDSHAKE);
}

static bool mg_tls_client_handshake(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  switch (tls->state) {
    case MG_TLS_STATE_CLIENT_START:
      if (!mg_tls_client_send_hello(c)) return false;
      tls->state = MG_TLS_STATE_CLIENT_WAIT_SH;
      // Fallthrough
    case MG_TLS_STATE_CLIENT_WAIT_SH:
      if (mg_tls_client_recv_hello(c) < 0) break;
      tls->state = MG_TLS_STATE_CLIENT_WAIT_EE;
      // Fallthrough
    case MG_TLS_STATE_CLIENT_WAIT_EE:
      if (mg_tls_client_recv_ext(c) < 0) break;
      tls->state = MG_TLS_STATE_CLIENT_WAIT_CERT;
      // Fallthrough
    case MG_TLS_STATE_CLIENT_WAIT_CERT:
      if (mg_tls_recv_cert(c, true) < 0) break;
      tls->state = MG_TLS_STATE_CLIENT_WAIT_CV;
      // Fallthrough
    case MG_TLS_STATE_CLIENT_WAIT_CV:
      if (mg_tls_recv_cert_verify(c) < 0) break;
      tls->state = MG_TLS_STATE_CLIENT_WAIT_FINISH;
      // Fallthrough
    case MG_TLS_STATE_CLIENT_WAIT_FINISH:
      if (mg_tls_client_recv_finish(c) < 0) break;
      if (tls->cert_requested && tls->cert_der.len > 0) {  // two-way auth
        // generate application keys at this point, keep using handshake keys
        struct tls_enc hs_keys = tls->enc;
        mg_tls_generate_application_keys(c);
        tls->app_keys = tls->enc;
        tls->enc = hs_keys;
        if (!mg_tls_send_cert(c, true) || !mg_tls_send_cert_verify(c, true) ||
            !mg_tls_client_send_finish(c))
          return false;
        tls->enc = tls->app_keys;
      } else {
        if (!mg_tls_client_send_finish(c)) return false;
        mg_tls_generate_application_keys(c);
      }
      tls->state = MG_TLS_STATE_CLIENT_CONNECTED;
      c->is_tls_hs = 0;
      mg_call(c, MG_EV_TLS_HS, NULL);
      break;
    default:
      mg_error(c, "unexpected client state: %d", tls->state);
      break;
  }
  return true;
}

static bool mg_tls_server_handshake(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  switch (tls->state) {
    case MG_TLS_STATE_SERVER_START:
      if (mg_tls_server_recv_hello(c) < 0) break;
      if (!mg_tls_server_send_hello(c)) return false;
      mg_tls_generate_handshake_keys(c);
      if (!mg_tls_server_send_ext(c)) return false;
      if (tls->is_twoway && !mg_tls_server_send_cert_request(c)) return false;
      if (!mg_tls_send_cert(c, false) || !mg_tls_send_cert_verify(c, false) ||
          !mg_tls_server_send_finish(c))
        return false;
      if (tls->is_twoway) {
        // generate application keys at this point, keep using handshake keys
        struct tls_enc hs_keys = tls->enc;
        mg_tls_generate_application_keys(c);
        tls->app_keys = tls->enc;
        tls->enc = hs_keys;
        tls->state = MG_TLS_STATE_SERVER_WAIT_CERT;
        break;
      }
      tls->state = MG_TLS_STATE_SERVER_NEGOTIATED;
      // fallthrough
    case MG_TLS_STATE_SERVER_NEGOTIATED:
      if (mg_tls_server_recv_finish(c) < 0) break;
      if (tls->is_twoway) {  // use previously generated keys
        tls->enc = tls->app_keys;
      } else {  // generate keys now
        mg_tls_generate_application_keys(c);
      }
      tls->state = MG_TLS_STATE_SERVER_CONNECTED;
      c->is_tls_hs = 0;
      break;
    case MG_TLS_STATE_SERVER_WAIT_CERT:
      if (mg_tls_recv_cert(c, false) < 0) break;
      tls->state = MG_TLS_STATE_SERVER_WAIT_CV;
      // Fallthrough
    case MG_TLS_STATE_SERVER_WAIT_CV:
      if (mg_tls_recv_cert_verify(c) < 0) break;
      tls->state = MG_TLS_STATE_SERVER_NEGOTIATED;
      break;
    default:
      mg_error(c, "unexpected server state: %d", tls->state);
      break;
  }
  return true;
}

void mg_tls_handshake(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  long n;
  bool res;
  if (c->is_closing) return;  // we don't clear rx buf, so ignore what's left
  if (c->is_client) {
    // will clear is_hs when sending last chunk
    res = mg_tls_client_handshake(c);
  } else {
    res = mg_tls_server_handshake(c);
  }
  if (!res) {
    mg_error(c, "TLS OOM");
    return;
  }
  while (tls->send.len > 0 &&
         (n = mg_io_send(c, tls->send.buf, tls->send.len)) > 0) {
    mg_iobuf_del(&tls->send, 0, (size_t) n);
  }  // if last chunk fails to be sent, it will be sent with first app data,
     // otherwise, it needs to be flushed
}

static int mg_rsa_parse_der_int(const uint8_t **p, const uint8_t *end,
                                struct mg_str *out) {
  const uint8_t *start = *p, *value_start, *value_end;
  uint8_t i;
  uint32_t len;

  if (end - start < 2) {
    MG_VERBOSE(("DER INT: not enough bytes (%d < 2)", (int) (end - start)));
    return -1;
  }
  if (start[0] != 0x02) {
    MG_VERBOSE(("DER INT: expected 0x02, got 0x%02x", start[0]));
    return -1;
  }

  len = start[1];
  *p = start + 2;

  if (len > 0x7F) {
    // Long form length
    uint8_t len_bytes = len & 0x7F;
    MG_VERBOSE(("DER INT: long form, %d length bytes", len_bytes));
    if (end - *p < len_bytes) {
      MG_VERBOSE(("DER INT: not enough bytes for length"));
      return -1;
    }
    len = 0;
    for (i = 0; i < len_bytes; i++) {
      len = (len << 8) | (*p)[i];
    }
    *p += len_bytes;
  }

  MG_VERBOSE(("DER INT: length=%u, remaining=%d", len, (int) (end - *p)));

  if (end - *p < (long) len) {
    MG_VERBOSE(("DER INT: length exceeds remaining bytes"));
    return -1;
  }

  // The encoded length tells us how many bytes to consume from the stream
  value_start = *p;
  value_end = *p + len;

  // Skip leading zero byte if present (for positive numbers)
  // This doesn't change how many bytes we consume, just what we expose
  if (len > 0 && (*p)[0] == 0x00) {
    (*p)++;
    len--;
  }

  out->buf = (char *) *p;
  out->len = len;

  // Advance pointer by the ORIGINAL encoded length, not the adjusted length
  *p = value_end;

  MG_VERBOSE(("DER INT: parsed %u bytes (skipped zero=%d)", len,
              (size_t) (value_end - value_start) != (size_t) len ? 1 : 0));
  return 0;
}

// RFC 5915 ECPrivateKey ::= SEQUENCE {
//   version INTEGER { ecPrivkeyVer1(1) },
//   privateKey OCTET STRING,
//   parameters [0] ECParameters {{ NamedCurve }} OPTIONAL,
//   publicKey [1] BIT STRING OPTIONAL
// }
static int mg_parse_ec_private_key(const uint8_t *der, size_t dersz,
                                   uint8_t *ec_key) {
  struct mg_der_tlv root, version, private_key_octets;

  if (mg_der_parse((uint8_t *) der, dersz, &root) < 0 || root.type != 0x30) {
    MG_ERROR(("EC private key: invalid SEQUENCE"));
    return -1;
  }

  if (mg_der_next(&root, &version) < 0 || version.type != 0x02) {
    MG_ERROR(("EC private key: invalid version"));
    return -1;
  }

  if (mg_der_next(&root, &private_key_octets) < 0 ||
      private_key_octets.type != 0x04) {
    MG_ERROR(("EC private key: invalid privateKey OCTET STRING"));
    return -1;
  }

  if (private_key_octets.len != 32) {
    MG_ERROR(
        ("EC private key: expected 32 bytes, got %u", private_key_octets.len));
    return -1;
  }

  memcpy(ec_key, private_key_octets.value, 32);
  return 0;
}

// Parse RSA private key from DER format
// RSAPrivateKey ::= SEQUENCE {
//   version           INTEGER (0),
//   modulus           INTEGER,  -- n
//   publicExponent    INTEGER,  -- e
//   privateExponent   INTEGER,  -- d
//   prime1            INTEGER,  -- p
//   prime2            INTEGER,  -- q
//   exponent1         INTEGER,  -- dP = d mod (p-1)
//   exponent2         INTEGER,  -- dQ = d mod (q-1)
//   coefficient       INTEGER,  -- qInv = (inverse of q) mod p
// }
static int mg_rsa_parse_key(const uint8_t *der, size_t dersz,
                            struct mg_rsa_key *key) {
  const uint8_t *p = der;
  const uint8_t *end = der + dersz;
  uint32_t seq_len;
  struct mg_str version;

  memset(key, 0, sizeof(*key));

  // Debug: show first few bytes
  MG_VERBOSE(
      ("RSA key DER first 16 bytes: %02x %02x %02x %02x %02x %02x %02x %02x "
       "%02x %02x %02x %02x %02x %02x %02x %02x",
       der[0], der[1], der[2], der[3], der[4], der[5], der[6], der[7], der[8],
       der[9], der[10], der[11], der[12], der[13], der[14], der[15]));

  // Parse outer SEQUENCE
  if (end - p < 2) {
    MG_ERROR(("RSA key too short for SEQUENCE header"));
    return -1;
  }
  if (p[0] != 0x30) {
    MG_ERROR(("RSA key: expected SEQUENCE (0x30), got 0x%02x", p[0]));
    return -1;
  }

  seq_len = p[1];
  p += 2;

  if (seq_len > 0x7F) {
    // Long form length
    uint8_t i, len_bytes = seq_len & 0x7F;
    MG_VERBOSE(("Long form length: %d bytes", len_bytes));
    if (end - p < len_bytes) {
      MG_ERROR(("Not enough bytes for long form length"));
      return -1;
    }
    seq_len = 0;
    for (i = 0; i < len_bytes; i++) {
      seq_len = (seq_len << 8) | p[i];
    }
    p += len_bytes;
  }

  MG_VERBOSE(
      ("SEQUENCE length: %u, total DER size: %u", seq_len, (unsigned) dersz));

  if (end - p < (long) seq_len) {
    MG_ERROR(("SEQUENCE length exceeds buffer"));
    return -1;
  }
  end = p + seq_len;  // Adjust end to sequence boundary

  // Parse version (should be 0)
  MG_VERBOSE(("Before version: offset=%d, bytes: %02x %02x %02x %02x",
              (int) (p - der), p[0], p[1], p[2], p[3]));
  if (mg_rsa_parse_der_int(&p, end, &version) < 0) {
    MG_ERROR(("Failed to parse version"));
    return -1;
  }
  MG_DEBUG(("Version: %d byte(s), value=%d, offset now=%d", (int) version.len,
            version.len > 0 ? (int) (unsigned char) version.buf[0] : -1,
            (int) (p - der)));

  // Parse the 8 components: n, e, d, p, q, dP, dQ, qInv
  MG_VERBOSE(("Before n: offset=%d, bytes: %02x %02x %02x %02x %02x %02x",
              (int) (p - der), p[0], p[1], p[2], p[3], p[4], p[5]));
  if (mg_rsa_parse_der_int(&p, end, &key->n) < 0) {
    MG_ERROR(("Failed to parse n (modulus)"));
    return -1;
  }
  MG_VERBOSE(("Parsed n: %d bytes, offset now=%d, consumed=%d bytes total",
              (int) key->n.len, (int) (p - der), (int) (p - der)));
  MG_VERBOSE(("  First 8 bytes of n: %02x %02x %02x %02x %02x %02x %02x %02x",
              (unsigned char) key->n.buf[0], (unsigned char) key->n.buf[1],
              (unsigned char) key->n.buf[2], (unsigned char) key->n.buf[3],
              (unsigned char) key->n.buf[4], (unsigned char) key->n.buf[5],
              (unsigned char) key->n.buf[6], (unsigned char) key->n.buf[7]));
  MG_VERBOSE(("  Next bytes after n: %02x %02x %02x %02x %02x %02x",
              p < end ? p[0] : 0xFF, p + 1 < end ? p[1] : 0xFF,
              p + 2 < end ? p[2] : 0xFF, p + 3 < end ? p[3] : 0xFF,
              p + 4 < end ? p[4] : 0xFF, p + 5 < end ? p[5] : 0xFF));

  if (mg_rsa_parse_der_int(&p, end, &key->e) < 0) {
    MG_ERROR(("Failed to parse e (public exponent), bytes remaining: %d",
              (int) (end - p)));
    if (end - p >= 4) {
      MG_ERROR(("  Next 4 bytes: %02x %02x %02x %02x", p[0], p[1], p[2], p[3]));
    }
    return -1;
  }
  if (mg_rsa_parse_der_int(&p, end, &key->d) < 0) {
    MG_ERROR(("Failed to parse d (private exponent)"));
    return -1;
  }
  if (mg_rsa_parse_der_int(&p, end, &key->p) < 0) {
    MG_ERROR(("Failed to parse p (prime1)"));
    return -1;
  }
  if (mg_rsa_parse_der_int(&p, end, &key->q) < 0) {
    MG_ERROR(("Failed to parse q (prime2)"));
    return -1;
  }
  if (mg_rsa_parse_der_int(&p, end, &key->dP) < 0) {
    MG_ERROR(("Failed to parse dP (exponent1)"));
    return -1;
  }
  if (mg_rsa_parse_der_int(&p, end, &key->dQ) < 0) {
    MG_ERROR(("Failed to parse dQ (exponent2)"));
    return -1;
  }
  if (mg_rsa_parse_der_int(&p, end, &key->qInv) < 0) {
    MG_ERROR(("Failed to parse qInv (coefficient)"));
    return -1;
  }

  MG_VERBOSE(("Successfully parsed RSA key"));
  return 0;
}

// PKCS#8 PrivateKeyInfo ::= SEQUENCE {
//   version INTEGER,
//   privateKeyAlgorithm AlgorithmIdentifier,
//   privateKey OCTET STRING,
//   attributes [0] Attributes OPTIONAL
// }
// AlgorithmIdentifier ::= SEQUENCE {
//   algorithm OBJECT IDENTIFIER,
//   parameters ANY OPTIONAL
// }
static int mg_parse_pkcs8_key(const uint8_t *der, size_t dersz,
                              struct tls_data *tls) {
  struct mg_der_tlv root, version, alg_id, private_key_octets;
  struct mg_der_tlv alg_oid, alg_params;

  if (mg_der_parse((uint8_t *) der, dersz, &root) < 0 || root.type != 0x30) {
    MG_ERROR(("PKCS#8: invalid PrivateKeyInfo SEQUENCE"));
    return -1;
  }

  if (mg_der_next(&root, &version) < 0 || version.type != 0x02) {
    MG_ERROR(("PKCS#8: invalid version"));
    return -1;
  }

  if (mg_der_next(&root, &alg_id) < 0 || alg_id.type != 0x30) {
    MG_ERROR(("PKCS#8: invalid AlgorithmIdentifier SEQUENCE"));
    return -1;
  }

  if (mg_der_next(&alg_id, &alg_oid) < 0 || alg_oid.type != 0x06) {
    MG_ERROR(("PKCS#8: invalid algorithm OID"));
    return -1;
  }

  if (mg_der_next(&root, &private_key_octets) < 0 ||
      private_key_octets.type != 0x04) {
    MG_ERROR(("PKCS#8: invalid privateKey OCTET STRING"));
    return -1;
  }

  if (alg_oid.len == sizeof(mg_rsa_oid) &&
      memcmp(alg_oid.value, mg_rsa_oid, sizeof(mg_rsa_oid)) == 0) {
    struct mg_rsa_key rsa_key;
    if (mg_rsa_parse_key(private_key_octets.value, private_key_octets.len,
                         &rsa_key) < 0) {
      MG_ERROR(("PKCS#8: failed to parse inner RSA key"));
      return -1;
    }
    tls->rsa = rsa_key;
    return 0;

  } else if (alg_oid.len == sizeof(mg_ec_public_key_oid) &&
             memcmp(alg_oid.value, mg_ec_public_key_oid,
                    sizeof(mg_ec_public_key_oid)) == 0) {
    if (mg_der_next(&alg_id, &alg_params) < 0 || alg_params.type != 0x06) {
      MG_ERROR(("PKCS#8: invalid EC parameters OID"));
      return -1;
    }

    if (alg_params.len != sizeof(mg_secp256r1_oid) ||
        memcmp(alg_params.value, mg_secp256r1_oid, sizeof(mg_secp256r1_oid)) !=
            0) {
      MG_ERROR(("PKCS#8: unsupported EC curve (only secp256r1 supported)"));
      return -1;
    }

    return mg_parse_ec_private_key(private_key_octets.value,
                                   private_key_octets.len, tls->ec_key);

  } else {
    MG_ERROR(("PKCS#8: unsupported algorithm"));
    return -1;
  }
}

static int mg_parse_pem(const struct mg_str pem, const struct mg_str label,
                        struct mg_str *der) {
  size_t n = 0, m = 0;
  char *s;
  const char *c;
  struct mg_str caps[6];  // number of wildcards + 1
  if (!mg_match(pem, mg_str("#-----BEGIN #-----#-----END #-----#"), caps)) {
    *der = mg_strdup(pem);
    return 0;
  }
  if (mg_strcmp(caps[1], label) != 0 || mg_strcmp(caps[3], label) != 0) {
    return -1;  // bad label
  }
  if ((s = (char *) mg_calloc(1, caps[2].len)) == NULL) {
    return -1;
  }

  for (c = caps[2].buf; c < caps[2].buf + caps[2].len; c++) {
    if (*c == ' ' || *c == '\n' || *c == '\r' || *c == '\t') {
      continue;
    }
    s[n++] = *c;
  }
  m = mg_base64_decode(s, n, s, n);
  if (m == 0) {
    mg_free(s);
    return -1;
  }
  der->buf = s;
  der->len = m;
  return 0;
}

static int mg_parse_pem_certs(const struct mg_str pem, struct mg_str **ders) {
  int count = 0;
  struct mg_str *certs = NULL;
  const char *p = pem.buf;
  const char *end = pem.buf + pem.len;
  const char *begin_marker = "-----BEGIN CERTIFICATE-----";
  const char *end_marker = "-----END CERTIFICATE-----";
  size_t begin_len = strlen(begin_marker);
  size_t end_len = strlen(end_marker);

  while (p < end) {
    const char *s, *begin = NULL, *finish = NULL;
    struct mg_str cert_pem, cert_der, *new_certs;
    int i;

    for (s = p; s <= end - (int) begin_len; s++) {
      if (memcmp(s, begin_marker, begin_len) == 0) {
        begin = s;
        break;
      }
    }
    if (begin == NULL) break;

    for (s = begin + begin_len; s <= end - (int) end_len; s++) {
      if (memcmp(s, end_marker, end_len) == 0) {
        finish = s + end_len;
        break;
      }
    }
    if (finish == NULL) {
      for (i = 0; i < count; i++) mg_free((void *) certs[i].buf);
      mg_free(certs);
      return -1;
    }

    cert_pem = mg_str_n(begin, (size_t) (finish - begin));
    if (mg_parse_pem(cert_pem, mg_str_s("CERTIFICATE"), &cert_der) < 0) {
      for (i = 0; i < count; i++) mg_free((void *) certs[i].buf);
      mg_free(certs);
      return -1;
    }

    new_certs =
        (struct mg_str *) mg_calloc((size_t) count + 1, sizeof(*new_certs));
    if (new_certs == NULL) {
      mg_free((void *) cert_der.buf);
      for (i = 0; i < count; i++) mg_free((void *) certs[i].buf);
      mg_free(certs);
      return -1;
    }
    if (count > 0) {
      memmove(new_certs, certs, (size_t) count * sizeof(struct mg_str));
      mg_free(certs);
    }
    certs = new_certs;

    certs[count++] = cert_der;
    p = finish;
  }

  *ders = certs;
  return count;
}

void mg_tls_init(struct mg_connection *c, const struct mg_tls_opts *opts) {
  struct mg_str key;
  struct tls_data *tls =
      (struct tls_data *) mg_calloc(1, sizeof(struct tls_data));
  if (tls == NULL) {
    mg_error(c, "tls oom");
    return;
  }

  tls->state =
      c->is_client ? MG_TLS_STATE_CLIENT_START : MG_TLS_STATE_SERVER_START;

  tls->skip_verification = opts->skip_verification;
  // tls->send.align = MG_IO_SIZE;

  c->tls = tls;
  c->is_tls = c->is_tls_hs = 1;
  mg_sha256_init(&tls->sha256);

  // save hostname (client extension)
  if (opts->name.len > 0) {
    if (opts->name.len >= sizeof(tls->hostname) - 1) {
      mg_error(c, "hostname too long");
      return;
    }
    strncpy((char *) tls->hostname, opts->name.buf, sizeof(tls->hostname) - 1);
    tls->hostname[opts->name.len] = 0;
  }
  // server CA certificate, store serial number
  if (opts->ca.len > 0) {
    if (mg_parse_pem(opts->ca, mg_str_s("CERTIFICATE"), &tls->ca_der) < 0) {
      MG_ERROR(("Failed to load certificate"));
      return;
    }
    if (!c->is_client) tls->is_twoway = true;  // server + CA: two-way auth
  }

  if (opts->cert.buf == NULL) {
    MG_VERBOSE(("No certificate provided"));
    return;
  }

  // parse PEM or DER certificate
  {
    struct mg_str *all_certs = NULL;
    int cert_count = mg_parse_pem_certs(opts->cert, &all_certs);

    if (cert_count > 0) {
      tls->cert_der.buf = all_certs[0].buf;
      tls->cert_der.len = all_certs[0].len;
      if (cert_count > 1) {
        tls->chain_len = (size_t) cert_count;
        tls->chain_der = all_certs;
      } else {
        mg_free(all_certs);
      }
    } else {
      if (mg_parse_pem(opts->cert, mg_str_s("CERTIFICATE"), &tls->cert_der) <
          0) {
        MG_ERROR(("Failed to load certificate"));
        return;
      }
    }
  }

  // parse PEM or DER EC key
  if (opts->key.buf == NULL) {
    mg_error(c, "Certificate provided without a private key");
    return;
  }

  if (mg_parse_pem(opts->key, mg_str_s("EC PRIVATE KEY"), &key) == 0) {
    if (key.len < 39) {
      MG_ERROR(("EC private key too short"));
      return;
    }
    // expect ASN.1 SEQUENCE=[INTEGER=1, BITSTRING of 32 bytes, ...]
    // 30 nn 02 01 01 04 20 [key] ...
    if (key.buf[0] != 0x30 || (key.buf[1] & 0x80) != 0) {
      MG_ERROR(("EC private key: ASN.1 bad sequence"));
      return;
    }
    if (memcmp(key.buf + 2, "\x02\x01\x01\x04\x20", 5) != 0) {
      MG_ERROR(("EC private key: ASN.1 bad data"));
    }
    memmove(tls->ec_key, key.buf + 7, 32);
    mg_free((void *) key.buf);
  } else if (mg_parse_pem(opts->key, mg_str_s("RSA PRIVATE KEY"), &key) == 0) {
    struct mg_rsa_key rsa_key;
    // RSA private key found, store it for later use
    tls->rsa_key_der = key;
    MG_INFO(("Parsed RSA private key: %d bytes", (int) key.len));

    // parse and validate the key structure
    // we keep the DER buffer, rsa_key just points into it
    if (mg_rsa_parse_key((const uint8_t *) key.buf, key.len, &rsa_key) < 0) {
      MG_ERROR(("Failed to parse RSA private key structure"));
      mg_free((void *) key.buf);
      tls->rsa_key_der = mg_str_n(NULL, 0);
      mg_error(c, "Invalid RSA private key format");
      return;
    }

    MG_VERBOSE(("RSA key components:"));
    MG_VERBOSE(("  n (modulus):  %d bytes", (int) rsa_key.n.len));
    MG_VERBOSE(("  e (pubexp):   %d bytes", (int) rsa_key.e.len));
    MG_VERBOSE(("  d (privexp):  %d bytes", (int) rsa_key.d.len));
    MG_VERBOSE(("  p (prime1):   %d bytes", (int) rsa_key.p.len));
    MG_VERBOSE(("  q (prime2):   %d bytes", (int) rsa_key.q.len));
    MG_VERBOSE(("  dP:           %d bytes", (int) rsa_key.dP.len));
    MG_VERBOSE(("  dQ:           %d bytes", (int) rsa_key.dQ.len));
    MG_VERBOSE(("  qInv:         %d bytes", (int) rsa_key.qInv.len));

    // Copy parsed RSA key components to tls->rsa for signing operations
    tls->rsa = rsa_key;
  } else if (mg_parse_pem(opts->key, mg_str_s("PRIVATE KEY"), &key) == 0) {
    if (mg_parse_pkcs8_key((const uint8_t *) key.buf, key.len, tls) == 0) {
      if (tls->rsa.n.len > 0) {
        tls->rsa_key_der = key;
        MG_INFO(("Parsed PKCS#8 RSA private key: %d bytes", (int) key.len));
      } else {
        mg_free((void *) key.buf);
        MG_INFO(("Parsed PKCS#8 EC private key"));
      }
    } else {
      mg_free((void *) key.buf);
      mg_error(c, "Unsupported PKCS#8 private key format, algorithm, or curve");
      return;
    }
  } else {
    mg_error(
        c, "Expected EC PRIVATE KEY, RSA PRIVATE KEY, or PRIVATE KEY (PKCS#8)");
  }
}

void mg_tls_free(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  size_t i;
  if (tls != NULL) {
    mg_iobuf_free(&tls->send);
    if (tls->chain_der != NULL) {
      for (i = 0; i < tls->chain_len; i++) {
        mg_free((void *) tls->chain_der[i].buf);
      }
      mg_free(tls->chain_der);
    } else {
      mg_free((void *) tls->cert_der.buf);
    }
    mg_free((void *) tls->ca_der.buf);
    mg_free((void *) tls->rsa_key_der.buf);
  }
  mg_free(c->tls);
  c->tls = NULL;
}

long mg_tls_send(struct mg_connection *c, const void *buf, size_t len) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  long n = MG_IO_WAIT;
  bool was_throttled = c->is_tls_throttled;  // see #3074
  if (!was_throttled) {                      // encrypt new data
    if (len > MG_IO_SIZE) len = MG_IO_SIZE;
    if (len > 16384) len = 16384;
    if (!mg_tls_encrypt(c, (const uint8_t *) buf, len, MG_TLS_APP_DATA))
      return 0;  // returning 0 means an OOM condition (iobuf couldn't resize),
                 // yet this is so far recoverable, let the caller decide
  }  // else, resend outstanding encrypted data in tls->send
  while (tls->send.len > 0 &&
         (n = mg_io_send(c, tls->send.buf, tls->send.len)) > 0) {
    mg_iobuf_del(&tls->send, 0, (size_t) n);
  }  // if last chunk fails to be sent, it needs to be flushed
  c->is_tls_throttled = (tls->send.len > 0 && n == MG_IO_WAIT);
  MG_VERBOSE(("%lu %ld %ld %ld %c %c", c->id, (long) len, (long) tls->send.len,
              n, was_throttled ? 'T' : 't', c->is_tls_throttled ? 'T' : 't'));
  if (n == MG_IO_ERR) return MG_IO_ERR;
  if (was_throttled) return MG_IO_WAIT;  // sent throttled data instead
  return (long) len;  // return len even when throttled, already encripted that
}

long mg_tls_recv(struct mg_connection *c, void *buf, size_t len) {
  int r = 0;
  struct tls_data *tls = (struct tls_data *) c->tls;
  unsigned char *recv_buf;
  size_t minlen;

  for (;;) {
    r = mg_tls_recv_record(c);
    if (r < 0) return r;
    if (tls->content_type == MG_TLS_APP_DATA) break;
    tls->recv_len = 0;
    mg_tls_drop_record(c);
  }

  if (buf == NULL || len == 0) return 0L;
  recv_buf = &c->rtls.buf[tls->recv_offset];
  minlen = len < tls->recv_len ? len : tls->recv_len;
  memmove(buf, recv_buf, minlen);
  tls->recv_offset += minlen;
  tls->recv_len -= minlen;
  if (tls->recv_len == 0) mg_tls_drop_record(c);
  return (long) minlen;
}

size_t mg_tls_pending(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  return tls != NULL ? tls->recv_len : 0;
}

void mg_tls_flush(struct mg_connection *c) {
  struct tls_data *tls = (struct tls_data *) c->tls;
  long n;
  while (tls->send.len > 0 &&
         (n = mg_io_send(c, tls->send.buf, tls->send.len)) > 0) {
    mg_iobuf_del(&tls->send, 0, (size_t) n);
  }
}

void mg_tls_ctx_init(struct mg_mgr *mgr) {
  (void) mgr;
}

void mg_tls_ctx_free(struct mg_mgr *mgr) {
  (void) mgr;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/tls_chacha20.c"
#endif
// portable8439 v1.0.1
// Source: https://github.com/DavyLandman/portable8439
// Licensed under CC0-1.0
// Contains poly1305-donna e6ad6e091d30d7f4ec2d4f978be1fcfcbce72781 (Public
// Domain)




#if MG_TLS == MG_TLS_BUILTIN
// ******* BEGIN: chacha-portable/chacha-portable.h ********

#if !defined(__cplusplus) && !defined(_MSC_VER) && \
    (!defined(__STDC_VERSION__) || __STDC_VERSION__ < 199901L)
#error "C99 or newer required"
#endif

#define CHACHA20_KEY_SIZE (32)
#define CHACHA20_NONCE_SIZE (12)

#if defined(_MSC_VER) || defined(__cplusplus)
// add restrict support
#if ((defined(_MSC_VER) && _MSC_VER >= 1900) && !defined(__cplusplus)) || \
    defined(__clang__) || defined(__GNUC__)
#define restrict __restrict
#else
#define restrict
#endif
#endif

// xor data with a ChaCha20 keystream as per RFC8439
static PORTABLE_8439_DECL void chacha20_xor_stream(
    uint8_t *restrict dest, const uint8_t *restrict source, size_t length,
    const uint8_t key[CHACHA20_KEY_SIZE],
    const uint8_t nonce[CHACHA20_NONCE_SIZE], uint32_t counter);

static PORTABLE_8439_DECL void rfc8439_keygen(
    uint8_t poly_key[32], const uint8_t key[CHACHA20_KEY_SIZE],
    const uint8_t nonce[CHACHA20_NONCE_SIZE]);

// ******* END:   chacha-portable/chacha-portable.h ********
// ******* BEGIN: poly1305-donna/poly1305-donna.h ********

#include <stddef.h>

typedef struct poly1305_context {
  size_t aligner;
  unsigned char opaque[136];
} poly1305_context;

static PORTABLE_8439_DECL void poly1305_init(poly1305_context *ctx,
                                             const unsigned char key[32]);
static PORTABLE_8439_DECL void poly1305_update(poly1305_context *ctx,
                                               const unsigned char *m,
                                               size_t bytes);
static PORTABLE_8439_DECL void poly1305_finish(poly1305_context *ctx,
                                               unsigned char mac[16]);

// ******* END:   poly1305-donna/poly1305-donna.h ********
// ******* BEGIN: chacha-portable.c ********

#include <assert.h>
#include <string.h>

// this is a fresh implementation of chacha20, based on the description in
// rfc8349 it's such a nice compact algorithm that it is easy to do. In
// relationship to other c implementation this implementation:
//  - pure c99
//  - big & little endian support
//  - safe for architectures that don't support unaligned reads
//
// Next to this, we try to be fast as possible without resorting inline
// assembly.

// based on https://sourceforge.net/p/predef/wiki/Endianness/
#if defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && \
    __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#define __HAVE_LITTLE_ENDIAN 1
#elif defined(__LITTLE_ENDIAN__) || defined(__ARMEL__) ||                 \
    defined(__THUMBEL__) || defined(__AARCH64EL__) || defined(_MIPSEL) || \
    defined(__MIPSEL) || defined(__MIPSEL__) || defined(__XTENSA_EL__) || \
    defined(__AVR__)
#define __HAVE_LITTLE_ENDIAN 1
#endif
// DO NOT test for LITTLE_ENDIAN, as it is defined as 1234 when including
// sys/types.h in GCC

#ifndef TEST_SLOW_PATH
#if defined(__HAVE_LITTLE_ENDIAN)
#define FAST_PATH
#endif
#endif

#define CHACHA20_STATE_WORDS (16)
#define CHACHA20_BLOCK_SIZE (CHACHA20_STATE_WORDS * sizeof(uint32_t))

#ifdef FAST_PATH
#define store_32_le(target, source) memcpy(&(target), source, sizeof(uint32_t))
#else
#define store_32_le(target, source)                                 \
  target = (uint32_t) (source)[0] | ((uint32_t) (source)[1]) << 8 | \
           ((uint32_t) (source)[2]) << 16 | ((uint32_t) (source)[3]) << 24
#endif

static void initialize_state(uint32_t state[CHACHA20_STATE_WORDS],
                             const uint8_t key[CHACHA20_KEY_SIZE],
                             const uint8_t nonce[CHACHA20_NONCE_SIZE],
                             uint32_t counter) {
#if 0
#ifdef static_assert
  static_assert(sizeof(uint32_t) == 4,
                "We don't support systems that do not conform to standard of "
                "uint32_t being exact 32bit wide");
#endif
#endif
  state[0] = 0x61707865;
  state[1] = 0x3320646e;
  state[2] = 0x79622d32;
  state[3] = 0x6b206574;
  store_32_le(state[4], key);
  store_32_le(state[5], key + 4);
  store_32_le(state[6], key + 8);
  store_32_le(state[7], key + 12);
  store_32_le(state[8], key + 16);
  store_32_le(state[9], key + 20);
  store_32_le(state[10], key + 24);
  store_32_le(state[11], key + 28);
  state[12] = counter;
  store_32_le(state[13], nonce);
  store_32_le(state[14], nonce + 4);
  store_32_le(state[15], nonce + 8);
}

#define increment_counter(state) (state)[12]++

// source: http://blog.regehr.org/archives/1063
#define rotl32a(x, n) ((x) << (n)) | ((x) >> (32 - (n)))

#define Qround(a, b, c, d) \
  a += b;                  \
  d ^= a;                  \
  d = rotl32a(d, 16);      \
  c += d;                  \
  b ^= c;                  \
  b = rotl32a(b, 12);      \
  a += b;                  \
  d ^= a;                  \
  d = rotl32a(d, 8);       \
  c += d;                  \
  b ^= c;                  \
  b = rotl32a(b, 7);

#define TIMES16(x)                                                          \
  x(0) x(1) x(2) x(3) x(4) x(5) x(6) x(7) x(8) x(9) x(10) x(11) x(12) x(13) \
      x(14) x(15)

static void core_block(const uint32_t *restrict start,
                       uint32_t *restrict output) {
  int i;
// instead of working on the output array,
// we let the compiler allocate 16 local variables on the stack
#define __LV(i) uint32_t __t##i = start[i];
  TIMES16(__LV)

#define __Q(a, b, c, d) Qround(__t##a, __t##b, __t##c, __t##d)

  for (i = 0; i < 10; i++) {
    __Q(0, 4, 8, 12);
    __Q(1, 5, 9, 13);
    __Q(2, 6, 10, 14);
    __Q(3, 7, 11, 15);
    __Q(0, 5, 10, 15);
    __Q(1, 6, 11, 12);
    __Q(2, 7, 8, 13);
    __Q(3, 4, 9, 14);
  }

#define __FIN(i) output[i] = start[i] + __t##i;
  TIMES16(__FIN)
}

#define U8(x) ((uint8_t) ((x) & 0xFF))

#ifdef FAST_PATH
#define xor32_le(dst, src, pad)            \
  uint32_t __value;                        \
  memcpy(&__value, src, sizeof(uint32_t)); \
  __value ^= *(pad);                       \
  memcpy(dst, &__value, sizeof(uint32_t));
#else
#define xor32_le(dst, src, pad)           \
  (dst)[0] = (src)[0] ^ U8(*(pad));       \
  (dst)[1] = (src)[1] ^ U8(*(pad) >> 8);  \
  (dst)[2] = (src)[2] ^ U8(*(pad) >> 16); \
  (dst)[3] = (src)[3] ^ U8(*(pad) >> 24);
#endif

#define index8_32(a, ix) ((a) + ((ix) * sizeof(uint32_t)))

#define xor32_blocks(dest, source, pad, words)                    \
  for (i = 0; i < words; i++) {                                   \
    xor32_le(index8_32(dest, i), index8_32(source, i), (pad) + i) \
  }

static void xor_block(uint8_t *restrict dest, const uint8_t *restrict source,
                      const uint32_t *restrict pad, unsigned int chunk_size) {
  unsigned int i, full_blocks = chunk_size / (unsigned int) sizeof(uint32_t);
  // have to be carefull, we are going back from uint32 to uint8, so endianness
  // matters again
  xor32_blocks(dest, source, pad, full_blocks)

      dest += full_blocks * sizeof(uint32_t);
  source += full_blocks * sizeof(uint32_t);
  pad += full_blocks;

  switch (chunk_size % sizeof(uint32_t)) {
    case 1:
      dest[0] = source[0] ^ U8(*pad);
      break;
    case 2:
      dest[0] = source[0] ^ U8(*pad);
      dest[1] = source[1] ^ U8(*pad >> 8);
      break;
    case 3:
      dest[0] = source[0] ^ U8(*pad);
      dest[1] = source[1] ^ U8(*pad >> 8);
      dest[2] = source[2] ^ U8(*pad >> 16);
      break;
  }
}

static void chacha20_xor_stream(uint8_t *restrict dest,
                                const uint8_t *restrict source, size_t length,
                                const uint8_t key[CHACHA20_KEY_SIZE],
                                const uint8_t nonce[CHACHA20_NONCE_SIZE],
                                uint32_t counter) {
  uint32_t state[CHACHA20_STATE_WORDS];
  uint32_t pad[CHACHA20_STATE_WORDS];
  size_t i, b, last_block, full_blocks = length / CHACHA20_BLOCK_SIZE;
  initialize_state(state, key, nonce, counter);
  for (b = 0; b < full_blocks; b++) {
    core_block(state, pad);
    increment_counter(state);
    xor32_blocks(dest, source, pad, CHACHA20_STATE_WORDS) dest +=
        CHACHA20_BLOCK_SIZE;
    source += CHACHA20_BLOCK_SIZE;
  }
  last_block = length % CHACHA20_BLOCK_SIZE;
  if (last_block > 0) {
    core_block(state, pad);
    xor_block(dest, source, pad, (unsigned int) last_block);
  }
}

#ifdef FAST_PATH
#define serialize(poly_key, result) memcpy(poly_key, result, 32)
#else
#define store32_le(target, source)   \
  (target)[0] = U8(*(source));       \
  (target)[1] = U8(*(source) >> 8);  \
  (target)[2] = U8(*(source) >> 16); \
  (target)[3] = U8(*(source) >> 24);

#define serialize(poly_key, result)                 \
  for (i = 0; i < 32 / sizeof(uint32_t); i++) {     \
    store32_le(index8_32(poly_key, i), result + i); \
  }
#endif

static void rfc8439_keygen(uint8_t poly_key[32],
                           const uint8_t key[CHACHA20_KEY_SIZE],
                           const uint8_t nonce[CHACHA20_NONCE_SIZE]) {
  uint32_t state[CHACHA20_STATE_WORDS];
  uint32_t result[CHACHA20_STATE_WORDS];
  size_t i;
  initialize_state(state, key, nonce, 0);
  core_block(state, result);
  serialize(poly_key, result);
  (void) i;
}
// ******* END: chacha-portable.c ********
// ******* BEGIN: poly1305-donna.c ********

/* auto detect between 32bit / 64bit */
#if /* uint128 available on 64bit system*/                              \
    (defined(__SIZEOF_INT128__) &&                                      \
     defined(__LP64__))                       /* MSVC 64bit compiler */ \
    || (defined(_MSC_VER) && defined(_M_X64)) /* gcc >= 4.4 64bit */    \
    || (defined(__GNUC__) && defined(__LP64__) &&                       \
        ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 4))))
#define __GUESS64
#else
#define __GUESS32
#endif

#if defined(POLY1305_8BIT)
/*
        poly1305 implementation using 8 bit * 8 bit = 16 bit multiplication and
32 bit addition

        based on the public domain reference version in supercop by djb
static */

#if defined(_MSC_VER) && _MSC_VER < 1700
#define POLY1305_NOINLINE
#elif defined(_MSC_VER)
#define POLY1305_NOINLINE __declspec(noinline)
#elif defined(__GNUC__)
#define POLY1305_NOINLINE __attribute__((noinline))
#else
#define POLY1305_NOINLINE
#endif

#define poly1305_block_size 16

/* 17 + sizeof(size_t) + 51*sizeof(unsigned char) */
typedef struct poly1305_state_internal_t {
  unsigned char buffer[poly1305_block_size];
  size_t leftover;
  unsigned char h[17];
  unsigned char r[17];
  unsigned char pad[17];
  unsigned char final;
} poly1305_state_internal_t;

static void poly1305_init(poly1305_context *ctx, const unsigned char key[32]) {
  poly1305_state_internal_t *st = (poly1305_state_internal_t *) ctx;
  size_t i;

  st->leftover = 0;

  /* h = 0 */
  for (i = 0; i < 17; i++) st->h[i] = 0;

  /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
  st->r[0] = key[0] & 0xff;
  st->r[1] = key[1] & 0xff;
  st->r[2] = key[2] & 0xff;
  st->r[3] = key[3] & 0x0f;
  st->r[4] = key[4] & 0xfc;
  st->r[5] = key[5] & 0xff;
  st->r[6] = key[6] & 0xff;
  st->r[7] = key[7] & 0x0f;
  st->r[8] = key[8] & 0xfc;
  st->r[9] = key[9] & 0xff;
  st->r[10] = key[10] & 0xff;
  st->r[11] = key[11] & 0x0f;
  st->r[12] = key[12] & 0xfc;
  st->r[13] = key[13] & 0xff;
  st->r[14] = key[14] & 0xff;
  st->r[15] = key[15] & 0x0f;
  st->r[16] = 0;

  /* save pad for later */
  for (i = 0; i < 16; i++) st->pad[i] = key[i + 16];
  st->pad[16] = 0;

  st->final = 0;
}

static void poly1305_add(unsigned char h[17], const unsigned char c[17]) {
  unsigned short u;
  unsigned int i;
  for (u = 0, i = 0; i < 17; i++) {
    u += (unsigned short) h[i] + (unsigned short) c[i];
    h[i] = (unsigned char) u & 0xff;
    u >>= 8;
  }
}

static void poly1305_squeeze(unsigned char h[17], unsigned long hr[17]) {
  unsigned long u;
  unsigned int i;
  u = 0;
  for (i = 0; i < 16; i++) {
    u += hr[i];
    h[i] = (unsigned char) u & 0xff;
    u >>= 8;
  }
  u += hr[16];
  h[16] = (unsigned char) u & 0x03;
  u >>= 2;
  u += (u << 2); /* u *= 5; */
  for (i = 0; i < 16; i++) {
    u += h[i];
    h[i] = (unsigned char) u & 0xff;
    u >>= 8;
  }
  h[16] += (unsigned char) u;
}

static void poly1305_freeze(unsigned char h[17]) {
  const unsigned char minusp[17] = {0x05, 0x00, 0x00, 0x00, 0x00, 0x00,
                                    0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                                    0x00, 0x00, 0x00, 0x00, 0xfc};
  unsigned char horig[17], negative;
  unsigned int i;

  /* compute h + -p */
  for (i = 0; i < 17; i++) horig[i] = h[i];
  poly1305_add(h, minusp);

  /* select h if h < p, or h + -p if h >= p */
  negative = -(h[16] >> 7);
  for (i = 0; i < 17; i++) h[i] ^= negative & (horig[i] ^ h[i]);
}

static void poly1305_blocks(poly1305_state_internal_t *st,
                            const unsigned char *m, size_t bytes) {
  const unsigned char hibit = st->final ^ 1; /* 1 << 128 */

  while (bytes >= poly1305_block_size) {
    unsigned long hr[17], u;
    unsigned char c[17];
    unsigned int i, j;

    /* h += m */
    for (i = 0; i < 16; i++) c[i] = m[i];
    c[16] = hibit;
    poly1305_add(st->h, c);

    /* h *= r */
    for (i = 0; i < 17; i++) {
      u = 0;
      for (j = 0; j <= i; j++) {
        u += (unsigned short) st->h[j] * st->r[i - j];
      }
      for (j = i + 1; j < 17; j++) {
        unsigned long v = (unsigned short) st->h[j] * st->r[i + 17 - j];
        v = ((v << 8) + (v << 6)); /* v *= (5 << 6); */
        u += v;
      }
      hr[i] = u;
    }

    /* (partial) h %= p */
    poly1305_squeeze(st->h, hr);

    m += poly1305_block_size;
    bytes -= poly1305_block_size;
  }
}

static POLY1305_NOINLINE void poly1305_finish(poly1305_context *ctx,
                                              unsigned char mac[16]) {
  poly1305_state_internal_t *st = (poly1305_state_internal_t *) ctx;
  size_t i;

  /* process the remaining block */
  if (st->leftover) {
    size_t i = st->leftover;
    st->buffer[i++] = 1;
    for (; i < poly1305_block_size; i++) st->buffer[i] = 0;
    st->final = 1;
    poly1305_blocks(st, st->buffer, poly1305_block_size);
  }

  /* fully reduce h */
  poly1305_freeze(st->h);

  /* h = (h + pad) % (1 << 128) */
  poly1305_add(st->h, st->pad);
  for (i = 0; i < 16; i++) mac[i] = st->h[i];

  /* zero out the state */
  for (i = 0; i < 17; i++) st->h[i] = 0;
  for (i = 0; i < 17; i++) st->r[i] = 0;
  for (i = 0; i < 17; i++) st->pad[i] = 0;
}
#elif defined(POLY1305_16BIT)
/*
        poly1305 implementation using 16 bit * 16 bit = 32 bit multiplication
and 32 bit addition static */

#if defined(_MSC_VER) && _MSC_VER < 1700
#define POLY1305_NOINLINE
#elif defined(_MSC_VER)
#define POLY1305_NOINLINE __declspec(noinline)
#elif defined(__GNUC__)
#define POLY1305_NOINLINE __attribute__((noinline))
#else
#define POLY1305_NOINLINE
#endif

#define poly1305_block_size 16

/* 17 + sizeof(size_t) + 18*sizeof(unsigned short) */
typedef struct poly1305_state_internal_t {
  unsigned char buffer[poly1305_block_size];
  size_t leftover;
  unsigned short r[10];
  unsigned short h[10];
  unsigned short pad[8];
  unsigned char final;
} poly1305_state_internal_t;

/* interpret two 8 bit unsigned integers as a 16 bit unsigned integer in little
 * endian */
static unsigned short U8TO16(const unsigned char *p) {
  return (((unsigned short) (p[0] & 0xff)) |
          ((unsigned short) (p[1] & 0xff) << 8));
}

/* store a 16 bit unsigned integer as two 8 bit unsigned integers in little
 * endian */
static void U16TO8(unsigned char *p, unsigned short v) {
  p[0] = (v) & 0xff;
  p[1] = (v >> 8) & 0xff;
}

static void poly1305_init(poly1305_context *ctx, const unsigned char key[32]) {
  poly1305_state_internal_t *st = (poly1305_state_internal_t *) ctx;
  unsigned short t0, t1, t2, t3, t4, t5, t6, t7;
  size_t i;

  /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
  t0 = U8TO16(&key[0]);
  st->r[0] = (t0) & 0x1fff;
  t1 = U8TO16(&key[2]);
  st->r[1] = ((t0 >> 13) | (t1 << 3)) & 0x1fff;
  t2 = U8TO16(&key[4]);
  st->r[2] = ((t1 >> 10) | (t2 << 6)) & 0x1f03;
  t3 = U8TO16(&key[6]);
  st->r[3] = ((t2 >> 7) | (t3 << 9)) & 0x1fff;
  t4 = U8TO16(&key[8]);
  st->r[4] = ((t3 >> 4) | (t4 << 12)) & 0x00ff;
  st->r[5] = ((t4 >> 1)) & 0x1ffe;
  t5 = U8TO16(&key[10]);
  st->r[6] = ((t4 >> 14) | (t5 << 2)) & 0x1fff;
  t6 = U8TO16(&key[12]);
  st->r[7] = ((t5 >> 11) | (t6 << 5)) & 0x1f81;
  t7 = U8TO16(&key[14]);
  st->r[8] = ((t6 >> 8) | (t7 << 8)) & 0x1fff;
  st->r[9] = ((t7 >> 5)) & 0x007f;

  /* h = 0 */
  for (i = 0; i < 10; i++) st->h[i] = 0;

  /* save pad for later */
  for (i = 0; i < 8; i++) st->pad[i] = U8TO16(&key[16 + (2 * i)]);

  st->leftover = 0;
  st->final = 0;
}

static void poly1305_blocks(poly1305_state_internal_t *st,
                            const unsigned char *m, size_t bytes) {
  const unsigned short hibit = (st->final) ? 0 : (1 << 11); /* 1 << 128 */
  unsigned short t0, t1, t2, t3, t4, t5, t6, t7;
  unsigned long d[10];
  unsigned long c;

  while (bytes >= poly1305_block_size) {
    size_t i, j;

    /* h += m[i] */
    t0 = U8TO16(&m[0]);
    st->h[0] += (t0) & 0x1fff;
    t1 = U8TO16(&m[2]);
    st->h[1] += ((t0 >> 13) | (t1 << 3)) & 0x1fff;
    t2 = U8TO16(&m[4]);
    st->h[2] += ((t1 >> 10) | (t2 << 6)) & 0x1fff;
    t3 = U8TO16(&m[6]);
    st->h[3] += ((t2 >> 7) | (t3 << 9)) & 0x1fff;
    t4 = U8TO16(&m[8]);
    st->h[4] += ((t3 >> 4) | (t4 << 12)) & 0x1fff;
    st->h[5] += ((t4 >> 1)) & 0x1fff;
    t5 = U8TO16(&m[10]);
    st->h[6] += ((t4 >> 14) | (t5 << 2)) & 0x1fff;
    t6 = U8TO16(&m[12]);
    st->h[7] += ((t5 >> 11) | (t6 << 5)) & 0x1fff;
    t7 = U8TO16(&m[14]);
    st->h[8] += ((t6 >> 8) | (t7 << 8)) & 0x1fff;
    st->h[9] += ((t7 >> 5)) | hibit;

    /* h *= r, (partial) h %= p */
    for (i = 0, c = 0; i < 10; i++) {
      d[i] = c;
      for (j = 0; j < 10; j++) {
        d[i] += (unsigned long) st->h[j] *
                ((j <= i) ? st->r[i - j] : (5 * st->r[i + 10 - j]));
        /* Sum(h[i] * r[i] * 5) will overflow slightly above 6 products with an
         * unclamped r, so carry at 5 */
        if (j == 4) {
          c = (d[i] >> 13);
          d[i] &= 0x1fff;
        }
      }
      c += (d[i] >> 13);
      d[i] &= 0x1fff;
    }
    c = ((c << 2) + c); /* c *= 5 */
    c += d[0];
    d[0] = ((unsigned short) c & 0x1fff);
    c = (c >> 13);
    d[1] += c;

    for (i = 0; i < 10; i++) st->h[i] = (unsigned short) d[i];

    m += poly1305_block_size;
    bytes -= poly1305_block_size;
  }
}

static POLY1305_NOINLINE void poly1305_finish(poly1305_context *ctx,
                                              unsigned char mac[16]) {
  poly1305_state_internal_t *st = (poly1305_state_internal_t *) ctx;
  unsigned short c;
  unsigned short g[10];
  unsigned short mask;
  unsigned long f;
  size_t i;

  /* process the remaining block */
  if (st->leftover) {
    size_t i = st->leftover;
    st->buffer[i++] = 1;
    for (; i < poly1305_block_size; i++) st->buffer[i] = 0;
    st->final = 1;
    poly1305_blocks(st, st->buffer, poly1305_block_size);
  }

  /* fully carry h */
  c = st->h[1] >> 13;
  st->h[1] &= 0x1fff;
  for (i = 2; i < 10; i++) {
    st->h[i] += c;
    c = st->h[i] >> 13;
    st->h[i] &= 0x1fff;
  }
  st->h[0] += (c * 5);
  c = st->h[0] >> 13;
  st->h[0] &= 0x1fff;
  st->h[1] += c;
  c = st->h[1] >> 13;
  st->h[1] &= 0x1fff;
  st->h[2] += c;

  /* compute h + -p */
  g[0] = st->h[0] + 5;
  c = g[0] >> 13;
  g[0] &= 0x1fff;
  for (i = 1; i < 10; i++) {
    g[i] = st->h[i] + c;
    c = g[i] >> 13;
    g[i] &= 0x1fff;
  }

  /* select h if h < p, or h + -p if h >= p */
  mask = (c ^ 1) - 1;
  for (i = 0; i < 10; i++) g[i] &= mask;
  mask = ~mask;
  for (i = 0; i < 10; i++) st->h[i] = (st->h[i] & mask) | g[i];

  /* h = h % (2^128) */
  st->h[0] = ((st->h[0]) | (st->h[1] << 13)) & 0xffff;
  st->h[1] = ((st->h[1] >> 3) | (st->h[2] << 10)) & 0xffff;
  st->h[2] = ((st->h[2] >> 6) | (st->h[3] << 7)) & 0xffff;
  st->h[3] = ((st->h[3] >> 9) | (st->h[4] << 4)) & 0xffff;
  st->h[4] = ((st->h[4] >> 12) | (st->h[5] << 1) | (st->h[6] << 14)) & 0xffff;
  st->h[5] = ((st->h[6] >> 2) | (st->h[7] << 11)) & 0xffff;
  st->h[6] = ((st->h[7] >> 5) | (st->h[8] << 8)) & 0xffff;
  st->h[7] = ((st->h[8] >> 8) | (st->h[9] << 5)) & 0xffff;

  /* mac = (h + pad) % (2^128) */
  f = (unsigned long) st->h[0] + st->pad[0];
  st->h[0] = (unsigned short) f;
  for (i = 1; i < 8; i++) {
    f = (unsigned long) st->h[i] + st->pad[i] + (f >> 16);
    st->h[i] = (unsigned short) f;
  }

  for (i = 0; i < 8; i++) U16TO8(mac + (i * 2), st->h[i]);

  /* zero out the state */
  for (i = 0; i < 10; i++) st->h[i] = 0;
  for (i = 0; i < 10; i++) st->r[i] = 0;
  for (i = 0; i < 8; i++) st->pad[i] = 0;
}
#elif defined(POLY1305_32BIT) || \
    (!defined(POLY1305_64BIT) && defined(__GUESS32))
/*
        poly1305 implementation using 32 bit * 32 bit = 64 bit multiplication
and 64 bit addition static */

#if defined(_MSC_VER) && _MSC_VER < 1700
#define POLY1305_NOINLINE
#elif defined(_MSC_VER)
#define POLY1305_NOINLINE __declspec(noinline)
#elif defined(__GNUC__)
#define POLY1305_NOINLINE __attribute__((noinline))
#else
#define POLY1305_NOINLINE
#endif

#define poly1305_block_size 16

/* 17 + sizeof(size_t) + 14*sizeof(unsigned long) */
typedef struct poly1305_state_internal_t {
  unsigned long r[5];
  unsigned long h[5];
  unsigned long pad[4];
  size_t leftover;
  unsigned char buffer[poly1305_block_size];
  unsigned char final;
} poly1305_state_internal_t;

/* interpret four 8 bit unsigned integers as a 32 bit unsigned integer in little
 * endian */
static unsigned long U8TO32(const unsigned char *p) {
  return (((unsigned long) (p[0] & 0xff)) |
          ((unsigned long) (p[1] & 0xff) << 8) |
          ((unsigned long) (p[2] & 0xff) << 16) |
          ((unsigned long) (p[3] & 0xff) << 24));
}

/* store a 32 bit unsigned integer as four 8 bit unsigned integers in little
 * endian */
static void U32TO8(unsigned char *p, unsigned long v) {
  p[0] = (unsigned char) ((v) & 0xff);
  p[1] = (unsigned char) ((v >> 8) & 0xff);
  p[2] = (unsigned char) ((v >> 16) & 0xff);
  p[3] = (unsigned char) ((v >> 24) & 0xff);
}

static void poly1305_init(poly1305_context *ctx, const unsigned char key[32]) {
  poly1305_state_internal_t *st = (poly1305_state_internal_t *) ctx;

  /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
  st->r[0] = (U8TO32(&key[0])) & 0x3ffffff;
  st->r[1] = (U8TO32(&key[3]) >> 2) & 0x3ffff03;
  st->r[2] = (U8TO32(&key[6]) >> 4) & 0x3ffc0ff;
  st->r[3] = (U8TO32(&key[9]) >> 6) & 0x3f03fff;
  st->r[4] = (U8TO32(&key[12]) >> 8) & 0x00fffff;

  /* h = 0 */
  st->h[0] = 0;
  st->h[1] = 0;
  st->h[2] = 0;
  st->h[3] = 0;
  st->h[4] = 0;

  /* save pad for later */
  st->pad[0] = U8TO32(&key[16]);
  st->pad[1] = U8TO32(&key[20]);
  st->pad[2] = U8TO32(&key[24]);
  st->pad[3] = U8TO32(&key[28]);

  st->leftover = 0;
  st->final = 0;
}

static void poly1305_blocks(poly1305_state_internal_t *st,
                            const unsigned char *m, size_t bytes) {
  const unsigned long hibit = (st->final) ? 0 : (1UL << 24); /* 1 << 128 */
  unsigned long r0, r1, r2, r3, r4;
  unsigned long s1, s2, s3, s4;
  unsigned long h0, h1, h2, h3, h4;
  uint64_t d0, d1, d2, d3, d4;
  unsigned long c;

  r0 = st->r[0];
  r1 = st->r[1];
  r2 = st->r[2];
  r3 = st->r[3];
  r4 = st->r[4];

  s1 = r1 * 5;
  s2 = r2 * 5;
  s3 = r3 * 5;
  s4 = r4 * 5;

  h0 = st->h[0];
  h1 = st->h[1];
  h2 = st->h[2];
  h3 = st->h[3];
  h4 = st->h[4];

  while (bytes >= poly1305_block_size) {
    /* h += m[i] */
    h0 += (U8TO32(m + 0)) & 0x3ffffff;
    h1 += (U8TO32(m + 3) >> 2) & 0x3ffffff;
    h2 += (U8TO32(m + 6) >> 4) & 0x3ffffff;
    h3 += (U8TO32(m + 9) >> 6) & 0x3ffffff;
    h4 += (U8TO32(m + 12) >> 8) | hibit;

    /* h *= r */
    d0 = ((uint64_t) h0 * r0) + ((uint64_t) h1 * s4) + ((uint64_t) h2 * s3) +
         ((uint64_t) h3 * s2) + ((uint64_t) h4 * s1);
    d1 = ((uint64_t) h0 * r1) + ((uint64_t) h1 * r0) + ((uint64_t) h2 * s4) +
         ((uint64_t) h3 * s3) + ((uint64_t) h4 * s2);
    d2 = ((uint64_t) h0 * r2) + ((uint64_t) h1 * r1) + ((uint64_t) h2 * r0) +
         ((uint64_t) h3 * s4) + ((uint64_t) h4 * s3);
    d3 = ((uint64_t) h0 * r3) + ((uint64_t) h1 * r2) + ((uint64_t) h2 * r1) +
         ((uint64_t) h3 * r0) + ((uint64_t) h4 * s4);
    d4 = ((uint64_t) h0 * r4) + ((uint64_t) h1 * r3) + ((uint64_t) h2 * r2) +
         ((uint64_t) h3 * r1) + ((uint64_t) h4 * r0);

    /* (partial) h %= p */
    c = (unsigned long) (d0 >> 26);
    h0 = (unsigned long) d0 & 0x3ffffff;
    d1 += c;
    c = (unsigned long) (d1 >> 26);
    h1 = (unsigned long) d1 & 0x3ffffff;
    d2 += c;
    c = (unsigned long) (d2 >> 26);
    h2 = (unsigned long) d2 & 0x3ffffff;
    d3 += c;
    c = (unsigned long) (d3 >> 26);
    h3 = (unsigned long) d3 & 0x3ffffff;
    d4 += c;
    c = (unsigned long) (d4 >> 26);
    h4 = (unsigned long) d4 & 0x3ffffff;
    h0 += c * 5;
    c = (h0 >> 26);
    h0 = h0 & 0x3ffffff;
    h1 += c;

    m += poly1305_block_size;
    bytes -= poly1305_block_size;
  }

  st->h[0] = h0;
  st->h[1] = h1;
  st->h[2] = h2;
  st->h[3] = h3;
  st->h[4] = h4;
}

static POLY1305_NOINLINE void poly1305_finish(poly1305_context *ctx,
                                              unsigned char mac[16]) {
  poly1305_state_internal_t *st = (poly1305_state_internal_t *) ctx;
  unsigned long h0, h1, h2, h3, h4, c;
  unsigned long g0, g1, g2, g3, g4;
  uint64_t f;
  unsigned long mask;

  /* process the remaining block */
  if (st->leftover) {
    size_t i = st->leftover;
    st->buffer[i++] = 1;
    for (; i < poly1305_block_size; i++) st->buffer[i] = 0;
    st->final = 1;
    poly1305_blocks(st, st->buffer, poly1305_block_size);
  }

  /* fully carry h */
  h0 = st->h[0];
  h1 = st->h[1];
  h2 = st->h[2];
  h3 = st->h[3];
  h4 = st->h[4];

  c = h1 >> 26;
  h1 = h1 & 0x3ffffff;
  h2 += c;
  c = h2 >> 26;
  h2 = h2 & 0x3ffffff;
  h3 += c;
  c = h3 >> 26;
  h3 = h3 & 0x3ffffff;
  h4 += c;
  c = h4 >> 26;
  h4 = h4 & 0x3ffffff;
  h0 += c * 5;
  c = h0 >> 26;
  h0 = h0 & 0x3ffffff;
  h1 += c;

  /* compute h + -p */
  g0 = h0 + 5;
  c = g0 >> 26;
  g0 &= 0x3ffffff;
  g1 = h1 + c;
  c = g1 >> 26;
  g1 &= 0x3ffffff;
  g2 = h2 + c;
  c = g2 >> 26;
  g2 &= 0x3ffffff;
  g3 = h3 + c;
  c = g3 >> 26;
  g3 &= 0x3ffffff;
  g4 = h4 + c - (1UL << 26);

  /* select h if h < p, or h + -p if h >= p */
  mask = (g4 >> ((sizeof(unsigned long) * 8) - 1)) - 1;
  g0 &= mask;
  g1 &= mask;
  g2 &= mask;
  g3 &= mask;
  g4 &= mask;
  mask = ~mask;
  h0 = (h0 & mask) | g0;
  h1 = (h1 & mask) | g1;
  h2 = (h2 & mask) | g2;
  h3 = (h3 & mask) | g3;
  h4 = (h4 & mask) | g4;

  /* h = h % (2^128) */
  h0 = ((h0) | (h1 << 26)) & 0xffffffff;
  h1 = ((h1 >> 6) | (h2 << 20)) & 0xffffffff;
  h2 = ((h2 >> 12) | (h3 << 14)) & 0xffffffff;
  h3 = ((h3 >> 18) | (h4 << 8)) & 0xffffffff;

  /* mac = (h + pad) % (2^128) */
  f = (uint64_t) h0 + st->pad[0];
  h0 = (unsigned long) f;
  f = (uint64_t) h1 + st->pad[1] + (f >> 32);
  h1 = (unsigned long) f;
  f = (uint64_t) h2 + st->pad[2] + (f >> 32);
  h2 = (unsigned long) f;
  f = (uint64_t) h3 + st->pad[3] + (f >> 32);
  h3 = (unsigned long) f;

  U32TO8(mac + 0, h0);
  U32TO8(mac + 4, h1);
  U32TO8(mac + 8, h2);
  U32TO8(mac + 12, h3);

  /* zero out the state */
  st->h[0] = 0;
  st->h[1] = 0;
  st->h[2] = 0;
  st->h[3] = 0;
  st->h[4] = 0;
  st->r[0] = 0;
  st->r[1] = 0;
  st->r[2] = 0;
  st->r[3] = 0;
  st->r[4] = 0;
  st->pad[0] = 0;
  st->pad[1] = 0;
  st->pad[2] = 0;
  st->pad[3] = 0;
}

#else
/*
        poly1305 implementation using 64 bit * 64 bit = 128 bit multiplication
and 128 bit addition static */

#if defined(_MSC_VER)

typedef struct uint128_t {
  uint64_t lo;
  uint64_t hi;
} uint128_t;

#define MUL128(out, x, y) out.lo = _umul128((x), (y), &out.hi)
#define ADD(out, in)                \
  {                                 \
    uint64_t t = out.lo;            \
    out.lo += in.lo;                \
    out.hi += (out.lo < t) + in.hi; \
  }
#define ADDLO(out, in)      \
  {                         \
    uint64_t t = out.lo;    \
    out.lo += in;           \
    out.hi += (out.lo < t); \
  }
#define SHR(in, shift) (__shiftright128(in.lo, in.hi, (shift)))
#define LO(in) (in.lo)

#if defined(_MSC_VER) && _MSC_VER < 1700
#define POLY1305_NOINLINE
#else
#define POLY1305_NOINLINE __declspec(noinline)
#endif
#elif defined(__GNUC__)
#if defined(__SIZEOF_INT128__)
// Get rid of GCC warning "ISO C does not support '__int128' types"
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpedantic"
typedef unsigned __int128 uint128_t;
#pragma GCC diagnostic pop
#else
typedef unsigned uint128_t __attribute__((mode(TI)));
#endif

#define MUL128(out, x, y) out = ((uint128_t) x * y)
#define ADD(out, in) out += in
#define ADDLO(out, in) out += in
#define SHR(in, shift) (uint64_t) (in >> (shift))
#define LO(in) (uint64_t) (in)

#define POLY1305_NOINLINE __attribute__((noinline))
#endif

#define poly1305_block_size 16

/* 17 + sizeof(size_t) + 8*sizeof(uint64_t) */
typedef struct poly1305_state_internal_t {
  uint64_t r[3];
  uint64_t h[3];
  uint64_t pad[2];
  size_t leftover;
  unsigned char buffer[poly1305_block_size];
  unsigned char final;
} poly1305_state_internal_t;

/* interpret eight 8 bit unsigned integers as a 64 bit unsigned integer in
 * little endian */
static uint64_t U8TO64(const unsigned char *p) {
  return (((uint64_t) (p[0] & 0xff)) | ((uint64_t) (p[1] & 0xff) << 8) |
          ((uint64_t) (p[2] & 0xff) << 16) | ((uint64_t) (p[3] & 0xff) << 24) |
          ((uint64_t) (p[4] & 0xff) << 32) | ((uint64_t) (p[5] & 0xff) << 40) |
          ((uint64_t) (p[6] & 0xff) << 48) | ((uint64_t) (p[7] & 0xff) << 56));
}

/* store a 64 bit unsigned integer as eight 8 bit unsigned integers in little
 * endian */
static void U64TO8(unsigned char *p, uint64_t v) {
  p[0] = (unsigned char) ((v) & 0xff);
  p[1] = (unsigned char) ((v >> 8) & 0xff);
  p[2] = (unsigned char) ((v >> 16) & 0xff);
  p[3] = (unsigned char) ((v >> 24) & 0xff);
  p[4] = (unsigned char) ((v >> 32) & 0xff);
  p[5] = (unsigned char) ((v >> 40) & 0xff);
  p[6] = (unsigned char) ((v >> 48) & 0xff);
  p[7] = (unsigned char) ((v >> 56) & 0xff);
}

static void poly1305_init(poly1305_context *ctx, const unsigned char key[32]) {
  poly1305_state_internal_t *st = (poly1305_state_internal_t *) ctx;
  uint64_t t0, t1;

  /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
  t0 = U8TO64(&key[0]);
  t1 = U8TO64(&key[8]);

  st->r[0] = (t0) & 0xffc0fffffff;
  st->r[1] = ((t0 >> 44) | (t1 << 20)) & 0xfffffc0ffff;
  st->r[2] = ((t1 >> 24)) & 0x00ffffffc0f;

  /* h = 0 */
  st->h[0] = 0;
  st->h[1] = 0;
  st->h[2] = 0;

  /* save pad for later */
  st->pad[0] = U8TO64(&key[16]);
  st->pad[1] = U8TO64(&key[24]);

  st->leftover = 0;
  st->final = 0;
}

static void poly1305_blocks(poly1305_state_internal_t *st,
                            const unsigned char *m, size_t bytes) {
  const uint64_t hibit = (st->final) ? 0 : ((uint64_t) 1 << 40); /* 1 << 128 */
  uint64_t r0, r1, r2;
  uint64_t s1, s2;
  uint64_t h0, h1, h2;
  uint64_t c;
  uint128_t d0, d1, d2, d;

  r0 = st->r[0];
  r1 = st->r[1];
  r2 = st->r[2];

  h0 = st->h[0];
  h1 = st->h[1];
  h2 = st->h[2];

  s1 = r1 * (5 << 2);
  s2 = r2 * (5 << 2);

  while (bytes >= poly1305_block_size) {
    uint64_t t0, t1;

    /* h += m[i] */
    t0 = U8TO64(&m[0]);
    t1 = U8TO64(&m[8]);

    h0 += ((t0) & 0xfffffffffff);
    h1 += (((t0 >> 44) | (t1 << 20)) & 0xfffffffffff);
    h2 += (((t1 >> 24)) & 0x3ffffffffff) | hibit;

    /* h *= r */
    MUL128(d0, h0, r0);
    MUL128(d, h1, s2);
    ADD(d0, d);
    MUL128(d, h2, s1);
    ADD(d0, d);
    MUL128(d1, h0, r1);
    MUL128(d, h1, r0);
    ADD(d1, d);
    MUL128(d, h2, s2);
    ADD(d1, d);
    MUL128(d2, h0, r2);
    MUL128(d, h1, r1);
    ADD(d2, d);
    MUL128(d, h2, r0);
    ADD(d2, d);

    /* (partial) h %= p */
    c = SHR(d0, 44);
    h0 = LO(d0) & 0xfffffffffff;
    ADDLO(d1, c);
    c = SHR(d1, 44);
    h1 = LO(d1) & 0xfffffffffff;
    ADDLO(d2, c);
    c = SHR(d2, 42);
    h2 = LO(d2) & 0x3ffffffffff;
    h0 += c * 5;
    c = (h0 >> 44);
    h0 = h0 & 0xfffffffffff;
    h1 += c;

    m += poly1305_block_size;
    bytes -= poly1305_block_size;
  }

  st->h[0] = h0;
  st->h[1] = h1;
  st->h[2] = h2;
}

static POLY1305_NOINLINE void poly1305_finish(poly1305_context *ctx,
                                              unsigned char mac[16]) {
  poly1305_state_internal_t *st = (poly1305_state_internal_t *) ctx;
  uint64_t h0, h1, h2, c;
  uint64_t g0, g1, g2;
  uint64_t t0, t1;

  /* process the remaining block */
  if (st->leftover) {
    size_t i = st->leftover;
    st->buffer[i] = 1;
    for (i = i + 1; i < poly1305_block_size; i++) st->buffer[i] = 0;
    st->final = 1;
    poly1305_blocks(st, st->buffer, poly1305_block_size);
  }

  /* fully carry h */
  h0 = st->h[0];
  h1 = st->h[1];
  h2 = st->h[2];

  c = (h1 >> 44);
  h1 &= 0xfffffffffff;
  h2 += c;
  c = (h2 >> 42);
  h2 &= 0x3ffffffffff;
  h0 += c * 5;
  c = (h0 >> 44);
  h0 &= 0xfffffffffff;
  h1 += c;
  c = (h1 >> 44);
  h1 &= 0xfffffffffff;
  h2 += c;
  c = (h2 >> 42);
  h2 &= 0x3ffffffffff;
  h0 += c * 5;
  c = (h0 >> 44);
  h0 &= 0xfffffffffff;
  h1 += c;

  /* compute h + -p */
  g0 = h0 + 5;
  c = (g0 >> 44);
  g0 &= 0xfffffffffff;
  g1 = h1 + c;
  c = (g1 >> 44);
  g1 &= 0xfffffffffff;
  g2 = h2 + c - ((uint64_t) 1 << 42);

  /* select h if h < p, or h + -p if h >= p */
  c = (g2 >> ((sizeof(uint64_t) * 8) - 1)) - 1;
  g0 &= c;
  g1 &= c;
  g2 &= c;
  c = ~c;
  h0 = (h0 & c) | g0;
  h1 = (h1 & c) | g1;
  h2 = (h2 & c) | g2;

  /* h = (h + pad) */
  t0 = st->pad[0];
  t1 = st->pad[1];

  h0 += ((t0) & 0xfffffffffff);
  c = (h0 >> 44);
  h0 &= 0xfffffffffff;
  h1 += (((t0 >> 44) | (t1 << 20)) & 0xfffffffffff) + c;
  c = (h1 >> 44);
  h1 &= 0xfffffffffff;
  h2 += (((t1 >> 24)) & 0x3ffffffffff) + c;
  h2 &= 0x3ffffffffff;

  /* mac = h % (2^128) */
  h0 = ((h0) | (h1 << 44));
  h1 = ((h1 >> 20) | (h2 << 24));

  U64TO8(&mac[0], h0);
  U64TO8(&mac[8], h1);

  /* zero out the state */
  st->h[0] = 0;
  st->h[1] = 0;
  st->h[2] = 0;
  st->r[0] = 0;
  st->r[1] = 0;
  st->r[2] = 0;
  st->pad[0] = 0;
  st->pad[1] = 0;
}

#endif

static void poly1305_update(poly1305_context *ctx, const unsigned char *m,
                            size_t bytes) {
  poly1305_state_internal_t *st = (poly1305_state_internal_t *) ctx;
  size_t i;

  /* handle leftover */
  if (st->leftover) {
    size_t want = (poly1305_block_size - st->leftover);
    if (want > bytes) want = bytes;
    for (i = 0; i < want; i++) st->buffer[st->leftover + i] = m[i];
    bytes -= want;
    m += want;
    st->leftover += want;
    if (st->leftover < poly1305_block_size) return;
    poly1305_blocks(st, st->buffer, poly1305_block_size);
    st->leftover = 0;
  }

  /* process full blocks */
  if (bytes >= poly1305_block_size) {
    size_t want = (bytes & (size_t) ~(poly1305_block_size - 1));
    poly1305_blocks(st, m, want);
    m += want;
    bytes -= want;
  }

  /* store leftover */
  if (bytes) {
    for (i = 0; i < bytes; i++) st->buffer[st->leftover + i] = m[i];
    st->leftover += bytes;
  }
}

// ******* END: poly1305-donna.c ********
// ******* BEGIN: portable8439.c ********

#define __CHACHA20_BLOCK_SIZE (64)
#define __POLY1305_KEY_SIZE (32)

static PORTABLE_8439_DECL uint8_t __ZEROES[16] = {0};
static PORTABLE_8439_DECL void pad_if_needed(poly1305_context *ctx,
                                             size_t size) {
  size_t padding = size % 16;
  if (padding != 0) {
    poly1305_update(ctx, __ZEROES, 16 - padding);
  }
}

#define __u8(v) ((uint8_t) ((v) & 0xFF))

// TODO: make this depending on the unaligned/native read size possible
static PORTABLE_8439_DECL void write_64bit_int(poly1305_context *ctx,
                                               uint64_t value) {
  uint8_t result[8];
  result[0] = __u8(value);
  result[1] = __u8(value >> 8);
  result[2] = __u8(value >> 16);
  result[3] = __u8(value >> 24);
  result[4] = __u8(value >> 32);
  result[5] = __u8(value >> 40);
  result[6] = __u8(value >> 48);
  result[7] = __u8(value >> 56);
  poly1305_update(ctx, result, 8);
}

static PORTABLE_8439_DECL void poly1305_calculate_mac(
    uint8_t *mac, const uint8_t *cipher_text, size_t cipher_text_size,
    const uint8_t key[RFC_8439_KEY_SIZE],
    const uint8_t nonce[RFC_8439_NONCE_SIZE], const uint8_t *ad,
    size_t ad_size) {
  // init poly key (section 2.6)
  uint8_t poly_key[__POLY1305_KEY_SIZE] = {0};
  poly1305_context poly_ctx;
  rfc8439_keygen(poly_key, key, nonce);
  // start poly1305 mac
  poly1305_init(&poly_ctx, poly_key);

  if (ad != NULL && ad_size > 0) {
    // write AD if present
    poly1305_update(&poly_ctx, ad, ad_size);
    pad_if_needed(&poly_ctx, ad_size);
  }

  // now write the cipher text
  poly1305_update(&poly_ctx, cipher_text, cipher_text_size);
  pad_if_needed(&poly_ctx, cipher_text_size);

  // write sizes
  write_64bit_int(&poly_ctx, ad_size);
  write_64bit_int(&poly_ctx, cipher_text_size);

  // calculate MAC
  poly1305_finish(&poly_ctx, mac);
}

#define MG_PM(p) ((size_t) (p))

// pointers overlap if the smaller either ahead of the end,
// or its end is before the start of the other
//
// s_size should be smaller or equal to b_size
#define MG_OVERLAPPING(s, s_size, b, b_size) \
  (MG_PM(s) < MG_PM((b) + (b_size))) && (MG_PM(b) < MG_PM((s) + (s_size)))

PORTABLE_8439_DECL size_t mg_chacha20_poly1305_encrypt(
    uint8_t *restrict cipher_text, const uint8_t key[RFC_8439_KEY_SIZE],
    const uint8_t nonce[RFC_8439_NONCE_SIZE], const uint8_t *restrict ad,
    size_t ad_size, const uint8_t *restrict plain_text,
    size_t plain_text_size) {
  size_t new_size = plain_text_size + RFC_8439_TAG_SIZE;
  if (MG_OVERLAPPING(plain_text, plain_text_size, cipher_text, new_size)) {
    return (size_t) -1;
  }
  chacha20_xor_stream(cipher_text, plain_text, plain_text_size, key, nonce, 1);
  poly1305_calculate_mac(cipher_text + plain_text_size, cipher_text,
                         plain_text_size, key, nonce, ad, ad_size);
  return new_size;
}

PORTABLE_8439_DECL size_t mg_chacha20_poly1305_decrypt(
    uint8_t *restrict plain_text, const uint8_t key[RFC_8439_KEY_SIZE],
    const uint8_t nonce[RFC_8439_NONCE_SIZE], const uint8_t *restrict ad,
    size_t ad_size, const uint8_t *restrict cipher_text,
    size_t cipher_text_size) {
  // first we calculate the mac and see if it lines up, only then do we decrypt
  size_t actual_size = cipher_text_size - RFC_8439_TAG_SIZE;
  uint8_t computed_mac[RFC_8439_TAG_SIZE];
  int diff = 0;
  size_t i;
  if (MG_OVERLAPPING(plain_text, actual_size, cipher_text, cipher_text_size)) {
    return (size_t) -1;
  }

  poly1305_calculate_mac(computed_mac, cipher_text, actual_size, key, nonce, ad,
                         ad_size);

  // compare tags
  for (i = 0; i < RFC_8439_TAG_SIZE; i++)
    diff |= computed_mac[i] ^ cipher_text[actual_size + i];
  if (diff != 0) return (size_t) -1;

  chacha20_xor_stream(plain_text, cipher_text, actual_size, key, nonce, 1);
  return actual_size;
}
// ******* END:   portable8439.c ********
#endif  // MG_TLS == MG_TLS_BUILTIN

#ifdef MG_ENABLE_LINES
#line 1 "src/tls_dummy.c"
#endif


#if MG_TLS == MG_TLS_NONE
void mg_tls_init(struct mg_connection *c, const struct mg_tls_opts *opts) {
  (void) opts;
  mg_error(c, "TLS is not enabled");
}
void mg_tls_handshake(struct mg_connection *c) {
  (void) c;
}
void mg_tls_free(struct mg_connection *c) {
  (void) c;
}
long mg_tls_recv(struct mg_connection *c, void *buf, size_t len) {
  return c == NULL || buf == NULL || len == 0 ? 0 : -1;
}
long mg_tls_send(struct mg_connection *c, const void *buf, size_t len) {
  return c == NULL || buf == NULL || len == 0 ? 0 : -1;
}
size_t mg_tls_pending(struct mg_connection *c) {
  (void) c;
  return 0;
}
void mg_tls_flush(struct mg_connection *c) {
  (void) c;
}
void mg_tls_ctx_init(struct mg_mgr *mgr) {
  (void) mgr;
}
void mg_tls_ctx_free(struct mg_mgr *mgr) {
  (void) mgr;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/tls_mbed.c"
#endif






#if MG_TLS == MG_TLS_MBED

#if defined(MBEDTLS_VERSION_NUMBER) && MBEDTLS_VERSION_NUMBER >= 0x03000000 && \
    MBEDTLS_VERSION_NUMBER < 0x04000000
#define MG_MBEDTLS_RNG_GET , mg_mbed_rng, NULL
#else
#define MG_MBEDTLS_RNG_GET
#endif

static int mg_tls_err(struct mg_connection *c, int rc) {
  char s[80];
  mbedtls_strerror(rc, s, sizeof(s));
  MG_ERROR(("%lu %s", ((struct mg_connection *) c)->id, s));
  return rc;
}

#if defined(MBEDTLS_VERSION_NUMBER) && MBEDTLS_VERSION_NUMBER >= 0x04000000
#else
static int mg_mbed_rng(void *ctx, unsigned char *buf, size_t len) {
  mg_random(buf, len);
  (void) ctx;
  return 0;
}
#endif

static bool mg_load_cert(struct mg_str str, mbedtls_x509_crt *p) {
  int rc;
  if (str.buf == NULL || str.buf[0] == '\0' || str.buf[0] == '*') return true;
  if (!MG_IS_DER(str.buf)) str.len++;  // PEM, include trailing NUL
  if ((rc = mbedtls_x509_crt_parse(p, (uint8_t *) str.buf, str.len)) != 0) {
    MG_ERROR(("cert err %#x", -rc));
    return false;
  }
  return true;
}

static bool mg_load_key(struct mg_str str, mbedtls_pk_context *p) {
  int rc;
  if (str.buf == NULL || str.buf[0] == '\0' || str.buf[0] == '*') return true;
  if (!MG_IS_DER(str.buf)) str.len++;  // PEM, include trailing NUL
  if ((rc = mbedtls_pk_parse_key(p, (uint8_t *) str.buf, str.len, NULL,
                                 0 MG_MBEDTLS_RNG_GET)) != 0) {
    MG_ERROR(("key err %#x", -rc));
    return false;
  }
  return true;
}

void mg_tls_free(struct mg_connection *c) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  if (tls != NULL) {
    mbedtls_ssl_free(&tls->ssl);
    mbedtls_pk_free(&tls->pk);
    mbedtls_x509_crt_free(&tls->ca);
    mbedtls_x509_crt_free(&tls->cert);
    mbedtls_ssl_config_free(&tls->conf);
#ifdef MBEDTLS_SSL_SESSION_TICKETS
    mbedtls_ssl_ticket_free(&tls->ticket);
#endif
    // PSA has global data. Do not call mbedtls_psa_crypto_free() here,
    // it will free all global resources. Call it when actually freeing all
    // application resources (main() exits)
    mg_free(tls);
    c->tls = NULL;
  }
}

static int mg_net_send(void *ctx, const unsigned char *buf, size_t len) {
  long n = mg_io_send((struct mg_connection *) ctx, buf, len);
  MG_VERBOSE(("%lu n=%ld e=%d", ((struct mg_connection *) ctx)->id, n, errno));
  if (n == MG_IO_WAIT) return MBEDTLS_ERR_SSL_WANT_WRITE;
  if (n == MG_IO_RESET) return MBEDTLS_ERR_NET_CONN_RESET;
  if (n == MG_IO_ERR) return MBEDTLS_ERR_NET_SEND_FAILED;
  return (int) n;
}

static int mg_net_recv(void *ctx, unsigned char *buf, size_t len) {
  long n = mg_io_recv((struct mg_connection *) ctx, buf, len);
  MG_VERBOSE(("%lu n=%ld", ((struct mg_connection *) ctx)->id, n));
  if (n == MG_IO_WAIT) return MBEDTLS_ERR_SSL_WANT_WRITE;
  if (n == MG_IO_RESET) return MBEDTLS_ERR_NET_CONN_RESET;
  if (n == MG_IO_ERR) return MBEDTLS_ERR_NET_RECV_FAILED;
  return (int) n;
}

void mg_tls_handshake(struct mg_connection *c) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  int rc = mbedtls_ssl_handshake(&tls->ssl);
  if (rc == 0) {  // Success
    MG_DEBUG(("%lu success", c->id));
    c->is_tls_hs = 0;
    mg_call(c, MG_EV_TLS_HS, NULL);
  } else if (rc == MBEDTLS_ERR_SSL_WANT_READ ||
             rc == MBEDTLS_ERR_SSL_WANT_WRITE) {  // Still pending
    MG_VERBOSE(("%lu pending, %d%d %d (-%#x)", c->id, c->is_connecting,
                c->is_tls_hs, rc, -rc));
  } else {
    mg_error(c, "TLS handshake: -%#x", -mg_tls_err(c, rc));  // Error
  }
}

static void debug_cb(void *c, int lev, const char *s, int n, const char *s2) {
  n = (int) strlen(s2) - 1;
  MG_INFO(("%lu %d %.*s", ((struct mg_connection *) c)->id, lev, n, s2));
  (void) s;
}

void mg_tls_init(struct mg_connection *c, const struct mg_tls_opts *opts) {
  struct mg_tls *tls = (struct mg_tls *) mg_calloc(1, sizeof(*tls));
  int rc = 0;
  c->tls = tls;
  if (c->tls == NULL) {
    mg_error(c, "TLS OOM");
    goto fail;
  }
  if (c->is_listening) goto fail;
  MG_DEBUG(("%lu Setting TLS", c->id));
  MG_PROF_ADD(c, "mbedtls_init_start");
#if defined(MBEDTLS_VERSION_NUMBER) && MBEDTLS_VERSION_NUMBER >= 0x03000000 && \
    defined(MBEDTLS_PSA_CRYPTO_C)
  psa_crypto_init();  // https://github.com/Mbed-TLS/mbedtls/issues/9072#issuecomment-2084845711
  // this initializes global resources and then just returns when called again
#endif
  mbedtls_ssl_init(&tls->ssl);
  mbedtls_ssl_config_init(&tls->conf);
  mbedtls_x509_crt_init(&tls->ca);
  mbedtls_x509_crt_init(&tls->cert);
  mbedtls_pk_init(&tls->pk);
  mbedtls_ssl_conf_dbg(&tls->conf, debug_cb, c);
#if defined(MG_MBEDTLS_DEBUG_LEVEL)
  mbedtls_debug_set_threshold(MG_MBEDTLS_DEBUG_LEVEL);
#endif
  if ((rc = mbedtls_ssl_config_defaults(
           &tls->conf,
           c->is_client ? MBEDTLS_SSL_IS_CLIENT : MBEDTLS_SSL_IS_SERVER,
           MBEDTLS_SSL_TRANSPORT_STREAM, MBEDTLS_SSL_PRESET_DEFAULT)) != 0) {
    mg_error(c, "tls defaults %#x", -mg_tls_err(c, rc));
    goto fail;
  }
#if defined(MBEDTLS_VERSION_NUMBER) && MBEDTLS_VERSION_NUMBER >= 0x04000000
  MG_INFO(("PSA is in control of random number generation"));
#else
  mbedtls_ssl_conf_rng(&tls->conf, mg_mbed_rng, c);
#endif

  if (opts->ca.len == 0 || mg_strcmp(opts->ca, mg_str("*")) == 0) {
    // NOTE: MBEDTLS_SSL_VERIFY_NONE is not supported for TLS1.3 on client side
    // See https://github.com/Mbed-TLS/mbedtls/issues/7075
    mbedtls_ssl_conf_authmode(&tls->conf, MBEDTLS_SSL_VERIFY_NONE);
  } else {
    if (mg_load_cert(opts->ca, &tls->ca) == false) goto fail;
    mbedtls_ssl_conf_ca_chain(&tls->conf, &tls->ca, NULL);
    if (c->is_client) {
      if (opts->name.buf != NULL && opts->name.buf[0] != '\0') {
        char *host = mg_mprintf("%.*s", opts->name.len, opts->name.buf);
        mbedtls_ssl_set_hostname(&tls->ssl, host);
        MG_DEBUG(("%lu hostname verification: %s", c->id, host));
        mg_free(host);
      } else {
        MG_DEBUG(("%lu skipping hostname verification", c->id));
        mbedtls_ssl_set_hostname(&tls->ssl, NULL);
      }
    }
    mbedtls_ssl_conf_authmode(&tls->conf, MBEDTLS_SSL_VERIFY_REQUIRED);
  }
  if (!mg_load_cert(opts->cert, &tls->cert)) goto fail;
  if (!mg_load_key(opts->key, &tls->pk)) goto fail;
  if (tls->cert.version &&
      (rc = mbedtls_ssl_conf_own_cert(&tls->conf, &tls->cert, &tls->pk)) != 0) {
    mg_error(c, "own cert %#x", -mg_tls_err(c, rc));
    goto fail;
  }

#ifdef MBEDTLS_SSL_SESSION_TICKETS
  mbedtls_ssl_conf_session_tickets_cb(
      &tls->conf, mbedtls_ssl_ticket_write, mbedtls_ssl_ticket_parse,
      &((struct mg_tls_ctx *) c->mgr->tls_ctx)->tickets);
#endif

  if ((rc = mbedtls_ssl_setup(&tls->ssl, &tls->conf)) != 0) {
    mg_error(c, "setup err %#x", -mg_tls_err(c, rc));
    goto fail;
  }
  c->is_tls = 1;
  c->is_tls_hs = 1;
  mbedtls_ssl_set_bio(&tls->ssl, c, mg_net_send, mg_net_recv, 0);
  MG_PROF_ADD(c, "mbedtls_init_end");
  return;
fail:
  mg_tls_free(c);
}

size_t mg_tls_pending(struct mg_connection *c) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  return tls == NULL ? 0 : mbedtls_ssl_get_bytes_avail(&tls->ssl);
}

long mg_tls_recv(struct mg_connection *c, void *buf, size_t len) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  long n = mbedtls_ssl_read(&tls->ssl, (unsigned char *) buf, len);
  if (!c->is_tls_hs && buf == NULL && n == 0) return 0;  // TODO(): MIP
  if (n == MBEDTLS_ERR_SSL_WANT_READ || n == MBEDTLS_ERR_SSL_WANT_WRITE)
    return MG_IO_WAIT;
#if defined(MBEDTLS_ERR_SSL_RECEIVED_NEW_SESSION_TICKET)
  if (n == MBEDTLS_ERR_SSL_RECEIVED_NEW_SESSION_TICKET) {
    return MG_IO_WAIT;
  }
#endif
  if (n <= 0) return MG_IO_ERR;
  return n;
}

long mg_tls_send(struct mg_connection *c, const void *buf, size_t len) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  long n;
  bool was_throttled = c->is_tls_throttled;  // see #3074
  n = was_throttled ? mbedtls_ssl_write(&tls->ssl, tls->throttled_buf,
                                        tls->throttled_len) /* flush old data */
                    : mbedtls_ssl_write(&tls->ssl, (unsigned char *) buf,
                                        len);  // encrypt current data
  c->is_tls_throttled =
      (n == MBEDTLS_ERR_SSL_WANT_READ || n == MBEDTLS_ERR_SSL_WANT_WRITE);
  if (was_throttled) return MG_IO_WAIT;  // flushed throttled data instead
  if (c->is_tls_throttled) {
    tls->throttled_buf =
        (unsigned char *) buf;  // MbedTLS code actually ignores
    tls->throttled_len = len;   //  these, but let's play API rules
    return (long) len;          // already encripted that when throttled
  }  // if last chunk fails to be sent, it needs to be flushed
  if (n <= 0) return MG_IO_ERR;
  return n;
}

void mg_tls_flush(struct mg_connection *c) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  if (c->is_tls_throttled) {
    long n =
        mbedtls_ssl_write(&tls->ssl, tls->throttled_buf, tls->throttled_len);
    c->is_tls_throttled =
        (n == MBEDTLS_ERR_SSL_WANT_READ || n == MBEDTLS_ERR_SSL_WANT_WRITE);
  }
}

void mg_tls_ctx_init(struct mg_mgr *mgr) {
  struct mg_tls_ctx *ctx = (struct mg_tls_ctx *) mg_calloc(1, sizeof(*ctx));
  if (ctx == NULL) {
    MG_ERROR(("TLS context init OOM"));
  } else {
#ifdef MBEDTLS_SSL_SESSION_TICKETS
    int rc;
    mbedtls_ssl_ticket_init(&ctx->tickets);
#if defined(MBEDTLS_VERSION_NUMBER) && MBEDTLS_VERSION_NUMBER >= 0x04000000
    if ((rc = mbedtls_ssl_ticket_setup(&ctx->tickets, PSA_ALG_GCM,
                                       PSA_KEY_TYPE_AES, 128, 86400))
#else
    if ((rc = mbedtls_ssl_ticket_setup(&ctx->tickets, mg_mbed_rng, NULL,
                                       MBEDTLS_CIPHER_AES_128_GCM, 86400))
#endif
        != 0) {
      MG_ERROR((" mbedtls_ssl_ticket_setup %#x", -rc));
    }
#endif
    mgr->tls_ctx = ctx;
  }
}

void mg_tls_ctx_free(struct mg_mgr *mgr) {
  struct mg_tls_ctx *ctx = (struct mg_tls_ctx *) mgr->tls_ctx;
  if (ctx != NULL) {
#ifdef MBEDTLS_SSL_SESSION_TICKETS
    mbedtls_ssl_ticket_free(&ctx->tickets);
#endif
    mg_free(ctx);
    mgr->tls_ctx = NULL;
  }
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/tls_openssl.c"
#endif




#if MG_TLS == MG_TLS_OPENSSL || MG_TLS == MG_TLS_WOLFSSL

static int tls_err_cb(const char *s, size_t len, void *c) {
  int n = (int) len - 1;
  MG_ERROR(("%lu %.*s", ((struct mg_connection *) c)->id, n, s));
  return 0;  // undocumented
}

static int mg_tls_err(struct mg_connection *c, struct mg_tls *tls, int res) {
  int err = SSL_get_error(tls->ssl, res);
  // We've just fetched the last error from the queue.
  // Now we need to clear the error queue. If we do not, then the following
  // can happen (actually reported):
  //  - A new connection is accept()-ed with cert error (e.g. self-signed cert)
  //  - Since all accept()-ed connections share listener's context,
  //  - *ALL* SSL accepted connection report read error on the next poll cycle.
  //    Thus a single errored connection can close all the rest, unrelated ones.
  // Clearing the error keeps the shared SSL_CTX in an OK state.

  if (err != 0) ERR_print_errors_cb(tls_err_cb, c);
  ERR_clear_error();
  if (err == SSL_ERROR_WANT_READ) return 0;
  if (err == SSL_ERROR_WANT_WRITE) return 0;
  return err;
}

#if MG_TLS != MG_TLS_WOLFSSL
static STACK_OF(X509_INFO) * load_ca_certs(struct mg_str ca) {
  BIO *bio = BIO_new_mem_buf(ca.buf, (int) ca.len);
  STACK_OF(X509_INFO) *certs =
      bio ? PEM_X509_INFO_read_bio(bio, NULL, NULL, NULL) : NULL;
  if (bio) BIO_free(bio);
  return certs;
}

static bool add_ca_certs(SSL_CTX *ctx, STACK_OF(X509_INFO) * certs) {
  int i;
  X509_STORE *cert_store = SSL_CTX_get_cert_store(ctx);
  if (cert_store == NULL) return false;
  for (i = 0; i < sk_X509_INFO_num(certs); i++) {
    X509_INFO *cert_info = sk_X509_INFO_value(certs, i);
    if (cert_info->x509 && !X509_STORE_add_cert(cert_store, cert_info->x509))
      return false;
  }
  return true;
}
#endif

static EVP_PKEY *load_key(struct mg_str s) {
  BIO *bio = BIO_new_mem_buf(s.buf, (int) (long) s.len);
  EVP_PKEY *key = bio ? PEM_read_bio_PrivateKey(bio, NULL, 0, NULL) : NULL;
  if (bio) BIO_free(bio);
  return key;
}

static X509 *load_cert(struct mg_str s) {
  BIO *bio = BIO_new_mem_buf(s.buf, (int) (long) s.len);
  X509 *cert = bio == NULL ? NULL
               : MG_IS_DER(s.buf)
                   ? d2i_X509_bio(bio, NULL)                    // DER
                   : PEM_read_bio_X509(bio, NULL, NULL, NULL);  // PEM
  if (bio) BIO_free(bio);
  return cert;
}

static long mg_bio_ctrl(BIO *b, int cmd, long larg, void *pargs) {
  long ret = 0;
  if (cmd == BIO_CTRL_PUSH) ret = 1;
  if (cmd == BIO_CTRL_POP) ret = 1;
  if (cmd == BIO_CTRL_FLUSH) ret = 1;
#if MG_TLS == MG_TLS_OPENSSL
  if (cmd == BIO_C_SET_NBIO) ret = 1;
#endif
  // MG_DEBUG(("%d -> %ld", cmd, ret));
  (void) b, (void) cmd, (void) larg, (void) pargs;
  return ret;
}

static int mg_bio_read(BIO *bio, char *buf, int len) {
  struct mg_connection *c = (struct mg_connection *) BIO_get_data(bio);
  long res = mg_io_recv(c, buf, (size_t) len);
  // MG_DEBUG(("%p %d %ld", buf, len, res));
  len = res > 0 ? (int) res : -1;
  if (res == MG_IO_WAIT) BIO_set_retry_read(bio);
  return len;
}

static int mg_bio_write(BIO *bio, const char *buf, int len) {
  struct mg_connection *c = (struct mg_connection *) BIO_get_data(bio);
  long res = mg_io_send(c, buf, (size_t) len);
  // MG_DEBUG(("%p %d %ld", buf, len, res));
  len = res > 0 ? (int) res : -1;
  if (res == MG_IO_WAIT) BIO_set_retry_write(bio);
  return len;
}

#ifdef MG_TLS_SSLKEYLOGFILE
static void ssl_keylog_cb(const SSL *ssl, const char *line) {
  char *keylogfile = getenv("SSLKEYLOGFILE");
  if (keylogfile == NULL) {
    return;
  }
  FILE *f = fopen(keylogfile, "a");
  fprintf(f, "%s\n", line);
  fflush(f);
  fclose(f);
  (void) ssl;
}
#endif

void mg_tls_free(struct mg_connection *c) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  if (tls == NULL) return;
  SSL_free(tls->ssl);
  SSL_CTX_free(tls->ctx);
  BIO_meth_free(tls->bm);
  mg_free(tls);
  c->tls = NULL;
}

void mg_tls_init(struct mg_connection *c, const struct mg_tls_opts *opts) {
  struct mg_tls *tls = (struct mg_tls *) mg_calloc(1, sizeof(*tls));
  const char *id = "mongoose";
  static unsigned char s_initialised = 0;
  BIO *bio = NULL;
  int rc;
  c->tls = tls;
  if (tls == NULL) {
    mg_error(c, "TLS OOM");
    goto fail;
  }

  if (!s_initialised) {
    SSL_library_init();
    s_initialised++;
  }
  MG_DEBUG(("%lu Setting TLS", c->id));
  tls->ctx = c->is_client ? SSL_CTX_new(TLS_client_method())
                          : SSL_CTX_new(TLS_server_method());
  if (tls->ctx == NULL) {
    mg_error(c, "SSL_CTX_new");
    goto fail;
  }
#ifdef MG_TLS_SSLKEYLOGFILE
  SSL_CTX_set_keylog_callback(tls->ctx, ssl_keylog_cb);
#endif
  if ((tls->ssl = SSL_new(tls->ctx)) == NULL) {
    mg_error(c, "SSL_new");
    goto fail;
  }
  SSL_set_session_id_context(tls->ssl, (const uint8_t *) id,
                             (unsigned) strlen(id));
  // Disable deprecated protocols
  SSL_set_options(tls->ssl, SSL_OP_NO_SSLv2);
  SSL_set_options(tls->ssl, SSL_OP_NO_SSLv3);
  SSL_set_options(tls->ssl, SSL_OP_NO_TLSv1);
  SSL_set_options(tls->ssl, SSL_OP_NO_TLSv1_1);
#ifdef MG_ENABLE_OPENSSL_NO_COMPRESSION
  SSL_set_options(tls->ssl, SSL_OP_NO_COMPRESSION);
#endif
#ifdef MG_ENABLE_OPENSSL_CIPHER_SERVER_PREFERENCE
  SSL_set_options(tls->ssl, SSL_OP_CIPHER_SERVER_PREFERENCE);
#endif

#if MG_TLS == MG_TLS_WOLFSSL && !defined(OPENSSL_COMPATIBLE_DEFAULTS)
  if (opts->ca.len == 0 || mg_strcmp(opts->ca, mg_str("*")) == 0) {
    // Older versions require that either the CA is loaded or SSL_VERIFY_NONE
    // explicitly set
    SSL_set_verify(tls->ssl, SSL_VERIFY_NONE, NULL);
  }
#endif

  if (opts->ca.buf != NULL && opts->ca.buf[0] != '\0') {
    SSL_set_verify(tls->ssl, SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
                   NULL);
#if MG_TLS == MG_TLS_WOLFSSL
    extern int wolfSSL_CTX_load_verify_buffer(SSL_CTX *, const unsigned char *,
                                              long, int);
    rc = wolfSSL_CTX_load_verify_buffer(tls->ctx,
                                        (const unsigned char *) opts->ca.buf,
                                        (long) opts->ca.len, SSL_FILETYPE_PEM);
    if (rc != 1) {
      mg_error(c, "CA err");
      goto fail;
    }
#else
    STACK_OF(X509_INFO) *certs = load_ca_certs(opts->ca);
    rc = add_ca_certs(tls->ctx, certs);
    sk_X509_INFO_pop_free(certs, X509_INFO_free);
    if (!rc) {
      mg_error(c, "CA err");
      goto fail;
    }
#endif
  }

  if (opts->cert.buf != NULL && opts->cert.buf[0] != '\0') {
    X509 *cert = load_cert(opts->cert);
    rc = cert == NULL ? 0 : SSL_use_certificate(tls->ssl, cert);
    X509_free(cert);
    if (cert == NULL || rc != 1) {
      mg_error(c, "CERT err %d", mg_tls_err(c, tls, rc));
      goto fail;
    }
  }
  if (opts->key.buf != NULL && opts->key.buf[0] != '\0') {
    EVP_PKEY *key = load_key(opts->key);
    rc = key == NULL ? 0 : SSL_use_PrivateKey(tls->ssl, key);
    EVP_PKEY_free(key);
    if (key == NULL || rc != 1) {
      mg_error(c, "KEY err %d", mg_tls_err(c, tls, rc));
      goto fail;
    }
  }

  SSL_set_mode(tls->ssl, SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);
#if MG_TLS == MG_TLS_OPENSSL && OPENSSL_VERSION_NUMBER > 0x10002000L
  (void) SSL_set_ecdh_auto(tls->ssl, 1);
#endif
#if OPENSSL_VERSION_NUMBER >= 0x10100000L
  if (opts->name.len > 0) {
    char *s = mg_mprintf("%.*s", (int) opts->name.len, opts->name.buf);
#if MG_TLS != MG_TLS_WOLFSSL || LIBWOLFSSL_VERSION_HEX >= 0x05005002
    SSL_set1_host(tls->ssl, s);
#else
    X509_VERIFY_PARAM_set1_host(SSL_get0_param(tls->ssl), s, 0);
#endif
    SSL_set_tlsext_host_name(tls->ssl, s);
    mg_free(s);
  }
#endif
#if MG_TLS == MG_TLS_WOLFSSL
  tls->bm = BIO_meth_new(0, "bio_mg");
#else
  tls->bm = BIO_meth_new(BIO_get_new_index() | BIO_TYPE_SOURCE_SINK, "bio_mg");
#endif
  BIO_meth_set_write(tls->bm, mg_bio_write);
  BIO_meth_set_read(tls->bm, mg_bio_read);
  BIO_meth_set_ctrl(tls->bm, mg_bio_ctrl);

  bio = BIO_new(tls->bm);
  BIO_set_data(bio, c);
  SSL_set_bio(tls->ssl, bio, bio);

  c->is_tls = 1;
  c->is_tls_hs = 1;
  MG_DEBUG(("%lu SSL %s OK", c->id, c->is_accepted ? "accept" : "client"));
  return;
fail:
  mg_tls_free(c);
}

void mg_tls_handshake(struct mg_connection *c) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  int rc = c->is_client ? SSL_connect(tls->ssl) : SSL_accept(tls->ssl);
  if (rc == 1) {
    MG_DEBUG(("%lu success", c->id));
    c->is_tls_hs = 0;
    mg_call(c, MG_EV_TLS_HS, NULL);
  } else {
    int code = mg_tls_err(c, tls, rc);
    if (code != 0) mg_error(c, "tls hs: rc %d, err %d", rc, code);
  }
}

size_t mg_tls_pending(struct mg_connection *c) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  return tls == NULL ? 0 : (size_t) SSL_pending(tls->ssl);
}

long mg_tls_recv(struct mg_connection *c, void *buf, size_t len) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  int n = SSL_read(tls->ssl, buf, (int) len);
  if (!c->is_tls_hs && buf == NULL && n == 0) return 0;  // TODO(): MIP
  if (n < 0 && mg_tls_err(c, tls, n) == 0) return MG_IO_WAIT;
  if (n <= 0) return MG_IO_ERR;
  return n;
}

long mg_tls_send(struct mg_connection *c, const void *buf, size_t len) {
  struct mg_tls *tls = (struct mg_tls *) c->tls;
  int n = SSL_write(tls->ssl, buf, (int) len);
  if (n < 0 && mg_tls_err(c, tls, n) == 0) return MG_IO_WAIT;
  if (n <= 0) return MG_IO_ERR;
  return n;
}

void mg_tls_flush(struct mg_connection *c) {
  (void) c;
}

void mg_tls_ctx_init(struct mg_mgr *mgr) {
  (void) mgr;
}

void mg_tls_ctx_free(struct mg_mgr *mgr) {
  (void) mgr;
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/tls_rsa.c"
#endif




#if MG_TLS == MG_TLS_BUILTIN

#define NS_INTERNAL static
typedef struct _bigint bigint; /**< An alias for _bigint */

/*
 * Copyright (c) 2007, Cameron Rich
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * * Neither the name of the axTLS project nor the names of its contributors
 *   may be used to endorse or promote products derived from this software
 *   without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/* Maintain a number of precomputed variables when doing reduction */
#define BIGINT_M_OFFSET 0 /**< Normal modulo offset. */
#define BIGINT_P_OFFSET 1 /**< p modulo offset. */
#define BIGINT_Q_OFFSET 2 /**< q module offset. */
#define BIGINT_NUM_MODS 3 /**< The number of modulus constants used. */

/* Architecture specific functions for big ints */
#if defined(CONFIG_INTEGER_8BIT)
#define COMP_RADIX 256U     /**< Max component + 1 */
#define COMP_MAX 0xFFFFU    /**< (Max dbl comp -1) */
#define COMP_BIT_SIZE 8     /**< Number of bits in a component. */
#define COMP_BYTE_SIZE 1    /**< Number of bytes in a component. */
#define COMP_NUM_NIBBLES 2  /**< Used For diagnostics only. */
typedef uint8_t comp;       /**< A single precision component. */
typedef uint16_t long_comp; /**< A double precision component. */
typedef int16_t slong_comp; /**< A signed double precision component. */
#elif defined(CONFIG_INTEGER_16BIT)
#define COMP_RADIX 65536U    /**< Max component + 1 */
#define COMP_MAX 0xFFFFFFFFU /**< (Max dbl comp -1) */
#define COMP_BIT_SIZE 16     /**< Number of bits in a component. */
#define COMP_BYTE_SIZE 2     /**< Number of bytes in a component. */
#define COMP_NUM_NIBBLES 4   /**< Used For diagnostics only. */
typedef uint16_t comp;            /**< A single precision component. */
typedef uint32_t long_comp;       /**< A double precision component. */
typedef int32_t slong_comp;       /**< A signed double precision component. */
#else                        /* regular 32 bit */
#ifdef _MSC_VER
#define COMP_RADIX 4294967296i64
#define COMP_MAX 0xFFFFFFFFFFFFFFFFui64
#else
#define COMP_RADIX 4294967296       /**< Max component + 1 */
#define COMP_MAX 0xFFFFFFFFFFFFFFFF /**< (Max dbl comp -1) */
#endif
#define COMP_BIT_SIZE 32   /**< Number of bits in a component. */
#define COMP_BYTE_SIZE 4   /**< Number of bytes in a component. */
#define COMP_NUM_NIBBLES 8 /**< Used For diagnostics only. */
typedef uint32_t comp;      /**< A single precision component. */
typedef uint64_t long_comp; /**< A double precision component. */
typedef int64_t slong_comp; /**< A signed double precision component. */
#endif

/**
 * @struct  _bigint
 * @brief A big integer basic object
 */
struct _bigint {
  struct _bigint *next; /**< The next bigint in the cache. */
  short size;           /**< The number of components in this bigint. */
  short max_comps;      /**< The heapsize allocated for this bigint */
  int refs;             /**< An internal reference count. */
  comp *comps;          /**< A ptr to the actual component data */
};

/**
 * Maintains the state of the cache, and a number of variables used in
 * reduction.
 */
struct _BI_CTX /**< A big integer "session" context. */
    {
  bigint *active_list;             /**< Bigints currently used. */
  bigint *free_list;               /**< Bigints not used. */
  bigint *bi_radix;                /**< The radix used. */
  bigint *bi_mod[BIGINT_NUM_MODS]; /**< modulus */

#if defined(CONFIG_BIGINT_MONTGOMERY)
  bigint *bi_RR_mod_m[BIGINT_NUM_MODS]; /**< R^2 mod m */
  bigint *bi_R_mod_m[BIGINT_NUM_MODS];  /**< R mod m */
  comp N0_dash[BIGINT_NUM_MODS];
#elif defined(CONFIG_BIGINT_BARRETT)
  bigint *bi_mu[BIGINT_NUM_MODS]; /**< Storage for mu */
#endif
  bigint *bi_normalised_mod[BIGINT_NUM_MODS]; /**< Normalised mod storage. */
  bigint **g;                                 /**< Used by sliding-window. */
  int window;       /**< The size of the sliding window */
  int active_count; /**< Number of active bigints. */
  int free_count;   /**< Number of free bigints. */

#ifdef CONFIG_BIGINT_MONTGOMERY
  uint8_t use_classical; /**< Use classical reduction. */
#endif
  uint8_t mod_offset; /**< The mod offset we are using */
};
typedef struct _BI_CTX BI_CTX;

#if !defined(MAX)
#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define MIN(a, b)  ((a) < (b) ? (a) : (b))
#endif

#define PERMANENT 0x7FFF55AA /**< A magic number for permanents. */

/*
 * Copyright (c) 2007, Cameron Rich
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * * Neither the name of the axTLS project nor the names of its contributors
 *   may be used to endorse or promote products derived from this software
 *   without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

NS_INTERNAL BI_CTX *bi_initialize(void);
NS_INTERNAL void bi_terminate(BI_CTX *ctx);
NS_INTERNAL void bi_permanent(bigint *bi);
NS_INTERNAL void bi_depermanent(bigint *bi);
NS_INTERNAL void bi_clear_cache(BI_CTX *ctx);
NS_INTERNAL void bi_free(BI_CTX *ctx, bigint *bi);
NS_INTERNAL bigint *bi_copy(bigint *bi);
NS_INTERNAL bigint *bi_clone(BI_CTX *ctx, const bigint *bi);
NS_INTERNAL void bi_export(BI_CTX *ctx, bigint *bi, uint8_t *data, int size);
NS_INTERNAL bigint *bi_import(BI_CTX *ctx, const uint8_t *data, int len);
NS_INTERNAL bigint *int_to_bi(BI_CTX *ctx, comp i);

/* the functions that actually do something interesting */
NS_INTERNAL bigint *bi_add(BI_CTX *ctx, bigint *bia, bigint *bib);
NS_INTERNAL bigint *bi_subtract(BI_CTX *ctx, bigint *bia, bigint *bib,
                                int *is_negative);
NS_INTERNAL bigint *bi_divide(BI_CTX *ctx, bigint *bia, bigint *bim,
                              int is_mod);
NS_INTERNAL bigint *bi_multiply(BI_CTX *ctx, bigint *bia, bigint *bib);
NS_INTERNAL bigint *bi_mod_power(BI_CTX *ctx, bigint *bi, bigint *biexp);
#if 0
NS_INTERNAL bigint *bi_mod_power2(BI_CTX *ctx, bigint *bi,
			bigint *bim, bigint *biexp);
#endif
NS_INTERNAL int bi_compare(bigint *bia, bigint *bib);
NS_INTERNAL void bi_set_mod(BI_CTX *ctx, bigint *bim, int mod_offset);
NS_INTERNAL void bi_free_mod(BI_CTX *ctx, int mod_offset);

#ifdef CONFIG_SSL_FULL_MODE
NS_INTERNAL void bi_print(const char *label, bigint *bi);
NS_INTERNAL bigint *bi_str_import(BI_CTX *ctx, const char *data);
#endif

/**
 * @def bi_mod
 * Find the residue of B. bi_set_mod() must be called before hand.
 */
#define bi_mod(A, B) bi_divide(A, B, ctx->bi_mod[ctx->mod_offset], 1)

/**
 * bi_residue() is technically the same as bi_mod(), but it uses the
 * appropriate reduction technique (which is bi_mod() when doing classical
 * reduction).
 */
#if defined(CONFIG_BIGINT_MONTGOMERY)
#define bi_residue(A, B) bi_mont(A, B)
NS_INTERNAL bigint *bi_mont(BI_CTX *ctx, bigint *bixy);
#elif defined(CONFIG_BIGINT_BARRETT)
#define bi_residue(A, B) bi_barrett(A, B)
NS_INTERNAL bigint *bi_barrett(BI_CTX *ctx, bigint *bi);
#else /* if defined(CONFIG_BIGINT_CLASSICAL) */
#define bi_residue(A, B) bi_mod(A, B)
#endif

#ifdef CONFIG_BIGINT_SQUARE
NS_INTERNAL bigint *bi_square(BI_CTX *ctx, bigint *bi);
#else
#define bi_square(A, B) bi_multiply(A, bi_copy(B), B)
#endif

//NS_INTERNAL bigint *bi_crt(BI_CTX *ctx, bigint *bi, bigint *dP, bigint *dQ,
//                           bigint *p, bigint *q, bigint *qInv);

/*
 * Copyright (c) 2007, Cameron Rich
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * * Neither the name of the axTLS project nor the names of its contributors
 *   may be used to endorse or promote products derived from this software
 *   without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * @defgroup bigint_api Big Integer API
 * @brief The bigint implementation as used by the axTLS project.
 *
 * The bigint library is for RSA encryption/decryption as well as signing.
 * This code tries to minimise use of malloc/free by maintaining a small
 * cache. A bigint context may maintain state by being made "permanent".
 * It be be later released with a bi_depermanent() and bi_free() call.
 *
 * It supports the following reduction techniques:
 * - Classical
 * - Barrett
 * - Montgomery
 *
 * It also implements the following:
 * - Karatsuba multiplication
 * - Squaring
 * - Sliding window exponentiation
 * - Chinese Remainder Theorem (implemented in rsa.c).
 *
 * All the algorithms used are pretty standard, and designed for different
 * data bus sizes. Negative numbers are not dealt with at all, so a subtraction
 * may need to be tested for negativity.
 *
 * This library steals some ideas from Jef Poskanzer
 * <http://cs.marlboro.edu/term/cs-fall02/algorithms/crypto/RSA/bigint>
 * and GMP <http://www.swox.com/gmp>. It gets most of its implementation
 * detail from "The Handbook of Applied Cryptography"
 * <http://www.cacr.math.uwaterloo.ca/hac/about/chap14.pdf>
 * @{
 */

#define V1 v->comps[v->size - 1]                     /**< v1 for division */
#define V2 v->comps[v->size - 2]                     /**< v2 for division */
#define U(j) tmp_u->comps[tmp_u->size - j - 1]       /**< uj for division */
#define Q(j) quotient->comps[quotient->size - j - 1] /**< qj for division */

static bigint *bi_int_multiply(BI_CTX *ctx, bigint *bi, comp i);
static bigint *bi_int_divide(BI_CTX *ctx, bigint *biR, comp denom);
static bigint *alloc(BI_CTX *ctx, int size);
static bigint *trim(bigint *bi);
static void more_comps(bigint *bi, int n);
#if defined(CONFIG_BIGINT_KARATSUBA) || defined(CONFIG_BIGINT_BARRETT) || \
    defined(CONFIG_BIGINT_MONTGOMERY)
static bigint *comp_right_shift(bigint *biR, int num_shifts);
static bigint *comp_left_shift(bigint *biR, int num_shifts);
#endif

#ifdef CONFIG_BIGINT_CHECK_ON
static void check(const bigint *bi);
#else
#define check(A) /**< disappears in normal production mode */
#endif

/**
 * @brief Start a new bigint context.
 * @return A bigint context.
 */
NS_INTERNAL BI_CTX *bi_initialize(void) {
  /* mg_calloc() sets everything to zero */
  BI_CTX *ctx = (BI_CTX *) mg_calloc(1, sizeof(BI_CTX));

  /* the radix */
  ctx->bi_radix = alloc(ctx, 2);
  ctx->bi_radix->comps[0] = 0;
  ctx->bi_radix->comps[1] = 1;
  bi_permanent(ctx->bi_radix);
  return ctx;
}

/**
 * @brief Close the bigint context and free any resources.
 *
 * Free up any used memory - a check is done if all objects were not
 * properly freed.
 * @param ctx [in]   The bigint session context.
 */
NS_INTERNAL void bi_terminate(BI_CTX *ctx) {
  bi_depermanent(ctx->bi_radix);
  bi_free(ctx, ctx->bi_radix);

  if (ctx->active_count != 0) {
#ifdef CONFIG_SSL_FULL_MODE
    printf("bi_terminate: there were %d un-freed bigints\n", ctx->active_count);
#endif
    abort();
  }

  bi_clear_cache(ctx);
  mg_free(ctx);
}

/**
 *@brief Clear the memory cache.
 */
NS_INTERNAL void bi_clear_cache(BI_CTX *ctx) {
  bigint *p, *pn;

  if (ctx->free_list == NULL) return;

  for (p = ctx->free_list; p != NULL; p = pn) {
    pn = p->next;
    mg_free(p->comps);
    mg_free(p);
  }

  ctx->free_count = 0;
  ctx->free_list = NULL;
}

/**
 * @brief Increment the number of references to this object.
 * It does not do a full copy.
 * @param bi [in]   The bigint to copy.
 * @return A reference to the same bigint.
 */
NS_INTERNAL bigint *bi_copy(bigint *bi) {
  check(bi);
  if (bi->refs != PERMANENT) bi->refs++;
  return bi;
}

/**
 * @brief Simply make a bigint object "unfreeable" if bi_free() is called on it.
 *
 * For this object to be freed, bi_depermanent() must be called.
 * @param bi [in]   The bigint to be made permanent.
 */
NS_INTERNAL void bi_permanent(bigint *bi) {
  check(bi);
  if (bi->refs != 1) {
#ifdef CONFIG_SSL_FULL_MODE
    printf("bi_permanent: refs was not 1\n");
#endif
    abort();
  }

  bi->refs = PERMANENT;
}

/**
 * @brief Take a permanent object and make it eligible for freedom.
 * @param bi [in]   The bigint to be made back to temporary.
 */
NS_INTERNAL void bi_depermanent(bigint *bi) {
  check(bi);
  if (bi->refs != PERMANENT) {
#ifdef CONFIG_SSL_FULL_MODE
    printf("bi_depermanent: bigint was not permanent\n");
#endif
    abort();
  }

  bi->refs = 1;
}

/**
 * @brief Free a bigint object so it can be used again.
 *
 * The memory itself it not actually freed, just tagged as being available
 * @param ctx [in]   The bigint session context.
 * @param bi [in]    The bigint to be freed.
 */
NS_INTERNAL void bi_free(BI_CTX *ctx, bigint *bi) {
  check(bi);
  if (bi->refs == PERMANENT) {
    return;
  }

  if (--bi->refs > 0) {
    return;
  }

  bi->next = ctx->free_list;
  ctx->free_list = bi;
  ctx->free_count++;

  if (--ctx->active_count < 0) {
#ifdef CONFIG_SSL_FULL_MODE
    printf(
        "bi_free: active_count went negative "
        "- double-freed bigint?\n");
#endif
    abort();
  }
}

/**
 * @brief Convert an (unsigned) integer into a bigint.
 * @param ctx [in]   The bigint session context.
 * @param i [in]     The (unsigned) integer to be converted.
 *
 */
NS_INTERNAL bigint *int_to_bi(BI_CTX *ctx, comp i) {
  bigint *biR = alloc(ctx, 1);
  biR->comps[0] = i;
  return biR;
}

/**
 * @brief Do a full copy of the bigint object.
 * @param ctx [in]   The bigint session context.
 * @param bi  [in]   The bigint object to be copied.
 */
NS_INTERNAL bigint *bi_clone(BI_CTX *ctx, const bigint *bi) {
  bigint *biR = alloc(ctx, bi->size);
  check(bi);
  memcpy(biR->comps, bi->comps, (size_t) bi->size * COMP_BYTE_SIZE);
  return biR;
}

/**
 * @brief Perform an addition operation between two bigints.
 * @param ctx [in]  The bigint session context.
 * @param bia [in]  A bigint.
 * @param bib [in]  Another bigint.
 * @return The result of the addition.
 */
NS_INTERNAL bigint *bi_add(BI_CTX *ctx, bigint *bia, bigint *bib) {
  int n;
  comp carry = 0;
  comp *pa, *pb;

  check(bia);
  check(bib);

  n = MAX(bia->size, bib->size);
  more_comps(bia, n + 1);
  more_comps(bib, n);
  pa = bia->comps;
  pb = bib->comps;

  do {
    comp sl, rl, cy1;
    sl = *pa + *pb++;
    rl = sl + carry;
    cy1 = sl < *pa;
    carry = cy1 | (rl < sl);
    *pa++ = rl;
  } while (--n != 0);

  *pa = carry; /* do overflow */
  bi_free(ctx, bib);
  return trim(bia);
}

/**
 * @brief Perform a subtraction operation between two bigints.
 * @param ctx [in]  The bigint session context.
 * @param bia [in]  A bigint.
 * @param bib [in]  Another bigint.
 * @param is_negative [out] If defined, indicates that the result was negative.
 * is_negative may be null.
 * @return The result of the subtraction. The result is always positive.
 */
NS_INTERNAL bigint *bi_subtract(BI_CTX *ctx, bigint *bia, bigint *bib,
                                int *is_negative) {
  int n = bia->size;
  comp *pa, *pb, carry = 0;

  check(bia);
  check(bib);

  more_comps(bib, n);
  pa = bia->comps;
  pb = bib->comps;

  do {
    comp sl, rl, cy1;
    sl = *pa - *pb++;
    rl = sl - carry;
    cy1 = sl > *pa;
    carry = cy1 | (rl > sl);
    *pa++ = rl;
  } while (--n != 0);

  if (is_negative) /* indicate a negative result */
  {
    *is_negative = (int) carry;
  }

  bi_free(ctx, trim(bib)); /* put bib back to the way it was */
  return trim(bia);
}

/**
 * Perform a multiply between a bigint an an (unsigned) integer
 */
static bigint *bi_int_multiply(BI_CTX *ctx, bigint *bia, comp b) {
  int j = 0, n = bia->size;
  bigint *biR = alloc(ctx, n + 1);
  comp carry = 0;
  comp *r = biR->comps;
  comp *a = bia->comps;

  check(bia);

  /* clear things to start with */
  memset(r, 0, (size_t) ((n + 1) * COMP_BYTE_SIZE));

  do {
    long_comp tmp = *r + (long_comp) a[j] * b + carry;
    *r++ = (comp) tmp; /* downsize */
    carry = (comp)(tmp >> COMP_BIT_SIZE);
  } while (++j < n);

  *r = carry;
  bi_free(ctx, bia);
  return trim(biR);
}

/**
 * @brief Does both division and modulo calculations.
 *
 * Used extensively when doing classical reduction.
 * @param ctx [in]  The bigint session context.
 * @param u [in]    A bigint which is the numerator.
 * @param v [in]    Either the denominator or the modulus depending on the mode.
 * @param is_mod [n] Determines if this is a normal division (0) or a reduction
 * (1).
 * @return  The result of the division/reduction.
 */
NS_INTERNAL bigint *bi_divide(BI_CTX *ctx, bigint *u, bigint *v, int is_mod) {
  int n = v->size, m = u->size - n;
  int j = 0, orig_u_size = u->size;
  uint8_t mod_offset = ctx->mod_offset;
  comp d;
  bigint *quotient, *tmp_u;
  comp q_dash;

  check(u);
  check(v);

  /* if doing reduction and we are < mod, then return mod */
  if (is_mod && bi_compare(v, u) > 0) {
    bi_free(ctx, v);
    return u;
  }

  quotient = alloc(ctx, m + 1);
  tmp_u = alloc(ctx, n + 1);
  v = trim(v); /* make sure we have no leading 0's */
  d = (comp)((long_comp) COMP_RADIX / (V1 + 1));

  /* clear things to start with */
  memset(quotient->comps, 0, (size_t) ((quotient->size) * COMP_BYTE_SIZE));

  /* normalise */
  if (d > 1) {
    u = bi_int_multiply(ctx, u, d);

    if (is_mod) {
      v = ctx->bi_normalised_mod[mod_offset];
    } else {
      v = bi_int_multiply(ctx, v, d);
    }
  }

  if (orig_u_size == u->size) /* new digit position u0 */
  {
    more_comps(u, orig_u_size + 1);
  }

  do {
    /* get a temporary short version of u */
    memcpy(tmp_u->comps, &u->comps[u->size - n - 1 - j],
           (size_t) (n + 1) * COMP_BYTE_SIZE);

    /* calculate q' */
    if (U(0) == V1) {
      q_dash = COMP_RADIX - 1;
    } else {
      q_dash = (comp)(((long_comp) U(0) * COMP_RADIX + U(1)) / V1);

      if (v->size > 1 && V2) {
        /* we are implementing the following:
        if (V2*q_dash > (((U(0)*COMP_RADIX + U(1) -
                q_dash*V1)*COMP_RADIX) + U(2))) ... */
        comp inner = (comp)((long_comp) COMP_RADIX * U(0) + U(1) -
                            (long_comp) q_dash * V1);
        if ((long_comp) V2 * q_dash > (long_comp) inner * COMP_RADIX + U(2)) {
          q_dash--;
        }
      }
    }

    /* multiply and subtract */
    if (q_dash) {
      int is_negative;
      tmp_u = bi_subtract(ctx, tmp_u, bi_int_multiply(ctx, bi_copy(v), q_dash),
                          &is_negative);
      more_comps(tmp_u, n + 1);

      Q(j) = q_dash;

      /* add back */
      if (is_negative) {
        Q(j)--;
        tmp_u = bi_add(ctx, tmp_u, bi_copy(v));

        /* lop off the carry */
        tmp_u->size--;
        v->size--;
      }
    } else {
      Q(j) = 0;
    }

    /* copy back to u */
    memcpy(&u->comps[u->size - n - 1 - j], tmp_u->comps,
           (size_t) (n + 1) * COMP_BYTE_SIZE);
  } while (++j <= m);

  bi_free(ctx, tmp_u);
  bi_free(ctx, v);

  if (is_mod) /* get the remainder */
  {
    bi_free(ctx, quotient);
    return bi_int_divide(ctx, trim(u), d);
  } else /* get the quotient */
  {
    bi_free(ctx, u);
    return trim(quotient);
  }
}

/*
 * Perform an integer divide on a bigint.
 */
static bigint *bi_int_divide(BI_CTX *ctx, bigint *biR, comp denom) {
  int i = biR->size - 1;
  long_comp r = 0;

  (void) ctx;
  check(biR);

  do {
    r = (r << COMP_BIT_SIZE) + biR->comps[i];
    biR->comps[i] = (comp)(r / denom);
    r %= denom;
  } while (--i >= 0);

  return trim(biR);
}

#ifdef CONFIG_BIGINT_MONTGOMERY
/**
 * There is a need for the value of integer N' such that B^-1(B-1)-N^-1N'=1,
 * where B^-1(B-1) mod N=1. Actually, only the least significant part of
 * N' is needed, hence the definition N0'=N' mod b. We reproduce below the
 * simple algorithm from an article by Dusse and Kaliski to efficiently
 * find N0' from N0 and b */
static comp modular_inverse(bigint *bim) {
  int i;
  comp t = 1;
  comp two_2_i_minus_1 = 2; /* 2^(i-1) */
  long_comp two_2_i = 4;    /* 2^i */
  comp N = bim->comps[0];

  for (i = 2; i <= COMP_BIT_SIZE; i++) {
    if ((long_comp) N * t % two_2_i >= two_2_i_minus_1) {
      t += two_2_i_minus_1;
    }

    two_2_i_minus_1 <<= 1;
    two_2_i <<= 1;
  }

  return (comp)(COMP_RADIX - t);
}
#endif

#if defined(CONFIG_BIGINT_KARATSUBA) || defined(CONFIG_BIGINT_BARRETT) || \
    defined(CONFIG_BIGINT_MONTGOMERY)
/**
 * Take each component and shift down (in terms of components)
 */
static bigint *comp_right_shift(bigint *biR, int num_shifts) {
  int i = biR->size - num_shifts;
  comp *x = biR->comps;
  comp *y = &biR->comps[num_shifts];

  check(biR);

  if (i <= 0) /* have we completely right shifted? */
  {
    biR->comps[0] = 0; /* return 0 */
    biR->size = 1;
    return biR;
  }

  do {
    *x++ = *y++;
  } while (--i > 0);

  biR->size -= num_shifts;
  return biR;
}

/**
 * Take each component and shift it up (in terms of components)
 */
static bigint *comp_left_shift(bigint *biR, int num_shifts) {
  int i = biR->size - 1;
  comp *x, *y;

  check(biR);

  if (num_shifts <= 0) {
    return biR;
  }

  more_comps(biR, biR->size + num_shifts);

  x = &biR->comps[i + num_shifts];
  y = &biR->comps[i];

  do {
    *x-- = *y--;
  } while (i--);

  memset(biR->comps, 0, (size_t) (num_shifts * COMP_BYTE_SIZE)); /* zero LS comps */
  return biR;
}
#endif

/**
 * @brief Allow a binary sequence to be imported as a bigint.
 * @param ctx [in]  The bigint session context.
 * @param data [in] The data to be converted.
 * @param size [in] The number of bytes of data.
 * @return A bigint representing this data.
 */
NS_INTERNAL bigint *bi_import(BI_CTX *ctx, const uint8_t *data, int size) {
  bigint *biR = alloc(ctx, (size + COMP_BYTE_SIZE - 1) / COMP_BYTE_SIZE);
  int i, j = 0, offset = 0;

  memset(biR->comps, 0, (size_t) (biR->size * COMP_BYTE_SIZE));

  for (i = size - 1; i >= 0; i--) {
    biR->comps[offset] += (comp) data[i] << (j * 8);

    if (++j == COMP_BYTE_SIZE) {
      j = 0;
      offset++;
    }
  }

  return trim(biR);
}

#ifdef CONFIG_SSL_FULL_MODE
/**
 * @brief The testharness uses this code to import text hex-streams and
 * convert them into bigints.
 * @param ctx [in]  The bigint session context.
 * @param data [in] A string consisting of hex characters. The characters must
 * be in upper case.
 * @return A bigint representing this data.
 */
NS_INTERNAL bigint *bi_str_import(BI_CTX *ctx, const char *data) {
  int size = strlen(data);
  bigint *biR = alloc(ctx, (size + COMP_NUM_NIBBLES - 1) / COMP_NUM_NIBBLES);
  int i, j = 0, offset = 0;
  memset(biR->comps, 0, (size_t) (biR->size * COMP_BYTE_SIZE));

  for (i = size - 1; i >= 0; i--) {
    int num = (data[i] <= '9') ? (data[i] - '0') : (data[i] - 'A' + 10);
    biR->comps[offset] += num << (j * 4);

    if (++j == COMP_NUM_NIBBLES) {
      j = 0;
      offset++;
    }
  }

  return biR;
}

NS_INTERNAL void bi_print(const char *label, bigint *x) {
  int i, j;

  if (x == NULL) {
    printf("%s: (null)\n", label);
    return;
  }

  printf("%s: (size %d)\n", label, x->size);
  for (i = x->size - 1; i >= 0; i--) {
    for (j = COMP_NUM_NIBBLES - 1; j >= 0; j--) {
      comp mask = 0x0f << (j * 4);
      comp num = (x->comps[i] & mask) >> (j * 4);
      putc((num <= 9) ? (num + '0') : (num + 'A' - 10), stdout);
    }
  }

  printf("\n");
}
#endif

/**
 * @brief Take a bigint and convert it into a byte sequence.
 *
 * This is useful after a decrypt operation.
 * @param ctx [in]  The bigint session context.
 * @param x [in]  The bigint to be converted.
 * @param data [out] The converted data as a byte stream.
 * @param size [in] The maximum size of the byte stream. Unused bytes will be
 * zeroed.
 */
NS_INTERNAL void bi_export(BI_CTX *ctx, bigint *x, uint8_t *data, int size) {
  int i, j, k = size - 1;

  check(x);
  memset(data, 0, (size_t) size); /* ensure all leading 0's are cleared */

  for (i = 0; i < x->size; i++) {
    for (j = 0; j < COMP_BYTE_SIZE; j++) {
      comp mask = (comp) 0xff << (j * 8);
      int num = (int) (x->comps[i] & mask) >> (j * 8);
      data[k--] = (uint8_t) num;

      if (k < 0) {
        goto buf_done;
      }
    }
  }
buf_done:

  bi_free(ctx, x);
}

/**
 * @brief Pre-calculate some of the expensive steps in reduction.
 *
 * This function should only be called once (normally when a session starts).
 * When the session is over, bi_free_mod() should be called. bi_mod_power()
 * relies on this function being called.
 * @param ctx [in]  The bigint session context.
 * @param bim [in]  The bigint modulus that will be used.
 * @param mod_offset [in] There are three moduluii that can be stored - the
 * standard modulus, and its two primes p and q. This offset refers to which
 * modulus we are referring to.
 * @see bi_free_mod(), bi_mod_power().
 */
NS_INTERNAL void bi_set_mod(BI_CTX *ctx, bigint *bim, int mod_offset) {
  int k = bim->size;
  comp d = (comp)((long_comp) COMP_RADIX / (bim->comps[k - 1] + 1));
#ifdef CONFIG_BIGINT_MONTGOMERY
  bigint *R, *R2;
#endif

  ctx->bi_mod[mod_offset] = bim;
  bi_permanent(ctx->bi_mod[mod_offset]);
  ctx->bi_normalised_mod[mod_offset] = bi_int_multiply(ctx, bim, d);
  bi_permanent(ctx->bi_normalised_mod[mod_offset]);

#if defined(CONFIG_BIGINT_MONTGOMERY)
  /* set montgomery variables */
  R = comp_left_shift(bi_clone(ctx, ctx->bi_radix), k - 1);      /* R */
  R2 = comp_left_shift(bi_clone(ctx, ctx->bi_radix), k * 2 - 1); /* R^2 */
  ctx->bi_RR_mod_m[mod_offset] = bi_mod(ctx, R2);                /* R^2 mod m */
  ctx->bi_R_mod_m[mod_offset] = bi_mod(ctx, R);                  /* R mod m */

  bi_permanent(ctx->bi_RR_mod_m[mod_offset]);
  bi_permanent(ctx->bi_R_mod_m[mod_offset]);

  ctx->N0_dash[mod_offset] = modular_inverse(ctx->bi_mod[mod_offset]);

#elif defined(CONFIG_BIGINT_BARRETT)
  ctx->bi_mu[mod_offset] =
      bi_divide(ctx, comp_left_shift(bi_clone(ctx, ctx->bi_radix), k * 2 - 1),
                ctx->bi_mod[mod_offset], 0);
  bi_permanent(ctx->bi_mu[mod_offset]);
#endif
}

/**
 * @brief Used when cleaning various bigints at the end of a session.
 * @param ctx [in]  The bigint session context.
 * @param mod_offset [in] The offset to use.
 * @see bi_set_mod().
 */
void bi_free_mod(BI_CTX *ctx, int mod_offset) {
  bi_depermanent(ctx->bi_mod[mod_offset]);
  bi_free(ctx, ctx->bi_mod[mod_offset]);
#if defined(CONFIG_BIGINT_MONTGOMERY)
  bi_depermanent(ctx->bi_RR_mod_m[mod_offset]);
  bi_depermanent(ctx->bi_R_mod_m[mod_offset]);
  bi_free(ctx, ctx->bi_RR_mod_m[mod_offset]);
  bi_free(ctx, ctx->bi_R_mod_m[mod_offset]);
#elif defined(CONFIG_BIGINT_BARRETT)
  bi_depermanent(ctx->bi_mu[mod_offset]);
  bi_free(ctx, ctx->bi_mu[mod_offset]);
#endif
  bi_depermanent(ctx->bi_normalised_mod[mod_offset]);
  bi_free(ctx, ctx->bi_normalised_mod[mod_offset]);
}

/**
 * Perform a standard multiplication between two bigints.
 *
 * Barrett reduction has no need for some parts of the product, so ignore bits
 * of the multiply. This routine gives Barrett its big performance
 * improvements over Classical/Montgomery reduction methods.
 */
static bigint *regular_multiply(BI_CTX *ctx, bigint *bia, bigint *bib,
                                int inner_partial, int outer_partial) {
  int i = 0, j;
  int n = bia->size;
  int t = bib->size;
  bigint *biR = alloc(ctx, n + t);
  comp *sr = biR->comps;
  comp *sa = bia->comps;
  comp *sb = bib->comps;

  check(bia);
  check(bib);

  /* clear things to start with */
  memset(biR->comps, 0, (size_t) ((n + t) * COMP_BYTE_SIZE));

  do {
    long_comp tmp;
    comp carry = 0;
    int r_index = i;
    j = 0;

    if (outer_partial && outer_partial - i > 0 && outer_partial < n) {
      r_index = outer_partial - 1;
      j = outer_partial - i - 1;
    }

    do {
      if (inner_partial && r_index >= inner_partial) {
        break;
      }

      tmp = sr[r_index] + ((long_comp) sa[j]) * sb[i] + carry;
      sr[r_index++] = (comp) tmp; /* downsize */
      carry = (comp) (tmp >> COMP_BIT_SIZE);
    } while (++j < n);

    sr[r_index] = carry;
  } while (++i < t);

  bi_free(ctx, bia);
  bi_free(ctx, bib);
  return trim(biR);
}

#ifdef CONFIG_BIGINT_KARATSUBA
/*
 * Karatsuba improves on regular multiplication due to only 3 multiplications
 * being done instead of 4. The additional additions/subtractions are O(N)
 * rather than O(N^2) and so for big numbers it saves on a few operations
 */
static bigint *karatsuba(BI_CTX *ctx, bigint *bia, bigint *bib, int is_square) {
  bigint *x0, *x1;
  bigint *p0, *p1, *p2;
  int m;

  if (is_square) {
    m = (bia->size + 1) / 2;
  } else {
    m = (MAX(bia->size, bib->size) + 1) / 2;
  }

  x0 = bi_clone(ctx, bia);
  x0->size = m;
  x1 = bi_clone(ctx, bia);
  comp_right_shift(x1, m);
  bi_free(ctx, bia);

  /* work out the 3 partial products */
  if (is_square) {
    p0 = bi_square(ctx, bi_copy(x0));
    p2 = bi_square(ctx, bi_copy(x1));
    p1 = bi_square(ctx, bi_add(ctx, x0, x1));
  } else /* normal multiply */
  {
    bigint *y0, *y1;
    y0 = bi_clone(ctx, bib);
    y0->size = m;
    y1 = bi_clone(ctx, bib);
    comp_right_shift(y1, m);
    bi_free(ctx, bib);

    p0 = bi_multiply(ctx, bi_copy(x0), bi_copy(y0));
    p2 = bi_multiply(ctx, bi_copy(x1), bi_copy(y1));
    p1 = bi_multiply(ctx, bi_add(ctx, x0, x1), bi_add(ctx, y0, y1));
  }

  p1 = bi_subtract(ctx, bi_subtract(ctx, p1, bi_copy(p2), NULL), bi_copy(p0),
                   NULL);

  comp_left_shift(p1, m);
  comp_left_shift(p2, 2 * m);
  return bi_add(ctx, p1, bi_add(ctx, p0, p2));
}
#endif

/**
 * @brief Perform a multiplication operation between two bigints.
 * @param ctx [in]  The bigint session context.
 * @param bia [in]  A bigint.
 * @param bib [in]  Another bigint.
 * @return The result of the multiplication.
 */
NS_INTERNAL bigint *bi_multiply(BI_CTX *ctx, bigint *bia, bigint *bib) {
  check(bia);
  check(bib);

#ifdef CONFIG_BIGINT_KARATSUBA
  if (MIN(bia->size, bib->size) < MUL_KARATSUBA_THRESH) {
    return regular_multiply(ctx, bia, bib, 0, 0);
  }

  return karatsuba(ctx, bia, bib, 0);
#else
  return regular_multiply(ctx, bia, bib, 0, 0);
#endif
}

#ifdef CONFIG_BIGINT_SQUARE
/*
 * Perform the actual square operion. It takes into account overflow.
 */
static bigint *regular_square(BI_CTX *ctx, bigint *bi) {
  int t = bi->size;
  int i = 0, j;
  bigint *biR = alloc(ctx, t * 2 + 1);
  comp *w = biR->comps;
  comp *x = bi->comps;
  long_comp carry;
  memset(w, 0, biR->size * COMP_BYTE_SIZE);

  do {
    long_comp tmp = w[2 * i] + (long_comp) x[i] * x[i];
    w[2 * i] = (comp) tmp;
    carry = tmp >> COMP_BIT_SIZE;

    for (j = i + 1; j < t; j++) {
      uint8_t c = 0;
      long_comp xx = (long_comp) x[i] * x[j];
      if ((COMP_MAX - xx) < xx) c = 1;

      tmp = (xx << 1);

      if ((COMP_MAX - tmp) < w[i + j]) c = 1;

      tmp += w[i + j];

      if ((COMP_MAX - tmp) < carry) c = 1;

      tmp += carry;
      w[i + j] = (comp) tmp;
      carry = tmp >> COMP_BIT_SIZE;

      if (c) carry += COMP_RADIX;
    }

    tmp = w[i + t] + carry;
    w[i + t] = (comp) tmp;
    w[i + t + 1] = tmp >> COMP_BIT_SIZE;
  } while (++i < t);

  bi_free(ctx, bi);
  return trim(biR);
}

/**
 * @brief Perform a square operation on a bigint.
 * @param ctx [in]  The bigint session context.
 * @param bia [in]  A bigint.
 * @return The result of the multiplication.
 */
NS_INTERNAL bigint *bi_square(BI_CTX *ctx, bigint *bia) {
  check(bia);

#ifdef CONFIG_BIGINT_KARATSUBA
  if (bia->size < SQU_KARATSUBA_THRESH) {
    return regular_square(ctx, bia);
  }

  return karatsuba(ctx, bia, NULL, 1);
#else
  return regular_square(ctx, bia);
#endif
}
#endif

/**
 * @brief Compare two bigints.
 * @param bia [in]  A bigint.
 * @param bib [in]  Another bigint.
 * @return -1 if smaller, 1 if larger and 0 if equal.
 */
NS_INTERNAL int bi_compare(bigint *bia, bigint *bib) {
  int r, i;

  check(bia);
  check(bib);

  if (bia->size > bib->size)
    r = 1;
  else if (bia->size < bib->size)
    r = -1;
  else {
    comp *a = bia->comps;
    comp *b = bib->comps;

    /* Same number of components.  Compare starting from the high end
     * and working down. */
    r = 0;
    i = bia->size - 1;

    do {
      if (a[i] > b[i]) {
        r = 1;
        break;
      } else if (a[i] < b[i]) {
        r = -1;
        break;
      }
    } while (--i >= 0);
  }

  return r;
}

/*
 * Allocate and zero more components.  Does not consume bi.
 */
static void more_comps(bigint *bi, int n) {
  if (n > bi->max_comps) {
    int max = MAX(bi->max_comps * 2, n);
    void *p = mg_calloc(1, (size_t) max * COMP_BYTE_SIZE);
    if (p != NULL && bi->size > 0) memcpy(p, bi->comps, (size_t) bi->max_comps * COMP_BYTE_SIZE);
    mg_free(bi->comps);
    bi->max_comps = (short) max;
    bi->comps = (comp *) p;
  }

  if (n > bi->size) {
    memset(&bi->comps[bi->size], 0, (size_t) (n - bi->size) * COMP_BYTE_SIZE);
  }

  bi->size = (short) n;
}

/*
 * Make a new empty bigint. It may just use an old one if one is available.
 * Otherwise get one off the heap.
 */
static bigint *alloc(BI_CTX *ctx, int size) {
  bigint *biR;

  /* Can we recycle an old bigint? */
  if (ctx->free_list != NULL) {
    biR = ctx->free_list;
    ctx->free_list = biR->next;
    ctx->free_count--;

    if (biR->refs != 0) {
#ifdef CONFIG_SSL_FULL_MODE
      printf("alloc: refs was not 0\n");
#endif
      abort(); /* create a stack trace from a core dump */
    }

    more_comps(biR, size);
  } else {
    /* No free bigints available - create a new one. */
    biR = (bigint *) mg_calloc(1, sizeof(bigint));
    biR->comps = (comp *) mg_calloc(1, (size_t) size * COMP_BYTE_SIZE);
    biR->max_comps = (short) size; /* give some space to spare */
  }

  biR->size = (short) size;
  biR->refs = 1;
  biR->next = NULL;
  ctx->active_count++;
  return biR;
}

/*
 * Work out the highest '1' bit in an exponent. Used when doing sliding-window
 * exponentiation.
 */
static int find_max_exp_index(bigint *biexp) {
  int i = COMP_BIT_SIZE - 1;
  comp shift = COMP_RADIX / 2;
  comp test = biexp->comps[biexp->size - 1]; /* assume no leading zeroes */

  check(biexp);

  do {
    if (test & shift) {
      return i + (biexp->size - 1) * COMP_BIT_SIZE;
    }

    shift >>= 1;
  } while (i-- != 0);

  return -1; /* error - must have been a leading 0 */
}

/*
 * Is a particular bit is an exponent 1 or 0? Used when doing sliding-window
 * exponentiation.
 */
static int exp_bit_is_one(bigint *biexp, int offset) {
  comp test = biexp->comps[offset / COMP_BIT_SIZE];
  int num_shifts = offset % COMP_BIT_SIZE;
  comp shift = 1;
  int i;

  check(biexp);

  for (i = 0; i < num_shifts; i++) {
    shift <<= 1;
  }

  return (test & shift) != 0;
}

#ifdef CONFIG_BIGINT_CHECK_ON
/*
 * Perform a sanity check on bi.
 */
static void check(const bigint *bi) {
  if (bi->refs <= 0) {
    printf("check: zero or negative refs in bigint\n");
    abort();
  }

  if (bi->next != NULL) {
    printf(
        "check: attempt to use a bigint from "
        "the free list\n");
    abort();
  }
}
#endif

/*
 * Delete any leading 0's (and allow for 0).
 */
static bigint *trim(bigint *bi) {
  check(bi);

  while (bi->comps[bi->size - 1] == 0 && bi->size > 1) {
    bi->size--;
  }

  return bi;
}

#if defined(CONFIG_BIGINT_MONTGOMERY)
/**
 * @brief Perform a single montgomery reduction.
 * @param ctx [in]  The bigint session context.
 * @param bixy [in]  A bigint.
 * @return The result of the montgomery reduction.
 */
NS_INTERNAL bigint *bi_mont(BI_CTX *ctx, bigint *bixy) {
  int i = 0, n;
  uint8_t mod_offset = ctx->mod_offset;
  bigint *bim = ctx->bi_mod[mod_offset];
  comp mod_inv = ctx->N0_dash[mod_offset];

  check(bixy);

  if (ctx->use_classical) /* just use classical instead */
  {
    return bi_mod(ctx, bixy);
  }

  n = bim->size;

  do {
    bixy = bi_add(ctx, bixy,
                  comp_left_shift(
                      bi_int_multiply(ctx, bim, bixy->comps[i] * mod_inv), i));
  } while (++i < n);

  comp_right_shift(bixy, n);

  if (bi_compare(bixy, bim) >= 0) {
    bixy = bi_subtract(ctx, bixy, bim, NULL);
  }

  return bixy;
}

#elif defined(CONFIG_BIGINT_BARRETT)
/*
 * Stomp on the most significant components to give the illusion of a "mod base
 * radix" operation
 */
static bigint *comp_mod(bigint *bi, int mod) {
  check(bi);

  if (bi->size > mod) {
    bi->size = mod;
  }

  return bi;
}

/**
 * @brief Perform a single Barrett reduction.
 * @param ctx [in]  The bigint session context.
 * @param bi [in]  A bigint.
 * @return The result of the Barrett reduction.
 */
NS_INTERNAL bigint *bi_barrett(BI_CTX *ctx, bigint *bi) {
  bigint *q1, *q2, *q3, *r1, *r2, *r;
  uint8_t mod_offset = ctx->mod_offset;
  bigint *bim = ctx->bi_mod[mod_offset];
  int k = bim->size;

  check(bi);
  check(bim);

  /* use Classical method instead  - Barrett cannot help here */
  if (bi->size > k * 2) {
    return bi_mod(ctx, bi);
  }

  q1 = comp_right_shift(bi_clone(ctx, bi), k - 1);

  /* do outer partial multiply */
  q2 = regular_multiply(ctx, q1, ctx->bi_mu[mod_offset], 0, k - 1);
  q3 = comp_right_shift(q2, k + 1);
  r1 = comp_mod(bi, k + 1);

  /* do inner partial multiply */
  r2 = comp_mod(regular_multiply(ctx, q3, bim, k + 1, 0), k + 1);
  r = bi_subtract(ctx, r1, r2, NULL);

  /* if (r >= m) r = r - m; */
  if (bi_compare(r, bim) >= 0) {
    r = bi_subtract(ctx, r, bim, NULL);
  }

  return r;
}
#endif /* CONFIG_BIGINT_BARRETT */

#ifdef CONFIG_BIGINT_SLIDING_WINDOW
/*
 * Work out g1, g3, g5, g7... etc for the sliding-window algorithm
 */
static void precompute_slide_window(BI_CTX *ctx, int window, bigint *g1) {
  int k = 1, i;
  bigint *g2;

  for (i = 0; i < window - 1; i++) /* compute 2^(window-1) */
  {
    k <<= 1;
  }

  ctx->g = (bigint **) mg_calloc(1, k * sizeof(bigint *));
  ctx->g[0] = bi_clone(ctx, g1);
  bi_permanent(ctx->g[0]);
  g2 = bi_residue(ctx, bi_square(ctx, ctx->g[0])); /* g^2 */

  for (i = 1; i < k; i++) {
    ctx->g[i] = bi_residue(ctx, bi_multiply(ctx, ctx->g[i - 1], bi_copy(g2)));
    bi_permanent(ctx->g[i]);
  }

  bi_free(ctx, g2);
  ctx->window = k;
}
#endif

/**
 * @brief Perform a modular exponentiation.
 *
 * This function requires bi_set_mod() to have been called previously. This is
 * one of the optimisations used for performance.
 * @param ctx [in]  The bigint session context.
 * @param bi  [in]  The bigint on which to perform the mod power operation.
 * @param biexp [in] The bigint exponent.
 * @return The result of the mod exponentiation operation
 * @see bi_set_mod().
 */
NS_INTERNAL bigint *bi_mod_power(BI_CTX *ctx, bigint *bi, bigint *biexp) {
  int i = find_max_exp_index(biexp), j, window_size = 1;
  bigint *biR = int_to_bi(ctx, 1);

#if defined(CONFIG_BIGINT_MONTGOMERY)
  uint8_t mod_offset = ctx->mod_offset;
  if (!ctx->use_classical) {
    /* preconvert */
    bi = bi_mont(ctx,
                 bi_multiply(ctx, bi, ctx->bi_RR_mod_m[mod_offset])); /* x' */
    bi_free(ctx, biR);
    biR = ctx->bi_R_mod_m[mod_offset]; /* A */
  }
#endif

  check(bi);
  check(biexp);

#ifdef CONFIG_BIGINT_SLIDING_WINDOW
  for (j = i; j > 32; j /= 5) /* work out an optimum size */
    window_size++;

  /* work out the slide constants */
  precompute_slide_window(ctx, window_size, bi);
#else /* just one constant */
  ctx->g = (bigint **) mg_calloc(1, sizeof(bigint *));
  ctx->g[0] = bi_clone(ctx, bi);
  ctx->window = 1;
  bi_permanent(ctx->g[0]);
#endif

  /* if sliding-window is off, then only one bit will be done at a time and
   * will reduce to standard left-to-right exponentiation */
  do {
    if (exp_bit_is_one(biexp, i)) {
      int l = i - window_size + 1;
      int part_exp = 0;

      if (l < 0) /* LSB of exponent will always be 1 */
        l = 0;
      else {
        while (exp_bit_is_one(biexp, l) == 0) l++; /* go back up */
      }

      /* build up the section of the exponent */
      for (j = i; j >= l; j--) {
        biR = bi_residue(ctx, bi_square(ctx, biR));
        if (exp_bit_is_one(biexp, j)) part_exp++;

        if (j != l) part_exp <<= 1;
      }

      part_exp = (part_exp - 1) / 2; /* adjust for array */
      biR = bi_residue(ctx, bi_multiply(ctx, biR, ctx->g[part_exp]));
      i = l - 1;
    } else /* square it */
    {
      biR = bi_residue(ctx, bi_square(ctx, biR));
      i--;
    }
  } while (i >= 0);

  /* cleanup */
  for (i = 0; i < ctx->window; i++) {
    bi_depermanent(ctx->g[i]);
    bi_free(ctx, ctx->g[i]);
  }

  mg_free(ctx->g);
  bi_free(ctx, bi);
  bi_free(ctx, biexp);
#if defined CONFIG_BIGINT_MONTGOMERY
  return ctx->use_classical ? biR : bi_mont(ctx, biR); /* convert back */
#else /* CONFIG_BIGINT_CLASSICAL or CONFIG_BIGINT_BARRETT */
  return biR;
#endif
}

/**
 * @brief Use the Chinese Remainder Theorem to quickly perform RSA decrypts.
 *
 * @param ctx [in]  The bigint session context.
 * @param bi  [in]  The bigint to perform the exp/mod.
 * @param dP [in] CRT's dP bigint
 * @param dQ [in] CRT's dQ bigint
 * @param p [in] CRT's p bigint
 * @param q [in] CRT's q bigint
 * @param qInv [in] CRT's qInv bigint
 * @return The result of the CRT operation
 */
#if 1
NS_INTERNAL bigint *bi_crt(BI_CTX *ctx, bigint *bi, bigint *dP, bigint *dQ,
                           bigint *p, bigint *q, bigint *qInv) {
  bigint *m1, *m2, *h;

/* Montgomery has a condition the 0 < x, y < m and these products violate
 * that condition. So disable Montgomery when using CRT */
#if defined(CONFIG_BIGINT_MONTGOMERY)
  ctx->use_classical = 1;
#endif
  ctx->mod_offset = BIGINT_P_OFFSET;
  m1 = bi_mod_power(ctx, bi_copy(bi), dP);

  ctx->mod_offset = BIGINT_Q_OFFSET;
  m2 = bi_mod_power(ctx, bi, dQ);

  h = bi_subtract(ctx, bi_add(ctx, m1, p), bi_copy(m2), NULL);
  h = bi_multiply(ctx, h, qInv);
  ctx->mod_offset = BIGINT_P_OFFSET;
  h = bi_residue(ctx, h);
#if defined(CONFIG_BIGINT_MONTGOMERY)
  ctx->use_classical = 0; /* reset for any further operation */
#endif
  return bi_add(ctx, m2, bi_multiply(ctx, q, h));
}
#endif

// Proper lib usage:
// - BI_CTX *c = bi_initialize()
// - allocate bigints (e.g.: calling bi_import(), int_to_bi(), ...)
// - function calls, allocate bigints, etc.
// - bigint *n = bi_import(c, indata, insize)
//   - bi_set_mod(c, n, x)
//   - mod function calls
//   - bigint *nn = bi_mod_pwr(c, m, e) <-- frees m, e
//   - bi_free_mod(c, x)                <-- frees n
// - bi_export(c, nn, outdata, outsize) <-- frees nn
// - function calls
// - free bigints calling bi_free()
// - bi_terminate(c)                    <-- frees c

int mg_rsa_mod_pow(const uint8_t *mod, size_t modsz, const uint8_t *exp, size_t expsz, const uint8_t *msg, size_t msgsz, uint8_t *out, size_t outsz) {
	BI_CTX *bi_ctx = bi_initialize();
	bigint *m1;
	bigint *n = bi_import(bi_ctx, mod, (int) modsz);
	bigint *e = bi_import(bi_ctx, exp, (int) expsz);
	bigint *h = bi_import(bi_ctx, msg, (int) msgsz);
	bi_set_mod(bi_ctx, n, 0);
	m1 = bi_mod_power(bi_ctx, h, e);
	bi_free_mod(bi_ctx, 0);
	bi_export(bi_ctx, m1, out, (int) outsz);
	bi_terminate(bi_ctx);
	return 0;
}

int mg_rsa_crt_sign(const uint8_t *em, size_t em_len,
                    const uint8_t *dP, size_t dP_len,
                    const uint8_t *dQ, size_t dQ_len,
                    const uint8_t *p, size_t p_len,
                    const uint8_t *q, size_t q_len,
                    const uint8_t *qInv, size_t qInv_len,
                    uint8_t *signature, size_t sig_len) {
  BI_CTX *ctx;
  bigint *em_bi, *dP_bi, *dQ_bi, *p_bi, *q_bi, *qInv_bi, *result_bi;
  int ret = -1;

  ctx = bi_initialize();
  if (ctx == NULL) {
    return -1;
  }

  em_bi = bi_import(ctx, em, (int) em_len);
  dP_bi = bi_import(ctx, dP, (int) dP_len);
  dQ_bi = bi_import(ctx, dQ, (int) dQ_len);
  p_bi = bi_import(ctx, p, (int) p_len);
  q_bi = bi_import(ctx, q, (int) q_len);
  qInv_bi = bi_import(ctx, qInv, (int) qInv_len);

  if (em_bi == NULL || dP_bi == NULL || dQ_bi == NULL ||
      p_bi == NULL || q_bi == NULL || qInv_bi == NULL) {
    goto cleanup;
  }

  bi_set_mod(ctx, bi_clone(ctx, p_bi), BIGINT_P_OFFSET);
  bi_set_mod(ctx, bi_clone(ctx, q_bi), BIGINT_Q_OFFSET);

  result_bi = bi_crt(ctx, em_bi, dP_bi, dQ_bi, p_bi, q_bi, qInv_bi);
  if (result_bi == NULL) {
    goto cleanup;
  }
  bi_export(ctx, result_bi, signature, (int) sig_len);
  ret = 0;  // Success!
cleanup:
  bi_free_mod(ctx, BIGINT_P_OFFSET);  // cloned p_bi stored in mod context
  bi_free_mod(ctx, BIGINT_Q_OFFSET);  // cloned q_bi stored in mod context
  bi_terminate(ctx);
  return ret;
}

#endif /* MG_TLS == MG_TLS_BUILTIN */

#ifdef MG_ENABLE_LINES
#line 1 "src/tls_uecc.c"
#endif
/* Copyright 2014, Kenneth MacKay. Licensed under the BSD 2-clause license. */




#if MG_TLS == MG_TLS_BUILTIN

#ifndef MG_UECC_RNG_MAX_TRIES
#define MG_UECC_RNG_MAX_TRIES 64
#endif

#if MG_UECC_ENABLE_VLI_API
#define MG_UECC_VLI_API
#else
#define MG_UECC_VLI_API static
#endif

#if (MG_UECC_PLATFORM == mg_uecc_avr) || (MG_UECC_PLATFORM == mg_uecc_arm) || \
    (MG_UECC_PLATFORM == mg_uecc_arm_thumb) ||                                \
    (MG_UECC_PLATFORM == mg_uecc_arm_thumb2)
#define MG_UECC_CONCATX(a, ...) a##__VA_ARGS__
#define MG_UECC_CONCAT(a, ...) MG_UECC_CONCATX(a, __VA_ARGS__)

#define STRX(a) #a
#define STR(a) STRX(a)

#define EVAL(...) EVAL1(EVAL1(EVAL1(EVAL1(__VA_ARGS__))))
#define EVAL1(...) EVAL2(EVAL2(EVAL2(EVAL2(__VA_ARGS__))))
#define EVAL2(...) EVAL3(EVAL3(EVAL3(EVAL3(__VA_ARGS__))))
#define EVAL3(...) EVAL4(EVAL4(EVAL4(EVAL4(__VA_ARGS__))))
#define EVAL4(...) __VA_ARGS__

#define DEC_1 0
#define DEC_2 1
#define DEC_3 2
#define DEC_4 3
#define DEC_5 4
#define DEC_6 5
#define DEC_7 6
#define DEC_8 7
#define DEC_9 8
#define DEC_10 9
#define DEC_11 10
#define DEC_12 11
#define DEC_13 12
#define DEC_14 13
#define DEC_15 14
#define DEC_16 15
#define DEC_17 16
#define DEC_18 17
#define DEC_19 18
#define DEC_20 19
#define DEC_21 20
#define DEC_22 21
#define DEC_23 22
#define DEC_24 23
#define DEC_25 24
#define DEC_26 25
#define DEC_27 26
#define DEC_28 27
#define DEC_29 28
#define DEC_30 29
#define DEC_31 30
#define DEC_32 31

#define DEC_(N) MG_UECC_CONCAT(DEC_, N)

#define SECOND_ARG(_, val, ...) val
#define SOME_CHECK_0 ~, 0
#define GET_SECOND_ARG(...) SECOND_ARG(__VA_ARGS__, SOME, )
#define SOME_OR_0(N) GET_SECOND_ARG(MG_UECC_CONCAT(SOME_CHECK_, N))

#define MG_UECC_EMPTY(...)
#define DEFER(...) __VA_ARGS__ MG_UECC_EMPTY()

#define REPEAT_NAME_0() REPEAT_0
#define REPEAT_NAME_SOME() REPEAT_SOME
#define REPEAT_0(...)
#define REPEAT_SOME(N, stuff) \
  DEFER(MG_UECC_CONCAT(REPEAT_NAME_, SOME_OR_0(DEC_(N))))()(DEC_(N), stuff) stuff
#define REPEAT(N, stuff) EVAL(REPEAT_SOME(N, stuff))

#define REPEATM_NAME_0() REPEATM_0
#define REPEATM_NAME_SOME() REPEATM_SOME
#define REPEATM_0(...)
#define REPEATM_SOME(N, macro) \
  macro(N) DEFER(MG_UECC_CONCAT(REPEATM_NAME_, SOME_OR_0(DEC_(N))))()(DEC_(N), macro)
#define REPEATM(N, macro) EVAL(REPEATM_SOME(N, macro))
#endif

// 

#if (MG_UECC_WORD_SIZE == 1)
#if MG_UECC_SUPPORTS_secp160r1
#define MG_UECC_MAX_WORDS 21 /* Due to the size of curve_n. */
#endif
#if MG_UECC_SUPPORTS_secp192r1
#undef MG_UECC_MAX_WORDS
#define MG_UECC_MAX_WORDS 24
#endif
#if MG_UECC_SUPPORTS_secp224r1
#undef MG_UECC_MAX_WORDS
#define MG_UECC_MAX_WORDS 28
#endif
#if (MG_UECC_SUPPORTS_secp256r1 || MG_UECC_SUPPORTS_secp256k1)
#undef MG_UECC_MAX_WORDS
#define MG_UECC_MAX_WORDS 32
#endif
#elif (MG_UECC_WORD_SIZE == 4)
#if MG_UECC_SUPPORTS_secp160r1
#define MG_UECC_MAX_WORDS 6 /* Due to the size of curve_n. */
#endif
#if MG_UECC_SUPPORTS_secp192r1
#undef MG_UECC_MAX_WORDS
#define MG_UECC_MAX_WORDS 6
#endif
#if MG_UECC_SUPPORTS_secp224r1
#undef MG_UECC_MAX_WORDS
#define MG_UECC_MAX_WORDS 7
#endif
#if (MG_UECC_SUPPORTS_secp256r1 || MG_UECC_SUPPORTS_secp256k1)
#undef MG_UECC_MAX_WORDS
#define MG_UECC_MAX_WORDS 8
#endif
#elif (MG_UECC_WORD_SIZE == 8)
#if MG_UECC_SUPPORTS_secp160r1
#define MG_UECC_MAX_WORDS 3
#endif
#if MG_UECC_SUPPORTS_secp192r1
#undef MG_UECC_MAX_WORDS
#define MG_UECC_MAX_WORDS 3
#endif
#if MG_UECC_SUPPORTS_secp224r1
#undef MG_UECC_MAX_WORDS
#define MG_UECC_MAX_WORDS 4
#endif
#if (MG_UECC_SUPPORTS_secp256r1 || MG_UECC_SUPPORTS_secp256k1)
#undef MG_UECC_MAX_WORDS
#define MG_UECC_MAX_WORDS 4
#endif
#endif /* MG_UECC_WORD_SIZE */

#define BITS_TO_WORDS(num_bits)                                \
  ((wordcount_t) ((num_bits + ((MG_UECC_WORD_SIZE * 8) - 1)) / \
                  (MG_UECC_WORD_SIZE * 8)))
#define BITS_TO_BYTES(num_bits) ((num_bits + 7) / 8)

struct MG_UECC_Curve_t {
  wordcount_t num_words;
  wordcount_t num_bytes;
  bitcount_t num_n_bits;
  mg_uecc_word_t p[MG_UECC_MAX_WORDS];
  mg_uecc_word_t n[MG_UECC_MAX_WORDS];
  mg_uecc_word_t G[MG_UECC_MAX_WORDS * 2];
  mg_uecc_word_t b[MG_UECC_MAX_WORDS];
  void (*double_jacobian)(mg_uecc_word_t *X1, mg_uecc_word_t *Y1,
                          mg_uecc_word_t *Z1, MG_UECC_Curve curve);
#if MG_UECC_SUPPORT_COMPRESSED_POINT
  void (*mod_sqrt)(mg_uecc_word_t *a, MG_UECC_Curve curve);
#endif
  void (*x_side)(mg_uecc_word_t *result, const mg_uecc_word_t *x,
                 MG_UECC_Curve curve);
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
  void (*mmod_fast)(mg_uecc_word_t *result, mg_uecc_word_t *product);
#endif
};

#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
static void bcopy(uint8_t *dst, const uint8_t *src, unsigned num_bytes) {
  while (0 != num_bytes) {
    num_bytes--;
    dst[num_bytes] = src[num_bytes];
  }
}
#endif

static cmpresult_t mg_uecc_vli_cmp_unsafe(const mg_uecc_word_t *left,
                                          const mg_uecc_word_t *right,
                                          wordcount_t num_words);

#if (MG_UECC_PLATFORM == mg_uecc_arm ||       \
     MG_UECC_PLATFORM == mg_uecc_arm_thumb || \
     MG_UECC_PLATFORM == mg_uecc_arm_thumb2)

#endif

#if (MG_UECC_PLATFORM == mg_uecc_avr)

#endif

#ifndef asm_clear
#define asm_clear 0
#endif
#ifndef asm_set
#define asm_set 0
#endif
#ifndef asm_add
#define asm_add 0
#endif
#ifndef asm_sub
#define asm_sub 0
#endif
#ifndef asm_mult
#define asm_mult 0
#endif
#ifndef asm_rshift1
#define asm_rshift1 0
#endif
#ifndef asm_mmod_fast_secp256r1
#define asm_mmod_fast_secp256r1 0
#endif

#if defined(default_RNG_defined) && default_RNG_defined
static MG_UECC_RNG_Function g_rng_function = &default_RNG;
#else
static MG_UECC_RNG_Function g_rng_function = 0;
#endif

void mg_uecc_set_rng(MG_UECC_RNG_Function rng_function) {
  g_rng_function = rng_function;
}

MG_UECC_RNG_Function mg_uecc_get_rng(void) {
  return g_rng_function;
}

int mg_uecc_curve_private_key_size(MG_UECC_Curve curve) {
  return BITS_TO_BYTES(curve->num_n_bits);
}

int mg_uecc_curve_public_key_size(MG_UECC_Curve curve) {
  return 2 * curve->num_bytes;
}

#if !asm_clear
MG_UECC_VLI_API void mg_uecc_vli_clear(mg_uecc_word_t *vli,
                                       wordcount_t num_words) {
  wordcount_t i;
  for (i = 0; i < num_words; ++i) {
    vli[i] = 0;
  }
}
#endif /* !asm_clear */

/* Constant-time comparison to zero - secure way to compare long integers */
/* Returns 1 if vli == 0, 0 otherwise. */
MG_UECC_VLI_API mg_uecc_word_t mg_uecc_vli_isZero(const mg_uecc_word_t *vli,
                                                  wordcount_t num_words) {
  mg_uecc_word_t bits = 0;
  wordcount_t i;
  for (i = 0; i < num_words; ++i) {
    bits |= vli[i];
  }
  return (bits == 0);
}

/* Returns nonzero if bit 'bit' of vli is set. */
MG_UECC_VLI_API mg_uecc_word_t mg_uecc_vli_testBit(const mg_uecc_word_t *vli,
                                                   bitcount_t bit) {
  return (vli[bit >> MG_UECC_WORD_BITS_SHIFT] &
          ((mg_uecc_word_t) 1 << (bit & MG_UECC_WORD_BITS_MASK)));
}

/* Counts the number of words in vli. */
static wordcount_t vli_numDigits(const mg_uecc_word_t *vli,
                                 const wordcount_t max_words) {
  wordcount_t i;
  /* Search from the end until we find a non-zero digit.
     We do it in reverse because we expect that most digits will be nonzero. */
  for (i = max_words - 1; i >= 0 && vli[i] == 0; --i) {
  }

  return (i + 1);
}

/* Counts the number of bits required to represent vli. */
MG_UECC_VLI_API bitcount_t mg_uecc_vli_numBits(const mg_uecc_word_t *vli,
                                               const wordcount_t max_words) {
  mg_uecc_word_t i;
  mg_uecc_word_t digit;

  wordcount_t num_digits = vli_numDigits(vli, max_words);
  if (num_digits == 0) {
    return 0;
  }

  digit = vli[num_digits - 1];
  for (i = 0; digit; ++i) {
    digit >>= 1;
  }

  return (((bitcount_t) ((num_digits - 1) << MG_UECC_WORD_BITS_SHIFT)) +
          (bitcount_t) i);
}

/* Sets dest = src. */
#if !asm_set
MG_UECC_VLI_API void mg_uecc_vli_set(mg_uecc_word_t *dest,
                                     const mg_uecc_word_t *src,
                                     wordcount_t num_words) {
  wordcount_t i;
  for (i = 0; i < num_words; ++i) {
    dest[i] = src[i];
  }
}
#endif /* !asm_set */

/* Returns sign of left - right. */
static cmpresult_t mg_uecc_vli_cmp_unsafe(const mg_uecc_word_t *left,
                                          const mg_uecc_word_t *right,
                                          wordcount_t num_words) {
  wordcount_t i;
  for (i = num_words - 1; i >= 0; --i) {
    if (left[i] > right[i]) {
      return 1;
    } else if (left[i] < right[i]) {
      return -1;
    }
  }
  return 0;
}

/* Constant-time comparison function - secure way to compare long integers */
/* Returns one if left == right, zero otherwise. */
MG_UECC_VLI_API mg_uecc_word_t mg_uecc_vli_equal(const mg_uecc_word_t *left,
                                                 const mg_uecc_word_t *right,
                                                 wordcount_t num_words) {
  mg_uecc_word_t diff = 0;
  wordcount_t i;
  for (i = num_words - 1; i >= 0; --i) {
    diff |= (left[i] ^ right[i]);
  }
  return (diff == 0);
}

MG_UECC_VLI_API mg_uecc_word_t mg_uecc_vli_sub(mg_uecc_word_t *result,
                                               const mg_uecc_word_t *left,
                                               const mg_uecc_word_t *right,
                                               wordcount_t num_words);

/* Returns sign of left - right, in constant time. */
MG_UECC_VLI_API cmpresult_t mg_uecc_vli_cmp(const mg_uecc_word_t *left,
                                            const mg_uecc_word_t *right,
                                            wordcount_t num_words) {
  mg_uecc_word_t tmp[MG_UECC_MAX_WORDS];
  mg_uecc_word_t neg = !!mg_uecc_vli_sub(tmp, left, right, num_words);
  mg_uecc_word_t equal = mg_uecc_vli_isZero(tmp, num_words);
  return (cmpresult_t) (!equal - 2 * neg);
}

/* Computes vli = vli >> 1. */
#if !asm_rshift1
MG_UECC_VLI_API void mg_uecc_vli_rshift1(mg_uecc_word_t *vli,
                                         wordcount_t num_words) {
  mg_uecc_word_t *end = vli;
  mg_uecc_word_t carry = 0;

  vli += num_words;
  while (vli-- > end) {
    mg_uecc_word_t temp = *vli;
    *vli = (temp >> 1) | carry;
    carry = temp << (MG_UECC_WORD_BITS - 1);
  }
}
#endif /* !asm_rshift1 */

/* Computes result = left + right, returning carry. Can modify in place. */
#if !asm_add
MG_UECC_VLI_API mg_uecc_word_t mg_uecc_vli_add(mg_uecc_word_t *result,
                                               const mg_uecc_word_t *left,
                                               const mg_uecc_word_t *right,
                                               wordcount_t num_words) {
  mg_uecc_word_t carry = 0;
  wordcount_t i;
  for (i = 0; i < num_words; ++i) {
    mg_uecc_word_t sum = left[i] + right[i] + carry;
    if (sum != left[i]) {
      carry = (sum < left[i]);
    }
    result[i] = sum;
  }
  return carry;
}
#endif /* !asm_add */

/* Computes result = left - right, returning borrow. Can modify in place. */
#if !asm_sub
MG_UECC_VLI_API mg_uecc_word_t mg_uecc_vli_sub(mg_uecc_word_t *result,
                                               const mg_uecc_word_t *left,
                                               const mg_uecc_word_t *right,
                                               wordcount_t num_words) {
  mg_uecc_word_t borrow = 0;
  wordcount_t i;
  for (i = 0; i < num_words; ++i) {
    mg_uecc_word_t diff = left[i] - right[i] - borrow;
    if (diff != left[i]) {
      borrow = (diff > left[i]);
    }
    result[i] = diff;
  }
  return borrow;
}
#endif /* !asm_sub */

#if !asm_mult || (MG_UECC_SQUARE_FUNC && !asm_square) ||               \
    (MG_UECC_SUPPORTS_secp256k1 && (MG_UECC_OPTIMIZATION_LEVEL > 0) && \
     ((MG_UECC_WORD_SIZE == 1) || (MG_UECC_WORD_SIZE == 8)))
static void muladd(mg_uecc_word_t a, mg_uecc_word_t b, mg_uecc_word_t *r0,
                   mg_uecc_word_t *r1, mg_uecc_word_t *r2) {
#if MG_UECC_WORD_SIZE == 8
  uint64_t a0 = a & 0xffffffff;
  uint64_t a1 = a >> 32;
  uint64_t b0 = b & 0xffffffff;
  uint64_t b1 = b >> 32;

  uint64_t i0 = a0 * b0;
  uint64_t i1 = a0 * b1;
  uint64_t i2 = a1 * b0;
  uint64_t i3 = a1 * b1;

  uint64_t p0, p1;

  i2 += (i0 >> 32);
  i2 += i1;
  if (i2 < i1) { /* overflow */
    i3 += 0x100000000;
  }

  p0 = (i0 & 0xffffffff) | (i2 << 32);
  p1 = i3 + (i2 >> 32);

  *r0 += p0;
  *r1 += (p1 + (*r0 < p0));
  *r2 += ((*r1 < p1) || (*r1 == p1 && *r0 < p0));
#else
  mg_uecc_dword_t p = (mg_uecc_dword_t) a * b;
  mg_uecc_dword_t r01 = ((mg_uecc_dword_t) (*r1) << MG_UECC_WORD_BITS) | *r0;
  r01 += p;
  *r2 += (r01 < p);
  *r1 = (mg_uecc_word_t) (r01 >> MG_UECC_WORD_BITS);
  *r0 = (mg_uecc_word_t) r01;
#endif
}
#endif /* muladd needed */

#if !asm_mult
MG_UECC_VLI_API void mg_uecc_vli_mult(mg_uecc_word_t *result,
                                      const mg_uecc_word_t *left,
                                      const mg_uecc_word_t *right,
                                      wordcount_t num_words) {
  mg_uecc_word_t r0 = 0;
  mg_uecc_word_t r1 = 0;
  mg_uecc_word_t r2 = 0;
  wordcount_t i, k;

  /* Compute each digit of result in sequence, maintaining the carries. */
  for (k = 0; k < num_words; ++k) {
    for (i = 0; i <= k; ++i) {
      muladd(left[i], right[k - i], &r0, &r1, &r2);
    }
    result[k] = r0;
    r0 = r1;
    r1 = r2;
    r2 = 0;
  }
  for (k = num_words; k < num_words * 2 - 1; ++k) {
    for (i = (wordcount_t) ((k + 1) - num_words); i < num_words; ++i) {
      muladd(left[i], right[k - i], &r0, &r1, &r2);
    }
    result[k] = r0;
    r0 = r1;
    r1 = r2;
    r2 = 0;
  }
  result[num_words * 2 - 1] = r0;
}
#endif /* !asm_mult */

#if MG_UECC_SQUARE_FUNC

#if !asm_square
static void mul2add(mg_uecc_word_t a, mg_uecc_word_t b, mg_uecc_word_t *r0,
                    mg_uecc_word_t *r1, mg_uecc_word_t *r2) {
#if MG_UECC_WORD_SIZE == 8
  uint64_t a0 = a & 0xffffffffull;
  uint64_t a1 = a >> 32;
  uint64_t b0 = b & 0xffffffffull;
  uint64_t b1 = b >> 32;

  uint64_t i0 = a0 * b0;
  uint64_t i1 = a0 * b1;
  uint64_t i2 = a1 * b0;
  uint64_t i3 = a1 * b1;

  uint64_t p0, p1;

  i2 += (i0 >> 32);
  i2 += i1;
  if (i2 < i1) { /* overflow */
    i3 += 0x100000000ull;
  }

  p0 = (i0 & 0xffffffffull) | (i2 << 32);
  p1 = i3 + (i2 >> 32);

  *r2 += (p1 >> 63);
  p1 = (p1 << 1) | (p0 >> 63);
  p0 <<= 1;

  *r0 += p0;
  *r1 += (p1 + (*r0 < p0));
  *r2 += ((*r1 < p1) || (*r1 == p1 && *r0 < p0));
#else
  mg_uecc_dword_t p = (mg_uecc_dword_t) a * b;
  mg_uecc_dword_t r01 = ((mg_uecc_dword_t) (*r1) << MG_UECC_WORD_BITS) | *r0;
  *r2 += (p >> (MG_UECC_WORD_BITS * 2 - 1));
  p *= 2;
  r01 += p;
  *r2 += (r01 < p);
  *r1 = r01 >> MG_UECC_WORD_BITS;
  *r0 = (mg_uecc_word_t) r01;
#endif
}

MG_UECC_VLI_API void mg_uecc_vli_square(mg_uecc_word_t *result,
                                        const mg_uecc_word_t *left,
                                        wordcount_t num_words) {
  mg_uecc_word_t r0 = 0;
  mg_uecc_word_t r1 = 0;
  mg_uecc_word_t r2 = 0;

  wordcount_t i, k;

  for (k = 0; k < num_words * 2 - 1; ++k) {
    mg_uecc_word_t min = (k < num_words ? 0 : (k + 1) - num_words);
    for (i = min; i <= k && i <= k - i; ++i) {
      if (i < k - i) {
        mul2add(left[i], left[k - i], &r0, &r1, &r2);
      } else {
        muladd(left[i], left[k - i], &r0, &r1, &r2);
      }
    }
    result[k] = r0;
    r0 = r1;
    r1 = r2;
    r2 = 0;
  }

  result[num_words * 2 - 1] = r0;
}
#endif /* !asm_square */

#else /* MG_UECC_SQUARE_FUNC */

#if MG_UECC_ENABLE_VLI_API
MG_UECC_VLI_API void mg_uecc_vli_square(mg_uecc_word_t *result,
                                        const mg_uecc_word_t *left,
                                        wordcount_t num_words) {
  mg_uecc_vli_mult(result, left, left, num_words);
}
#endif /* MG_UECC_ENABLE_VLI_API */

#endif /* MG_UECC_SQUARE_FUNC */

/* Computes result = (left + right) % mod.
   Assumes that left < mod and right < mod, and that result does not overlap
   mod. */
MG_UECC_VLI_API void mg_uecc_vli_modAdd(mg_uecc_word_t *result,
                                        const mg_uecc_word_t *left,
                                        const mg_uecc_word_t *right,
                                        const mg_uecc_word_t *mod,
                                        wordcount_t num_words) {
  mg_uecc_word_t carry = mg_uecc_vli_add(result, left, right, num_words);
  if (carry || mg_uecc_vli_cmp_unsafe(mod, result, num_words) != 1) {
    /* result > mod (result = mod + remainder), so subtract mod to get
     * remainder. */
    mg_uecc_vli_sub(result, result, mod, num_words);
  }
}

/* Computes result = (left - right) % mod.
   Assumes that left < mod and right < mod, and that result does not overlap
   mod. */
MG_UECC_VLI_API void mg_uecc_vli_modSub(mg_uecc_word_t *result,
                                        const mg_uecc_word_t *left,
                                        const mg_uecc_word_t *right,
                                        const mg_uecc_word_t *mod,
                                        wordcount_t num_words) {
  mg_uecc_word_t l_borrow = mg_uecc_vli_sub(result, left, right, num_words);
  if (l_borrow) {
    /* In this case, result == -diff == (max int) - diff. Since -x % d == d - x,
       we can get the correct result from result + mod (with overflow). */
    mg_uecc_vli_add(result, result, mod, num_words);
  }
}

/* Computes result = product % mod, where product is 2N words long. */
/* Currently only designed to work for curve_p or curve_n. */
MG_UECC_VLI_API void mg_uecc_vli_mmod(mg_uecc_word_t *result,
                                      mg_uecc_word_t *product,
                                      const mg_uecc_word_t *mod,
                                      wordcount_t num_words) {
  mg_uecc_word_t mod_multiple[2 * MG_UECC_MAX_WORDS];
  mg_uecc_word_t tmp[2 * MG_UECC_MAX_WORDS];
  mg_uecc_word_t *v[2] = {tmp, product};
  mg_uecc_word_t index;

  /* Shift mod so its highest set bit is at the maximum position. */
  bitcount_t shift = (bitcount_t) ((num_words * 2 * MG_UECC_WORD_BITS) -
                                   mg_uecc_vli_numBits(mod, num_words));
  wordcount_t word_shift = (wordcount_t) (shift / MG_UECC_WORD_BITS);
  wordcount_t bit_shift = (wordcount_t) (shift % MG_UECC_WORD_BITS);
  mg_uecc_word_t carry = 0;
  mg_uecc_vli_clear(mod_multiple, word_shift);
  if (bit_shift > 0) {
    for (index = 0; index < (mg_uecc_word_t) num_words; ++index) {
      mod_multiple[(mg_uecc_word_t) word_shift + index] =
          (mg_uecc_word_t) (mod[index] << bit_shift) | carry;
      carry = mod[index] >> (MG_UECC_WORD_BITS - bit_shift);
    }
  } else {
    mg_uecc_vli_set(mod_multiple + word_shift, mod, num_words);
  }

  for (index = 1; shift >= 0; --shift) {
    mg_uecc_word_t borrow = 0;
    wordcount_t i;
    for (i = 0; i < num_words * 2; ++i) {
      mg_uecc_word_t diff = v[index][i] - mod_multiple[i] - borrow;
      if (diff != v[index][i]) {
        borrow = (diff > v[index][i]);
      }
      v[1 - index][i] = diff;
    }
    index = !(index ^ borrow); /* Swap the index if there was no borrow */
    mg_uecc_vli_rshift1(mod_multiple, num_words);
    mod_multiple[num_words - 1] |= mod_multiple[num_words]
                                   << (MG_UECC_WORD_BITS - 1);
    mg_uecc_vli_rshift1(mod_multiple + num_words, num_words);
  }
  mg_uecc_vli_set(result, v[index], num_words);
}

/* Computes result = (left * right) % mod. */
MG_UECC_VLI_API void mg_uecc_vli_modMult(mg_uecc_word_t *result,
                                         const mg_uecc_word_t *left,
                                         const mg_uecc_word_t *right,
                                         const mg_uecc_word_t *mod,
                                         wordcount_t num_words) {
  mg_uecc_word_t product[2 * MG_UECC_MAX_WORDS];
  mg_uecc_vli_mult(product, left, right, num_words);
  mg_uecc_vli_mmod(result, product, mod, num_words);
}

MG_UECC_VLI_API void mg_uecc_vli_modMult_fast(mg_uecc_word_t *result,
                                              const mg_uecc_word_t *left,
                                              const mg_uecc_word_t *right,
                                              MG_UECC_Curve curve) {
  mg_uecc_word_t product[2 * MG_UECC_MAX_WORDS];
  mg_uecc_vli_mult(product, left, right, curve->num_words);
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
  curve->mmod_fast(result, product);
#else
  mg_uecc_vli_mmod(result, product, curve->p, curve->num_words);
#endif
}

#if MG_UECC_SQUARE_FUNC

#if MG_UECC_ENABLE_VLI_API
/* Computes result = left^2 % mod. */
MG_UECC_VLI_API void mg_uecc_vli_modSquare(mg_uecc_word_t *result,
                                           const mg_uecc_word_t *left,
                                           const mg_uecc_word_t *mod,
                                           wordcount_t num_words) {
  mg_uecc_word_t product[2 * MG_UECC_MAX_WORDS];
  mg_uecc_vli_square(product, left, num_words);
  mg_uecc_vli_mmod(result, product, mod, num_words);
}
#endif /* MG_UECC_ENABLE_VLI_API */

MG_UECC_VLI_API void mg_uecc_vli_modSquare_fast(mg_uecc_word_t *result,
                                                const mg_uecc_word_t *left,
                                                MG_UECC_Curve curve) {
  mg_uecc_word_t product[2 * MG_UECC_MAX_WORDS];
  mg_uecc_vli_square(product, left, curve->num_words);
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
  curve->mmod_fast(result, product);
#else
  mg_uecc_vli_mmod(result, product, curve->p, curve->num_words);
#endif
}

#else /* MG_UECC_SQUARE_FUNC */

#if MG_UECC_ENABLE_VLI_API
MG_UECC_VLI_API void mg_uecc_vli_modSquare(mg_uecc_word_t *result,
                                           const mg_uecc_word_t *left,
                                           const mg_uecc_word_t *mod,
                                           wordcount_t num_words) {
  mg_uecc_vli_modMult(result, left, left, mod, num_words);
}
#endif /* MG_UECC_ENABLE_VLI_API */

MG_UECC_VLI_API void mg_uecc_vli_modSquare_fast(mg_uecc_word_t *result,
                                                const mg_uecc_word_t *left,
                                                MG_UECC_Curve curve) {
  mg_uecc_vli_modMult_fast(result, left, left, curve);
}

#endif /* MG_UECC_SQUARE_FUNC */

#define EVEN(vli) (!(vli[0] & 1))
static void vli_modInv_update(mg_uecc_word_t *uv, const mg_uecc_word_t *mod,
                              wordcount_t num_words) {
  mg_uecc_word_t carry = 0;
  if (!EVEN(uv)) {
    carry = mg_uecc_vli_add(uv, uv, mod, num_words);
  }
  mg_uecc_vli_rshift1(uv, num_words);
  if (carry) {
    uv[num_words - 1] |= HIGH_BIT_SET;
  }
}

/* Computes result = (1 / input) % mod. All VLIs are the same size.
   See "From Euclid's GCD to Montgomery Multiplication to the Great Divide" */
MG_UECC_VLI_API void mg_uecc_vli_modInv(mg_uecc_word_t *result,
                                        const mg_uecc_word_t *input,
                                        const mg_uecc_word_t *mod,
                                        wordcount_t num_words) {
  mg_uecc_word_t a[MG_UECC_MAX_WORDS], b[MG_UECC_MAX_WORDS],
      u[MG_UECC_MAX_WORDS], v[MG_UECC_MAX_WORDS];
  cmpresult_t cmpResult;

  if (mg_uecc_vli_isZero(input, num_words)) {
    mg_uecc_vli_clear(result, num_words);
    return;
  }

  mg_uecc_vli_set(a, input, num_words);
  mg_uecc_vli_set(b, mod, num_words);
  mg_uecc_vli_clear(u, num_words);
  u[0] = 1;
  mg_uecc_vli_clear(v, num_words);
  while ((cmpResult = mg_uecc_vli_cmp_unsafe(a, b, num_words)) != 0) {
    if (EVEN(a)) {
      mg_uecc_vli_rshift1(a, num_words);
      vli_modInv_update(u, mod, num_words);
    } else if (EVEN(b)) {
      mg_uecc_vli_rshift1(b, num_words);
      vli_modInv_update(v, mod, num_words);
    } else if (cmpResult > 0) {
      mg_uecc_vli_sub(a, a, b, num_words);
      mg_uecc_vli_rshift1(a, num_words);
      if (mg_uecc_vli_cmp_unsafe(u, v, num_words) < 0) {
        mg_uecc_vli_add(u, u, mod, num_words);
      }
      mg_uecc_vli_sub(u, u, v, num_words);
      vli_modInv_update(u, mod, num_words);
    } else {
      mg_uecc_vli_sub(b, b, a, num_words);
      mg_uecc_vli_rshift1(b, num_words);
      if (mg_uecc_vli_cmp_unsafe(v, u, num_words) < 0) {
        mg_uecc_vli_add(v, v, mod, num_words);
      }
      mg_uecc_vli_sub(v, v, u, num_words);
      vli_modInv_update(v, mod, num_words);
    }
  }
  mg_uecc_vli_set(result, u, num_words);
}

/* ------ Point operations ------ */

/* Copyright 2015, Kenneth MacKay. Licensed under the BSD 2-clause license. */

#ifndef _UECC_CURVE_SPECIFIC_H_
#define _UECC_CURVE_SPECIFIC_H_

#define num_bytes_secp160r1 20
#define num_bytes_secp192r1 24
#define num_bytes_secp224r1 28
#define num_bytes_secp256r1 32
#define num_bytes_secp256k1 32

#if (MG_UECC_WORD_SIZE == 1)

#define num_words_secp160r1 20
#define num_words_secp192r1 24
#define num_words_secp224r1 28
#define num_words_secp256r1 32
#define num_words_secp256k1 32

#define BYTES_TO_WORDS_8(a, b, c, d, e, f, g, h) \
  0x##a, 0x##b, 0x##c, 0x##d, 0x##e, 0x##f, 0x##g, 0x##h
#define BYTES_TO_WORDS_4(a, b, c, d) 0x##a, 0x##b, 0x##c, 0x##d

#elif (MG_UECC_WORD_SIZE == 4)

#define num_words_secp160r1 5
#define num_words_secp192r1 6
#define num_words_secp224r1 7
#define num_words_secp256r1 8
#define num_words_secp256k1 8

#define BYTES_TO_WORDS_8(a, b, c, d, e, f, g, h) 0x##d##c##b##a, 0x##h##g##f##e
#define BYTES_TO_WORDS_4(a, b, c, d) 0x##d##c##b##a

#elif (MG_UECC_WORD_SIZE == 8)

#define num_words_secp160r1 3
#define num_words_secp192r1 3
#define num_words_secp224r1 4
#define num_words_secp256r1 4
#define num_words_secp256k1 4

#define BYTES_TO_WORDS_8(a, b, c, d, e, f, g, h) 0x##h##g##f##e##d##c##b##a##U
#define BYTES_TO_WORDS_4(a, b, c, d) 0x##d##c##b##a##U

#endif /* MG_UECC_WORD_SIZE */

#if MG_UECC_SUPPORTS_secp160r1 || MG_UECC_SUPPORTS_secp192r1 || \
    MG_UECC_SUPPORTS_secp224r1 || MG_UECC_SUPPORTS_secp256r1
static void double_jacobian_default(mg_uecc_word_t *X1, mg_uecc_word_t *Y1,
                                    mg_uecc_word_t *Z1, MG_UECC_Curve curve) {
  /* t1 = X, t2 = Y, t3 = Z */
  mg_uecc_word_t t4[MG_UECC_MAX_WORDS];
  mg_uecc_word_t t5[MG_UECC_MAX_WORDS];
  wordcount_t num_words = curve->num_words;

  if (mg_uecc_vli_isZero(Z1, num_words)) {
    return;
  }

  mg_uecc_vli_modSquare_fast(t4, Y1, curve);   /* t4 = y1^2 */
  mg_uecc_vli_modMult_fast(t5, X1, t4, curve); /* t5 = x1*y1^2 = A */
  mg_uecc_vli_modSquare_fast(t4, t4, curve);   /* t4 = y1^4 */
  mg_uecc_vli_modMult_fast(Y1, Y1, Z1, curve); /* t2 = y1*z1 = z3 */
  mg_uecc_vli_modSquare_fast(Z1, Z1, curve);   /* t3 = z1^2 */

  mg_uecc_vli_modAdd(X1, X1, Z1, curve->p, num_words); /* t1 = x1 + z1^2 */
  mg_uecc_vli_modAdd(Z1, Z1, Z1, curve->p, num_words); /* t3 = 2*z1^2 */
  mg_uecc_vli_modSub(Z1, X1, Z1, curve->p, num_words); /* t3 = x1 - z1^2 */
  mg_uecc_vli_modMult_fast(X1, X1, Z1, curve);         /* t1 = x1^2 - z1^4 */

  mg_uecc_vli_modAdd(Z1, X1, X1, curve->p,
                     num_words); /* t3 = 2*(x1^2 - z1^4) */
  mg_uecc_vli_modAdd(X1, X1, Z1, curve->p,
                     num_words); /* t1 = 3*(x1^2 - z1^4) */
  if (mg_uecc_vli_testBit(X1, 0)) {
    mg_uecc_word_t l_carry = mg_uecc_vli_add(X1, X1, curve->p, num_words);
    mg_uecc_vli_rshift1(X1, num_words);
    X1[num_words - 1] |= l_carry << (MG_UECC_WORD_BITS - 1);
  } else {
    mg_uecc_vli_rshift1(X1, num_words);
  }
  /* t1 = 3/2*(x1^2 - z1^4) = B */

  mg_uecc_vli_modSquare_fast(Z1, X1, curve);           /* t3 = B^2 */
  mg_uecc_vli_modSub(Z1, Z1, t5, curve->p, num_words); /* t3 = B^2 - A */
  mg_uecc_vli_modSub(Z1, Z1, t5, curve->p, num_words); /* t3 = B^2 - 2A = x3 */
  mg_uecc_vli_modSub(t5, t5, Z1, curve->p, num_words); /* t5 = A - x3 */
  mg_uecc_vli_modMult_fast(X1, X1, t5, curve);         /* t1 = B * (A - x3) */
  mg_uecc_vli_modSub(t4, X1, t4, curve->p,
                     num_words); /* t4 = B * (A - x3) - y1^4 = y3 */

  mg_uecc_vli_set(X1, Z1, num_words);
  mg_uecc_vli_set(Z1, Y1, num_words);
  mg_uecc_vli_set(Y1, t4, num_words);
}

/* Computes result = x^3 + ax + b. result must not overlap x. */
static void x_side_default(mg_uecc_word_t *result, const mg_uecc_word_t *x,
                           MG_UECC_Curve curve) {
  mg_uecc_word_t _3[MG_UECC_MAX_WORDS] = {3}; /* -a = 3 */
  wordcount_t num_words = curve->num_words;

  mg_uecc_vli_modSquare_fast(result, x, curve);                /* r = x^2 */
  mg_uecc_vli_modSub(result, result, _3, curve->p, num_words); /* r = x^2 - 3 */
  mg_uecc_vli_modMult_fast(result, result, x, curve); /* r = x^3 - 3x */
  mg_uecc_vli_modAdd(result, result, curve->b, curve->p,
                     num_words); /* r = x^3 - 3x + b */
}
#endif /* MG_UECC_SUPPORTS_secp... */

#if MG_UECC_SUPPORT_COMPRESSED_POINT
#if MG_UECC_SUPPORTS_secp160r1 || MG_UECC_SUPPORTS_secp192r1 || \
    MG_UECC_SUPPORTS_secp256r1 || MG_UECC_SUPPORTS_secp256k1
/* Compute a = sqrt(a) (mod curve_p). */
static void mod_sqrt_default(mg_uecc_word_t *a, MG_UECC_Curve curve) {
  bitcount_t i;
  mg_uecc_word_t p1[MG_UECC_MAX_WORDS] = {1};
  mg_uecc_word_t l_result[MG_UECC_MAX_WORDS] = {1};
  wordcount_t num_words = curve->num_words;

  /* When curve->p == 3 (mod 4), we can compute
     sqrt(a) = a^((curve->p + 1) / 4) (mod curve->p). */
  mg_uecc_vli_add(p1, curve->p, p1, num_words); /* p1 = curve_p + 1 */
  for (i = mg_uecc_vli_numBits(p1, num_words) - 1; i > 1; --i) {
    mg_uecc_vli_modSquare_fast(l_result, l_result, curve);
    if (mg_uecc_vli_testBit(p1, i)) {
      mg_uecc_vli_modMult_fast(l_result, l_result, a, curve);
    }
  }
  mg_uecc_vli_set(a, l_result, num_words);
}
#endif /* MG_UECC_SUPPORTS_secp... */
#endif /* MG_UECC_SUPPORT_COMPRESSED_POINT */

#if MG_UECC_SUPPORTS_secp160r1

#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
static void vli_mmod_fast_secp160r1(mg_uecc_word_t *result,
                                    mg_uecc_word_t *product);
#endif

static const struct MG_UECC_Curve_t curve_secp160r1 = {
    num_words_secp160r1,
    num_bytes_secp160r1,
    161, /* num_n_bits */
    {BYTES_TO_WORDS_8(FF, FF, FF, 7F, FF, FF, FF, FF),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF),
     BYTES_TO_WORDS_4(FF, FF, FF, FF)},
    {BYTES_TO_WORDS_8(57, 22, 75, CA, D3, AE, 27, F9),
     BYTES_TO_WORDS_8(C8, F4, 01, 00, 00, 00, 00, 00),
     BYTES_TO_WORDS_8(00, 00, 00, 00, 01, 00, 00, 00)},
    {BYTES_TO_WORDS_8(82, FC, CB, 13, B9, 8B, C3, 68),
     BYTES_TO_WORDS_8(89, 69, 64, 46, 28, 73, F5, 8E),
     BYTES_TO_WORDS_4(68, B5, 96, 4A),

     BYTES_TO_WORDS_8(32, FB, C5, 7A, 37, 51, 23, 04),
     BYTES_TO_WORDS_8(12, C9, DC, 59, 7D, 94, 68, 31),
     BYTES_TO_WORDS_4(55, 28, A6, 23)},
    {BYTES_TO_WORDS_8(45, FA, 65, C5, AD, D4, D4, 81),
     BYTES_TO_WORDS_8(9F, F8, AC, 65, 8B, 7A, BD, 54),
     BYTES_TO_WORDS_4(FC, BE, 97, 1C)},
    &double_jacobian_default,
#if MG_UECC_SUPPORT_COMPRESSED_POINT
    &mod_sqrt_default,
#endif
    &x_side_default,
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
    &vli_mmod_fast_secp160r1
#endif
};

MG_UECC_Curve mg_uecc_secp160r1(void) {
  return &curve_secp160r1;
}

#if (MG_UECC_OPTIMIZATION_LEVEL > 0 && !asm_mmod_fast_secp160r1)
/* Computes result = product % curve_p
    see http://www.isys.uni-klu.ac.at/PDF/2001-0126-MT.pdf page 354

    Note that this only works if log2(omega) < log2(p) / 2 */
static void omega_mult_secp160r1(mg_uecc_word_t *result,
                                 const mg_uecc_word_t *right);
#if MG_UECC_WORD_SIZE == 8
static void vli_mmod_fast_secp160r1(mg_uecc_word_t *result,
                                    mg_uecc_word_t *product) {
  mg_uecc_word_t tmp[2 * num_words_secp160r1];
  mg_uecc_word_t copy;

  mg_uecc_vli_clear(tmp, num_words_secp160r1);
  mg_uecc_vli_clear(tmp + num_words_secp160r1, num_words_secp160r1);

  omega_mult_secp160r1(tmp,
                       product + num_words_secp160r1 - 1); /* (Rq, q) = q * c */

  product[num_words_secp160r1 - 1] &= 0xffffffff;
  copy = tmp[num_words_secp160r1 - 1];
  tmp[num_words_secp160r1 - 1] &= 0xffffffff;
  mg_uecc_vli_add(result, product, tmp,
                  num_words_secp160r1); /* (C, r) = r + q */
  mg_uecc_vli_clear(product, num_words_secp160r1);
  tmp[num_words_secp160r1 - 1] = copy;
  omega_mult_secp160r1(product, tmp + num_words_secp160r1 - 1); /* Rq*c */
  mg_uecc_vli_add(result, result, product,
                  num_words_secp160r1); /* (C1, r) = r + Rq*c */

  while (mg_uecc_vli_cmp_unsafe(result, curve_secp160r1.p,
                                num_words_secp160r1) > 0) {
    mg_uecc_vli_sub(result, result, curve_secp160r1.p, num_words_secp160r1);
  }
}

static void omega_mult_secp160r1(uint64_t *result, const uint64_t *right) {
  uint32_t carry;
  unsigned i;

  /* Multiply by (2^31 + 1). */
  carry = 0;
  for (i = 0; i < num_words_secp160r1; ++i) {
    uint64_t tmp = (right[i] >> 32) | (right[i + 1] << 32);
    result[i] = (tmp << 31) + tmp + carry;
    carry = (tmp >> 33) + (result[i] < tmp || (carry && result[i] == tmp));
  }
  result[i] = carry;
}
#else
static void vli_mmod_fast_secp160r1(mg_uecc_word_t *result,
                                    mg_uecc_word_t *product) {
  mg_uecc_word_t tmp[2 * num_words_secp160r1];
  mg_uecc_word_t carry;

  mg_uecc_vli_clear(tmp, num_words_secp160r1);
  mg_uecc_vli_clear(tmp + num_words_secp160r1, num_words_secp160r1);

  omega_mult_secp160r1(tmp,
                       product + num_words_secp160r1); /* (Rq, q) = q * c */

  carry = mg_uecc_vli_add(result, product, tmp,
                          num_words_secp160r1); /* (C, r) = r + q */
  mg_uecc_vli_clear(product, num_words_secp160r1);
  omega_mult_secp160r1(product, tmp + num_words_secp160r1); /* Rq*c */
  carry += mg_uecc_vli_add(result, result, product,
                           num_words_secp160r1); /* (C1, r) = r + Rq*c */

  while (carry > 0) {
    --carry;
    mg_uecc_vli_sub(result, result, curve_secp160r1.p, num_words_secp160r1);
  }
  if (mg_uecc_vli_cmp_unsafe(result, curve_secp160r1.p, num_words_secp160r1) >
      0) {
    mg_uecc_vli_sub(result, result, curve_secp160r1.p, num_words_secp160r1);
  }
}
#endif

#if MG_UECC_WORD_SIZE == 1
static void omega_mult_secp160r1(uint8_t *result, const uint8_t *right) {
  uint8_t carry;
  uint8_t i;

  /* Multiply by (2^31 + 1). */
  mg_uecc_vli_set(result + 4, right, num_words_secp160r1); /* 2^32 */
  mg_uecc_vli_rshift1(result + 4, num_words_secp160r1);    /* 2^31 */
  result[3] = right[0] << 7; /* get last bit from shift */

  carry = mg_uecc_vli_add(result, result, right,
                          num_words_secp160r1); /* 2^31 + 1 */
  for (i = num_words_secp160r1; carry; ++i) {
    uint16_t sum = (uint16_t) result[i] + carry;
    result[i] = (uint8_t) sum;
    carry = sum >> 8;
  }
}
#elif MG_UECC_WORD_SIZE == 4
static void omega_mult_secp160r1(uint32_t *result, const uint32_t *right) {
  uint32_t carry;
  unsigned i;

  /* Multiply by (2^31 + 1). */
  mg_uecc_vli_set(result + 1, right, num_words_secp160r1); /* 2^32 */
  mg_uecc_vli_rshift1(result + 1, num_words_secp160r1);    /* 2^31 */
  result[0] = right[0] << 31; /* get last bit from shift */

  carry = mg_uecc_vli_add(result, result, right,
                          num_words_secp160r1); /* 2^31 + 1 */
  for (i = num_words_secp160r1; carry; ++i) {
    uint64_t sum = (uint64_t) result[i] + carry;
    result[i] = (uint32_t) sum;
    carry = sum >> 32;
  }
}
#endif /* MG_UECC_WORD_SIZE */
#endif /* (MG_UECC_OPTIMIZATION_LEVEL > 0 && !asm_mmod_fast_secp160r1) */

#endif /* MG_UECC_SUPPORTS_secp160r1 */

#if MG_UECC_SUPPORTS_secp192r1

#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
static void vli_mmod_fast_secp192r1(mg_uecc_word_t *result,
                                    mg_uecc_word_t *product);
#endif

static const struct MG_UECC_Curve_t curve_secp192r1 = {
    num_words_secp192r1,
    num_bytes_secp192r1,
    192, /* num_n_bits */
    {BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF),
     BYTES_TO_WORDS_8(FE, FF, FF, FF, FF, FF, FF, FF),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF)},
    {BYTES_TO_WORDS_8(31, 28, D2, B4, B1, C9, 6B, 14),
     BYTES_TO_WORDS_8(36, F8, DE, 99, FF, FF, FF, FF),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF)},
    {BYTES_TO_WORDS_8(12, 10, FF, 82, FD, 0A, FF, F4),
     BYTES_TO_WORDS_8(00, 88, A1, 43, EB, 20, BF, 7C),
     BYTES_TO_WORDS_8(F6, 90, 30, B0, 0E, A8, 8D, 18),

     BYTES_TO_WORDS_8(11, 48, 79, 1E, A1, 77, F9, 73),
     BYTES_TO_WORDS_8(D5, CD, 24, 6B, ED, 11, 10, 63),
     BYTES_TO_WORDS_8(78, DA, C8, FF, 95, 2B, 19, 07)},
    {BYTES_TO_WORDS_8(B1, B9, 46, C1, EC, DE, B8, FE),
     BYTES_TO_WORDS_8(49, 30, 24, 72, AB, E9, A7, 0F),
     BYTES_TO_WORDS_8(E7, 80, 9C, E5, 19, 05, 21, 64)},
    &double_jacobian_default,
#if MG_UECC_SUPPORT_COMPRESSED_POINT
    &mod_sqrt_default,
#endif
    &x_side_default,
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
    &vli_mmod_fast_secp192r1
#endif
};

MG_UECC_Curve mg_uecc_secp192r1(void) {
  return &curve_secp192r1;
}

#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
/* Computes result = product % curve_p.
   See algorithm 5 and 6 from http://www.isys.uni-klu.ac.at/PDF/2001-0126-MT.pdf
 */
#if MG_UECC_WORD_SIZE == 1
static void vli_mmod_fast_secp192r1(uint8_t *result, uint8_t *product) {
  uint8_t tmp[num_words_secp192r1];
  uint8_t carry;

  mg_uecc_vli_set(result, product, num_words_secp192r1);

  mg_uecc_vli_set(tmp, &product[24], num_words_secp192r1);
  carry = mg_uecc_vli_add(result, result, tmp, num_words_secp192r1);

  tmp[0] = tmp[1] = tmp[2] = tmp[3] = tmp[4] = tmp[5] = tmp[6] = tmp[7] = 0;
  tmp[8] = product[24];
  tmp[9] = product[25];
  tmp[10] = product[26];
  tmp[11] = product[27];
  tmp[12] = product[28];
  tmp[13] = product[29];
  tmp[14] = product[30];
  tmp[15] = product[31];
  tmp[16] = product[32];
  tmp[17] = product[33];
  tmp[18] = product[34];
  tmp[19] = product[35];
  tmp[20] = product[36];
  tmp[21] = product[37];
  tmp[22] = product[38];
  tmp[23] = product[39];
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp192r1);

  tmp[0] = tmp[8] = product[40];
  tmp[1] = tmp[9] = product[41];
  tmp[2] = tmp[10] = product[42];
  tmp[3] = tmp[11] = product[43];
  tmp[4] = tmp[12] = product[44];
  tmp[5] = tmp[13] = product[45];
  tmp[6] = tmp[14] = product[46];
  tmp[7] = tmp[15] = product[47];
  tmp[16] = tmp[17] = tmp[18] = tmp[19] = tmp[20] = tmp[21] = tmp[22] =
      tmp[23] = 0;
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp192r1);

  while (carry || mg_uecc_vli_cmp_unsafe(curve_secp192r1.p, result,
                                         num_words_secp192r1) != 1) {
    carry -=
        mg_uecc_vli_sub(result, result, curve_secp192r1.p, num_words_secp192r1);
  }
}
#elif MG_UECC_WORD_SIZE == 4
static void vli_mmod_fast_secp192r1(uint32_t *result, uint32_t *product) {
  uint32_t tmp[num_words_secp192r1];
  int carry;

  mg_uecc_vli_set(result, product, num_words_secp192r1);

  mg_uecc_vli_set(tmp, &product[6], num_words_secp192r1);
  carry = mg_uecc_vli_add(result, result, tmp, num_words_secp192r1);

  tmp[0] = tmp[1] = 0;
  tmp[2] = product[6];
  tmp[3] = product[7];
  tmp[4] = product[8];
  tmp[5] = product[9];
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp192r1);

  tmp[0] = tmp[2] = product[10];
  tmp[1] = tmp[3] = product[11];
  tmp[4] = tmp[5] = 0;
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp192r1);

  while (carry || mg_uecc_vli_cmp_unsafe(curve_secp192r1.p, result,
                                         num_words_secp192r1) != 1) {
    carry -=
        mg_uecc_vli_sub(result, result, curve_secp192r1.p, num_words_secp192r1);
  }
}
#else
static void vli_mmod_fast_secp192r1(uint64_t *result, uint64_t *product) {
  uint64_t tmp[num_words_secp192r1];
  int carry;

  mg_uecc_vli_set(result, product, num_words_secp192r1);

  mg_uecc_vli_set(tmp, &product[3], num_words_secp192r1);
  carry = (int) mg_uecc_vli_add(result, result, tmp, num_words_secp192r1);

  tmp[0] = 0;
  tmp[1] = product[3];
  tmp[2] = product[4];
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp192r1);

  tmp[0] = tmp[1] = product[5];
  tmp[2] = 0;
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp192r1);

  while (carry || mg_uecc_vli_cmp_unsafe(curve_secp192r1.p, result,
                                         num_words_secp192r1) != 1) {
    carry -=
        mg_uecc_vli_sub(result, result, curve_secp192r1.p, num_words_secp192r1);
  }
}
#endif /* MG_UECC_WORD_SIZE */
#endif /* (MG_UECC_OPTIMIZATION_LEVEL > 0) */

#endif /* MG_UECC_SUPPORTS_secp192r1 */

#if MG_UECC_SUPPORTS_secp224r1

#if MG_UECC_SUPPORT_COMPRESSED_POINT
static void mod_sqrt_secp224r1(mg_uecc_word_t *a, MG_UECC_Curve curve);
#endif
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
static void vli_mmod_fast_secp224r1(mg_uecc_word_t *result,
                                    mg_uecc_word_t *product);
#endif

static const struct MG_UECC_Curve_t curve_secp224r1 = {
    num_words_secp224r1,
    num_bytes_secp224r1,
    224, /* num_n_bits */
    {BYTES_TO_WORDS_8(01, 00, 00, 00, 00, 00, 00, 00),
     BYTES_TO_WORDS_8(00, 00, 00, 00, FF, FF, FF, FF),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF),
     BYTES_TO_WORDS_4(FF, FF, FF, FF)},
    {BYTES_TO_WORDS_8(3D, 2A, 5C, 5C, 45, 29, DD, 13),
     BYTES_TO_WORDS_8(3E, F0, B8, E0, A2, 16, FF, FF),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF),
     BYTES_TO_WORDS_4(FF, FF, FF, FF)},
    {BYTES_TO_WORDS_8(21, 1D, 5C, 11, D6, 80, 32, 34),
     BYTES_TO_WORDS_8(22, 11, C2, 56, D3, C1, 03, 4A),
     BYTES_TO_WORDS_8(B9, 90, 13, 32, 7F, BF, B4, 6B),
     BYTES_TO_WORDS_4(BD, 0C, 0E, B7),

     BYTES_TO_WORDS_8(34, 7E, 00, 85, 99, 81, D5, 44),
     BYTES_TO_WORDS_8(64, 47, 07, 5A, A0, 75, 43, CD),
     BYTES_TO_WORDS_8(E6, DF, 22, 4C, FB, 23, F7, B5),
     BYTES_TO_WORDS_4(88, 63, 37, BD)},
    {BYTES_TO_WORDS_8(B4, FF, 55, 23, 43, 39, 0B, 27),
     BYTES_TO_WORDS_8(BA, D8, BF, D7, B7, B0, 44, 50),
     BYTES_TO_WORDS_8(56, 32, 41, F5, AB, B3, 04, 0C),
     BYTES_TO_WORDS_4(85, 0A, 05, B4)},
    &double_jacobian_default,
#if MG_UECC_SUPPORT_COMPRESSED_POINT
    &mod_sqrt_secp224r1,
#endif
    &x_side_default,
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
    &vli_mmod_fast_secp224r1
#endif
};

MG_UECC_Curve mg_uecc_secp224r1(void) {
  return &curve_secp224r1;
}

#if MG_UECC_SUPPORT_COMPRESSED_POINT
/* Routine 3.2.4 RS;  from http://www.nsa.gov/ia/_files/nist-routines.pdf */
static void mod_sqrt_secp224r1_rs(mg_uecc_word_t *d1, mg_uecc_word_t *e1,
                                  mg_uecc_word_t *f1, const mg_uecc_word_t *d0,
                                  const mg_uecc_word_t *e0,
                                  const mg_uecc_word_t *f0) {
  mg_uecc_word_t t[num_words_secp224r1];

  mg_uecc_vli_modSquare_fast(t, d0, &curve_secp224r1);    /* t <-- d0 ^ 2 */
  mg_uecc_vli_modMult_fast(e1, d0, e0, &curve_secp224r1); /* e1 <-- d0 * e0 */
  mg_uecc_vli_modAdd(d1, t, f0, curve_secp224r1.p,
                     num_words_secp224r1); /* d1 <-- t  + f0 */
  mg_uecc_vli_modAdd(e1, e1, e1, curve_secp224r1.p,
                     num_words_secp224r1);               /* e1 <-- e1 + e1 */
  mg_uecc_vli_modMult_fast(f1, t, f0, &curve_secp224r1); /* f1 <-- t  * f0 */
  mg_uecc_vli_modAdd(f1, f1, f1, curve_secp224r1.p,
                     num_words_secp224r1); /* f1 <-- f1 + f1 */
  mg_uecc_vli_modAdd(f1, f1, f1, curve_secp224r1.p,
                     num_words_secp224r1); /* f1 <-- f1 + f1 */
}

/* Routine 3.2.5 RSS;  from http://www.nsa.gov/ia/_files/nist-routines.pdf */
static void mod_sqrt_secp224r1_rss(mg_uecc_word_t *d1, mg_uecc_word_t *e1,
                                   mg_uecc_word_t *f1, const mg_uecc_word_t *d0,
                                   const mg_uecc_word_t *e0,
                                   const mg_uecc_word_t *f0,
                                   const bitcount_t j) {
  bitcount_t i;

  mg_uecc_vli_set(d1, d0, num_words_secp224r1); /* d1 <-- d0 */
  mg_uecc_vli_set(e1, e0, num_words_secp224r1); /* e1 <-- e0 */
  mg_uecc_vli_set(f1, f0, num_words_secp224r1); /* f1 <-- f0 */
  for (i = 1; i <= j; i++) {
    mod_sqrt_secp224r1_rs(d1, e1, f1, d1, e1, f1); /* RS (d1,e1,f1,d1,e1,f1) */
  }
}

/* Routine 3.2.6 RM;  from http://www.nsa.gov/ia/_files/nist-routines.pdf */
static void mod_sqrt_secp224r1_rm(mg_uecc_word_t *d2, mg_uecc_word_t *e2,
                                  mg_uecc_word_t *f2, const mg_uecc_word_t *c,
                                  const mg_uecc_word_t *d0,
                                  const mg_uecc_word_t *e0,
                                  const mg_uecc_word_t *d1,
                                  const mg_uecc_word_t *e1) {
  mg_uecc_word_t t1[num_words_secp224r1];
  mg_uecc_word_t t2[num_words_secp224r1];

  mg_uecc_vli_modMult_fast(t1, e0, e1, &curve_secp224r1); /* t1 <-- e0 * e1 */
  mg_uecc_vli_modMult_fast(t1, t1, c, &curve_secp224r1);  /* t1 <-- t1 * c */
  /* t1 <-- p  - t1 */
  mg_uecc_vli_modSub(t1, curve_secp224r1.p, t1, curve_secp224r1.p,
                     num_words_secp224r1);
  mg_uecc_vli_modMult_fast(t2, d0, d1, &curve_secp224r1); /* t2 <-- d0 * d1 */
  mg_uecc_vli_modAdd(t2, t2, t1, curve_secp224r1.p,
                     num_words_secp224r1);                /* t2 <-- t2 + t1 */
  mg_uecc_vli_modMult_fast(t1, d0, e1, &curve_secp224r1); /* t1 <-- d0 * e1 */
  mg_uecc_vli_modMult_fast(e2, d1, e0, &curve_secp224r1); /* e2 <-- d1 * e0 */
  mg_uecc_vli_modAdd(e2, e2, t1, curve_secp224r1.p,
                     num_words_secp224r1);               /* e2 <-- e2 + t1 */
  mg_uecc_vli_modSquare_fast(f2, e2, &curve_secp224r1);  /* f2 <-- e2^2 */
  mg_uecc_vli_modMult_fast(f2, f2, c, &curve_secp224r1); /* f2 <-- f2 * c */
  /* f2 <-- p  - f2 */
  mg_uecc_vli_modSub(f2, curve_secp224r1.p, f2, curve_secp224r1.p,
                     num_words_secp224r1);
  mg_uecc_vli_set(d2, t2, num_words_secp224r1); /* d2 <-- t2 */
}

/* Routine 3.2.7 RP;  from http://www.nsa.gov/ia/_files/nist-routines.pdf */
static void mod_sqrt_secp224r1_rp(mg_uecc_word_t *d1, mg_uecc_word_t *e1,
                                  mg_uecc_word_t *f1, const mg_uecc_word_t *c,
                                  const mg_uecc_word_t *r) {
  wordcount_t i;
  wordcount_t pow2i = 1;
  mg_uecc_word_t d0[num_words_secp224r1];
  mg_uecc_word_t e0[num_words_secp224r1] = {1}; /* e0 <-- 1 */
  mg_uecc_word_t f0[num_words_secp224r1];

  mg_uecc_vli_set(d0, r, num_words_secp224r1); /* d0 <-- r */
  /* f0 <-- p  - c */
  mg_uecc_vli_modSub(f0, curve_secp224r1.p, c, curve_secp224r1.p,
                     num_words_secp224r1);
  for (i = 0; i <= 6; i++) {
    mod_sqrt_secp224r1_rss(d1, e1, f1, d0, e0, f0,
                           pow2i); /* RSS (d1,e1,f1,d0,e0,f0,2^i) */
    mod_sqrt_secp224r1_rm(d1, e1, f1, c, d1, e1, d0,
                          e0); /* RM (d1,e1,f1,c,d1,e1,d0,e0) */
    mg_uecc_vli_set(d0, d1, num_words_secp224r1); /* d0 <-- d1 */
    mg_uecc_vli_set(e0, e1, num_words_secp224r1); /* e0 <-- e1 */
    mg_uecc_vli_set(f0, f1, num_words_secp224r1); /* f0 <-- f1 */
    pow2i *= 2;
  }
}

/* Compute a = sqrt(a) (mod curve_p). */
/* Routine 3.2.8 mp_mod_sqrt_224; from
 * http://www.nsa.gov/ia/_files/nist-routines.pdf */
static void mod_sqrt_secp224r1(mg_uecc_word_t *a, MG_UECC_Curve curve) {
  (void) curve;
  bitcount_t i;
  mg_uecc_word_t e1[num_words_secp224r1];
  mg_uecc_word_t f1[num_words_secp224r1];
  mg_uecc_word_t d0[num_words_secp224r1];
  mg_uecc_word_t e0[num_words_secp224r1];
  mg_uecc_word_t f0[num_words_secp224r1];
  mg_uecc_word_t d1[num_words_secp224r1];

  /* s = a; using constant instead of random value */
  mod_sqrt_secp224r1_rp(d0, e0, f0, a, a); /* RP (d0, e0, f0, c, s) */
  mod_sqrt_secp224r1_rs(d1, e1, f1, d0, e0,
                        f0); /* RS (d1, e1, f1, d0, e0, f0) */
  for (i = 1; i <= 95; i++) {
    mg_uecc_vli_set(d0, d1, num_words_secp224r1); /* d0 <-- d1 */
    mg_uecc_vli_set(e0, e1, num_words_secp224r1); /* e0 <-- e1 */
    mg_uecc_vli_set(f0, f1, num_words_secp224r1); /* f0 <-- f1 */
    mod_sqrt_secp224r1_rs(d1, e1, f1, d0, e0,
                          f0); /* RS (d1, e1, f1, d0, e0, f0) */
    if (mg_uecc_vli_isZero(d1, num_words_secp224r1)) { /* if d1 == 0 */
      break;
    }
  }
  mg_uecc_vli_modInv(f1, e0, curve_secp224r1.p,
                     num_words_secp224r1);               /* f1 <-- 1 / e0 */
  mg_uecc_vli_modMult_fast(a, d0, f1, &curve_secp224r1); /* a  <-- d0 / e0 */
}
#endif /* MG_UECC_SUPPORT_COMPRESSED_POINT */

#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
/* Computes result = product % curve_p
   from http://www.nsa.gov/ia/_files/nist-routines.pdf */
#if MG_UECC_WORD_SIZE == 1
static void vli_mmod_fast_secp224r1(uint8_t *result, uint8_t *product) {
  uint8_t tmp[num_words_secp224r1];
  int8_t carry;

  /* t */
  mg_uecc_vli_set(result, product, num_words_secp224r1);

  /* s1 */
  tmp[0] = tmp[1] = tmp[2] = tmp[3] = 0;
  tmp[4] = tmp[5] = tmp[6] = tmp[7] = 0;
  tmp[8] = tmp[9] = tmp[10] = tmp[11] = 0;
  tmp[12] = product[28];
  tmp[13] = product[29];
  tmp[14] = product[30];
  tmp[15] = product[31];
  tmp[16] = product[32];
  tmp[17] = product[33];
  tmp[18] = product[34];
  tmp[19] = product[35];
  tmp[20] = product[36];
  tmp[21] = product[37];
  tmp[22] = product[38];
  tmp[23] = product[39];
  tmp[24] = product[40];
  tmp[25] = product[41];
  tmp[26] = product[42];
  tmp[27] = product[43];
  carry = mg_uecc_vli_add(result, result, tmp, num_words_secp224r1);

  /* s2 */
  tmp[12] = product[44];
  tmp[13] = product[45];
  tmp[14] = product[46];
  tmp[15] = product[47];
  tmp[16] = product[48];
  tmp[17] = product[49];
  tmp[18] = product[50];
  tmp[19] = product[51];
  tmp[20] = product[52];
  tmp[21] = product[53];
  tmp[22] = product[54];
  tmp[23] = product[55];
  tmp[24] = tmp[25] = tmp[26] = tmp[27] = 0;
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp224r1);

  /* d1 */
  tmp[0] = product[28];
  tmp[1] = product[29];
  tmp[2] = product[30];
  tmp[3] = product[31];
  tmp[4] = product[32];
  tmp[5] = product[33];
  tmp[6] = product[34];
  tmp[7] = product[35];
  tmp[8] = product[36];
  tmp[9] = product[37];
  tmp[10] = product[38];
  tmp[11] = product[39];
  tmp[12] = product[40];
  tmp[13] = product[41];
  tmp[14] = product[42];
  tmp[15] = product[43];
  tmp[16] = product[44];
  tmp[17] = product[45];
  tmp[18] = product[46];
  tmp[19] = product[47];
  tmp[20] = product[48];
  tmp[21] = product[49];
  tmp[22] = product[50];
  tmp[23] = product[51];
  tmp[24] = product[52];
  tmp[25] = product[53];
  tmp[26] = product[54];
  tmp[27] = product[55];
  carry -= mg_uecc_vli_sub(result, result, tmp, num_words_secp224r1);

  /* d2 */
  tmp[0] = product[44];
  tmp[1] = product[45];
  tmp[2] = product[46];
  tmp[3] = product[47];
  tmp[4] = product[48];
  tmp[5] = product[49];
  tmp[6] = product[50];
  tmp[7] = product[51];
  tmp[8] = product[52];
  tmp[9] = product[53];
  tmp[10] = product[54];
  tmp[11] = product[55];
  tmp[12] = tmp[13] = tmp[14] = tmp[15] = 0;
  tmp[16] = tmp[17] = tmp[18] = tmp[19] = 0;
  tmp[20] = tmp[21] = tmp[22] = tmp[23] = 0;
  tmp[24] = tmp[25] = tmp[26] = tmp[27] = 0;
  carry -= mg_uecc_vli_sub(result, result, tmp, num_words_secp224r1);

  if (carry < 0) {
    do {
      carry += mg_uecc_vli_add(result, result, curve_secp224r1.p,
                               num_words_secp224r1);
    } while (carry < 0);
  } else {
    while (carry || mg_uecc_vli_cmp_unsafe(curve_secp224r1.p, result,
                                           num_words_secp224r1) != 1) {
      carry -= mg_uecc_vli_sub(result, result, curve_secp224r1.p,
                               num_words_secp224r1);
    }
  }
}
#elif MG_UECC_WORD_SIZE == 4
static void vli_mmod_fast_secp224r1(uint32_t *result, uint32_t *product) {
  uint32_t tmp[num_words_secp224r1];
  int carry;

  /* t */
  mg_uecc_vli_set(result, product, num_words_secp224r1);

  /* s1 */
  tmp[0] = tmp[1] = tmp[2] = 0;
  tmp[3] = product[7];
  tmp[4] = product[8];
  tmp[5] = product[9];
  tmp[6] = product[10];
  carry = mg_uecc_vli_add(result, result, tmp, num_words_secp224r1);

  /* s2 */
  tmp[3] = product[11];
  tmp[4] = product[12];
  tmp[5] = product[13];
  tmp[6] = 0;
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp224r1);

  /* d1 */
  tmp[0] = product[7];
  tmp[1] = product[8];
  tmp[2] = product[9];
  tmp[3] = product[10];
  tmp[4] = product[11];
  tmp[5] = product[12];
  tmp[6] = product[13];
  carry -= mg_uecc_vli_sub(result, result, tmp, num_words_secp224r1);

  /* d2 */
  tmp[0] = product[11];
  tmp[1] = product[12];
  tmp[2] = product[13];
  tmp[3] = tmp[4] = tmp[5] = tmp[6] = 0;
  carry -= mg_uecc_vli_sub(result, result, tmp, num_words_secp224r1);

  if (carry < 0) {
    do {
      carry += mg_uecc_vli_add(result, result, curve_secp224r1.p,
                               num_words_secp224r1);
    } while (carry < 0);
  } else {
    while (carry || mg_uecc_vli_cmp_unsafe(curve_secp224r1.p, result,
                                           num_words_secp224r1) != 1) {
      carry -= mg_uecc_vli_sub(result, result, curve_secp224r1.p,
                               num_words_secp224r1);
    }
  }
}
#else
static void vli_mmod_fast_secp224r1(uint64_t *result, uint64_t *product) {
  uint64_t tmp[num_words_secp224r1];
  int carry = 0;

  /* t */
  mg_uecc_vli_set(result, product, num_words_secp224r1);
  result[num_words_secp224r1 - 1] &= 0xffffffff;

  /* s1 */
  tmp[0] = 0;
  tmp[1] = product[3] & 0xffffffff00000000ull;
  tmp[2] = product[4];
  tmp[3] = product[5] & 0xffffffff;
  mg_uecc_vli_add(result, result, tmp, num_words_secp224r1);

  /* s2 */
  tmp[1] = product[5] & 0xffffffff00000000ull;
  tmp[2] = product[6];
  tmp[3] = 0;
  mg_uecc_vli_add(result, result, tmp, num_words_secp224r1);

  /* d1 */
  tmp[0] = (product[3] >> 32) | (product[4] << 32);
  tmp[1] = (product[4] >> 32) | (product[5] << 32);
  tmp[2] = (product[5] >> 32) | (product[6] << 32);
  tmp[3] = product[6] >> 32;
  carry -= mg_uecc_vli_sub(result, result, tmp, num_words_secp224r1);

  /* d2 */
  tmp[0] = (product[5] >> 32) | (product[6] << 32);
  tmp[1] = product[6] >> 32;
  tmp[2] = tmp[3] = 0;
  carry -= mg_uecc_vli_sub(result, result, tmp, num_words_secp224r1);

  if (carry < 0) {
    do {
      carry += mg_uecc_vli_add(result, result, curve_secp224r1.p,
                               num_words_secp224r1);
    } while (carry < 0);
  } else {
    while (mg_uecc_vli_cmp_unsafe(curve_secp224r1.p, result,
                                  num_words_secp224r1) != 1) {
      mg_uecc_vli_sub(result, result, curve_secp224r1.p, num_words_secp224r1);
    }
  }
}
#endif /* MG_UECC_WORD_SIZE */
#endif /* (MG_UECC_OPTIMIZATION_LEVEL > 0) */

#endif /* MG_UECC_SUPPORTS_secp224r1 */

#if MG_UECC_SUPPORTS_secp256r1

#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
static void vli_mmod_fast_secp256r1(mg_uecc_word_t *result,
                                    mg_uecc_word_t *product);
#endif

static const struct MG_UECC_Curve_t curve_secp256r1 = {
    num_words_secp256r1,
    num_bytes_secp256r1,
    256, /* num_n_bits */
    {BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, 00, 00, 00, 00),
     BYTES_TO_WORDS_8(00, 00, 00, 00, 00, 00, 00, 00),
     BYTES_TO_WORDS_8(01, 00, 00, 00, FF, FF, FF, FF)},
    {BYTES_TO_WORDS_8(51, 25, 63, FC, C2, CA, B9, F3),
     BYTES_TO_WORDS_8(84, 9E, 17, A7, AD, FA, E6, BC),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF),
     BYTES_TO_WORDS_8(00, 00, 00, 00, FF, FF, FF, FF)},
    {BYTES_TO_WORDS_8(96, C2, 98, D8, 45, 39, A1, F4),
     BYTES_TO_WORDS_8(A0, 33, EB, 2D, 81, 7D, 03, 77),
     BYTES_TO_WORDS_8(F2, 40, A4, 63, E5, E6, BC, F8),
     BYTES_TO_WORDS_8(47, 42, 2C, E1, F2, D1, 17, 6B),

     BYTES_TO_WORDS_8(F5, 51, BF, 37, 68, 40, B6, CB),
     BYTES_TO_WORDS_8(CE, 5E, 31, 6B, 57, 33, CE, 2B),
     BYTES_TO_WORDS_8(16, 9E, 0F, 7C, 4A, EB, E7, 8E),
     BYTES_TO_WORDS_8(9B, 7F, 1A, FE, E2, 42, E3, 4F)},
    {BYTES_TO_WORDS_8(4B, 60, D2, 27, 3E, 3C, CE, 3B),
     BYTES_TO_WORDS_8(F6, B0, 53, CC, B0, 06, 1D, 65),
     BYTES_TO_WORDS_8(BC, 86, 98, 76, 55, BD, EB, B3),
     BYTES_TO_WORDS_8(E7, 93, 3A, AA, D8, 35, C6, 5A)},
    &double_jacobian_default,
#if MG_UECC_SUPPORT_COMPRESSED_POINT
    &mod_sqrt_default,
#endif
    &x_side_default,
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
    &vli_mmod_fast_secp256r1
#endif
};

MG_UECC_Curve mg_uecc_secp256r1(void) {
  return &curve_secp256r1;
}

#if (MG_UECC_OPTIMIZATION_LEVEL > 0 && !asm_mmod_fast_secp256r1)
/* Computes result = product % curve_p
   from http://www.nsa.gov/ia/_files/nist-routines.pdf */
#if MG_UECC_WORD_SIZE == 1
static void vli_mmod_fast_secp256r1(uint8_t *result, uint8_t *product) {
  uint8_t tmp[num_words_secp256r1];
  int8_t carry;

  /* t */
  mg_uecc_vli_set(result, product, num_words_secp256r1);

  /* s1 */
  tmp[0] = tmp[1] = tmp[2] = tmp[3] = 0;
  tmp[4] = tmp[5] = tmp[6] = tmp[7] = 0;
  tmp[8] = tmp[9] = tmp[10] = tmp[11] = 0;
  tmp[12] = product[44];
  tmp[13] = product[45];
  tmp[14] = product[46];
  tmp[15] = product[47];
  tmp[16] = product[48];
  tmp[17] = product[49];
  tmp[18] = product[50];
  tmp[19] = product[51];
  tmp[20] = product[52];
  tmp[21] = product[53];
  tmp[22] = product[54];
  tmp[23] = product[55];
  tmp[24] = product[56];
  tmp[25] = product[57];
  tmp[26] = product[58];
  tmp[27] = product[59];
  tmp[28] = product[60];
  tmp[29] = product[61];
  tmp[30] = product[62];
  tmp[31] = product[63];
  carry = mg_uecc_vli_add(tmp, tmp, tmp, num_words_secp256r1);
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* s2 */
  tmp[12] = product[48];
  tmp[13] = product[49];
  tmp[14] = product[50];
  tmp[15] = product[51];
  tmp[16] = product[52];
  tmp[17] = product[53];
  tmp[18] = product[54];
  tmp[19] = product[55];
  tmp[20] = product[56];
  tmp[21] = product[57];
  tmp[22] = product[58];
  tmp[23] = product[59];
  tmp[24] = product[60];
  tmp[25] = product[61];
  tmp[26] = product[62];
  tmp[27] = product[63];
  tmp[28] = tmp[29] = tmp[30] = tmp[31] = 0;
  carry += mg_uecc_vli_add(tmp, tmp, tmp, num_words_secp256r1);
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* s3 */
  tmp[0] = product[32];
  tmp[1] = product[33];
  tmp[2] = product[34];
  tmp[3] = product[35];
  tmp[4] = product[36];
  tmp[5] = product[37];
  tmp[6] = product[38];
  tmp[7] = product[39];
  tmp[8] = product[40];
  tmp[9] = product[41];
  tmp[10] = product[42];
  tmp[11] = product[43];
  tmp[12] = tmp[13] = tmp[14] = tmp[15] = 0;
  tmp[16] = tmp[17] = tmp[18] = tmp[19] = 0;
  tmp[20] = tmp[21] = tmp[22] = tmp[23] = 0;
  tmp[24] = product[56];
  tmp[25] = product[57];
  tmp[26] = product[58];
  tmp[27] = product[59];
  tmp[28] = product[60];
  tmp[29] = product[61];
  tmp[30] = product[62];
  tmp[31] = product[63];
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* s4 */
  tmp[0] = product[36];
  tmp[1] = product[37];
  tmp[2] = product[38];
  tmp[3] = product[39];
  tmp[4] = product[40];
  tmp[5] = product[41];
  tmp[6] = product[42];
  tmp[7] = product[43];
  tmp[8] = product[44];
  tmp[9] = product[45];
  tmp[10] = product[46];
  tmp[11] = product[47];
  tmp[12] = product[52];
  tmp[13] = product[53];
  tmp[14] = product[54];
  tmp[15] = product[55];
  tmp[16] = product[56];
  tmp[17] = product[57];
  tmp[18] = product[58];
  tmp[19] = product[59];
  tmp[20] = product[60];
  tmp[21] = product[61];
  tmp[22] = product[62];
  tmp[23] = product[63];
  tmp[24] = product[52];
  tmp[25] = product[53];
  tmp[26] = product[54];
  tmp[27] = product[55];
  tmp[28] = product[32];
  tmp[29] = product[33];
  tmp[30] = product[34];
  tmp[31] = product[35];
  carry += mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* d1 */
  tmp[0] = product[44];
  tmp[1] = product[45];
  tmp[2] = product[46];
  tmp[3] = product[47];
  tmp[4] = product[48];
  tmp[5] = product[49];
  tmp[6] = product[50];
  tmp[7] = product[51];
  tmp[8] = product[52];
  tmp[9] = product[53];
  tmp[10] = product[54];
  tmp[11] = product[55];
  tmp[12] = tmp[13] = tmp[14] = tmp[15] = 0;
  tmp[16] = tmp[17] = tmp[18] = tmp[19] = 0;
  tmp[20] = tmp[21] = tmp[22] = tmp[23] = 0;
  tmp[24] = product[32];
  tmp[25] = product[33];
  tmp[26] = product[34];
  tmp[27] = product[35];
  tmp[28] = product[40];
  tmp[29] = product[41];
  tmp[30] = product[42];
  tmp[31] = product[43];
  carry -= mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  /* d2 */
  tmp[0] = product[48];
  tmp[1] = product[49];
  tmp[2] = product[50];
  tmp[3] = product[51];
  tmp[4] = product[52];
  tmp[5] = product[53];
  tmp[6] = product[54];
  tmp[7] = product[55];
  tmp[8] = product[56];
  tmp[9] = product[57];
  tmp[10] = product[58];
  tmp[11] = product[59];
  tmp[12] = product[60];
  tmp[13] = product[61];
  tmp[14] = product[62];
  tmp[15] = product[63];
  tmp[16] = tmp[17] = tmp[18] = tmp[19] = 0;
  tmp[20] = tmp[21] = tmp[22] = tmp[23] = 0;
  tmp[24] = product[36];
  tmp[25] = product[37];
  tmp[26] = product[38];
  tmp[27] = product[39];
  tmp[28] = product[44];
  tmp[29] = product[45];
  tmp[30] = product[46];
  tmp[31] = product[47];
  carry -= mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  /* d3 */
  tmp[0] = product[52];
  tmp[1] = product[53];
  tmp[2] = product[54];
  tmp[3] = product[55];
  tmp[4] = product[56];
  tmp[5] = product[57];
  tmp[6] = product[58];
  tmp[7] = product[59];
  tmp[8] = product[60];
  tmp[9] = product[61];
  tmp[10] = product[62];
  tmp[11] = product[63];
  tmp[12] = product[32];
  tmp[13] = product[33];
  tmp[14] = product[34];
  tmp[15] = product[35];
  tmp[16] = product[36];
  tmp[17] = product[37];
  tmp[18] = product[38];
  tmp[19] = product[39];
  tmp[20] = product[40];
  tmp[21] = product[41];
  tmp[22] = product[42];
  tmp[23] = product[43];
  tmp[24] = tmp[25] = tmp[26] = tmp[27] = 0;
  tmp[28] = product[48];
  tmp[29] = product[49];
  tmp[30] = product[50];
  tmp[31] = product[51];
  carry -= mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  /* d4 */
  tmp[0] = product[56];
  tmp[1] = product[57];
  tmp[2] = product[58];
  tmp[3] = product[59];
  tmp[4] = product[60];
  tmp[5] = product[61];
  tmp[6] = product[62];
  tmp[7] = product[63];
  tmp[8] = tmp[9] = tmp[10] = tmp[11] = 0;
  tmp[12] = product[36];
  tmp[13] = product[37];
  tmp[14] = product[38];
  tmp[15] = product[39];
  tmp[16] = product[40];
  tmp[17] = product[41];
  tmp[18] = product[42];
  tmp[19] = product[43];
  tmp[20] = product[44];
  tmp[21] = product[45];
  tmp[22] = product[46];
  tmp[23] = product[47];
  tmp[24] = tmp[25] = tmp[26] = tmp[27] = 0;
  tmp[28] = product[52];
  tmp[29] = product[53];
  tmp[30] = product[54];
  tmp[31] = product[55];
  carry -= mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  if (carry < 0) {
    do {
      carry += mg_uecc_vli_add(result, result, curve_secp256r1.p,
                               num_words_secp256r1);
    } while (carry < 0);
  } else {
    while (carry || mg_uecc_vli_cmp_unsafe(curve_secp256r1.p, result,
                                           num_words_secp256r1) != 1) {
      carry -= mg_uecc_vli_sub(result, result, curve_secp256r1.p,
                               num_words_secp256r1);
    }
  }
}
#elif MG_UECC_WORD_SIZE == 4
static void vli_mmod_fast_secp256r1(uint32_t *result, uint32_t *product) {
  uint32_t tmp[num_words_secp256r1];
  int carry;

  /* t */
  mg_uecc_vli_set(result, product, num_words_secp256r1);

  /* s1 */
  tmp[0] = tmp[1] = tmp[2] = 0;
  tmp[3] = product[11];
  tmp[4] = product[12];
  tmp[5] = product[13];
  tmp[6] = product[14];
  tmp[7] = product[15];
  carry = (int) mg_uecc_vli_add(tmp, tmp, tmp, num_words_secp256r1);
  carry += (int) mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* s2 */
  tmp[3] = product[12];
  tmp[4] = product[13];
  tmp[5] = product[14];
  tmp[6] = product[15];
  tmp[7] = 0;
  carry += (int) mg_uecc_vli_add(tmp, tmp, tmp, num_words_secp256r1);
  carry += (int) mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* s3 */
  tmp[0] = product[8];
  tmp[1] = product[9];
  tmp[2] = product[10];
  tmp[3] = tmp[4] = tmp[5] = 0;
  tmp[6] = product[14];
  tmp[7] = product[15];
  carry += (int) mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* s4 */
  tmp[0] = product[9];
  tmp[1] = product[10];
  tmp[2] = product[11];
  tmp[3] = product[13];
  tmp[4] = product[14];
  tmp[5] = product[15];
  tmp[6] = product[13];
  tmp[7] = product[8];
  carry += (int) mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* d1 */
  tmp[0] = product[11];
  tmp[1] = product[12];
  tmp[2] = product[13];
  tmp[3] = tmp[4] = tmp[5] = 0;
  tmp[6] = product[8];
  tmp[7] = product[10];
  carry -= (int) mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  /* d2 */
  tmp[0] = product[12];
  tmp[1] = product[13];
  tmp[2] = product[14];
  tmp[3] = product[15];
  tmp[4] = tmp[5] = 0;
  tmp[6] = product[9];
  tmp[7] = product[11];
  carry -= (int) mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  /* d3 */
  tmp[0] = product[13];
  tmp[1] = product[14];
  tmp[2] = product[15];
  tmp[3] = product[8];
  tmp[4] = product[9];
  tmp[5] = product[10];
  tmp[6] = 0;
  tmp[7] = product[12];
  carry -= (int) mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  /* d4 */
  tmp[0] = product[14];
  tmp[1] = product[15];
  tmp[2] = 0;
  tmp[3] = product[9];
  tmp[4] = product[10];
  tmp[5] = product[11];
  tmp[6] = 0;
  tmp[7] = product[13];
  carry -= (int) mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  if (carry < 0) {
    do {
      carry += (int) mg_uecc_vli_add(result, result, curve_secp256r1.p,
                                     num_words_secp256r1);
    } while (carry < 0);
  } else {
    while (carry || mg_uecc_vli_cmp_unsafe(curve_secp256r1.p, result,
                                           num_words_secp256r1) != 1) {
      carry -= (int) mg_uecc_vli_sub(result, result, curve_secp256r1.p,
                                     num_words_secp256r1);
    }
  }
}
#else
static void vli_mmod_fast_secp256r1(uint64_t *result, uint64_t *product) {
  uint64_t tmp[num_words_secp256r1];
  int carry;

  /* t */
  mg_uecc_vli_set(result, product, num_words_secp256r1);

  /* s1 */
  tmp[0] = 0;
  tmp[1] = product[5] & 0xffffffff00000000U;
  tmp[2] = product[6];
  tmp[3] = product[7];
  carry = (int) mg_uecc_vli_add(tmp, tmp, tmp, num_words_secp256r1);
  carry += (int) mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* s2 */
  tmp[1] = product[6] << 32;
  tmp[2] = (product[6] >> 32) | (product[7] << 32);
  tmp[3] = product[7] >> 32;
  carry += (int) mg_uecc_vli_add(tmp, tmp, tmp, num_words_secp256r1);
  carry += (int) mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* s3 */
  tmp[0] = product[4];
  tmp[1] = product[5] & 0xffffffff;
  tmp[2] = 0;
  tmp[3] = product[7];
  carry += (int) mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* s4 */
  tmp[0] = (product[4] >> 32) | (product[5] << 32);
  tmp[1] = (product[5] >> 32) | (product[6] & 0xffffffff00000000U);
  tmp[2] = product[7];
  tmp[3] = (product[6] >> 32) | (product[4] << 32);
  carry += (int) mg_uecc_vli_add(result, result, tmp, num_words_secp256r1);

  /* d1 */
  tmp[0] = (product[5] >> 32) | (product[6] << 32);
  tmp[1] = (product[6] >> 32);
  tmp[2] = 0;
  tmp[3] = (product[4] & 0xffffffff) | (product[5] << 32);
  carry -= (int) mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  /* d2 */
  tmp[0] = product[6];
  tmp[1] = product[7];
  tmp[2] = 0;
  tmp[3] = (product[4] >> 32) | (product[5] & 0xffffffff00000000);
  carry -= (int) mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  /* d3 */
  tmp[0] = (product[6] >> 32) | (product[7] << 32);
  tmp[1] = (product[7] >> 32) | (product[4] << 32);
  tmp[2] = (product[4] >> 32) | (product[5] << 32);
  tmp[3] = (product[6] << 32);
  carry -= (int) mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  /* d4 */
  tmp[0] = product[7];
  tmp[1] = product[4] & 0xffffffff00000000U;
  tmp[2] = product[5];
  tmp[3] = product[6] & 0xffffffff00000000U;
  carry -= (int) mg_uecc_vli_sub(result, result, tmp, num_words_secp256r1);

  if (carry < 0) {
    do {
      carry += (int) mg_uecc_vli_add(result, result, curve_secp256r1.p,
                                     num_words_secp256r1);
    } while (carry < 0);
  } else {
    while (carry || mg_uecc_vli_cmp_unsafe(curve_secp256r1.p, result,
                                           num_words_secp256r1) != 1) {
      carry -= (int) mg_uecc_vli_sub(result, result, curve_secp256r1.p,
                                     num_words_secp256r1);
    }
  }
}
#endif /* MG_UECC_WORD_SIZE */
#endif /* (MG_UECC_OPTIMIZATION_LEVEL > 0 && !asm_mmod_fast_secp256r1) */

#endif /* MG_UECC_SUPPORTS_secp256r1 */

#if MG_UECC_SUPPORTS_secp256k1

static void double_jacobian_secp256k1(mg_uecc_word_t *X1, mg_uecc_word_t *Y1,
                                      mg_uecc_word_t *Z1, MG_UECC_Curve curve);
static void x_side_secp256k1(mg_uecc_word_t *result, const mg_uecc_word_t *x,
                             MG_UECC_Curve curve);
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
static void vli_mmod_fast_secp256k1(mg_uecc_word_t *result,
                                    mg_uecc_word_t *product);
#endif

static const struct MG_UECC_Curve_t curve_secp256k1 = {
    num_words_secp256k1,
    num_bytes_secp256k1,
    256, /* num_n_bits */
    {BYTES_TO_WORDS_8(2F, FC, FF, FF, FE, FF, FF, FF),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF)},
    {BYTES_TO_WORDS_8(41, 41, 36, D0, 8C, 5E, D2, BF),
     BYTES_TO_WORDS_8(3B, A0, 48, AF, E6, DC, AE, BA),
     BYTES_TO_WORDS_8(FE, FF, FF, FF, FF, FF, FF, FF),
     BYTES_TO_WORDS_8(FF, FF, FF, FF, FF, FF, FF, FF)},
    {BYTES_TO_WORDS_8(98, 17, F8, 16, 5B, 81, F2, 59),
     BYTES_TO_WORDS_8(D9, 28, CE, 2D, DB, FC, 9B, 02),
     BYTES_TO_WORDS_8(07, 0B, 87, CE, 95, 62, A0, 55),
     BYTES_TO_WORDS_8(AC, BB, DC, F9, 7E, 66, BE, 79),

     BYTES_TO_WORDS_8(B8, D4, 10, FB, 8F, D0, 47, 9C),
     BYTES_TO_WORDS_8(19, 54, 85, A6, 48, B4, 17, FD),
     BYTES_TO_WORDS_8(A8, 08, 11, 0E, FC, FB, A4, 5D),
     BYTES_TO_WORDS_8(65, C4, A3, 26, 77, DA, 3A, 48)},
    {BYTES_TO_WORDS_8(07, 00, 00, 00, 00, 00, 00, 00),
     BYTES_TO_WORDS_8(00, 00, 00, 00, 00, 00, 00, 00),
     BYTES_TO_WORDS_8(00, 00, 00, 00, 00, 00, 00, 00),
     BYTES_TO_WORDS_8(00, 00, 00, 00, 00, 00, 00, 00)},
    &double_jacobian_secp256k1,
#if MG_UECC_SUPPORT_COMPRESSED_POINT
    &mod_sqrt_default,
#endif
    &x_side_secp256k1,
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
    &vli_mmod_fast_secp256k1
#endif
};

MG_UECC_Curve mg_uecc_secp256k1(void) {
  return &curve_secp256k1;
}

/* Double in place */
static void double_jacobian_secp256k1(mg_uecc_word_t *X1, mg_uecc_word_t *Y1,
                                      mg_uecc_word_t *Z1, MG_UECC_Curve curve) {
  /* t1 = X, t2 = Y, t3 = Z */
  mg_uecc_word_t t4[num_words_secp256k1];
  mg_uecc_word_t t5[num_words_secp256k1];

  if (mg_uecc_vli_isZero(Z1, num_words_secp256k1)) {
    return;
  }

  mg_uecc_vli_modSquare_fast(t5, Y1, curve);   /* t5 = y1^2 */
  mg_uecc_vli_modMult_fast(t4, X1, t5, curve); /* t4 = x1*y1^2 = A */
  mg_uecc_vli_modSquare_fast(X1, X1, curve);   /* t1 = x1^2 */
  mg_uecc_vli_modSquare_fast(t5, t5, curve);   /* t5 = y1^4 */
  mg_uecc_vli_modMult_fast(Z1, Y1, Z1, curve); /* t3 = y1*z1 = z3 */

  mg_uecc_vli_modAdd(Y1, X1, X1, curve->p,
                     num_words_secp256k1); /* t2 = 2*x1^2 */
  mg_uecc_vli_modAdd(Y1, Y1, X1, curve->p,
                     num_words_secp256k1); /* t2 = 3*x1^2 */
  if (mg_uecc_vli_testBit(Y1, 0)) {
    mg_uecc_word_t carry =
        mg_uecc_vli_add(Y1, Y1, curve->p, num_words_secp256k1);
    mg_uecc_vli_rshift1(Y1, num_words_secp256k1);
    Y1[num_words_secp256k1 - 1] |= carry << (MG_UECC_WORD_BITS - 1);
  } else {
    mg_uecc_vli_rshift1(Y1, num_words_secp256k1);
  }
  /* t2 = 3/2*(x1^2) = B */

  mg_uecc_vli_modSquare_fast(X1, Y1, curve); /* t1 = B^2 */
  mg_uecc_vli_modSub(X1, X1, t4, curve->p,
                     num_words_secp256k1); /* t1 = B^2 - A */
  mg_uecc_vli_modSub(X1, X1, t4, curve->p,
                     num_words_secp256k1); /* t1 = B^2 - 2A = x3 */

  mg_uecc_vli_modSub(t4, t4, X1, curve->p,
                     num_words_secp256k1);     /* t4 = A - x3 */
  mg_uecc_vli_modMult_fast(Y1, Y1, t4, curve); /* t2 = B * (A - x3) */
  mg_uecc_vli_modSub(Y1, Y1, t5, curve->p,
                     num_words_secp256k1); /* t2 = B * (A - x3) - y1^4 = y3 */
}

/* Computes result = x^3 + b. result must not overlap x. */
static void x_side_secp256k1(mg_uecc_word_t *result, const mg_uecc_word_t *x,
                             MG_UECC_Curve curve) {
  mg_uecc_vli_modSquare_fast(result, x, curve);       /* r = x^2 */
  mg_uecc_vli_modMult_fast(result, result, x, curve); /* r = x^3 */
  mg_uecc_vli_modAdd(result, result, curve->b, curve->p,
                     num_words_secp256k1); /* r = x^3 + b */
}

#if (MG_UECC_OPTIMIZATION_LEVEL > 0 && !asm_mmod_fast_secp256k1)
static void omega_mult_secp256k1(mg_uecc_word_t *result,
                                 const mg_uecc_word_t *right);
static void vli_mmod_fast_secp256k1(mg_uecc_word_t *result,
                                    mg_uecc_word_t *product) {
  mg_uecc_word_t tmp[2 * num_words_secp256k1];
  mg_uecc_word_t carry;

  mg_uecc_vli_clear(tmp, num_words_secp256k1);
  mg_uecc_vli_clear(tmp + num_words_secp256k1, num_words_secp256k1);

  omega_mult_secp256k1(tmp,
                       product + num_words_secp256k1); /* (Rq, q) = q * c */

  carry = mg_uecc_vli_add(result, product, tmp,
                          num_words_secp256k1); /* (C, r) = r + q       */
  mg_uecc_vli_clear(product, num_words_secp256k1);
  omega_mult_secp256k1(product, tmp + num_words_secp256k1); /* Rq*c */
  carry += mg_uecc_vli_add(result, result, product,
                           num_words_secp256k1); /* (C1, r) = r + Rq*c */

  while (carry > 0) {
    --carry;
    mg_uecc_vli_sub(result, result, curve_secp256k1.p, num_words_secp256k1);
  }
  if (mg_uecc_vli_cmp_unsafe(result, curve_secp256k1.p, num_words_secp256k1) >
      0) {
    mg_uecc_vli_sub(result, result, curve_secp256k1.p, num_words_secp256k1);
  }
}

#if MG_UECC_WORD_SIZE == 1
static void omega_mult_secp256k1(uint8_t *result, const uint8_t *right) {
  /* Multiply by (2^32 + 2^9 + 2^8 + 2^7 + 2^6 + 2^4 + 1). */
  mg_uecc_word_t r0 = 0;
  mg_uecc_word_t r1 = 0;
  mg_uecc_word_t r2 = 0;
  wordcount_t k;

  /* Multiply by (2^9 + 2^8 + 2^7 + 2^6 + 2^4 + 1). */
  muladd(0xD1, right[0], &r0, &r1, &r2);
  result[0] = r0;
  r0 = r1;
  r1 = r2;
  /* r2 is still 0 */

  for (k = 1; k < num_words_secp256k1; ++k) {
    muladd(0x03, right[k - 1], &r0, &r1, &r2);
    muladd(0xD1, right[k], &r0, &r1, &r2);
    result[k] = r0;
    r0 = r1;
    r1 = r2;
    r2 = 0;
  }
  muladd(0x03, right[num_words_secp256k1 - 1], &r0, &r1, &r2);
  result[num_words_secp256k1] = r0;
  result[num_words_secp256k1 + 1] = r1;
  /* add the 2^32 multiple */
  result[4 + num_words_secp256k1] =
      mg_uecc_vli_add(result + 4, result + 4, right, num_words_secp256k1);
}
#elif MG_UECC_WORD_SIZE == 4
static void omega_mult_secp256k1(uint32_t *result, const uint32_t *right) {
  /* Multiply by (2^9 + 2^8 + 2^7 + 2^6 + 2^4 + 1). */
  uint32_t carry = 0;
  wordcount_t k;

  for (k = 0; k < num_words_secp256k1; ++k) {
    uint64_t p = (uint64_t) 0x3D1 * right[k] + carry;
    result[k] = (uint32_t) p;
    carry = p >> 32;
  }
  result[num_words_secp256k1] = carry;
  /* add the 2^32 multiple */
  result[1 + num_words_secp256k1] =
      mg_uecc_vli_add(result + 1, result + 1, right, num_words_secp256k1);
}
#else
static void omega_mult_secp256k1(uint64_t *result, const uint64_t *right) {
  mg_uecc_word_t r0 = 0;
  mg_uecc_word_t r1 = 0;
  mg_uecc_word_t r2 = 0;
  wordcount_t k;

  /* Multiply by (2^32 + 2^9 + 2^8 + 2^7 + 2^6 + 2^4 + 1). */
  for (k = 0; k < num_words_secp256k1; ++k) {
    muladd(0x1000003D1ull, right[k], &r0, &r1, &r2);
    result[k] = r0;
    r0 = r1;
    r1 = r2;
    r2 = 0;
  }
  result[num_words_secp256k1] = r0;
}
#endif /* MG_UECC_WORD_SIZE */
#endif /* (MG_UECC_OPTIMIZATION_LEVEL > 0 &&  && !asm_mmod_fast_secp256k1) */

#endif /* MG_UECC_SUPPORTS_secp256k1 */

#endif /* _UECC_CURVE_SPECIFIC_H_ */

/* Returns 1 if 'point' is the point at infinity, 0 otherwise. */
#define EccPoint_isZero(point, curve) \
  mg_uecc_vli_isZero((point), (wordcount_t) ((curve)->num_words * 2))

/* Point multiplication algorithm using Montgomery's ladder with co-Z
coordinates. From http://eprint.iacr.org/2011/338.pdf
*/

/* Modify (x1, y1) => (x1 * z^2, y1 * z^3) */
static void apply_z(mg_uecc_word_t *X1, mg_uecc_word_t *Y1,
                    const mg_uecc_word_t *const Z, MG_UECC_Curve curve) {
  mg_uecc_word_t t1[MG_UECC_MAX_WORDS];

  mg_uecc_vli_modSquare_fast(t1, Z, curve);    /* z^2 */
  mg_uecc_vli_modMult_fast(X1, X1, t1, curve); /* x1 * z^2 */
  mg_uecc_vli_modMult_fast(t1, t1, Z, curve);  /* z^3 */
  mg_uecc_vli_modMult_fast(Y1, Y1, t1, curve); /* y1 * z^3 */
}

/* P = (x1, y1) => 2P, (x2, y2) => P' */
static void XYcZ_initial_double(mg_uecc_word_t *X1, mg_uecc_word_t *Y1,
                                mg_uecc_word_t *X2, mg_uecc_word_t *Y2,
                                const mg_uecc_word_t *const initial_Z,
                                MG_UECC_Curve curve) {
  mg_uecc_word_t z[MG_UECC_MAX_WORDS];
  wordcount_t num_words = curve->num_words;
  if (initial_Z) {
    mg_uecc_vli_set(z, initial_Z, num_words);
  } else {
    mg_uecc_vli_clear(z, num_words);
    z[0] = 1;
  }

  mg_uecc_vli_set(X2, X1, num_words);
  mg_uecc_vli_set(Y2, Y1, num_words);

  apply_z(X1, Y1, z, curve);
  curve->double_jacobian(X1, Y1, z, curve);
  apply_z(X2, Y2, z, curve);
}

/* Input P = (x1, y1, Z), Q = (x2, y2, Z)
   Output P' = (x1', y1', Z3), P + Q = (x3, y3, Z3)
   or P => P', Q => P + Q
*/
static void XYcZ_add(mg_uecc_word_t *X1, mg_uecc_word_t *Y1, mg_uecc_word_t *X2,
                     mg_uecc_word_t *Y2, MG_UECC_Curve curve) {
  /* t1 = X1, t2 = Y1, t3 = X2, t4 = Y2 */
  mg_uecc_word_t t5[MG_UECC_MAX_WORDS] = {0};
  wordcount_t num_words = curve->num_words;

  mg_uecc_vli_modSub(t5, X2, X1, curve->p, num_words); /* t5 = x2 - x1 */
  mg_uecc_vli_modSquare_fast(t5, t5, curve);   /* t5 = (x2 - x1)^2 = A */
  mg_uecc_vli_modMult_fast(X1, X1, t5, curve); /* t1 = x1*A = B */
  mg_uecc_vli_modMult_fast(X2, X2, t5, curve); /* t3 = x2*A = C */
  mg_uecc_vli_modSub(Y2, Y2, Y1, curve->p, num_words); /* t4 = y2 - y1 */
  mg_uecc_vli_modSquare_fast(t5, Y2, curve); /* t5 = (y2 - y1)^2 = D */

  mg_uecc_vli_modSub(t5, t5, X1, curve->p, num_words); /* t5 = D - B */
  mg_uecc_vli_modSub(t5, t5, X2, curve->p, num_words); /* t5 = D - B - C = x3 */
  mg_uecc_vli_modSub(X2, X2, X1, curve->p, num_words); /* t3 = C - B */
  mg_uecc_vli_modMult_fast(Y1, Y1, X2, curve);         /* t2 = y1*(C - B) */
  mg_uecc_vli_modSub(X2, X1, t5, curve->p, num_words); /* t3 = B - x3 */
  mg_uecc_vli_modMult_fast(Y2, Y2, X2, curve); /* t4 = (y2 - y1)*(B - x3) */
  mg_uecc_vli_modSub(Y2, Y2, Y1, curve->p, num_words); /* t4 = y3 */

  mg_uecc_vli_set(X2, t5, num_words);
}

/* Input P = (x1, y1, Z), Q = (x2, y2, Z)
   Output P + Q = (x3, y3, Z3), P - Q = (x3', y3', Z3)
   or P => P - Q, Q => P + Q
*/
static void XYcZ_addC(mg_uecc_word_t *X1, mg_uecc_word_t *Y1,
                      mg_uecc_word_t *X2, mg_uecc_word_t *Y2,
                      MG_UECC_Curve curve) {
  /* t1 = X1, t2 = Y1, t3 = X2, t4 = Y2 */
  mg_uecc_word_t t5[MG_UECC_MAX_WORDS] = {0};
  mg_uecc_word_t t6[MG_UECC_MAX_WORDS];
  mg_uecc_word_t t7[MG_UECC_MAX_WORDS];
  wordcount_t num_words = curve->num_words;

  mg_uecc_vli_modSub(t5, X2, X1, curve->p, num_words); /* t5 = x2 - x1 */
  mg_uecc_vli_modSquare_fast(t5, t5, curve);   /* t5 = (x2 - x1)^2 = A */
  mg_uecc_vli_modMult_fast(X1, X1, t5, curve); /* t1 = x1*A = B */
  mg_uecc_vli_modMult_fast(X2, X2, t5, curve); /* t3 = x2*A = C */
  mg_uecc_vli_modAdd(t5, Y2, Y1, curve->p, num_words); /* t5 = y2 + y1 */
  mg_uecc_vli_modSub(Y2, Y2, Y1, curve->p, num_words); /* t4 = y2 - y1 */

  mg_uecc_vli_modSub(t6, X2, X1, curve->p, num_words); /* t6 = C - B */
  mg_uecc_vli_modMult_fast(Y1, Y1, t6, curve); /* t2 = y1 * (C - B) = E */
  mg_uecc_vli_modAdd(t6, X1, X2, curve->p, num_words); /* t6 = B + C */
  mg_uecc_vli_modSquare_fast(X2, Y2, curve); /* t3 = (y2 - y1)^2 = D */
  mg_uecc_vli_modSub(X2, X2, t6, curve->p,
                     num_words); /* t3 = D - (B + C) = x3 */

  mg_uecc_vli_modSub(t7, X1, X2, curve->p, num_words); /* t7 = B - x3 */
  mg_uecc_vli_modMult_fast(Y2, Y2, t7, curve); /* t4 = (y2 - y1)*(B - x3) */
  mg_uecc_vli_modSub(Y2, Y2, Y1, curve->p,
                     num_words); /* t4 = (y2 - y1)*(B - x3) - E = y3 */

  mg_uecc_vli_modSquare_fast(t7, t5, curve); /* t7 = (y2 + y1)^2 = F */
  mg_uecc_vli_modSub(t7, t7, t6, curve->p,
                     num_words); /* t7 = F - (B + C) = x3' */
  mg_uecc_vli_modSub(t6, t7, X1, curve->p, num_words); /* t6 = x3' - B */
  mg_uecc_vli_modMult_fast(t6, t6, t5, curve); /* t6 = (y2+y1)*(x3' - B) */
  mg_uecc_vli_modSub(Y1, t6, Y1, curve->p,
                     num_words); /* t2 = (y2+y1)*(x3' - B) - E = y3' */

  mg_uecc_vli_set(X1, t7, num_words);
}

/* result may overlap point. */
static void EccPoint_mult(mg_uecc_word_t *result, const mg_uecc_word_t *point,
                          const mg_uecc_word_t *scalar,
                          const mg_uecc_word_t *initial_Z, bitcount_t num_bits,
                          MG_UECC_Curve curve) {
  /* R0 and R1 */
  mg_uecc_word_t Rx[2][MG_UECC_MAX_WORDS];
  mg_uecc_word_t Ry[2][MG_UECC_MAX_WORDS];
  mg_uecc_word_t z[MG_UECC_MAX_WORDS];
  bitcount_t i;
  mg_uecc_word_t nb;
  wordcount_t num_words = curve->num_words;

  mg_uecc_vli_set(Rx[1], point, num_words);
  mg_uecc_vli_set(Ry[1], point + num_words, num_words);

  XYcZ_initial_double(Rx[1], Ry[1], Rx[0], Ry[0], initial_Z, curve);

  for (i = num_bits - 2; i > 0; --i) {
    nb = !mg_uecc_vli_testBit(scalar, i);
    XYcZ_addC(Rx[1 - nb], Ry[1 - nb], Rx[nb], Ry[nb], curve);
    XYcZ_add(Rx[nb], Ry[nb], Rx[1 - nb], Ry[1 - nb], curve);
  }

  nb = !mg_uecc_vli_testBit(scalar, 0);
  XYcZ_addC(Rx[1 - nb], Ry[1 - nb], Rx[nb], Ry[nb], curve);

  /* Find final 1/Z value. */
  mg_uecc_vli_modSub(z, Rx[1], Rx[0], curve->p, num_words); /* X1 - X0 */
  mg_uecc_vli_modMult_fast(z, z, Ry[1 - nb], curve);        /* Yb * (X1 - X0) */
  mg_uecc_vli_modMult_fast(z, z, point, curve);  /* xP * Yb * (X1 - X0) */
  mg_uecc_vli_modInv(z, z, curve->p, num_words); /* 1 / (xP * Yb * (X1 - X0)) */
  /* yP / (xP * Yb * (X1 - X0)) */
  mg_uecc_vli_modMult_fast(z, z, point + num_words, curve);
  mg_uecc_vli_modMult_fast(z, z, Rx[1 - nb],
                           curve); /* Xb * yP / (xP * Yb * (X1 - X0)) */
  /* End 1/Z calculation */

  XYcZ_add(Rx[nb], Ry[nb], Rx[1 - nb], Ry[1 - nb], curve);
  apply_z(Rx[0], Ry[0], z, curve);

  mg_uecc_vli_set(result, Rx[0], num_words);
  mg_uecc_vli_set(result + num_words, Ry[0], num_words);
}

static mg_uecc_word_t regularize_k(const mg_uecc_word_t *const k,
                                   mg_uecc_word_t *k0, mg_uecc_word_t *k1,
                                   MG_UECC_Curve curve) {
  wordcount_t num_n_words = BITS_TO_WORDS(curve->num_n_bits);
  bitcount_t num_n_bits = curve->num_n_bits;
  mg_uecc_word_t carry =
      mg_uecc_vli_add(k0, k, curve->n, num_n_words) ||
      (num_n_bits < ((bitcount_t) num_n_words * MG_UECC_WORD_SIZE * 8) &&
       mg_uecc_vli_testBit(k0, num_n_bits));
  mg_uecc_vli_add(k1, k0, curve->n, num_n_words);
  return carry;
}

/* Generates a random integer in the range 0 < random < top.
   Both random and top have num_words words. */
MG_UECC_VLI_API int mg_uecc_generate_random_int(mg_uecc_word_t *random,
                                                const mg_uecc_word_t *top,
                                                wordcount_t num_words) {
  mg_uecc_word_t mask = (mg_uecc_word_t) -1;
  mg_uecc_word_t tries;
  bitcount_t num_bits = mg_uecc_vli_numBits(top, num_words);

  if (!g_rng_function) {
    return 0;
  }

  for (tries = 0; tries < MG_UECC_RNG_MAX_TRIES; ++tries) {
    if (!g_rng_function((uint8_t *) random,
                        (unsigned int) (num_words * MG_UECC_WORD_SIZE))) {
      return 0;
    }
    random[num_words - 1] &=
        mask >> ((bitcount_t) (num_words * MG_UECC_WORD_SIZE * 8 - num_bits));
    if (!mg_uecc_vli_isZero(random, num_words) &&
        mg_uecc_vli_cmp(top, random, num_words) == 1) {
      return 1;
    }
  }
  return 0;
}

static mg_uecc_word_t EccPoint_compute_public_key(mg_uecc_word_t *result,
                                                  mg_uecc_word_t *private_key,
                                                  MG_UECC_Curve curve) {
  mg_uecc_word_t tmp1[MG_UECC_MAX_WORDS];
  mg_uecc_word_t tmp2[MG_UECC_MAX_WORDS];
  mg_uecc_word_t *p2[2] = {tmp1, tmp2};
  mg_uecc_word_t *initial_Z = 0;
  mg_uecc_word_t carry;

  /* Regularize the bitcount for the private key so that attackers cannot use a
     side channel attack to learn the number of leading zeros. */
  carry = regularize_k(private_key, tmp1, tmp2, curve);

  /* If an RNG function was specified, try to get a random initial Z value to
     improve protection against side-channel attacks. */
  if (g_rng_function) {
    if (!mg_uecc_generate_random_int(p2[carry], curve->p, curve->num_words)) {
      return 0;
    }
    initial_Z = p2[carry];
  }
  EccPoint_mult(result, curve->G, p2[!carry], initial_Z,
                (bitcount_t) (curve->num_n_bits + 1), curve);

  if (EccPoint_isZero(result, curve)) {
    return 0;
  }
  return 1;
}

#if MG_UECC_WORD_SIZE == 1

MG_UECC_VLI_API void mg_uecc_vli_nativeToBytes(uint8_t *bytes, int num_bytes,
                                               const uint8_t *native) {
  wordcount_t i;
  for (i = 0; i < num_bytes; ++i) {
    bytes[i] = native[(num_bytes - 1) - i];
  }
}

MG_UECC_VLI_API void mg_uecc_vli_bytesToNative(uint8_t *native,
                                               const uint8_t *bytes,
                                               int num_bytes) {
  mg_uecc_vli_nativeToBytes(native, num_bytes, bytes);
}

#else

MG_UECC_VLI_API void mg_uecc_vli_nativeToBytes(uint8_t *bytes, int num_bytes,
                                               const mg_uecc_word_t *native) {
  int i;
  for (i = 0; i < num_bytes; ++i) {
    unsigned b = (unsigned) (num_bytes - 1 - i);
    bytes[i] = (uint8_t) (native[b / MG_UECC_WORD_SIZE] >>
                          (8 * (b % MG_UECC_WORD_SIZE)));
  }
}

MG_UECC_VLI_API void mg_uecc_vli_bytesToNative(mg_uecc_word_t *native,
                                               const uint8_t *bytes,
                                               int num_bytes) {
  int i;
  mg_uecc_vli_clear(native,
                    (wordcount_t) ((num_bytes + (MG_UECC_WORD_SIZE - 1)) /
                                   MG_UECC_WORD_SIZE));
  for (i = 0; i < num_bytes; ++i) {
    unsigned b = (unsigned) (num_bytes - 1 - i);
    native[b / MG_UECC_WORD_SIZE] |= (mg_uecc_word_t) bytes[i]
                                     << (8 * (b % MG_UECC_WORD_SIZE));
  }
}

#endif /* MG_UECC_WORD_SIZE */

int mg_uecc_make_key(uint8_t *public_key, uint8_t *private_key,
                     MG_UECC_Curve curve) {
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  mg_uecc_word_t *_private = (mg_uecc_word_t *) private_key;
  mg_uecc_word_t *_public = (mg_uecc_word_t *) public_key;
#else
  mg_uecc_word_t _private[MG_UECC_MAX_WORDS];
  mg_uecc_word_t _public[MG_UECC_MAX_WORDS * 2];
#endif
  mg_uecc_word_t tries;

  for (tries = 0; tries < MG_UECC_RNG_MAX_TRIES; ++tries) {
    if (!mg_uecc_generate_random_int(_private, curve->n,
                                     BITS_TO_WORDS(curve->num_n_bits))) {
      return 0;
    }

    if (EccPoint_compute_public_key(_public, _private, curve)) {
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN == 0
      mg_uecc_vli_nativeToBytes(private_key, BITS_TO_BYTES(curve->num_n_bits),
                                _private);
      mg_uecc_vli_nativeToBytes(public_key, curve->num_bytes, _public);
      mg_uecc_vli_nativeToBytes(public_key + curve->num_bytes, curve->num_bytes,
                                _public + curve->num_words);
#endif
      return 1;
    }
  }
  return 0;
}

int mg_uecc_shared_secret(const uint8_t *public_key, const uint8_t *private_key,
                          uint8_t *secret, MG_UECC_Curve curve) {
  mg_uecc_word_t _public[MG_UECC_MAX_WORDS * 2];
  mg_uecc_word_t _private[MG_UECC_MAX_WORDS];

  mg_uecc_word_t tmp[MG_UECC_MAX_WORDS];
  mg_uecc_word_t *p2[2] = {_private, tmp};
  mg_uecc_word_t *initial_Z = 0;
  mg_uecc_word_t carry;
  wordcount_t num_words = curve->num_words;
  wordcount_t num_bytes = curve->num_bytes;

#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  bcopy((uint8_t *) _private, private_key, num_bytes);
  bcopy((uint8_t *) _public, public_key, num_bytes * 2);
#else
  mg_uecc_vli_bytesToNative(_private, private_key,
                            BITS_TO_BYTES(curve->num_n_bits));
  mg_uecc_vli_bytesToNative(_public, public_key, num_bytes);
  mg_uecc_vli_bytesToNative(_public + num_words, public_key + num_bytes,
                            num_bytes);
#endif

  /* Regularize the bitcount for the private key so that attackers cannot use a
     side channel attack to learn the number of leading zeros. */
  carry = regularize_k(_private, _private, tmp, curve);

  /* If an RNG function was specified, try to get a random initial Z value to
     improve protection against side-channel attacks. */
  if (g_rng_function) {
    if (!mg_uecc_generate_random_int(p2[carry], curve->p, num_words)) {
      return 0;
    }
    initial_Z = p2[carry];
  }

  EccPoint_mult(_public, _public, p2[!carry], initial_Z,
                (bitcount_t) (curve->num_n_bits + 1), curve);
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  bcopy((uint8_t *) secret, (uint8_t *) _public, num_bytes);
#else
  mg_uecc_vli_nativeToBytes(secret, num_bytes, _public);
#endif
  return !EccPoint_isZero(_public, curve);
}

#if MG_UECC_SUPPORT_COMPRESSED_POINT
void mg_uecc_compress(const uint8_t *public_key, uint8_t *compressed,
                      MG_UECC_Curve curve) {
  wordcount_t i;
  for (i = 0; i < curve->num_bytes; ++i) {
    compressed[i + 1] = public_key[i];
  }
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  compressed[0] = 2 + (public_key[curve->num_bytes] & 0x01);
#else
  compressed[0] = 2 + (public_key[curve->num_bytes * 2 - 1] & 0x01);
#endif
}

void mg_uecc_decompress(const uint8_t *compressed, uint8_t *public_key,
                        MG_UECC_Curve curve) {
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  mg_uecc_word_t *point = (mg_uecc_word_t *) public_key;
#else
  mg_uecc_word_t point[MG_UECC_MAX_WORDS * 2];
#endif
  mg_uecc_word_t *y = point + curve->num_words;
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  bcopy(public_key, compressed + 1, curve->num_bytes);
#else
  mg_uecc_vli_bytesToNative(point, compressed + 1, curve->num_bytes);
#endif
  curve->x_side(y, point, curve);
  curve->mod_sqrt(y, curve);

  if ((uint8_t) (y[0] & 0x01) != (compressed[0] & 0x01)) {
    mg_uecc_vli_sub(y, curve->p, y, curve->num_words);
  }

#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN == 0
  mg_uecc_vli_nativeToBytes(public_key, curve->num_bytes, point);
  mg_uecc_vli_nativeToBytes(public_key + curve->num_bytes, curve->num_bytes, y);
#endif
}
#endif /* MG_UECC_SUPPORT_COMPRESSED_POINT */

MG_UECC_VLI_API int mg_uecc_valid_point(const mg_uecc_word_t *point,
                                        MG_UECC_Curve curve) {
  mg_uecc_word_t tmp1[MG_UECC_MAX_WORDS];
  mg_uecc_word_t tmp2[MG_UECC_MAX_WORDS];
  wordcount_t num_words = curve->num_words;

  /* The point at infinity is invalid. */
  if (EccPoint_isZero(point, curve)) {
    return 0;
  }

  /* x and y must be smaller than p. */
  if (mg_uecc_vli_cmp_unsafe(curve->p, point, num_words) != 1 ||
      mg_uecc_vli_cmp_unsafe(curve->p, point + num_words, num_words) != 1) {
    return 0;
  }

  mg_uecc_vli_modSquare_fast(tmp1, point + num_words, curve);
  curve->x_side(tmp2, point, curve); /* tmp2 = x^3 + ax + b */

  /* Make sure that y^2 == x^3 + ax + b */
  return (int) (mg_uecc_vli_equal(tmp1, tmp2, num_words));
}

int mg_uecc_valid_public_key(const uint8_t *public_key, MG_UECC_Curve curve) {
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  mg_uecc_word_t *_public = (mg_uecc_word_t *) public_key;
#else
  mg_uecc_word_t _public[MG_UECC_MAX_WORDS * 2];
#endif

#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN == 0
  mg_uecc_vli_bytesToNative(_public, public_key, curve->num_bytes);
  mg_uecc_vli_bytesToNative(_public + curve->num_words,
                            public_key + curve->num_bytes, curve->num_bytes);
#endif
  return mg_uecc_valid_point(_public, curve);
}

int mg_uecc_compute_public_key(const uint8_t *private_key, uint8_t *public_key,
                               MG_UECC_Curve curve) {
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  mg_uecc_word_t *_private = (mg_uecc_word_t *) private_key;
  mg_uecc_word_t *_public = (mg_uecc_word_t *) public_key;
#else
  mg_uecc_word_t _private[MG_UECC_MAX_WORDS];
  mg_uecc_word_t _public[MG_UECC_MAX_WORDS * 2];
#endif

#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN == 0
  mg_uecc_vli_bytesToNative(_private, private_key,
                            BITS_TO_BYTES(curve->num_n_bits));
#endif

  /* Make sure the private key is in the range [1, n-1]. */
  if (mg_uecc_vli_isZero(_private, BITS_TO_WORDS(curve->num_n_bits))) {
    return 0;
  }

  if (mg_uecc_vli_cmp(curve->n, _private, BITS_TO_WORDS(curve->num_n_bits)) !=
      1) {
    return 0;
  }

  /* Compute public key. */
  if (!EccPoint_compute_public_key(_public, _private, curve)) {
    return 0;
  }

#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN == 0
  mg_uecc_vli_nativeToBytes(public_key, curve->num_bytes, _public);
  mg_uecc_vli_nativeToBytes(public_key + curve->num_bytes, curve->num_bytes,
                            _public + curve->num_words);
#endif
  return 1;
}

/* -------- ECDSA code -------- */

static void bits2int(mg_uecc_word_t *native, const uint8_t *bits,
                     unsigned bits_size, MG_UECC_Curve curve) {
  unsigned num_n_bytes = (unsigned) BITS_TO_BYTES(curve->num_n_bits);
  unsigned num_n_words = (unsigned) BITS_TO_WORDS(curve->num_n_bits);
  int shift;
  mg_uecc_word_t carry;
  mg_uecc_word_t *ptr;

  if (bits_size > num_n_bytes) {
    bits_size = num_n_bytes;
  }

  mg_uecc_vli_clear(native, (wordcount_t) num_n_words);
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  bcopy((uint8_t *) native, bits, bits_size);
#else
  mg_uecc_vli_bytesToNative(native, bits, (int) bits_size);
#endif
  if (bits_size * 8 <= (unsigned) curve->num_n_bits) {
    return;
  }
  shift = (int) bits_size * 8 - curve->num_n_bits;
  carry = 0;
  ptr = native + num_n_words;
  while (ptr-- > native) {
    mg_uecc_word_t temp = *ptr;
    *ptr = (temp >> shift) | carry;
    carry = temp << (MG_UECC_WORD_BITS - shift);
  }

  /* Reduce mod curve_n */
  if (mg_uecc_vli_cmp_unsafe(curve->n, native, (wordcount_t) num_n_words) !=
      1) {
    mg_uecc_vli_sub(native, native, curve->n, (wordcount_t) num_n_words);
  }
}

static int mg_uecc_sign_with_k_internal(const uint8_t *private_key,
                                        const uint8_t *message_hash,
                                        unsigned hash_size, mg_uecc_word_t *k,
                                        uint8_t *signature,
                                        MG_UECC_Curve curve) {
  mg_uecc_word_t tmp[MG_UECC_MAX_WORDS];
  mg_uecc_word_t s[MG_UECC_MAX_WORDS];
  mg_uecc_word_t *k2[2] = {tmp, s};
  mg_uecc_word_t *initial_Z = 0;
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  mg_uecc_word_t *p = (mg_uecc_word_t *) signature;
#else
  mg_uecc_word_t p[MG_UECC_MAX_WORDS * 2];
#endif
  mg_uecc_word_t carry;
  wordcount_t num_words = curve->num_words;
  wordcount_t num_n_words = BITS_TO_WORDS(curve->num_n_bits);
  bitcount_t num_n_bits = curve->num_n_bits;

  /* Make sure 0 < k < curve_n */
  if (mg_uecc_vli_isZero(k, num_words) ||
      mg_uecc_vli_cmp(curve->n, k, num_n_words) != 1) {
    return 0;
  }

  carry = regularize_k(k, tmp, s, curve);
  /* If an RNG function was specified, try to get a random initial Z value to
     improve protection against side-channel attacks. */
  if (g_rng_function) {
    if (!mg_uecc_generate_random_int(k2[carry], curve->p, num_words)) {
      return 0;
    }
    initial_Z = k2[carry];
  }
  EccPoint_mult(p, curve->G, k2[!carry], initial_Z,
                (bitcount_t) (num_n_bits + 1), curve);
  if (mg_uecc_vli_isZero(p, num_words)) {
    return 0;
  }

  /* If an RNG function was specified, get a random number
     to prevent side channel analysis of k. */
  if (!g_rng_function) {
    mg_uecc_vli_clear(tmp, num_n_words);
    tmp[0] = 1;
  } else if (!mg_uecc_generate_random_int(tmp, curve->n, num_n_words)) {
    return 0;
  }

  /* Prevent side channel analysis of mg_uecc_vli_modInv() to determine
     bits of k / the private key by premultiplying by a random number */
  mg_uecc_vli_modMult(k, k, tmp, curve->n, num_n_words); /* k' = rand * k */
  mg_uecc_vli_modInv(k, k, curve->n, num_n_words);       /* k = 1 / k' */
  mg_uecc_vli_modMult(k, k, tmp, curve->n, num_n_words); /* k = 1 / k */

#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN == 0
  mg_uecc_vli_nativeToBytes(signature, curve->num_bytes, p); /* store r */
#endif

#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  bcopy((uint8_t *) tmp, private_key, BITS_TO_BYTES(curve->num_n_bits));
#else
  mg_uecc_vli_bytesToNative(tmp, private_key,
                            BITS_TO_BYTES(curve->num_n_bits)); /* tmp = d */
#endif

  s[num_n_words - 1] = 0;
  mg_uecc_vli_set(s, p, num_words);
  mg_uecc_vli_modMult(s, tmp, s, curve->n, num_n_words); /* s = r*d */

  bits2int(tmp, message_hash, hash_size, curve);
  mg_uecc_vli_modAdd(s, tmp, s, curve->n, num_n_words); /* s = e + r*d */
  mg_uecc_vli_modMult(s, s, k, curve->n, num_n_words);  /* s = (e + r*d) / k */
  if (mg_uecc_vli_numBits(s, num_n_words) > (bitcount_t) curve->num_bytes * 8) {
    return 0;
  }
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  bcopy((uint8_t *) signature + curve->num_bytes, (uint8_t *) s,
        curve->num_bytes);
#else
  mg_uecc_vli_nativeToBytes(signature + curve->num_bytes, curve->num_bytes, s);
#endif
  return 1;
}

#if 0
/* For testing - sign with an explicitly specified k value */
int mg_uecc_sign_with_k(const uint8_t *private_key, const uint8_t *message_hash,
                     unsigned hash_size, const uint8_t *k, uint8_t *signature,
                     MG_UECC_Curve curve) {
  mg_uecc_word_t k2[MG_UECC_MAX_WORDS];
  bits2int(k2, k, (unsigned) BITS_TO_BYTES(curve->num_n_bits), curve);
  return mg_uecc_sign_with_k_internal(private_key, message_hash, hash_size, k2,
                                   signature, curve);
}
#endif

int mg_uecc_sign(const uint8_t *private_key, const uint8_t *message_hash,
                 unsigned hash_size, uint8_t *signature, MG_UECC_Curve curve) {
  mg_uecc_word_t k[MG_UECC_MAX_WORDS];
  mg_uecc_word_t tries;

  for (tries = 0; tries < MG_UECC_RNG_MAX_TRIES; ++tries) {
    if (!mg_uecc_generate_random_int(k, curve->n,
                                     BITS_TO_WORDS(curve->num_n_bits))) {
      return 0;
    }

    if (mg_uecc_sign_with_k_internal(private_key, message_hash, hash_size, k,
                                     signature, curve)) {
      return 1;
    }
  }
  return 0;
}

/* Compute an HMAC using K as a key (as in RFC 6979). Note that K is always
   the same size as the hash result size. */
static void HMAC_init(const MG_UECC_HashContext *hash_context,
                      const uint8_t *K) {
  uint8_t *pad = hash_context->tmp + 2 * hash_context->result_size;
  unsigned i;
  for (i = 0; i < hash_context->result_size; ++i) pad[i] = K[i] ^ 0x36;
  for (; i < hash_context->block_size; ++i) pad[i] = 0x36;

  hash_context->init_hash(hash_context);
  hash_context->update_hash(hash_context, pad, hash_context->block_size);
}

static void HMAC_update(const MG_UECC_HashContext *hash_context,
                        const uint8_t *message, unsigned message_size) {
  hash_context->update_hash(hash_context, message, message_size);
}

static void HMAC_finish(const MG_UECC_HashContext *hash_context,
                        const uint8_t *K, uint8_t *result) {
  uint8_t *pad = hash_context->tmp + 2 * hash_context->result_size;
  unsigned i;
  for (i = 0; i < hash_context->result_size; ++i) pad[i] = K[i] ^ 0x5c;
  for (; i < hash_context->block_size; ++i) pad[i] = 0x5c;

  hash_context->finish_hash(hash_context, result);

  hash_context->init_hash(hash_context);
  hash_context->update_hash(hash_context, pad, hash_context->block_size);
  hash_context->update_hash(hash_context, result, hash_context->result_size);
  hash_context->finish_hash(hash_context, result);
}

/* V = HMAC_K(V) */
static void update_V(const MG_UECC_HashContext *hash_context, uint8_t *K,
                     uint8_t *V) {
  HMAC_init(hash_context, K);
  HMAC_update(hash_context, V, hash_context->result_size);
  HMAC_finish(hash_context, K, V);
}

/* Deterministic signing, similar to RFC 6979. Differences are:
    * We just use H(m) directly rather than bits2octets(H(m))
      (it is not reduced modulo curve_n).
    * We generate a value for k (aka T) directly rather than converting
   endianness.

   Layout of hash_context->tmp: <K> | <V> | (1 byte overlapped 0x00 or 0x01) /
   <HMAC pad> */
int mg_uecc_sign_deterministic(const uint8_t *private_key,
                               const uint8_t *message_hash, unsigned hash_size,
                               const MG_UECC_HashContext *hash_context,
                               uint8_t *signature, MG_UECC_Curve curve) {
  uint8_t *K = hash_context->tmp;
  uint8_t *V = K + hash_context->result_size;
  wordcount_t num_bytes = curve->num_bytes;
  wordcount_t num_n_words = BITS_TO_WORDS(curve->num_n_bits);
  bitcount_t num_n_bits = curve->num_n_bits;
  mg_uecc_word_t tries;
  unsigned i;
  for (i = 0; i < hash_context->result_size; ++i) {
    V[i] = 0x01;
    K[i] = 0;
  }

  /* K = HMAC_K(V || 0x00 || int2octets(x) || h(m)) */
  HMAC_init(hash_context, K);
  V[hash_context->result_size] = 0x00;
  HMAC_update(hash_context, V, hash_context->result_size + 1);
  HMAC_update(hash_context, private_key, (unsigned int) num_bytes);
  HMAC_update(hash_context, message_hash, hash_size);
  HMAC_finish(hash_context, K, K);

  update_V(hash_context, K, V);

  /* K = HMAC_K(V || 0x01 || int2octets(x) || h(m)) */
  HMAC_init(hash_context, K);
  V[hash_context->result_size] = 0x01;
  HMAC_update(hash_context, V, hash_context->result_size + 1);
  HMAC_update(hash_context, private_key, (unsigned int) num_bytes);
  HMAC_update(hash_context, message_hash, hash_size);
  HMAC_finish(hash_context, K, K);

  update_V(hash_context, K, V);

  for (tries = 0; tries < MG_UECC_RNG_MAX_TRIES; ++tries) {
    mg_uecc_word_t T[MG_UECC_MAX_WORDS];
    uint8_t *T_ptr = (uint8_t *) T;
    wordcount_t T_bytes = 0;
    for (;;) {
      update_V(hash_context, K, V);
      for (i = 0; i < hash_context->result_size; ++i) {
        T_ptr[T_bytes++] = V[i];
        if (T_bytes >= num_n_words * MG_UECC_WORD_SIZE) {
          goto filled;
        }
      }
    }
  filled:
    if ((bitcount_t) num_n_words * MG_UECC_WORD_SIZE * 8 > num_n_bits) {
      mg_uecc_word_t mask = (mg_uecc_word_t) -1;
      T[num_n_words - 1] &=
          mask >>
          ((bitcount_t) (num_n_words * MG_UECC_WORD_SIZE * 8 - num_n_bits));
    }

    if (mg_uecc_sign_with_k_internal(private_key, message_hash, hash_size, T,
                                     signature, curve)) {
      return 1;
    }

    /* K = HMAC_K(V || 0x00) */
    HMAC_init(hash_context, K);
    V[hash_context->result_size] = 0x00;
    HMAC_update(hash_context, V, hash_context->result_size + 1);
    HMAC_finish(hash_context, K, K);

    update_V(hash_context, K, V);
  }
  return 0;
}

static bitcount_t smax(bitcount_t a, bitcount_t b) {
  return (a > b ? a : b);
}

int mg_uecc_verify(const uint8_t *public_key, const uint8_t *message_hash,
                   unsigned hash_size, const uint8_t *signature,
                   MG_UECC_Curve curve) {
  mg_uecc_word_t u1[MG_UECC_MAX_WORDS], u2[MG_UECC_MAX_WORDS];
  mg_uecc_word_t z[MG_UECC_MAX_WORDS];
  mg_uecc_word_t sum[MG_UECC_MAX_WORDS * 2];
  mg_uecc_word_t rx[MG_UECC_MAX_WORDS];
  mg_uecc_word_t ry[MG_UECC_MAX_WORDS];
  mg_uecc_word_t tx[MG_UECC_MAX_WORDS];
  mg_uecc_word_t ty[MG_UECC_MAX_WORDS];
  mg_uecc_word_t tz[MG_UECC_MAX_WORDS];
  const mg_uecc_word_t *points[4];
  const mg_uecc_word_t *point;
  bitcount_t num_bits;
  bitcount_t i;
#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  mg_uecc_word_t *_public = (mg_uecc_word_t *) public_key;
#else
  mg_uecc_word_t _public[MG_UECC_MAX_WORDS * 2];
#endif
  mg_uecc_word_t r[MG_UECC_MAX_WORDS], s[MG_UECC_MAX_WORDS];
  wordcount_t num_words = curve->num_words;
  wordcount_t num_n_words = BITS_TO_WORDS(curve->num_n_bits);

  rx[num_n_words - 1] = 0;
  r[num_n_words - 1] = 0;
  s[num_n_words - 1] = 0;

#if MG_UECC_VLI_NATIVE_LITTLE_ENDIAN
  bcopy((uint8_t *) r, signature, curve->num_bytes);
  bcopy((uint8_t *) s, signature + curve->num_bytes, curve->num_bytes);
#else
  mg_uecc_vli_bytesToNative(_public, public_key, curve->num_bytes);
  mg_uecc_vli_bytesToNative(_public + num_words, public_key + curve->num_bytes,
                            curve->num_bytes);
  mg_uecc_vli_bytesToNative(r, signature, curve->num_bytes);
  mg_uecc_vli_bytesToNative(s, signature + curve->num_bytes, curve->num_bytes);
#endif

  /* r, s must not be 0. */
  if (mg_uecc_vli_isZero(r, num_words) || mg_uecc_vli_isZero(s, num_words)) {
    return 0;
  }

  /* r, s must be < n. */
  if (mg_uecc_vli_cmp_unsafe(curve->n, r, num_n_words) != 1 ||
      mg_uecc_vli_cmp_unsafe(curve->n, s, num_n_words) != 1) {
    return 0;
  }

  /* Calculate u1 and u2. */
  mg_uecc_vli_modInv(z, s, curve->n, num_n_words); /* z = 1/s */
  u1[num_n_words - 1] = 0;
  bits2int(u1, message_hash, hash_size, curve);
  mg_uecc_vli_modMult(u1, u1, z, curve->n, num_n_words); /* u1 = e/s */
  mg_uecc_vli_modMult(u2, r, z, curve->n, num_n_words);  /* u2 = r/s */

  /* Calculate sum = G + Q. */
  mg_uecc_vli_set(sum, _public, num_words);
  mg_uecc_vli_set(sum + num_words, _public + num_words, num_words);
  mg_uecc_vli_set(tx, curve->G, num_words);
  mg_uecc_vli_set(ty, curve->G + num_words, num_words);
  mg_uecc_vli_modSub(z, sum, tx, curve->p, num_words); /* z = x2 - x1 */
  XYcZ_add(tx, ty, sum, sum + num_words, curve);
  mg_uecc_vli_modInv(z, z, curve->p, num_words); /* z = 1/z */
  apply_z(sum, sum + num_words, z, curve);

  /* Use Shamir's trick to calculate u1*G + u2*Q */
  points[0] = 0;
  points[1] = curve->G;
  points[2] = _public;
  points[3] = sum;
  num_bits = smax(mg_uecc_vli_numBits(u1, num_n_words),
                  mg_uecc_vli_numBits(u2, num_n_words));
  point =
      points[(!!mg_uecc_vli_testBit(u1, (bitcount_t) (num_bits - 1))) |
             ((!!mg_uecc_vli_testBit(u2, (bitcount_t) (num_bits - 1))) << 1)];
  mg_uecc_vli_set(rx, point, num_words);
  mg_uecc_vli_set(ry, point + num_words, num_words);
  mg_uecc_vli_clear(z, num_words);
  z[0] = 1;

  for (i = num_bits - 2; i >= 0; --i) {
    mg_uecc_word_t index;
    curve->double_jacobian(rx, ry, z, curve);

    index = (!!mg_uecc_vli_testBit(u1, i)) |
            (mg_uecc_word_t) ((!!mg_uecc_vli_testBit(u2, i)) << 1);
    point = points[index];
    if (point) {
      mg_uecc_vli_set(tx, point, num_words);
      mg_uecc_vli_set(ty, point + num_words, num_words);
      apply_z(tx, ty, z, curve);
      mg_uecc_vli_modSub(tz, rx, tx, curve->p, num_words); /* Z = x2 - x1 */
      XYcZ_add(tx, ty, rx, ry, curve);
      mg_uecc_vli_modMult_fast(z, z, tz, curve);
    }
  }

  mg_uecc_vli_modInv(z, z, curve->p, num_words); /* Z = 1/Z */
  apply_z(rx, ry, z, curve);

  /* v = x1 (mod n) */
  if (mg_uecc_vli_cmp_unsafe(curve->n, rx, num_n_words) != 1) {
    mg_uecc_vli_sub(rx, rx, curve->n, num_n_words);
  }

  /* Accept only if v == r. */
  return (int) (mg_uecc_vli_equal(rx, r, num_words));
}

#if MG_UECC_ENABLE_VLI_API

unsigned mg_uecc_curve_num_words(MG_UECC_Curve curve) {
  return curve->num_words;
}

unsigned mg_uecc_curve_num_bytes(MG_UECC_Curve curve) {
  return curve->num_bytes;
}

unsigned mg_uecc_curve_num_bits(MG_UECC_Curve curve) {
  return curve->num_bytes * 8;
}

unsigned mg_uecc_curve_num_n_words(MG_UECC_Curve curve) {
  return BITS_TO_WORDS(curve->num_n_bits);
}

unsigned mg_uecc_curve_num_n_bytes(MG_UECC_Curve curve) {
  return BITS_TO_BYTES(curve->num_n_bits);
}

unsigned mg_uecc_curve_num_n_bits(MG_UECC_Curve curve) {
  return curve->num_n_bits;
}

const mg_uecc_word_t *mg_uecc_curve_p(MG_UECC_Curve curve) {
  return curve->p;
}

const mg_uecc_word_t *mg_uecc_curve_n(MG_UECC_Curve curve) {
  return curve->n;
}

const mg_uecc_word_t *mg_uecc_curve_G(MG_UECC_Curve curve) {
  return curve->G;
}

const mg_uecc_word_t *mg_uecc_curve_b(MG_UECC_Curve curve) {
  return curve->b;
}

#if MG_UECC_SUPPORT_COMPRESSED_POINT
void mg_uecc_vli_mod_sqrt(mg_uecc_word_t *a, MG_UECC_Curve curve) {
  curve->mod_sqrt(a, curve);
}
#endif

void mg_uecc_vli_mmod_fast(mg_uecc_word_t *result, mg_uecc_word_t *product,
                           MG_UECC_Curve curve) {
#if (MG_UECC_OPTIMIZATION_LEVEL > 0)
  curve->mmod_fast(result, product);
#else
  mg_uecc_vli_mmod(result, product, curve->p, curve->num_words);
#endif
}

void mg_uecc_point_mult(mg_uecc_word_t *result, const mg_uecc_word_t *point,
                        const mg_uecc_word_t *scalar, MG_UECC_Curve curve) {
  mg_uecc_word_t tmp1[MG_UECC_MAX_WORDS];
  mg_uecc_word_t tmp2[MG_UECC_MAX_WORDS];
  mg_uecc_word_t *p2[2] = {tmp1, tmp2};
  mg_uecc_word_t carry = regularize_k(scalar, tmp1, tmp2, curve);

  EccPoint_mult(result, point, p2[!carry], 0, curve->num_n_bits + 1, curve);
}

#endif  /* MG_UECC_ENABLE_VLI_API */
#endif  // MG_TLS_BUILTIN
// End of uecc BSD-2

#ifdef MG_ENABLE_LINES
#line 1 "src/tls_x25519.c"
#endif
/**
 * Adapted from STROBE: https://strobe.sourceforge.io/
 * Copyright (c) 2015-2016 Cryptography Research, Inc.
 * Author: Mike Hamburg
 * License: MIT License
 */




#if MG_TLS == MG_TLS_BUILTIN

const uint8_t X25519_BASE_POINT[X25519_BYTES] = {9};

#define X25519_WBITS 32

typedef uint32_t limb_t;
typedef uint64_t dlimb_t;
typedef int64_t sdlimb_t;

#define NLIMBS (256 / X25519_WBITS)
typedef limb_t mg_fe[NLIMBS];

static limb_t umaal(limb_t *carry, limb_t acc, limb_t mand, limb_t mier) {
  dlimb_t tmp = (dlimb_t) mand * mier + acc + *carry;
  *carry = (limb_t) (tmp >> X25519_WBITS);
  return (limb_t) tmp;
}

// These functions are implemented in terms of umaal on ARM
static limb_t adc(limb_t *carry, limb_t acc, limb_t mand) {
  dlimb_t total = (dlimb_t) *carry + acc + mand;
  *carry = (limb_t) (total >> X25519_WBITS);
  return (limb_t) total;
}

static limb_t adc0(limb_t *carry, limb_t acc) {
  dlimb_t total = (dlimb_t) *carry + acc;
  *carry = (limb_t) (total >> X25519_WBITS);
  return (limb_t) total;
}

// - Precondition: carry is small.
// - Invariant: result of propagate is < 2^255 + 1 word
// - In particular, always less than 2p.
// - Also, output x >= min(x,19)
static void propagate(mg_fe x, limb_t over) {
  unsigned i;
  limb_t carry;
  over = x[NLIMBS - 1] >> (X25519_WBITS - 1) | over << 1;
  x[NLIMBS - 1] &= ~((limb_t) 1 << (X25519_WBITS - 1));

  carry = over * 19;
  for (i = 0; i < NLIMBS; i++) {
    x[i] = adc0(&carry, x[i]);
  }
}

static void add(mg_fe out, const mg_fe a, const mg_fe b) {
  unsigned i;
  limb_t carry = 0;
  for (i = 0; i < NLIMBS; i++) {
    out[i] = adc(&carry, a[i], b[i]);
  }
  propagate(out, carry);
}

static void sub(mg_fe out, const mg_fe a, const mg_fe b) {
  unsigned i;
  sdlimb_t carry = -38;
  for (i = 0; i < NLIMBS; i++) {
    carry = carry + a[i] - b[i];
    out[i] = (limb_t) carry;
    carry >>= X25519_WBITS;
  }
  propagate(out, (limb_t) (1 + carry));
}

// `b` can contain less than 8 limbs, thus we use `limb_t *` instead of `mg_fe`
// to avoid build warnings
static void mul(mg_fe out, const mg_fe a, const limb_t *b, unsigned nb) {
  limb_t accum[2 * NLIMBS] = {0};
  unsigned i, j;

  limb_t carry2;
  for (i = 0; i < nb; i++) {
    limb_t mand = b[i];
    carry2 = 0;
    for (j = 0; j < NLIMBS; j++) {
      limb_t tmp;                        // "a" may be misaligned
      memcpy(&tmp, &a[j], sizeof(tmp));  // So make an aligned copy
      accum[i + j] = umaal(&carry2, accum[i + j], mand, tmp);
    }
    accum[i + j] = carry2;
  }

  carry2 = 0;
  for (j = 0; j < NLIMBS; j++) {
    out[j] = umaal(&carry2, accum[j], 38, accum[j + NLIMBS]);
  }
  propagate(out, carry2);
}

static void sqr(mg_fe out, const mg_fe a) {
  mul(out, a, a, NLIMBS);
}
static void mul1(mg_fe out, const mg_fe a) {
  mul(out, a, out, NLIMBS);
}
static void sqr1(mg_fe a) {
  mul1(a, a);
}

static void condswap(limb_t a[2 * NLIMBS], limb_t b[2 * NLIMBS],
                     limb_t doswap) {
  unsigned i;
  for (i = 0; i < 2 * NLIMBS; i++) {
    limb_t xor_ab = (a[i] ^ b[i]) & doswap;
    a[i] ^= xor_ab;
    b[i] ^= xor_ab;
  }
}

// Canonicalize a field element x, reducing it to the least residue which is
// congruent to it mod 2^255-19
// - Precondition: x < 2^255 + 1 word
static limb_t canon(mg_fe x) {
  // First, add 19.
  unsigned i;
  limb_t carry0 = 19;
  limb_t res;
  sdlimb_t carry;
  for (i = 0; i < NLIMBS; i++) {
    x[i] = adc0(&carry0, x[i]);
  }
  propagate(x, carry0);

  // Here, 19 <= x2 < 2^255
  // - This is because we added 19, so before propagate it can't be less
  // than 19. After propagate, it still can't be less than 19, because if
  // propagate does anything it adds 19.
  // - We know that the high bit must be clear, because either the input was ~
  // 2^255 + one word + 19 (in which case it propagates to at most 2 words) or
  // it was < 2^255. So now, if we subtract 19, we will get back to something in
  // [0,2^255-19).
  carry = -19;
  res = 0;
  for (i = 0; i < NLIMBS; i++) {
    carry += x[i];
    res |= x[i] = (limb_t) carry;
    carry >>= X25519_WBITS;
  }
  return (limb_t) (((dlimb_t) res - 1) >> X25519_WBITS);
}

static const limb_t a24[1] = {121665};

static void ladder_part1(mg_fe xs[5]) {
  limb_t *x2 = xs[0], *z2 = xs[1], *x3 = xs[2], *z3 = xs[3], *t1 = xs[4];
  add(t1, x2, z2);                                 // t1 = A
  sub(z2, x2, z2);                                 // z2 = B
  add(x2, x3, z3);                                 // x2 = C
  sub(z3, x3, z3);                                 // z3 = D
  mul1(z3, t1);                                    // z3 = DA
  mul1(x2, z2);                                    // x3 = BC
  add(x3, z3, x2);                                 // x3 = DA+CB
  sub(z3, z3, x2);                                 // z3 = DA-CB
  sqr1(t1);                                        // t1 = AA
  sqr1(z2);                                        // z2 = BB
  sub(x2, t1, z2);                                 // x2 = E = AA-BB
  mul(z2, x2, a24, sizeof(a24) / sizeof(a24[0]));  // z2 = E*a24
  add(z2, z2, t1);                                 // z2 = E*a24 + AA
}

static void ladder_part2(mg_fe xs[5], const mg_fe x1) {
  limb_t *x2 = xs[0], *z2 = xs[1], *x3 = xs[2], *z3 = xs[3], *t1 = xs[4];
  sqr1(z3);         // z3 = (DA-CB)^2
  mul1(z3, x1);     // z3 = x1 * (DA-CB)^2
  sqr1(x3);         // x3 = (DA+CB)^2
  mul1(z2, x2);     // z2 = AA*(E*a24+AA)
  sub(x2, t1, x2);  // x2 = BB again
  mul1(x2, t1);     // x2 = AA*BB
}

static void x25519_core(mg_fe xs[5], const uint8_t scalar[X25519_BYTES],
                        const uint8_t *x1, int clamp) {
  int i;
  mg_fe x1_limbs;
  limb_t swap = 0;
  limb_t *x2 = xs[0], *x3 = xs[2], *z3 = xs[3];
  memset(xs, 0, 4 * sizeof(mg_fe));
  x2[0] = z3[0] = 1;
  for (i = 0; i < NLIMBS; i++) {
    x3[i] = x1_limbs[i] =
        MG_U32(x1[i * 4 + 3], x1[i * 4 + 2], x1[i * 4 + 1], x1[i * 4]);
  }

  for (i = 255; i >= 0; i--) {
    uint8_t bytei = scalar[i / 8];
    limb_t doswap;
    if (clamp) {
      if (i / 8 == 0) {
        bytei &= (uint8_t) ~7U;
      } else if (i / 8 == X25519_BYTES - 1) {
        bytei &= 0x7F;
        bytei |= 0x40;
      }
    }
    doswap = 0 - (limb_t) ((bytei >> (i % 8)) & 1);
    condswap(x2, x3, swap ^ doswap);
    swap = doswap;

    ladder_part1(xs);
    ladder_part2(xs, (const limb_t *) x1_limbs);
  }
  condswap(x2, x3, swap);
}

int mg_tls_x25519(uint8_t out[X25519_BYTES], const uint8_t scalar[X25519_BYTES],
                  const uint8_t x1[X25519_BYTES], int clamp) {
  int i, ret;
  mg_fe xs[5], out_limbs;
  limb_t *x2, *z2, *z3, *prev;
  static const struct {
    uint8_t a, c, n;
  } steps[13] = {{2, 1, 1},  {2, 1, 1},  {4, 2, 3},  {2, 4, 6},  {3, 1, 1},
                 {3, 2, 12}, {4, 3, 25}, {2, 3, 25}, {2, 4, 50}, {3, 2, 125},
                 {3, 1, 2},  {3, 1, 2},  {3, 1, 1}};
  x25519_core(xs, scalar, x1, clamp);

  // Precomputed inversion chain
  x2 = xs[0];
  z2 = xs[1];
  z3 = xs[3];

  prev = z2;
  for (i = 0; i < 13; i++) {
    int j;
    limb_t *a = xs[steps[i].a];
    for (j = steps[i].n; j > 0; j--) {
      sqr(a, prev);
      prev = a;
    }
    mul1(a, xs[steps[i].c]);
  }

  // Here prev = z3
  // x2 /= z2
  mul(out_limbs, x2, z3, NLIMBS);
  ret = (int) canon(out_limbs);
  if (!clamp) ret = 0;
  for (i = 0; i < NLIMBS; i++) {
    uint32_t n = out_limbs[i];
    out[i * 4] = (uint8_t) (n & 0xff);
    out[i * 4 + 1] = (uint8_t) ((n >> 8) & 0xff);
    out[i * 4 + 2] = (uint8_t) ((n >> 16) & 0xff);
    out[i * 4 + 3] = (uint8_t) ((n >> 24) & 0xff);
  }
  return ret;
}

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/url.c"
#endif


struct url {
  size_t key, user, pass, host, port, uri, end;
};

int mg_url_is_ssl(const char *url) {
  return strncmp(url, "wss:", 4) == 0 || strncmp(url, "https:", 6) == 0 ||
         strncmp(url, "mqtts:", 6) == 0 || strncmp(url, "ssl:", 4) == 0 ||
         strncmp(url, "tls:", 4) == 0 || strncmp(url, "tcps:", 5) == 0;
}

static struct url urlparse(const char *url) {
  size_t i;
  struct url u;
  memset(&u, 0, sizeof(u));
  for (i = 0; url[i] != '\0'; i++) {
    if (url[i] == '/' && i > 0 && u.host == 0 && url[i - 1] == '/') {
      u.host = i + 1;
      u.port = 0;
    } else if (url[i] == ']') {
      u.port = 0;  // IPv6 URLs, like http://[::1]/bar
    } else if (url[i] == ':' && u.port == 0 && u.uri == 0) {
      u.port = i + 1;
    } else if (url[i] == '@' && u.user == 0 && u.pass == 0 && u.uri == 0) {
      u.user = u.host;
      u.pass = u.port;
      u.host = i + 1;
      u.port = 0;
    } else if (url[i] == '/' && u.host && u.uri == 0) {
      u.uri = i;
    }
  }
  u.end = i;
#if 0
  printf("[%s] %d %d %d %d %d\n", url, u.user, u.pass, u.host, u.port, u.uri);
#endif
  return u;
}

struct mg_str mg_url_host(const char *url) {
  struct url u = urlparse(url);
  size_t n = u.port  ? u.port - u.host - 1
             : u.uri ? u.uri - u.host
                     : u.end - u.host;
  struct mg_str s = mg_str_n(url + u.host, n);
  return s;
}

const char *mg_url_uri(const char *url) {
  struct url u = urlparse(url);
  return u.uri ? url + u.uri : "/";
}

unsigned short mg_url_port(const char *url) {
  struct url u = urlparse(url);
  unsigned short port = 0;
  if (strncmp(url, "http:", 5) == 0 || strncmp(url, "ws:", 3) == 0) port = 80;
  if (strncmp(url, "wss:", 4) == 0 || strncmp(url, "https:", 6) == 0)
    port = 443;
  if (strncmp(url, "mqtt:", 5) == 0) port = 1883;
  if (strncmp(url, "mqtts:", 6) == 0) port = 8883;
  if (u.port) port = (unsigned short) atoi(url + u.port);
  return port;
}

struct mg_str mg_url_user(const char *url) {
  struct url u = urlparse(url);
  struct mg_str s = mg_str("");
  if (u.user && (u.pass || u.host)) {
    size_t n = u.pass ? u.pass - u.user - 1 : u.host - u.user - 1;
    s = mg_str_n(url + u.user, n);
  }
  return s;
}

struct mg_str mg_url_pass(const char *url) {
  struct url u = urlparse(url);
  struct mg_str s = mg_str_n("", 0UL);
  if (u.pass && u.host) {
    size_t n = u.host - u.pass - 1;
    s = mg_str_n(url + u.pass, n);
  }
  return s;
}

#ifdef MG_ENABLE_LINES
#line 1 "src/util.c"
#endif



// Not using memset for zeroing memory, cause it can be dropped by compiler
// See https://github.com/cesanta/mongoose/pull/1265
void mg_bzero(volatile unsigned char *buf, size_t len) {
  if (buf != NULL) {
    while (len--) *buf++ = 0;
  }
}

#if MG_ENABLE_CUSTOM_RANDOM
#else
bool mg_random(void *buf, size_t len) {
  bool success = false;
  unsigned char *p = (unsigned char *) buf;
#if MG_ARCH == MG_ARCH_ESP32
  while (len--) *p++ = (unsigned char) (esp_random() & 255);
  success = true;
#elif MG_ARCH == MG_ARCH_CUBE && defined(HAL_RNG_MODULE_ENABLED)
  extern RNG_HandleTypeDef hrng;
  for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
    uint32_t r = HAL_RNG_ReadLastRandomNumber(&hrng);
    memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
  }
  success = true;
#elif MG_ARCH == MG_ARCH_PICOSDK
  while (len--) *p++ = (unsigned char) (get_rand_32() & 255);
  success = true;
#elif MG_ARCH == MG_ARCH_ZEPHYR
#if MG_TLS == MG_TLS_BUILTIN ||                                    \
    (MG_TLS == MG_TLS_MBED && (!defined(MBEDTLS_VERSION_NUMBER) || \
                               MBEDTLS_VERSION_NUMBER < 0x04000000))
  return (sys_csrand_get(buf, len) == 0);  // do not fallback on reseed error
#else
  sys_rand_get(buf, len);
  success = true;
#endif
#elif MG_ARCH == MG_ARCH_WIN32
#if defined(_MSC_VER) && _MSC_VER < 1700
  static bool initialised = false;
  static HCRYPTPROV hProv;
  // CryptGenRandom() implementation earlier than 2008 is weak, see
  // https://en.wikipedia.org/wiki/CryptGenRandom
  if (!initialised) {
    initialised = CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL,
                                      CRYPT_VERIFYCONTEXT);
  }
  if (initialised) success = CryptGenRandom(hProv, len, p);
#else
  size_t i;
  for (i = 0; i < len; i++) {
    unsigned int rand_v;
    if (rand_s(&rand_v) == 0) {
      p[i] = (unsigned char) (rand_v & 255);
    } else {
      break;
    }
  }
  success = (i == len);
#endif

#elif MG_ARCH == MG_ARCH_UNIX
  FILE *fp = fopen("/dev/urandom", "rb");
  if (fp != NULL) {
    if (fread(buf, 1, len, fp) == len) success = true;
    fclose(fp);
  }
#endif
  // If everything above did not work, fallback to a pseudo random generator
  if (success == false) {
    MG_ERROR(("Weak RNG: using rand()"));
    while (len--) *p++ = (unsigned char) (rand() & 255);
  }
  return success;
}
#endif

char *mg_random_str(char *buf, size_t len) {
  size_t i;
  mg_random(buf, len);
  for (i = 0; i < len; i++) {
    uint8_t c = ((uint8_t *) buf)[i] % 62U;
    buf[i] = i == len - 1 ? (char) '\0'            // 0-terminate last byte
             : c < 26     ? (char) ('a' + c)       // lowercase
             : c < 52     ? (char) ('A' + c - 26)  // uppercase
                          : (char) ('0' + c - 52);     // numeric
  }
  return buf;
}

uint32_t mg_crc32(uint32_t crc, const char *buf, size_t len) {
  static const uint32_t crclut[16] = {
      // table for polynomial 0xEDB88320 (reflected)
      0x00000000, 0x1DB71064, 0x3B6E20C8, 0x26D930AC, 0x76DC4190, 0x6B6B51F4,
      0x4DB26158, 0x5005713C, 0xEDB88320, 0xF00F9344, 0xD6D6A3E8, 0xCB61B38C,
      0x9B64C2B0, 0x86D3D2D4, 0xA00AE278, 0xBDBDF21C};
  crc = ~crc;
  while (len--) {
    uint8_t b = *(uint8_t *) buf++;
    crc = crclut[(crc ^ b) & 0x0F] ^ (crc >> 4);
    crc = crclut[(crc ^ (b >> 4)) & 0x0F] ^ (crc >> 4);
  }
  return ~crc;
}

static int isbyte(int n) {
  return n >= 0 && n <= 255;
}

static int parse_net(const char *spec, uint32_t *net, uint32_t *mask) {
  int n, a, b, c, d, slash = 32, len = 0;
  if ((sscanf(spec, "%d.%d.%d.%d/%d%n", &a, &b, &c, &d, &slash, &n) == 5 ||
       sscanf(spec, "%d.%d.%d.%d%n", &a, &b, &c, &d, &n) == 4) &&
      isbyte(a) && isbyte(b) && isbyte(c) && isbyte(d) && slash >= 0 &&
      slash < 33) {
    len = n;
    *net = ((uint32_t) a << 24) | ((uint32_t) b << 16) | ((uint32_t) c << 8) |
           (uint32_t) d;
    *mask = slash ? (uint32_t) (0xffffffffU << (32 - slash)) : (uint32_t) 0;
  }
  return len;
}

int mg_check_ip_acl(struct mg_str acl, struct mg_addr *remote_ip) {
  struct mg_str entry;
  int allowed = acl.len == 0 ? '+' : '-';  // If any ACL is set, deny by default
  uint32_t remote_ip4;
  if (remote_ip->is_ip6) {
    return -1;  // TODO(): handle IPv6 ACL and addresses
  } else {      // IPv4
    memcpy((void *) &remote_ip4, remote_ip->addr.ip, sizeof(remote_ip4));
    while (mg_span(acl, &entry, &acl, ',')) {
      uint32_t net, mask;
      if (entry.buf[0] != '+' && entry.buf[0] != '-') return -1;
      if (parse_net(&entry.buf[1], &net, &mask) == 0) return -2;
      if ((mg_ntohl(remote_ip4) & mask) == net) allowed = entry.buf[0];
    }
  }
  return allowed == '+';
}

bool mg_path_is_sane(const struct mg_str path) {
  const char *s = path.buf;
  size_t n = path.len;
  if (path.buf[0] == '~') return false;                        // Starts with ~
  if (path.buf[0] == '.' && path.buf[1] == '.') return false;  // Starts with ..
  for (; s[0] != '\0' && n > 0; s++, n--) {
    if ((s[0] == '/' || s[0] == '\\') && n >= 2) {   // Subdir?
      if (s[1] == '.' && s[2] == '.') return false;  // Starts with ..
    }
  }
  return true;
}

#if MG_ENABLE_CUSTOM_MILLIS
#else
uint64_t mg_millis(void) {
#if MG_ARCH == MG_ARCH_WIN32
  return GetTickCount();
#elif MG_ARCH == MG_ARCH_PICOSDK
  return time_us_64() / 1000;
#elif MG_ARCH == MG_ARCH_ESP8266 || MG_ARCH == MG_ARCH_ESP32 || \
    MG_ARCH == MG_ARCH_FREERTOS
  return xTaskGetTickCount() * portTICK_PERIOD_MS;
#elif MG_ARCH == MG_ARCH_CUBE
  return (uint64_t) HAL_GetTick();
#elif MG_ARCH == MG_ARCH_THREADX
  return tx_time_get() * (1000 /* MS per SEC */ / TX_TIMER_TICKS_PER_SECOND);
#elif MG_ARCH == MG_ARCH_TIRTOS
  return (uint64_t) Clock_getTicks();
#elif MG_ARCH == MG_ARCH_ZEPHYR
  return (uint64_t) k_uptime_get();
#elif MG_ARCH == MG_ARCH_CMSIS_RTOS1
  return (uint64_t) rt_time_get();
#elif MG_ARCH == MG_ARCH_CMSIS_RTOS2
  return (uint64_t) ((osKernelGetTickCount() * 1000) / osKernelGetTickFreq());
#elif MG_ARCH == MG_ARCH_RTTHREAD
  return (uint64_t) ((rt_tick_get() * 1000) / RT_TICK_PER_SECOND);
#elif MG_ARCH == MG_ARCH_UNIX && defined(__APPLE__)
  // Apple CLOCK_MONOTONIC_RAW is equivalent to CLOCK_BOOTTIME on linux
  // Apple CLOCK_UPTIME_RAW is equivalent to CLOCK_MONOTONIC_RAW on linux
  return clock_gettime_nsec_np(CLOCK_UPTIME_RAW) / 1000000;
#elif MG_ARCH == MG_ARCH_UNIX
  struct timespec ts = {0, 0};
  // See #1615 - prefer monotonic clock
#if defined(CLOCK_MONOTONIC_RAW)
  // Raw hardware-based time that is not subject to NTP adjustment
  clock_gettime(CLOCK_MONOTONIC_RAW, &ts);
#elif defined(CLOCK_MONOTONIC)
  // Affected by the incremental adjustments performed by adjtime and NTP
  clock_gettime(CLOCK_MONOTONIC, &ts);
#else
  // Affected by discontinuous jumps in the system time and by the incremental
  // adjustments performed by adjtime and NTP
  clock_gettime(CLOCK_REALTIME, &ts);
#endif
  return ((uint64_t) ts.tv_sec * 1000 + (uint64_t) ts.tv_nsec / 1000000);
#elif defined(ARDUINO)
  return (uint64_t) millis();
#else
  return (uint64_t) (time(NULL) * 1000);
#endif
}
#endif

// network format equates big endian order
uint16_t mg_ntohs(uint16_t net) {
  return MG_LOAD_BE16(&net);
}

uint32_t mg_ntohl(uint32_t net) {
  return MG_LOAD_BE32(&net);
}

uint64_t mg_ntohll(uint64_t net) {
  return MG_LOAD_BE64(&net);
}

void mg_delayms(unsigned int ms) {
  uint64_t to = mg_millis() + ms + 1;
  while (mg_millis() < to) (void) 0;
}

#if MG_ENABLE_CUSTOM_CALLOC
#else
void *mg_calloc(size_t count, size_t size) {
  return calloc(count, size);
}

void mg_free(void *ptr) {
  free(ptr);
}
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/wifi_dummy.c"
#endif


#if (!defined(MG_ENABLE_DRIVER_PICO_W) || !MG_ENABLE_DRIVER_PICO_W) && \
    (!defined(MG_ENABLE_DRIVER_CYW) || !MG_ENABLE_DRIVER_CYW) && \
    (!defined(MG_ENABLE_DRIVER_CYW_SDIO) || !MG_ENABLE_DRIVER_CYW_SDIO) && \
    (!defined(MG_ENABLE_DRIVER_NXP_WIFI) || !MG_ENABLE_DRIVER_NXP_WIFI) && \
    (!defined(MG_ENABLE_DRIVER_ST67W6) || !MG_ENABLE_DRIVER_ST67W6)


bool mg_wifi_scan(void) {
  MG_ERROR(("No Wi-Fi driver enabled"));
  return false;
}

bool mg_wifi_connect(struct mg_wifi_data *wifi) {
  (void) wifi;
  return mg_wifi_scan();
}

bool mg_wifi_disconnect(void) {
  return mg_wifi_scan();
}

bool mg_wifi_ap_start(struct mg_wifi_data *wifi) {
  (void) wifi;
  return mg_wifi_scan();
}

bool mg_wifi_ap_stop(void) {
  return mg_wifi_scan();
}

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/ws.c"
#endif











struct ws_msg {
  uint8_t flags;
  size_t header_len;
  size_t data_len;
};

size_t mg_ws_vprintf(struct mg_connection *c, int op, const char *fmt,
                     va_list *ap) {
  size_t len = c->send.len;
  size_t n = mg_vxprintf(mg_pfn_iobuf, &c->send, fmt, ap);
  mg_ws_wrap(c, c->send.len - len, op);
  return n;
}

size_t mg_ws_printf(struct mg_connection *c, int op, const char *fmt, ...) {
  size_t len = 0;
  va_list ap;
  va_start(ap, fmt);
  len = mg_ws_vprintf(c, op, fmt, &ap);
  va_end(ap);
  return len;
}

static void ws_handshake(struct mg_connection *c, const struct mg_str *wskey,
                         const struct mg_str *wsproto, const char *fmt,
                         va_list *ap) {
  const char *magic = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
  unsigned char sha[20], b64_sha[30];

  mg_sha1_ctx sha_ctx;
  mg_sha1_init(&sha_ctx);
  mg_sha1_update(&sha_ctx, (unsigned char *) wskey->buf, wskey->len);
  mg_sha1_update(&sha_ctx, (unsigned char *) magic, 36);
  mg_sha1_final(sha, &sha_ctx);
  mg_base64_encode(sha, sizeof(sha), (char *) b64_sha, sizeof(b64_sha));
  mg_xprintf(mg_pfn_iobuf, &c->send,
             "HTTP/1.1 101 Switching Protocols\r\n"
             "Upgrade: websocket\r\n"
             "Connection: Upgrade\r\n"
             "Sec-WebSocket-Accept: %s\r\n",
             b64_sha);
  if (fmt != NULL) mg_vxprintf(mg_pfn_iobuf, &c->send, fmt, ap);
  if (wsproto != NULL) {
    mg_printf(c, "Sec-WebSocket-Protocol: %.*s\r\n", (int) wsproto->len,
              wsproto->buf);
  }
  if (!mg_send(c, "\r\n", 2)) mg_error(c, "OOM");
}

static uint32_t be32(const uint8_t *p) {
  return (((uint32_t) p[3]) << 0) | (((uint32_t) p[2]) << 8) |
         (((uint32_t) p[1]) << 16) | (((uint32_t) p[0]) << 24);
}

static size_t ws_process(uint8_t *buf, size_t len, struct ws_msg *msg) {
  size_t i, n = 0, mask_len = 0;
  memset(msg, 0, sizeof(*msg));
  if (len >= 2) {
    n = buf[1] & 0x7f;                // Frame length
    mask_len = buf[1] & 128 ? 4 : 0;  // last bit is a mask bit
    msg->flags = buf[0];
    if (n < 126 && len >= mask_len) {
      msg->data_len = n;
      msg->header_len = 2 + mask_len;
    } else if (n == 126 && len >= 4 + mask_len) {
      msg->header_len = 4 + mask_len;
      msg->data_len = (((size_t) buf[2]) << 8) | buf[3];
    } else if (len >= 10 + mask_len) {
      msg->header_len = 10 + mask_len;
      msg->data_len =
          (size_t) (((uint64_t) be32(buf + 2) << 32) + be32(buf + 6));
    }
  }
  // Sanity check, and integer overflow protection for the boundary check below
  // data_len should not be larger than 1 Gb
  if (msg->data_len > 1024 * 1024 * 1024) return 0;
  if (msg->header_len + msg->data_len > len) return 0;
  if (mask_len > 0) {
    uint8_t *p = buf + msg->header_len, *m = p - mask_len;
    for (i = 0; i < msg->data_len; i++) p[i] ^= m[i & 3];
  }
  return msg->header_len + msg->data_len;
}

static size_t mkhdr(size_t len, int op, bool is_client, uint8_t *buf) {
  size_t n = 0;
  buf[0] = (uint8_t) (op | 128);
  if (len < 126) {
    buf[1] = (unsigned char) len;
    n = 2;
  } else if (len < 65536) {
    uint16_t tmp = mg_htons((uint16_t) len);
    buf[1] = 126;
    memcpy(&buf[2], &tmp, sizeof(tmp));
    n = 4;
  } else {
    uint32_t tmp;
    buf[1] = 127;
    tmp = mg_htonl((uint32_t) (((uint64_t) len) >> 32));
    memcpy(&buf[2], &tmp, sizeof(tmp));
    tmp = mg_htonl((uint32_t) (len & 0xffffffffU));
    memcpy(&buf[6], &tmp, sizeof(tmp));
    n = 10;
  }
  if (is_client) {
    buf[1] |= 1 << 7;  // Set masking flag
    mg_random(&buf[n], 4);
    n += 4;
  }
  return n;
}

static void mg_ws_mask(struct mg_connection *c, size_t len) {
  if (c->is_client && c->send.buf != NULL) {
    size_t i;
    uint8_t *p = c->send.buf + c->send.len - len, *mask = p - 4;
    for (i = 0; i < len; i++) p[i] ^= mask[i & 3];
  }
}

size_t mg_ws_send(struct mg_connection *c, const void *buf, size_t len,
                  int op) {
  uint8_t header[14];
  size_t header_len = mkhdr(len, op, c->is_client, header);
  if (!mg_send(c, header, header_len)) return 0;
  if (!mg_send(c, buf, len)) return header_len;
  MG_VERBOSE(("WS out: %d [%.*s]", (int) len, (int) len, buf));
  mg_ws_mask(c, len);
  return header_len + len;
}

static bool mg_ws_client_handshake(struct mg_connection *c) {
  int n = mg_http_get_request_len(c->recv.buf, c->recv.len);
  if (n < 0) {
    mg_error(c, "not http");  // Some just, not an HTTP request
  } else if (n > 0) {
    if (n < 15 || memcmp(c->recv.buf + 9, "101", 3) != 0) {
      mg_error(c, "ws handshake error");
    } else {
      struct mg_http_message hm;
      if (mg_http_parse((char *) c->recv.buf, c->recv.len, &hm)) {
        c->is_websocket = 1;
        mg_call(c, MG_EV_WS_OPEN, &hm);
      } else {
        mg_error(c, "ws handshake error");
      }
    }
    mg_iobuf_del(&c->recv, 0, (size_t) n);
  } else {
    return true;  // Request is not yet received, quit event handler
  }
  return false;  // Continue event handler
}

static void mg_ws_cb(struct mg_connection *c, int ev, void *ev_data) {
  struct ws_msg msg;
  size_t ofs = (size_t) c->pfn_data;

  // assert(ofs < c->recv.len);
  if (ev == MG_EV_READ) {
    if (c->is_client && !c->is_websocket && mg_ws_client_handshake(c)) return;

    while (ws_process(c->recv.buf + ofs, c->recv.len - ofs, &msg) > 0) {
      char *s = (char *) c->recv.buf + ofs + msg.header_len;
      struct mg_ws_message m;
      size_t len;
      uint8_t final, op;
      m.data.buf = s, m.data.len = msg.data_len, m.flags = msg.flags;
      len = msg.header_len + msg.data_len;
      final = msg.flags & 128;
      op = msg.flags & 15;
      // MG_VERBOSE ("fin %d op %d len %d [%.*s]", final, op,
      //                       (int) m.data.len, (int) m.data.len, m.data.buf));
      switch (op) {
        case WEBSOCKET_OP_CONTINUE:
          mg_call(c, MG_EV_WS_CTL, &m);
          break;
        case WEBSOCKET_OP_PING:
          MG_DEBUG(("%s", "WS PONG"));
          mg_ws_send(c, s, msg.data_len, WEBSOCKET_OP_PONG);
          mg_call(c, MG_EV_WS_CTL, &m);
          break;
        case WEBSOCKET_OP_PONG:
          mg_call(c, MG_EV_WS_CTL, &m);
          break;
        case WEBSOCKET_OP_TEXT:
        case WEBSOCKET_OP_BINARY:
          if (final) mg_call(c, MG_EV_WS_MSG, &m);
          break;
        case WEBSOCKET_OP_CLOSE:
          MG_DEBUG(("%lu WS CLOSE", c->id));
          mg_call(c, MG_EV_WS_CTL, &m);
          // Echo the payload of the received CLOSE message back to the sender
          mg_ws_send(c, m.data.buf, m.data.len, WEBSOCKET_OP_CLOSE);
          c->is_draining = 1;
          break;
        default:
          // Per RFC6455, close conn when an unknown op is recvd
          mg_error(c, "unknown WS op %d", op);
          break;
      }

      // Handle fragmented frames: strip header, keep in c->recv
      if (final == 0 || op == 0) {
        if (op) ofs++, len--, msg.header_len--;       // First frame
        mg_iobuf_del(&c->recv, ofs, msg.header_len);  // Strip header
        len -= msg.header_len;
        ofs += len;
        c->pfn_data = (void *) ofs;
        // MG_INFO(("FRAG %d [%.*s]", (int) ofs, (int) ofs, c->recv.buf));
      }
      // Remove non-fragmented frame
      if (final && op) mg_iobuf_del(&c->recv, ofs, len);
      // Last chunk of the fragmented frame
      if (final && !op && (ofs > 0)) {
        m.flags = c->recv.buf[0];
        m.data = mg_str_n((char *) &c->recv.buf[1], (size_t) (ofs - 1));
        mg_call(c, MG_EV_WS_MSG, &m);
        mg_iobuf_del(&c->recv, 0, ofs);
        ofs = 0;
        c->pfn_data = NULL;
      }
    }
  }
  (void) ev_data;
}

struct mg_connection *mg_ws_connect(struct mg_mgr *mgr, const char *url,
                                    mg_event_handler_t fn, void *fn_data,
                                    const char *fmt, ...) {
  struct mg_connection *c = mg_connect(mgr, url, fn, fn_data);
  if (c != NULL) {
    char nonce[16], key[30];
    struct mg_str host = mg_url_host(url);
    mg_random(nonce, sizeof(nonce));
    mg_base64_encode((unsigned char *) nonce, sizeof(nonce), key, sizeof(key));
    mg_xprintf(mg_pfn_iobuf, &c->send,
               "GET %s HTTP/1.1\r\n"
               "Upgrade: websocket\r\n"
               "Host: %.*s\r\n"
               "Connection: Upgrade\r\n"
               "Sec-WebSocket-Version: 13\r\n"
               "Sec-WebSocket-Key: %s\r\n",
               mg_url_uri(url), (int) host.len, host.buf, key);
    if (fmt != NULL) {
      va_list ap;
      va_start(ap, fmt);
      mg_vxprintf(mg_pfn_iobuf, &c->send, fmt, &ap);
      va_end(ap);
    }
    mg_xprintf(mg_pfn_iobuf, &c->send, "\r\n");
    c->pfn = mg_ws_cb;
    c->pfn_data = NULL;
  }
  return c;
}

void mg_ws_upgrade(struct mg_connection *c, struct mg_http_message *hm,
                   const char *fmt, ...) {
  struct mg_str *wskey = mg_http_get_header(hm, "Sec-WebSocket-Key");
  c->pfn = mg_ws_cb;
  c->pfn_data = NULL;
  if (wskey == NULL) {
    mg_http_reply(c, 426, "", "WS upgrade expected\n");
    c->is_draining = 1;
  } else {
    struct mg_str *wsproto = mg_http_get_header(hm, "Sec-WebSocket-Protocol");
    va_list ap;
    va_start(ap, fmt);
    ws_handshake(c, wskey, wsproto, fmt, &ap);
    va_end(ap);
    c->is_websocket = 1;
    c->is_resp = 0;
    mg_call(c, MG_EV_WS_OPEN, hm);
  }
}

size_t mg_ws_wrap(struct mg_connection *c, size_t len, int op) {
  uint8_t header[14], *p;
  size_t header_len = mkhdr(len, op, c->is_client, header);

  // NOTE: order of operations is important!
  if (mg_iobuf_add(&c->send, c->send.len, NULL, header_len) != 0) {
    p = &c->send.buf[c->send.len - len];         // p points to data
    memmove(p, p - header_len, len);             // Shift data
    memcpy(p - header_len, header, header_len);  // Prepend header
    mg_ws_mask(c, len);                          // Mask data
  }  // returning 0 means an OOM condition (iobuf couldn't resize), yet this is
  return c->send.len;  // so far recoverable, let the caller decide
}

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/cmsis.c"
#endif
// https://arm-software.github.io/CMSIS_5/Driver/html/index.html

#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_CMSIS) && MG_ENABLE_DRIVER_CMSIS





extern ARM_DRIVER_ETH_MAC Driver_ETH_MAC0;
extern ARM_DRIVER_ETH_PHY Driver_ETH_PHY0;

static struct mg_tcpip_if *s_ifp;

static void mac_cb(uint32_t);
static bool cmsis_init(struct mg_tcpip_if *);
static bool cmsis_poll(struct mg_tcpip_if *, bool);
static size_t cmsis_tx(const void *, size_t, struct mg_tcpip_if *);
static size_t cmsis_rx(void *, size_t, struct mg_tcpip_if *);

struct mg_tcpip_driver mg_tcpip_driver_cmsis = {cmsis_init, cmsis_tx, NULL,
                                                cmsis_poll};

static bool cmsis_init(struct mg_tcpip_if *ifp) {
  ARM_ETH_MAC_ADDR addr;
  s_ifp = ifp;

  ARM_DRIVER_ETH_MAC *mac = &Driver_ETH_MAC0;
  ARM_DRIVER_ETH_PHY *phy = &Driver_ETH_PHY0;
  ARM_ETH_MAC_CAPABILITIES cap = mac->GetCapabilities();
  if (mac->Initialize(mac_cb) != ARM_DRIVER_OK) return false;
  if (phy->Initialize(mac->PHY_Read, mac->PHY_Write) != ARM_DRIVER_OK)
    return false;
  if (cap.event_rx_frame == 0)  // polled mode driver
    mg_tcpip_driver_cmsis.rx = cmsis_rx;
  mac->PowerControl(ARM_POWER_FULL);
  if (cap.mac_address) {  // driver provides MAC address
    mac->GetMacAddress(&addr);
    memcpy(ifp->mac, &addr, sizeof(ifp->mac));
  } else {  // we provide MAC address
    memcpy(&addr, ifp->mac, sizeof(addr));
    mac->SetMacAddress(&addr);
  }
  phy->PowerControl(ARM_POWER_FULL);
  phy->SetInterface(cap.media_interface);
  phy->SetMode(ARM_ETH_PHY_AUTO_NEGOTIATE);
  return true;
}

static size_t cmsis_tx(const void *buf, size_t len, struct mg_tcpip_if *ifp) {
  ARM_DRIVER_ETH_MAC *mac = &Driver_ETH_MAC0;
  if (mac->SendFrame(buf, (uint32_t) len, 0) != ARM_DRIVER_OK) {
    ifp->nerr++;
    return 0;
  }
  ifp->nsent++;
  return len;
}

static void cmsis_update_hash_table(struct mg_tcpip_if *ifp) {
  // TODO(): read database, rebuild hash table
  ARM_DRIVER_ETH_MAC *mac = &Driver_ETH_MAC0;
  ARM_ETH_MAC_ADDR addr;
  memcpy(&addr, mcast_addr, sizeof(addr));
  mac->SetAddressFilter(&addr, 1);
  (void) ifp;
}

static bool cmsis_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (ifp->update_mac_hash_table) {
    cmsis_update_hash_table(ifp);
    ifp->update_mac_hash_table = false;
  }
  if (!s1) return false;
  ARM_DRIVER_ETH_PHY *phy = &Driver_ETH_PHY0;
  ARM_DRIVER_ETH_MAC *mac = &Driver_ETH_MAC0;
  bool up = (phy->GetLinkState() == ARM_ETH_LINK_UP) ? 1 : 0;  // link state
  if ((ifp->state == MG_TCPIP_STATE_DOWN) && up) {             // just went up
    ARM_ETH_LINK_INFO st = phy->GetLinkInfo();
    mac->Control(ARM_ETH_MAC_CONFIGURE,
                 (st.speed << ARM_ETH_MAC_SPEED_Pos) |
                     (st.duplex << ARM_ETH_MAC_DUPLEX_Pos) |
                     ARM_ETH_MAC_ADDRESS_BROADCAST);
    MG_DEBUG(("Link is %uM %s-duplex",
              (st.speed == 2) ? 1000
              : st.speed      ? 100
                              : 10,
              st.duplex ? "full" : "half"));
    mac->Control(ARM_ETH_MAC_CONTROL_TX, 1);
    mac->Control(ARM_ETH_MAC_CONTROL_RX, 1);
  } else if ((ifp->state != MG_TCPIP_STATE_DOWN) && !up) {  // just went down
    mac->Control(ARM_ETH_MAC_FLUSH,
                 ARM_ETH_MAC_FLUSH_TX | ARM_ETH_MAC_FLUSH_RX);
    mac->Control(ARM_ETH_MAC_CONTROL_TX, 0);
    mac->Control(ARM_ETH_MAC_CONTROL_RX, 0);
  }
  return up;
}

static void mac_cb(uint32_t ev) {
  if ((ev & ARM_ETH_MAC_EVENT_RX_FRAME) == 0) return;
  ARM_DRIVER_ETH_MAC *mac = &Driver_ETH_MAC0;
  uint32_t len = mac->GetRxFrameSize();  // CRC already stripped
  if (len >= 60 && len <= 1518) {        // proper frame
    char *p;
    if (mg_queue_book(&s_ifp->recv_queue, &p, len) >= len) {  // have room
      if ((len = mac->ReadFrame((uint8_t *) p, len)) > 0) {   // copy succeeds
        mg_queue_add(&s_ifp->recv_queue, len);
        s_ifp->nrecv++;
      }
      return;
    }
    s_ifp->ndrop++;
  }
  mac->ReadFrame(NULL, 0);  // otherwise, discard
}

static size_t cmsis_rx(void *buf, size_t buflen, struct mg_tcpip_if *ifp) {
  ARM_DRIVER_ETH_MAC *mac = &Driver_ETH_MAC0;
  uint32_t len = mac->GetRxFrameSize();  // CRC already stripped
  if (len >= 60 && len <= 1518 &&
      ((len = mac->ReadFrame(buf, (uint32_t) buflen)) > 0))
    return len;
  if (len > 0) mac->ReadFrame(NULL, 0);  // discard bad frames
  (void) ifp;
  return 0;
}

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/cyw.c"
#endif



#if MG_ENABLE_TCPIP &&                                          \
    ((defined(MG_ENABLE_DRIVER_CYW) && MG_ENABLE_DRIVER_CYW) || \
     (defined(MG_ENABLE_DRIVER_CYW_SDIO) && MG_ENABLE_DRIVER_CYW_SDIO))

#ifndef MG_ENABLE_DRIVER_CYW
#define MG_ENABLE_DRIVER_CYW 0
#endif
#ifndef MG_ENABLE_DRIVER_CYW_SDIO
#define MG_ENABLE_DRIVER_CYW_SDIO 0
#endif

static struct mg_tcpip_if *s_ifp;
static uint32_t s_ip, s_mask;
static bool s_link, s_auth, s_join;

static void wifi_cb(struct mg_tcpip_if *ifp, int ev, void *ev_data) {
  struct mg_wifi_data *wifi = &((struct mg_tcpip_driver_cyw_data *) ifp->driver_data)->wifi;
  if (wifi->apmode && ev == MG_TCPIP_EV_ST_CHG && *(uint8_t *) ev_data == MG_TCPIP_STATE_UP) {
    MG_DEBUG(("Access Point started"));
    s_ip = ifp->ip, ifp->ip = wifi->apip;
    s_mask = ifp->mask, ifp->mask = wifi->apmask;
    ifp->enable_dhcp_client = false;
    ifp->enable_dhcp_server = true;
  }
}

static bool cyw_init(uint8_t *mac);
static void cyw_poll(void);

static bool mg_tcpip_driver_cyw_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_cyw_data *d =
      (struct mg_tcpip_driver_cyw_data *) ifp->driver_data;
  struct mg_wifi_data *wifi = &d->wifi;
  if (MG_BIG_ENDIAN) {
    MG_ERROR(("Big-endian host"));
    return false;
  }
  s_ifp = ifp;
  s_ip = ifp->ip;
  s_mask = ifp->mask;
  s_link = s_auth = s_join = false;
  ifp->pfn = wifi_cb;
  if (!cyw_init(ifp->mac)) return false;

  if (wifi->apmode) {
    return mg_wifi_ap_start(wifi);
  } else if (wifi->ssid != NULL && wifi->pass != NULL) {
    return mg_wifi_connect(wifi);
  }
  return true;
}

static size_t mg_cyw_tx(unsigned int ifc, void *data, size_t len);
size_t mg_tcpip_driver_cyw_output(const void *buf, size_t len,
                                  struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_cyw_data *d =
      (struct mg_tcpip_driver_cyw_data *) ifp->driver_data;
  return mg_cyw_tx(d->wifi.apmode ? 1 : 0, (void *) buf, len) >= len ? len : 0;
}

static bool mg_tcpip_driver_cyw_poll(struct mg_tcpip_if *ifp, bool s1) {
  cyw_poll();
  if (!s1) return false;
  struct mg_tcpip_driver_cyw_data *d =
      (struct mg_tcpip_driver_cyw_data *) ifp->driver_data;
  return d->wifi.apmode ? s_link : s_link && s_auth && s_join;
}

struct mg_tcpip_driver mg_tcpip_driver_cyw = {mg_tcpip_driver_cyw_init,
                                              mg_tcpip_driver_cyw_output, NULL,
                                              mg_tcpip_driver_cyw_poll};

// - DS:
// https://www.mouser.com/datasheet/2/196/Infineon_CYW43439_DataSheet_v03_00_EN-3074791.pdf
// - WHD: https://github.com/Infineon/wifi-host-driver
//
//              |  e   <-- event data
//              |-----
//          net | vnd   <-- network (TCP/IP) | vendor header (Broadcom (bcm))
//         -----|-----
//  IOCTL | ETH | ETH  <-- IOCTL/IOVAR: chip control | ETH: Ethernet header
// -------|-----|-----
//   CDC  | BDC | BDC
// ------- ----- -----
//        SDPCM        <-- includes SDIO bus arbitration, not used in SPI
// -------------------
//    SPI   |  SDIO    <-- padded to 32-bit | 64-bytes
//
// - SDPCM has 3 channels (control, data, and asynchronous data)
// - SPI has 4 "functions", F0 to F3, to access different blocks in the chip,
// like the SPI/SDIO controller, chip backplane, and 2 DMA I/Os; these are
// usually handled by SDPCM but we need to explicitly access the I/O controller
// and chip backplane during initialization
// - SDIO has 3 functions (proper SDIO terminology), F0 to F2, coincident with
// those for SPI, accessed through standard SDIO practices. There is no F3.

// Processor core firmware is loaded to TCM RAM, along with module-dependent
// (hardware design) NVRAM data, via the chip backplane access through the bus
// Once the chip has been initialized, information regarding regulatory
// constraints (CLM blob, “Country Locale Matrix”), is loaded as an IOVAR. This
// is tied to the module being certified, hence it is also module-dependent.
// - Result: chip firmware + module NVRAM data + module CLM blob

#pragma pack(push, 1)
// all little endian

struct cdc_hdr {
  uint32_t cmd;   // ioctl command value
  uint16_t olen;  // output buflen
  uint16_t ilen;  // input buflen (excludes header)
  uint32_t flags;
  uint32_t status;
};

struct bdc_hdr {
  uint8_t flags;     // Flags
  uint8_t priority;  // 802.1d Priority (low 3 bits)
  uint8_t flags2;
  uint8_t data_offset;  // Offset from end of BDC header to packet data, in
                        // 4-uint8_t words. Leaves room for optional headers.
};

struct sdpcm_sw_hdr {
  uint8_t sequence;           // Sequence number of pkt
  uint8_t channel_and_flags;  // IOCTL/IOVAR or User Data or Event
  uint8_t next_length;
  uint8_t header_length;  // Offset to BDC or CDC header
  uint8_t wireless_flow_control;
  uint8_t bus_data_credit;  // Credit from WLAN Chip
  uint8_t _reserved[2];
};

struct sdpcm_hdr {
  uint16_t len;
  uint16_t _len;  // ~len
  struct sdpcm_sw_hdr sw_hdr;
};

struct data_hdr {
  struct sdpcm_hdr sdpcm;
  uint8_t pad[2];
  struct bdc_hdr bdc;
};

// gSPI, CYW43439 DS 4.2.1 Fig.12, 2-bit field
#define CYW_SPID_FUNC_BUS 0   // F0
#define CYW_SPID_FUNC_CHIP 1  // F1
#define CYW_SPID_FUNC_WLAN 2  // F2

// SDIO functions, 3-bit field; CYW4343W and CYW43439 DS 4.1
#define CYW_SDIO_FUNC_BUS 0   // F0
#define CYW_SDIO_FUNC_CHIP 1  // F1
#define CYW_SDIO_FUNC_WLAN 2  // F2

#define CYW_SDPCM_CTRL_HDR 0
#define CYW_SDPCM_ASYNC_HDR 1
#define CYW_SDPCM_DATA_HDR 2

#pragma pack(pop)

static uint8_t s_tx_seqno;
static uint32_t txdata[2048 / 4], resp[2048 / 4];

static void cyw_handle_cdc(struct cdc_hdr *cdc, size_t len);
static void cyw_handle_bdc(struct bdc_hdr *bdc, size_t len);
static void cyw_handle_bdc_evnt(struct bdc_hdr *bdc, size_t len);

static size_t cyw_bus_specific_poll(uint32_t *dest);
static void cyw_update_hash_table(void);

// High-level comm stuff

static void cyw_poll(void) {
  struct sdpcm_hdr *sdpcm = (struct sdpcm_hdr *) resp;
  unsigned int channel;
  if (s_ifp->update_mac_hash_table) {
    // first call to _poll() is after _init(), so this is safe
    cyw_update_hash_table();
    s_ifp->update_mac_hash_table = false;
  }
  if (cyw_bus_specific_poll(resp) == 0) return;
  if ((sdpcm->len ^ sdpcm->_len) != 0xffff || sdpcm->len < sizeof(*sdpcm) ||
      sdpcm->len > 2048 - sizeof(*sdpcm))
    return;
  channel = sdpcm->sw_hdr.channel_and_flags & 0x0F;
  if (channel == CYW_SDPCM_CTRL_HDR) {
    if (sdpcm->len >= sizeof(*sdpcm) + sizeof(struct cdc_hdr)) {
      struct cdc_hdr *cdc =
          (struct cdc_hdr *) ((size_t) sdpcm + sdpcm->sw_hdr.header_length);
      size_t len = sdpcm->len - sdpcm->sw_hdr.header_length;
      cyw_handle_cdc(cdc, len);
    }
  } else if (channel == CYW_SDPCM_DATA_HDR) {
    if (sdpcm->len >= sizeof(*sdpcm) + sizeof(struct bdc_hdr)) {
      struct bdc_hdr *bdc =
          (struct bdc_hdr *) ((size_t) sdpcm + sdpcm->sw_hdr.header_length);
      size_t len = sdpcm->len - sdpcm->sw_hdr.header_length;
      cyw_handle_bdc(bdc, len);
    }
  } else if (channel == CYW_SDPCM_ASYNC_HDR) {
    struct bdc_hdr *bdc =
        (struct bdc_hdr *) ((size_t) sdpcm + sdpcm->sw_hdr.header_length);
    size_t len_ = sdpcm->len - sdpcm->sw_hdr.header_length;
    cyw_handle_bdc_evnt(bdc, len_);
  }  // else silently discard
}

// WLAN frame reception
static void cyw_handle_bdc(struct bdc_hdr *bdc, size_t len) {
  uint8_t *payload = (uint8_t *) &bdc[bdc->data_offset + 1];
  mg_tcpip_qwrite(payload, len - (payload - (uint8_t *) bdc), s_ifp);
}

static size_t cyw_bus_specific_tx(uint32_t *data, uint16_t len);

// WLAN frame transmission
static size_t mg_cyw_tx(unsigned int ifc, void *data, size_t len) {
  struct data_hdr *hdr = (struct data_hdr *) txdata;
  uint16_t txlen = (uint16_t) (len + sizeof(*hdr));
  memset(txdata, 0, sizeof(*hdr));
  memcpy((uint8_t *) txdata + sizeof(*hdr), data, len);
  // TODO(): hdr->bdc.priority = map IP to TOS if supporting QoS/ToS
  hdr->bdc.flags = 2 << 4;          // BDC version 2
  hdr->bdc.flags2 = (uint8_t) ifc;  // 0 -> STA, 1 -> AP
  // hdr->bdc.data_offset = 0; // actually zeroed above
  hdr->sdpcm.len = txlen;
  hdr->sdpcm._len = (uint16_t) ~txlen;
  hdr->sdpcm.sw_hdr.sequence = ++s_tx_seqno;
  hdr->sdpcm.sw_hdr.channel_and_flags = CYW_SDPCM_DATA_HDR,
  hdr->sdpcm.sw_hdr.header_length = offsetof(struct data_hdr, bdc);
  return cyw_bus_specific_tx(txdata, txlen);
}

// WLAN event handling
#pragma pack(push, 1)
// all in network order

struct eth_hdr {  // TODO(scaprile) reuse 'eth' in net_builtin.c
  uint8_t dest[6];
  uint8_t src[6];
  uint16_t type;
};

struct bcm_vendor_hdr {
  uint16_t subtype;  // vendor specific: 0x8001
  uint16_t length;   // bytes following this field
  uint8_t version;   // 0
  uint8_t oui[3];    // vendor specific: 0x00 0x10 0x18
  uint16_t usr_subtype;
};

struct bcm_evnt_hdr {
  uint16_t version;  // 1: fields up to ifname; 2: as shown
  uint16_t flags;
  uint32_t event_type;
  uint32_t status;
  uint32_t reason;
  uint32_t auth_type;
  uint32_t datalen;
  uint8_t addr[6];  // Station address (if applicable)
  char ifname[16];
  uint8_t ifidx;
  uint8_t bss_cfg_idx;
};

struct evnt_msg {
  struct eth_hdr eth;
  //  struct vendor_hdr; but we only handle Broadcom (Wi-Fi processor) events
  struct bcm_vendor_hdr bcm;
  struct bcm_evnt_hdr event;
};

#pragma pack(pop)

struct scan_result;
static void cyw_handle_scan_result(uint32_t status, struct scan_result *data,
                                   size_t len);

// Do not call any IOCTL functions here, otherwise revise cyw_ioctl_wait()
static void cyw_handle_bdc_evnt(struct bdc_hdr *bdc, size_t len) {
  struct evnt_msg *msg = (struct evnt_msg *) &bdc[bdc->data_offset + 1];
  MG_VERBOSE(("%u bytes event", len));
  if (mg_log_level >= MG_LL_VERBOSE) mg_hexdump((void *) bdc, len);
  if (mg_ntohs(msg->eth.type) != 0x886C || msg->bcm.oui[0] != 0x00 ||
      msg->bcm.oui[1] != 0x10 || msg->bcm.oui[2] != 0x18)
    return;  // discard if not Broadcom
  if (mg_ntohl(msg->event.datalen) <=
      len - ((uint8_t *) msg - (uint8_t *) bdc)) {
    uint32_t event_type = mg_ntohl(msg->event.event_type);
    uint32_t status = mg_ntohl(msg->event.status);
    uint32_t reason = mg_ntohl(msg->event.reason);
    uint16_t flags = mg_ntohs(msg->event.flags);
    MG_VERBOSE(("BCM evt %lu %lu %lu %p", event_type, status, reason, flags));
    if (event_type == 16 && status == 0) {  // Link
      s_link = flags & 1;
    } else if (event_type == 46 && s_link) {  // PSK sup with link up
      if (status == 6) {                      // Keyed
      } else if ((status == 4 || status == 8 || status == 10) &&
                 reason == 15) {  // Wait M1/M3/G1
        MG_ERROR(("AUTH TIMEOUT"));
        s_auth = false;
      } else {
        MG_ERROR(("AUTH FAILED"));
        s_auth = false;
      }
    } else if (event_type == 3 && status != 6) {  // Auth (not unsolicited)
      if (status == 0) {                          // Success
        s_auth = true;
      } else {
        MG_ERROR(("AUTH TIMEOUT"));
        s_auth = false;
      }
    } else if (event_type == 1) {  // Join
      if (status == 0) {           // Success
        s_join = true;
      } else {
        MG_ERROR(("%s", status == 3 /* No networks */ ? "SSID NOT FOUND"
                                                      : "JOIN FAILED"));
        s_join = false;
        mg_tcpip_call(s_ifp, MG_TCPIP_EV_WIFI_CONNECT_ERR, &status);
      }
    } else if (event_type == 12 || event_type == 5) {  // Disassoc, Deauth
      s_auth = false;
    } else if (event_type == 69) {  // Scan result
      struct scan_result *data = (struct scan_result *) (&msg->event + 1);
      size_t dlen = mg_ntohl(msg->event.datalen);
      if (dlen > len - ((uint8_t *) data - (uint8_t *) bdc)) return;
      cyw_handle_scan_result(status, data, dlen);
    }
  }  // else silently discard
}

static bool cyw_ioctl_get_(unsigned int ifc, unsigned int cmd, void *data,
                           size_t len);
static bool cyw_ioctl_set_(unsigned int ifc, unsigned int cmd, void *data,
                           size_t len);
static bool cyw_ioctl_iovar_get_(unsigned int ifc, char *var, void *data,
                                 size_t len);
static bool cyw_ioctl_iovar_set_(unsigned int ifc, char *var, void *data,
                                 size_t len);
// clang-format off
// convenience: ioctl funcs on default ifc (0), as only AP needs ifc 1
__attribute__((unused)) static bool cyw_ioctl_get(unsigned int cmd, void *data, size_t len) { return cyw_ioctl_get_(0, cmd, data, len); }
static bool cyw_ioctl_set(unsigned int cmd, void *data, size_t len) { return cyw_ioctl_set_(0, cmd, data, len); }
static bool cyw_ioctl_iovar_get(char *var, void *data, size_t len) { return cyw_ioctl_iovar_get_(0, var, data, len); }
static bool cyw_ioctl_iovar_set(char *var, void *data, size_t len) { return cyw_ioctl_iovar_set_(0, var, data, len); }
// clang-format on

// Wi-Fi network stuff

// clang-format off
static bool cyw_wifi_connect(char *ssid, char *pass) {
  uint32_t sup_wpa[2] = {0, 1}; // bss index 0 = STA, not open
  static const uint32_t eapver[2] = {0, (uint32_t) -1}, // accept AP version
                              tmo[2] = {0, 2500};
  uint32_t data[64/4 + 1]; // max pass length: 64 for WPA, 128 for WPA3 SAE
  uint16_t *da = (uint16_t *) data;
  unsigned int len;
  uint32_t val;
  val = 4; // security type: 0 for none, 2 for WPA, 4 for WPA2/WPA3, 6 for mixed WPA/WPA2
  // sup_wpa[1] = 0 if not using security
  if (!(cyw_ioctl_set(134 /* SET_WSEC */, (uint8_t *)&val, sizeof(val))
        && cyw_ioctl_iovar_set("bsscfg:sup_wpa", (void *)sup_wpa, sizeof(sup_wpa))
        && cyw_ioctl_iovar_set("bsscfg:sup_wpa2_eapver", (void *)eapver, sizeof(eapver))
        && cyw_ioctl_iovar_set("bsscfg:sup_wpa_tmo", (void *)tmo, sizeof(tmo)))
     ) return false;
  mg_delayms(2); // allow radio firmware to be ready
  // skip if not using auth
  memset(data, 0, sizeof(data));
  len = strlen(pass);
  da[0] = (uint16_t) len;
  da[1] = 1; // indicates wireless security key, skip for WPA3 SAE
  memcpy((uint8_t *)data + 2 * sizeof(uint16_t), pass, len); // skip for WPA3 SAE
  if (!cyw_ioctl_set(268 /* SET_WSEC_PMK */, data, sizeof(data))) return false; // skip for WPA3 SAE, sizeof/2 if supporting SAE but using WPA
  // for WPA3 SAE: memcpy((uint8_t *)data + sizeof(uint16_t), pass, len); cyw_ioctl_iovar_set("sae_password", data, sizeof(data));
  // resume if not using auth
  val = 1; if (!cyw_ioctl_set(20 /* SET_INFRA */, (uint8_t *)&val, sizeof(val))) return false;
  val = 0; // auth type: 0 for open, 3 for SAE
  if (!cyw_ioctl_set(22 /* SET_AUTH */, (uint8_t *)&val, sizeof(val))) return false;
  val = 1; // MFP capable: 1 for yes, 0 for no; recommended to be set for WPA2+ (2 for 'required', WPA3)
  cyw_ioctl_iovar_set("mfp", (uint8_t *)&val, sizeof(val)); // Old chipsets do not support MFP
  val = 0x80; // auth type: 0 for none, 4 for WPA PSK, 0x80 for WPA2 PSK, 0x40000 for WPA3 SAE PSK
  if (!cyw_ioctl_set(165 /* SET_WPA_AUTH */, (uint8_t *)&val, sizeof(val))) return false;
  len = strlen(ssid);
  data[0] = (uint32_t) len;
  memcpy((uint8_t *)&data[1], ssid, len);
  if (!cyw_ioctl_set(26 /* SET_SSID */, data, len + sizeof(uint32_t))) return false;
  return true;
}

static bool cyw_wifi_disconnect(void) {
  return cyw_ioctl_set(52 /* DISASSOC */, NULL, 0);
}

// For AP functions, we use explicit ifc selection; both for clarity and maintenance, as some actions are performed on ifc 0, with or without a bss_index, and others are performed on ifc 1

static bool cyw_wifi_ap_start(char *ssid, char *pass, unsigned int channel) {
  uint32_t data[64/4 + 2]; // max pass length: 64 for WPA, 128 for WPA3 SAE
  uint16_t *da = (uint16_t *) data;
  unsigned int len;
  uint32_t val;
  // CHIP DEPENDENCY
  // RPi set the AMPDU parameter for AP (window size = 2) *****************
  // val = 2 ; cyw_ioctl_iovar_set_(0, "ampdu_ba_wsize", (uint8_t *)&val, sizeof(val));
  // some chips might require to turn APSTA off and issue a SET_AP IOCTL
  len = strlen(ssid);
  data[0] = 1; // bss index 1 = AP
  data[1] = (uint32_t) len;
  memcpy((uint8_t *)&data[2], ssid, len);
  // TODO(scaprile): this takes some time to process, or requires a delay before doing it
  if (!cyw_ioctl_iovar_set_(0, "bsscfg:ssid", (uint8_t *)&data, len + 2 * sizeof(uint32_t))) return false;
  // TODO(scaprile): but sometimes this one takes some time to process
  val = (uint32_t) channel; if (!cyw_ioctl_set_(0, 30 /* SET_CHANNEL */, (uint8_t *)&val, sizeof(val))) return false;
  data[0] = 1; // bss index 1 = AP
  data[1] = 0x00400004; // security type: 0 for none, 0x00200002 for WPA, 0x00400004 for WPA2, 0x01000004 for WPA3, 0x01400004 for mixed WPA2/WPA3, 0x00400006 for mixed WPA/WPA2
  // NOTE(): WHD writes & 0xFF if WPS is not enabled (?)
  if (!cyw_ioctl_iovar_set_(0, "bsscfg:wsec", (uint8_t *)&data, 2 * sizeof(uint32_t))) return false;
  val = 1; // MFP capable: 1 for yes, 0 for no; recommended to be set for WPA2+ (2 for 'required', WPA3)
  cyw_ioctl_iovar_set_(1, "mfp", (uint8_t *)&val, sizeof(val)); // Old chipsets do not support MFP
  mg_delayms(2); // allow radio firmware to be ready
  // skip if not using auth
  // WPA, WPA2, mixed WPA/WPA2, mixed WPA2/WPA3
  // NOTE(): WHD does not set SAE password for shared WPA2/WPA3, same do we
  memset(data, 0, sizeof(data));
  len = strlen(pass);
  da[0] = (uint16_t) len; // skip for WPA3 SAE (43430 does NOT support WPA3 in AP)
  da[1] = 1; // indicates wireless security key, skip for WPA3 SAE
  memcpy((uint8_t *)data + 2 * sizeof(uint16_t), pass, len); // skip for WPA3 SAE
  if (!cyw_ioctl_set_(1, 268 /* SET_WSEC_PMK */, data, sizeof(data))) return false; // skip for WPA3 SAE, sizeof/2 if supporting SAE but using WPA
  /* for WPA3 SAE:
    memcpy((uint8_t *)data + sizeof(uint16_t), pass, len);
    cyw_ioctl_iovar_set_(1, "sae_password", data, sizeof(data)); */
  /* for WPA3 or mixed WPA2/WPA3:
    val = 5 ; cyw_ioctl_iovar_set_(1, "sae_max_pwe_loop", (uint8_t *)&val, sizeof(val));  // Some chipsets do not support this */
  // resume if not using auth

  data[0] = 1; // bss index 1 = AP
  data[1] = 0x80; // auth type: 0 for none, 4 for WPA PSK, 0x80 for WPA2 PSK, 0x40000 for WPA3 SAE PSK; ored if mixed
  if (!cyw_ioctl_iovar_set_(0, "bsscfg:wpa_auth", (uint8_t *)&data, 2 * sizeof(uint32_t))) return false;

  val = 1 /* auto */; if (!cyw_ioctl_set_(1, 110 /* SET_GMODE */, (uint8_t *)&val, sizeof(val))) return false;
  // Set multicast tx rate to 11Mbps, may fail in some chipsets, we are enforcing it
  val = 11000000 / 500000; if (!cyw_ioctl_iovar_set_(1, "2g_mrate", (uint8_t *)&val, sizeof(val))) return false;
  val = 1; if (!cyw_ioctl_set_(1, 78 /* SET_DTIMPRD */, (uint8_t *)&val, sizeof(val))) return false;
  data[0] = 1; // bss index 1 = AP
  data[1] = 1; // UP
  // TODO(scaprile): this takes a long time to process
  if (!cyw_ioctl_iovar_set_(0, "bss", (uint8_t *)&data, 2 * sizeof(uint32_t))) return false;
  return true;
}

static bool cyw_wifi_ap_stop(void) {
  uint32_t data[2];
  data[0] = 1; // bss index 1 = AP
  data[1] = 0; // DOWN
  if (!cyw_ioctl_iovar_set_(0, "bss", (uint8_t *)&data, 2 * sizeof(uint32_t))) return false;
  // DO WE NEED TO CLEAR CHANNEL ???
  // CHIP DEPENDENCY
  //val = 8 ; cyw_ioctl_iovar_set_(0, "ampdu_ba_wsize", (uint8_t *)&val, sizeof(val));
  return true;
}

// WLAN scan handling

#pragma pack(push, 1)
// in little endian

struct wifi_scan_opt {
    uint32_t version;
    uint16_t action;
    uint16_t _;
    uint32_t ssid_len;
    uint8_t ssid[32];
    uint8_t bssid[6];
    int8_t bss_type;
    int8_t scan_type;
    int32_t nprobes;
    int32_t active_time;
    int32_t passive_time;
    int32_t home_time;
    int32_t channel_num;
    uint16_t channel_list[1];
};
#pragma pack(pop)

static bool cyw_wifi_scan(void) {
  struct wifi_scan_opt opts;
  memset(&opts, 0, sizeof(opts));
  opts.version = 1;
  opts.action = 1; // start
  opts._ = 0;
  memset(opts.bssid, 0xff, sizeof(opts.bssid));
  opts.bss_type = 2; // any
  opts.nprobes = -1;
  opts.active_time = -1;
  opts.passive_time = -1;
  opts.home_time = -1;
  opts.channel_num = 0;
  opts.channel_list[0] = 0;
  return cyw_ioctl_iovar_set("escan", (uint8_t *)&opts, sizeof(opts));
}


#pragma pack(push, 1)
// in little endian

struct scan_bss {
    uint32_t version;              // version field
    uint32_t length;               // byte length of data in this record, starting at version and including IEs
    uint8_t BSSID[6];              // Unique 6-byte MAC address
    uint16_t beacon_period;        // Interval between two consecutive beacon frames. Units are Kusec
    uint16_t capability;           // Capability information
    uint8_t SSID_len;              // SSID length
    uint8_t SSID[32];              // Array to store SSID
    uint8_t reserved1[1];          // Reserved(padding)
    uint32_t rateset_count;        // Count of rates in this set
    uint8_t rateset_rates[16];     // rates in 500kbps units, higher bit set if basic
    uint16_t chanspec;             // Channel specification for basic service set
    uint16_t atim_window;          // Announcement traffic indication message window size. Units are Kusec
    uint8_t dtim_period;           // Delivery traffic indication message period
    uint8_t reserved2[1];          // Reserved(padding)
    int16_t RSSI;                  // receive signal strength (in dBm)
    int8_t phy_noise;              // noise (in dBm)
    uint8_t n_cap;                 // BSS is 802.11n Capable
    uint8_t reserved3[2];          // Reserved(padding)
    uint32_t nbss_cap;             // 802.11n BSS Capabilities (based on HT_CAP_*)
    uint8_t ctl_ch;                // 802.11n BSS control channel number
    uint8_t reserved4[3];          // Reserved(padding)
    uint32_t reserved32[1];        // Reserved for expansion of BSS properties
    uint8_t flags;                 // flags
    uint8_t vht_cap;               // BSS is vht capable
    uint8_t reserved5[2];          // Reserved(padding)
    uint8_t basic_mcs[16];         // 802.11N BSS required MCS set
    uint16_t ie_offset;            // offset at which IEs start, from beginning
    uint16_t reserved16[1];        // Reserved(padding)
    uint32_t ie_length;            // byte length of Information Elements
    int16_t SNR;                   // Average SNR during frame reception
};

struct scan_result {
    uint32_t buflen;
    uint32_t version;
    uint16_t sync_id;
    uint16_t bss_count;
    struct scan_bss bss[1];
};

#pragma pack(pop)

// CHIP DEPENDENCY
#define CYW_BSS_BANDMASK 0xc000
#define CYW_BSS_BAND2G 0
//

static void cyw_handle_scan_result(uint32_t status, struct scan_result *data, size_t len) {
  MG_VERBOSE(("scan event, status: %ld", status));
  if (status == 0) { // SUCCESS
    MG_VERBOSE(("scan complete"));
    mg_tcpip_call(s_ifp, MG_TCPIP_EV_WIFI_SCAN_END, NULL);
  } else if (status == 8) { // PARTIAL
    struct mg_wifi_scan_bss_data bss;
    struct scan_bss *sbss = data->bss;
    unsigned int band = sbss->chanspec & CYW_BSS_BANDMASK;
    if (data->version != 109 || data->bss_count != 1) {
      MG_ERROR(("Unsupported: %lu %u", data->version, data->bss_count));
      return;
    }
    if (sbss->length > len - offsetof(struct scan_result, bss) || sbss->SSID_len > sizeof(sbss->SSID) || sbss->ie_offset < sizeof(*sbss) || sbss->ie_offset > (sizeof(*sbss) + sbss->ie_length) || sbss->ie_offset + sbss->ie_length > sbss->length)
      return; // silently discard malformed data
    if (!(sbss->flags & MG_BIT(2))) return; // RSSI_ONCHANNEL, ignore off-channel results
    bss.SSID = mg_str_n((char *)sbss->SSID, sbss->SSID_len);
    bss.BSSID = (char *)sbss->BSSID;
    bss.RSSI = (int8_t)sbss->RSSI;
    bss.has_n = sbss->n_cap != 0;
    bss.channel = bss.has_n ? sbss->ctl_ch : (uint8_t)(sbss->chanspec & 0xff); // n 40MHz vs a/b/g and 20MHz
    bss.band = band & CYW_BSS_BAND2G ? MG_WIFI_BAND_2G : MG_WIFI_BAND_5G;
    bss.security = (sbss->capability & MG_BIT(4) /* CAP_PRIVACY */) ? MG_WIFI_SECURITY_WEP : MG_WIFI_SECURITY_OPEN;
    { // travel IEs (Information Elements) in search of security definitions
      const uint8_t wot1[4] = {0x00, 0x50, 0xf2, 0x01}; // WPA_OUI_TYPE1
      uint8_t *ie = (uint8_t *)sbss + sbss->ie_offset;
      int bytes = (int) sbss->ie_length;
      while (bytes > 0 && ie[1] + 2 < bytes) { // ie[0] -> type, ie[1] -> bytes from ie[2]
        if (ie[0] == 48 /* IE_ID_RSN */) bss.security |= MG_WIFI_SECURITY_WPA2;
        if (ie[0] == 221 /* IE_ID_VENDOR_SPECIFIC */ && memcmp(&ie[2], wot1, 4) == 0)
          bss.security |= MG_WIFI_SECURITY_WPA;
        ie += ie[1] + 2;
        bytes -= ie[1] + 2;
      }
    }
    MG_VERBOSE(("BSS: %.*s (%u) (%M) %d dBm %u", bss.SSID.len, bss.SSID.buf, bss.channel, mg_print_mac, bss.BSSID, (int) bss.RSSI, bss.security));
    mg_tcpip_call(s_ifp, MG_TCPIP_EV_WIFI_SCAN_RESULT, &bss);
  } else {
    MG_ERROR(("scan error"));
  }
}
// clang-format on

// IOCTL stuff. All values read and written are in little endian format

static uint16_t s_ioctl_reqid;

// CDC handler for waiting loop
static uint8_t *s_ioctl_resp;
static bool s_ioctl_err;

static void cyw_handle_cdc(struct cdc_hdr *cdc, size_t len) {
  uint8_t *r = (uint8_t *) cdc + sizeof(*cdc);
  MG_VERBOSE(("%u bytes CDC frame", len));
  if ((cdc->flags >> 16) != s_ioctl_reqid) return;
  if (cdc->flags & 1) {
    MG_ERROR(("IOCTL error: %ld", -cdc->status));
    s_ioctl_err = true;
    return;
  }
  if (mg_log_level >= MG_LL_VERBOSE) mg_hexdump((void *) cdc, len);
  MG_VERBOSE(("IOCTL result: %02x %02x %02x %02x ..", r[0], r[1], r[2], r[3]));
  s_ioctl_resp = r;
}
// NOTE(): alt no loop handler dispatching IOCTL response to current handler:
// static void *s_ioctl_hnd; *s_ioctl_hnd(ioctl, len);
// app is a state machine calling get/sets and advancing via these callbacks

#pragma pack(push, 1)
// all little endian

struct ctrl_hdr {
  struct sdpcm_hdr sdpcm;
  struct cdc_hdr cdc;
};

#pragma pack(pop)

// IOCTL command send
static void cyw_ioctl_send_cmd(unsigned int ifc, unsigned int cmd, bool set,
                               size_t len) {
  struct ctrl_hdr *hdr = (struct ctrl_hdr *) txdata;
  uint16_t txlen = (uint16_t) (len + sizeof(*hdr));
  memset(txdata, 0, sizeof(*hdr));
  hdr->cdc.cmd = cmd;
  hdr->cdc.olen = (uint16_t) len;
  // hdr->cdc.ilen = 0; // actually zeroed above
  hdr->cdc.flags = ((uint32_t) ++s_ioctl_reqid << 16) | ((ifc & 0xf) << 12) |
                   (set ? MG_BIT(1) : 0);
  hdr->sdpcm.len = txlen;
  hdr->sdpcm._len = (uint16_t) ~txlen;
  hdr->sdpcm.sw_hdr.sequence = ++s_tx_seqno;
  hdr->sdpcm.sw_hdr.channel_and_flags = CYW_SDPCM_CTRL_HDR;
  hdr->sdpcm.sw_hdr.header_length = offsetof(struct ctrl_hdr, cdc);
  cyw_bus_specific_tx(txdata, txlen);
}

// just send respective commands, response handled via CDC handler
static void cyw_ioctl_send_get(unsigned int ifc, unsigned int cmd) {
  cyw_ioctl_send_cmd(ifc, cmd, false, 0);
}

static void cyw_ioctl_send_set(unsigned int ifc, unsigned int cmd, void *data,
                               size_t len) {
  if (data != NULL && len > 0)
    memcpy((uint8_t *) txdata + sizeof(struct ctrl_hdr), data, len);
  cyw_ioctl_send_cmd(ifc, cmd, true, (uint16_t) len);
}

static void cyw_ioctl_send_iovar_get(unsigned int ifc, char *var, size_t len) {
  unsigned int namelen = strlen(var) + 1;  // include '\0'
  // cmd = GET IOVAR, "set" the name...
  cyw_ioctl_send_set(ifc, 262, var, len > namelen ? len : namelen);
}

static void cyw_ioctl_send_iovar_set2(unsigned int ifc, char *var, void *data1,
                                      size_t len1, void *data2, size_t len2) {
  struct ctrl_hdr *hdr = (struct ctrl_hdr *) txdata;
  unsigned int namelen = strlen(var) + 1;  // include '\0'
  uint16_t txlen, payload_len = (uint16_t) (namelen + len1 + len2);
  memcpy((uint8_t *) txdata + sizeof(*hdr), var, namelen);
  memcpy((uint8_t *) txdata + namelen + sizeof(*hdr), data1, len1);
  if (data2 != NULL)
    memcpy((uint8_t *) txdata + namelen + sizeof(*hdr) + len1, data2, len2);
  txlen = (uint16_t) (payload_len + sizeof(*hdr));
  cyw_ioctl_send_cmd(ifc, 263, true, txlen);  // cmd = SET IOVAR
}

__attribute__((unused)) static void cyw_ioctl_send_iovar_set(unsigned int ifc,
                                                             char *var,
                                                             void *data,
                                                             size_t len) {
  cyw_ioctl_send_iovar_set2(ifc, var, data, len, NULL, 0);
}

static inline bool delayms(unsigned int ms) {
  mg_delayms(ms);
  return true;
}

// wait for a response, meanwhile delivering received frames and events
static bool cyw_ioctl_wait(void) {
  unsigned int times = 100;
  s_ioctl_resp = NULL;
  s_ioctl_err = false;
  do {  // IOCTL response processing does not call any other IOCTL function
    cyw_poll();  // otherwise we can't allow them to pile up here
    // network frames will be pushed to the queue so that is safe
  } while (s_ioctl_resp == NULL && !s_ioctl_err && times-- > 0 && delayms(1));
  MG_VERBOSE(("resp: %lp, err: %c, times: %d", s_ioctl_resp,
              s_ioctl_err ? '1' : '0', (int) times));
  return s_ioctl_resp != NULL;
}

static bool cyw_ioctl_waitdata(void *data, size_t len) {
  if (!cyw_ioctl_wait()) return false;
  memcpy(data, s_ioctl_resp, len);
  return true;
}

// send respective commands, wait for a response or timeout
static bool cyw_ioctl_get_(unsigned int ifc, unsigned int cmd, void *data,
                           size_t len) {
  cyw_ioctl_send_get(ifc, cmd);
  return cyw_ioctl_waitdata(data, len);
}
static bool cyw_ioctl_set_(unsigned int ifc, unsigned int cmd, void *data,
                           size_t len) {
  cyw_ioctl_send_set(ifc, cmd, data, len);
  return cyw_ioctl_wait();
}

static bool cyw_ioctl_iovar_get_(unsigned int ifc, char *var, void *data,
                                 size_t len) {
  cyw_ioctl_send_iovar_get(ifc, var, len);
  return cyw_ioctl_waitdata(data, len);
}
static bool cyw_ioctl_iovar_set2_(unsigned int ifc, char *var, void *data1,
                                  size_t len1, void *data2, size_t len2) {
  cyw_ioctl_send_iovar_set2(ifc, var, data1, len1, data2, len2);
  return cyw_ioctl_wait();
}
static bool cyw_ioctl_iovar_set_(unsigned int ifc, char *var, void *data,
                                 size_t len) {
  return cyw_ioctl_iovar_set2_(ifc, var, data, len, NULL, 0);
}

// CYW43 chipset specifics. All values read and written are in little endian
// format

#pragma pack(push, 1)
// all little endian

struct cyw_country {
  uint32_t a;
  int32_t rev;
  uint32_t c;
};

struct clm_hdr {
  uint16_t flag;
  uint16_t type;
  uint32_t len;
  uint32_t crc;
};

#pragma pack(pop)

// worlwide rev0, TODO(): try rev 17 for 4343W
static const uint32_t country_code = 'X' + ('X' << 8) + (0 << 16);

static bool cyw_bus_specific_init();
static bool cyw_load_clmll(void *data, size_t len);

static bool cyw_load_clm(struct mg_tcpip_driver_cyw_firmware *fw) {
  return cyw_load_clmll((void *) fw->clm_addr, fw->clm_len);
}

// clang-format off
static bool cyw_init(uint8_t *mac) {
  struct mg_tcpip_driver_cyw_data *d = (struct mg_tcpip_driver_cyw_data *) s_ifp->driver_data;
  uint32_t val = 0;
  if (!cyw_bus_specific_init()) return false;
  if (!cyw_load_clm(d->fw)) return false;  // Load CLM blob
  // BT-ENABLED DEPENDENCY
  // set Wi-Fi up
  val = 0 /* disable */; cyw_ioctl_iovar_set("bus:txglom", (uint8_t *)&val, sizeof(val));
  val = 1 /* on */; cyw_ioctl_iovar_set("apsta", (uint8_t *)&val, sizeof(val));
  // CHIP DEPENDENCY
  val = 8 ; cyw_ioctl_iovar_set("ampdu_ba_wsize", (uint8_t *)&val, sizeof(val));
  val = 4 ; cyw_ioctl_iovar_set("ampdu_mpdu", (uint8_t *)&val, sizeof(val));
  val = 0 /* 8K */; cyw_ioctl_iovar_set("ampdu_rx_factor", (uint8_t *)&val, sizeof(val));
  //
  {
    struct cyw_country c;
    unsigned int rev = (unsigned int) (country_code >> 16) & 0xffff;
    c.c = c.a = country_code & 0xffff;
    c.rev = rev == 0 ? -1 : (int32_t) rev; // if rev is 0, set it to -1, the chip will use any NVRAM/OTP configured aggregate or default to rev 0
    cyw_ioctl_iovar_set("country", (void *)&c, sizeof(c));
  } // this takes some time to process
  { // so do some retries while enabling events of interest
    // we care for SET_SSID(0), JOIN(1), AUTH(3), DEAUTH(5), DISASSOC_IND(12), LINK(16), PSK_SUP(46), SCAN_RESULT(69); all < 128
    uint32_t data[128/8/4 + 1];
    data[0] = 0; // bss index: 0 = STA
    memset(&data[1], 0, 128/8); // mark all as not desired
    data[1] = MG_BIT(0) | MG_BIT(1) | MG_BIT(3) | MG_BIT(5) | MG_BIT(12) | MG_BIT(16); // events 0 to 31
    data[2] = MG_BIT(46 - 32); // events 32 to 63
    data[3] = MG_BIT(69 - 64); // events 64 to 95
    unsigned int times = 100;
    while (times --)
      if (cyw_ioctl_iovar_set("bsscfg:event_msgs", (uint8_t *)data, sizeof(data))) break;
    if (times == (unsigned int) ~0) return false;
  }
  val = 0; if (!cyw_ioctl_set(64 /* SET_ANTDIV */, (uint8_t *)&val, sizeof(val))) return false;
  if (!cyw_ioctl_set(2 /* UP, interface up */, NULL, 0)) return false;
  // use PM2 power saving for max throughput
  val = 200 /* ms */; if (!cyw_ioctl_iovar_set("pm2_sleep_ret", (uint8_t *)&val, sizeof(val))) return false;
  // set beacon intervals to reduce power consumption while associated to an AP but idle
  val = 1; if (!cyw_ioctl_iovar_set("bcn_li_bcn", (uint8_t *)&val, sizeof(val))) return false;
  val = 1; if (!cyw_ioctl_iovar_set("bcn_li_dtim", (uint8_t *)&val, sizeof(val))) return false;
  val = 10; if (!cyw_ioctl_iovar_set("assoc_listen", (uint8_t *)&val, sizeof(val))) return false;
  val = 1 /* auto */; if (!cyw_ioctl_set(110 /* SET_GMODE */, (uint8_t *)&val, sizeof(val))) return false;
  val = 0 /* any */; if (!cyw_ioctl_set(142 /* SET_BAND */, (uint8_t *)&val, sizeof(val))) return false;
  if (mg_log_level >= MG_LL_DEBUG) {
    char text[256]; // this is huge, but we're just starting up
    if (cyw_ioctl_iovar_get("ver", (uint8_t *)text, sizeof(text))) {
      unsigned int len = strnlen(text, sizeof(text));
      MG_DEBUG(("Firmware:\n%.*s", len, text));
    }
    text[0] = '\0';
    if (cyw_ioctl_iovar_get("clmver", (uint8_t *)text, sizeof(text)) && text[0] != '\0') {
      unsigned int len = strnlen(text, sizeof(text));
      MG_DEBUG(("CLM:\n%.*s", len, text));
    }
  }
  {
    if(cyw_ioctl_iovar_get("cur_etheraddr", mac, 6)) {
      MG_DEBUG(("MAC: %M", mg_print_mac, mac));
    } else {
      MG_ERROR(("read MAC failed"));
    }
  }
  return true;
}
// clang-format on

static bool cyw_load_fwll(void *fwdata, size_t fwlen, void *nvramdata,
                          size_t nvramlen);

static bool cyw_load_firmware(struct mg_tcpip_driver_cyw_firmware *fw) {
  return cyw_load_fwll((void *) fw->code_addr, fw->code_len,
                       (void *) fw->nvram_addr, fw->nvram_len);
}

// clang-format off
static bool cyw_load_clmll(void *data, size_t len) {
  unsigned int sent = 0, offset = 0;
  struct clm_hdr hdr = {
      .flag = 1 << 12 /* DLOAD_HANDLER_VER */ | MG_BIT(1) /* DL_BEGIN */,
      .type = 2,
      .crc = 0};
  while (sent < len) {
    unsigned int bytes = len - sent;
    if (bytes > 1024) bytes = 1024;
    if (sent + bytes >= len) hdr.flag |= MG_BIT(2);  // DL_END;
    hdr.len = bytes;
    if (!cyw_ioctl_iovar_set2_(0, "clmload", (void *) &hdr, sizeof(hdr), (uint8_t *) data + offset, bytes))
      break;
    sent += bytes;
    offset += bytes;
    hdr.flag &= (uint16_t)~MG_BIT(1);  // DL_BEGIN
  }
  return sent >= len;
}
// clang-format on

static void cyw_update_hash_table(void) {
  // TODO(): read database, rebuild hash table
  uint32_t val = 0;
  val = 1;
  cyw_ioctl_iovar_set2_(0, "mcast_list", (uint8_t *) &val, sizeof(val),
                        (uint8_t *) mcast_addr, sizeof(mcast_addr));
  mg_delayms(50);
}

// CYW43 chip backplane specifics. All values read and written are in little
// endian format

// Access to chip backplane is done windowed in 32KB banks
// - addr = area base address + register offset
// - set the window address to addr & ~ADDRMSK
// - access addr & ADDRMSK for non-32-bit quantities
// - if accesing 32-bit quantities, do it on (addr & ADDRMSK) | ACCSS4B
#define CYW_CHIP_CHIPCOMMON 0x18000000
#define CYW_CHIP_BCKPLN_WINSZ 0x8000
#define CYW_CHIP_BCKPLN_ADDRMSK 0x7fff
#define CYW_CHIP_BCKPLN_ACCSS4B MG_BIT(15)
#define CYW_CHIP_BCKPLN_WRAPPOFF 0x100000
// BUS DEPENDENCY: max bus to backplane transfer size, bus function id
#define CYW_CHIP_BCKPLN_SPIMAX 64
#define CYW_CHIP_BCKPLN_SDIOMAX 1536
#if MG_ENABLE_DRIVER_CYW_SDIO
#define CYW_CHIP_BCKPLN_BUSMAX CYW_CHIP_BCKPLN_SDIOMAX
#define CYW_BUS_FUNC_CHIP CYW_SDIO_FUNC_CHIP
#else
#define CYW_CHIP_BCKPLN_BUSMAX CYW_CHIP_BCKPLN_SPIMAX
#define CYW_BUS_FUNC_CHIP CYW_SPID_FUNC_CHIP
#endif

// CHIP DEPENDENCY
#define CYW_CHIP_ARMCORE_BASE (CYW_CHIP_CHIPCOMMON + 0x3000)
#define CYW_CHIP_SOCSRAM_BASE (CYW_CHIP_CHIPCOMMON + 0x4000)
#define CYW_CHIP_ARMCORE (CYW_CHIP_ARMCORE_BASE + CYW_CHIP_BCKPLN_WRAPPOFF)
#define CYW_CHIP_SOCSRAM (CYW_CHIP_SOCSRAM_BASE + CYW_CHIP_BCKPLN_WRAPPOFF)
#define CYW_CHIP_ATCMRAM_BASE 0
#define CYW_CHIP_RAM_SIZE 0x80000
//

#define CYW_CHIP_ADDRLOW 0x1000a
#define CYW_CHIP_ADDRMID 0x1000b
#define CYW_CHIP_ADDRHIGH 0x1000c
#define CYW_CHIP_SPIFRCTRL 0x1000d
#define CYW_CHIP_CLOCKCSR 0x1000e
#define CYW_CHIP_PULLUP 0x1000f
#define CYW_CHIP_WAKEUPCTL 0x1001e
#define CYW_CHIP_SLEEPCSR 0x1001f

#define CYW_CHIP_SOCSRAM_BANKXIDX 0x010
#define CYW_CHIP_SOCSRAM_BANKXPDA 0x044
#define CYW_CHIP_AI_IOCTRL 0x408
#define CYW_CHIP_AI_RESETCTRL 0x800

static bool cyw_bus_write(unsigned int f, uint32_t addr, void *data,
                          uint16_t len);
static bool cyw_bus_read(unsigned int f, uint32_t addr, void *data,
                         uint16_t len);

// clang-format off
// set backplane window to requested area.
static void cyw_set_backplane_window(uint32_t addr) {
  uint32_t val;
  addr &= ~CYW_CHIP_BCKPLN_ADDRMSK;
  val = (addr >> 24) & 0xff; cyw_bus_write(CYW_BUS_FUNC_CHIP, CYW_CHIP_ADDRHIGH, &val, 1);
  val = (addr >> 16) & 0xff; cyw_bus_write(CYW_BUS_FUNC_CHIP, CYW_CHIP_ADDRMID, &val, 1);
  val = (addr >> 8) & 0xff; cyw_bus_write(CYW_BUS_FUNC_CHIP, CYW_CHIP_ADDRLOW, &val, 1);
}

static bool cyw_core_reset(uint32_t core_base, bool check) {
  uint32_t val = 0;
  // core disabled after chip reset
  cyw_set_backplane_window(core_base); // set backplane window for requested area; we do know offsets fall within that window
  // possible CHIP DEPENDENCY: AI_RESETSTATUS check and wait (instead of these cool reads) to ensure backplane operations end
  cyw_bus_read(CYW_BUS_FUNC_CHIP, (core_base + CYW_CHIP_AI_IOCTRL) & CYW_CHIP_BCKPLN_ADDRMSK, &val, 1); // ensure backplane operations end
  val = MG_BIT(1) | MG_BIT(0) /* SICF_FGC | SICF_CLOCK_EN */; cyw_bus_write(CYW_BUS_FUNC_CHIP, (core_base + CYW_CHIP_AI_IOCTRL) & CYW_CHIP_BCKPLN_ADDRMSK, &val, 1); // reset
  cyw_bus_read(CYW_BUS_FUNC_CHIP, (core_base + CYW_CHIP_AI_IOCTRL) & CYW_CHIP_BCKPLN_ADDRMSK, &val, 1); // ensure backplane operations end
  val = 0x00; cyw_bus_write(CYW_BUS_FUNC_CHIP, (core_base + CYW_CHIP_AI_RESETCTRL) & CYW_CHIP_BCKPLN_ADDRMSK, &val, 1); // release reset
  mg_delayms(1);
  val = MG_BIT(0) /* SICF_CLOCK_EN */; cyw_bus_write(CYW_BUS_FUNC_CHIP, (core_base + CYW_CHIP_AI_IOCTRL) & CYW_CHIP_BCKPLN_ADDRMSK, &val, 1);
  cyw_bus_read(CYW_BUS_FUNC_CHIP, (core_base + CYW_CHIP_AI_IOCTRL) & CYW_CHIP_BCKPLN_ADDRMSK, &val, 1); // ensure backplane operations end
  mg_delayms(1);

  if (check) {
    // Verify only clock is enabled
    cyw_bus_read(CYW_BUS_FUNC_CHIP, (core_base + CYW_CHIP_AI_IOCTRL) & CYW_CHIP_BCKPLN_ADDRMSK, &val, 1);
    if ((val & (MG_BIT(1) | MG_BIT(0)) /* SICF_FGC | SICF_CLOCK_EN) */) != MG_BIT(0)) return false;
    // Verify it is not in reset state
    cyw_bus_read(CYW_BUS_FUNC_CHIP, (core_base + CYW_CHIP_AI_RESETCTRL) & CYW_CHIP_BCKPLN_ADDRMSK, &val, 1);
    if (val & MG_BIT(0)) return false; // AIRC_RESET
  }
  return true;
}

static void cyw_socram_init(void) {
  uint32_t val;
  // CHIP DEPENDENCY: disable remap for SRAM_3: 43430 and 43439 only
  cyw_set_backplane_window(CYW_CHIP_SOCSRAM_BASE); // set backplane window for requested area; we do know offsets fall within that window
  val = 0x03; cyw_bus_write(CYW_BUS_FUNC_CHIP, ((CYW_CHIP_SOCSRAM_BASE + CYW_CHIP_SOCSRAM_BANKXIDX) & CYW_CHIP_BCKPLN_ADDRMSK), &val, sizeof(val));
  val = 0x00; cyw_bus_write(CYW_BUS_FUNC_CHIP, ((CYW_CHIP_SOCSRAM_BASE + CYW_CHIP_SOCSRAM_BANKXPDA) & CYW_CHIP_BCKPLN_ADDRMSK), &val, sizeof(val));
}

// transfer is fractioned in bus-to-backplane-size units within backplane windows
static void cyw_load_data(uint32_t dest, void *data, size_t len) {
  size_t sent = 0, offset = 0;
  uint32_t last_addr = (uint32_t) ~0;
  while (sent < len)  {
    size_t bytes = len - sent, avail;
    uint32_t addr = dest + offset;
    if (addr - last_addr >= CYW_CHIP_BCKPLN_WINSZ || last_addr == (uint32_t) ~0) {
      cyw_set_backplane_window(addr); // set backplane window for requested area
      last_addr = addr & ~CYW_CHIP_BCKPLN_ADDRMSK;
    }
    addr &= CYW_CHIP_BCKPLN_ADDRMSK;
    avail = CYW_CHIP_BCKPLN_WINSZ - (unsigned int) addr; // internal backplane limit
    if (bytes > avail) bytes = avail;
    if (bytes > CYW_CHIP_BCKPLN_BUSMAX) bytes = CYW_CHIP_BCKPLN_BUSMAX; // bus to backplane transfer limit
    cyw_bus_write(CYW_BUS_FUNC_CHIP, addr, (uint8_t *)data + offset, (uint16_t) bytes);
    sent += bytes;
    offset += bytes;
  }
}

// CHIP DEPENDENCY: no SOCSRAM base address; start address in fwdata image (Cortex-R4 chips)
static bool cyw_load_fwll(void *fwdata, size_t fwlen, void *nvramdata, size_t nvramlen) {
  uint32_t val = ((~(nvramlen / 4) & 0xffff) << 16) | (nvramlen / 4); // ~len len in 32-bit words
  cyw_core_reset(CYW_CHIP_SOCSRAM, false);  // cores were disabled at chip reset
  cyw_socram_init();
  cyw_load_data(CYW_CHIP_ATCMRAM_BASE, fwdata, fwlen);
  mg_delayms(5); // TODO(scaprile): CHECK IF THIS IS ACTUALLY NEEDED
  // Load NVRAM and place 'length ~length' at the end; end of chip RAM
  {
    const uint32_t start = CYW_CHIP_RAM_SIZE - 4 - nvramlen;
    cyw_load_data(start, nvramdata, nvramlen); // nvramlen must be a multiple of 4
    // RAM_SIZE is a multiple of WINSZ, so the place for len ~len will be at the end of the window
    cyw_bus_write(CYW_BUS_FUNC_CHIP, (CYW_CHIP_BCKPLN_WINSZ - 4), &val, sizeof(val));
  }
  // Reset ARM core and check it starts
  if (!cyw_core_reset(CYW_CHIP_ARMCORE, true)) return false;
  return true;
}
// clang-format on

#if !MG_ENABLE_DRIVER_CYW_SDIO

// CYW43 SPI bus specifics

#define CYW_BUS_SPI_BUSCTRL 0x00     // 4 regs, 0 to 3
#define CYW_BUS_SPI_INT 0x04         // 2 regs, 4 to 5
#define CYW_BUS_SPI_INTEN 0x06       // 16-bit register
#define CYW_BUS_SPI_STATUS 0x08      // 32-bit register
#define CYW_BUS_SPI_TEST 0x14        // 32-bit register
#define CYW_BUS_SPI_RESPDLY_F1 0x1d  // 8-bit register, F1: chip

#define CYW_BUS_STS_LEN(x) ((x >> 9) & 0x7ff)

static bool cyw_spi_write(unsigned int f, uint32_t addr, void *data,
                          uint16_t len);
static void cyw_spi_read(unsigned int f, uint32_t addr, void *data,
                         uint16_t len);

// clang-format off
static size_t cyw_spi_poll(uint8_t *response) {
  size_t len;
  uint32_t res;
  // SPI poll
  cyw_spi_read(CYW_SPID_FUNC_BUS, CYW_BUS_SPI_STATUS, &res, sizeof(res));
  if (res == (uint32_t) ~0 || !(res & MG_BIT(8) /* packet available */ )) return 0;
  len = CYW_BUS_STS_LEN(res);
  if (len == 0) { // just ack IRQ
    uint16_t val = 1;
    cyw_spi_write(CYW_SPID_FUNC_CHIP, CYW_CHIP_SPIFRCTRL, &val, 1);
    cyw_spi_read(CYW_SPID_FUNC_BUS, CYW_BUS_SPI_INT, &val, sizeof(val));
    cyw_spi_write(CYW_SPID_FUNC_BUS, CYW_BUS_SPI_INT, &val, sizeof(val));
    return 0;
  }
  cyw_spi_read(CYW_SPID_FUNC_WLAN, 0,  response, (uint16_t)len);
  return len;
}

static size_t cyw_spi_tx(uint32_t *data, uint16_t len) {
  while (len & 3) data[len++] = 0; // SPI 32-bit padding
  return cyw_spi_write(CYW_SPID_FUNC_WLAN, 0, data, len) ? len: 0;
}

// this can be integrated in lowest level SPI read/write _driver_ functions
// (those calling hal SPI transaction functions), though is only used at start
uint32_t sw16_2(uint32_t data) {
  return ((uint32_t)mg_htons((uint16_t)(data >> 16)) << 16) + mg_htons((uint16_t)data);
}

// DS 4.2.2 Table 6: signal we're working in 16-bit mode
#define CYW_SPI_16bMODE MG_BIT(2) // arbitrary bit out of the FUNC space

static bool cyw_spi_init() {
  struct mg_tcpip_driver_cyw_data *d = (struct mg_tcpip_driver_cyw_data *) s_ifp->driver_data;
  uint32_t val = 0;
  // DS 4.2.3 Boot-Up Sequence; WHD: other chips might require more effort
  unsigned int times = 51;
  while (times--) {
    cyw_spi_read(CYW_SPID_FUNC_BUS | CYW_SPI_16bMODE, CYW_BUS_SPI_TEST, &val, sizeof(val));
    if (sw16_2(val) == 0xFEEDBEAD) break;
    mg_delayms(1);
  }
  if (times == (unsigned int) ~0) return false;
  // DS 4.2.3 Table 6. Chip starts in 16-bit little-endian mode.
  // Configure SPI and switch to 32-bit big-endian mode:
  // - High-speed mode: d->hs true
  // - IRQ POLARITY high
  // - SPI RESPONSE DELAY 4 bytes time [not in DS] TODO(scaprile): logic ana
  // - Status not sent after command, IRQ with status
  val = sw16_2(0x000204a3 | (d->hs ? MG_BIT(4) : 0)); // 4 reg content
  cyw_spi_write(CYW_SPID_FUNC_BUS | CYW_SPI_16bMODE, CYW_BUS_SPI_BUSCTRL, &val, sizeof(val));
  mg_tcpip_call(s_ifp, MG_TCPIP_EV_DRIVER, NULL);
  cyw_spi_read(CYW_SPID_FUNC_BUS, CYW_BUS_SPI_TEST, &val, sizeof(val));
  if (val != 0xFEEDBEAD) return false;
  val = 4; cyw_spi_write(CYW_SPID_FUNC_BUS, CYW_BUS_SPI_RESPDLY_F1, &val, 1);
  val = 0x99; // clear error bits DATA_UNAVAILABLE, COMMAND_ERROR, DATA_ERROR, F1_OVERFLOW
  cyw_spi_write(CYW_SPID_FUNC_BUS, CYW_BUS_SPI_INT, &val, 1);
  val = 0x00be; // Enable IRQs F2_F3_FIFO_RD_UNDERFLOW, F2_F3_FIFO_WR_OVERFLOW, COMMAND_ERROR, DATA_ERROR, F2_PACKET_AVAILABLE, F1_OVERFLOW
  // BT-ENABLED DEPENDENCY: add F1_INTR (bit 13)
  cyw_spi_write(CYW_SPID_FUNC_BUS, CYW_BUS_SPI_INTEN, &val, sizeof(uint16_t));

  // chip backplane is ready, initialize it
  // request ALP (Active Low Power) clock
  val = MG_BIT(3) /* ALP_REQ */; cyw_spi_write(CYW_SPID_FUNC_CHIP, CYW_CHIP_CLOCKCSR, &val, 1);
  // BT-ENABLED DEPENDENCY
  times = 10;
  while (times--) {
    cyw_spi_read(CYW_SPID_FUNC_CHIP, CYW_CHIP_CLOCKCSR, &val, 1);
    if (val & MG_BIT(6)) break; // ALP_AVAIL
    mg_delayms(1);
  }
  if (times == (unsigned int) ~0) return false;
  // clear request
  val = 0; cyw_spi_write(CYW_SPID_FUNC_CHIP, CYW_CHIP_CLOCKCSR, &val, 1);
  cyw_set_backplane_window(CYW_CHIP_CHIPCOMMON); // set backplane window to start of CHIPCOMMON area
  cyw_spi_read(CYW_SPID_FUNC_CHIP, (CYW_CHIP_CHIPCOMMON + 0x00) & CYW_CHIP_BCKPLN_ADDRMSK, &val, 2);
  if (val == 43430) val = 4343;
  MG_INFO(("WLAN chip is CYW%u%c", val, val == 4343 ? 'W' : ' '));

  // Load firmware (code and NVRAM)
  if (!cyw_load_firmware(d->fw)) return false;

  // Wait for High Throughput (HT) clock ready
  times = 50;
  while (times--) {
    cyw_spi_read(CYW_SPID_FUNC_CHIP, CYW_CHIP_CLOCKCSR, &val, 1);
    if (val & MG_BIT(7)) break; // HT_AVAIL
    mg_delayms(1);
  }
  if (times == (unsigned int) ~0) return false;
  // Wait for backplane ready
  times = 1000;
  while (times--) {
    cyw_spi_read(CYW_SPID_FUNC_BUS, CYW_BUS_SPI_STATUS, &val, sizeof(val));
    if (val & MG_BIT(5)) break; // F2_RX_READY
    mg_delayms(1);
  }
  if (times == (unsigned int) ~0) return false;

  // CHIP DEPENDENCY
  // Enable save / restore
  // Configure WakeupCtrl, set HT_AVAIL in CLOCK_CSR
  cyw_spi_read(CYW_SPID_FUNC_CHIP, CYW_CHIP_WAKEUPCTL, &val, 1);
  val |= MG_BIT(1) /* WAKE_TILL_HT_AVAIL */; cyw_spi_write(CYW_SPID_FUNC_CHIP, CYW_CHIP_WAKEUPCTL, &val, 1);
#if 0
  // Set BRCM_CARDCAP to CMD_NODEC. NOTE(): This is probably only necessary for SDIO, not SPI
  val = MG_BIT(3); cyw_spi_write(CYW_SPID_FUNC_BUS, 0xf0 /* SDIOD_CCCR_BRCM_CARDCAP */, &val, 1);
#endif
  // Force HT request to chip backplane
  val = MG_BIT(1) /* FORCE_HT */; cyw_spi_write(CYW_SPID_FUNC_CHIP, CYW_CHIP_CLOCKCSR, &val, 1);
  // Enable Keep SDIO On (KSO)
  cyw_spi_read(CYW_SPID_FUNC_CHIP, CYW_CHIP_SLEEPCSR, &val, 1);
  if (!(val & MG_BIT(0))) {
      val |= MG_BIT(0); cyw_spi_write(CYW_SPID_FUNC_CHIP, CYW_CHIP_SLEEPCSR, &val, 1);
  }
  // The SPI bus can be configured for sleep (KSO controls wlan block sleep)
  cyw_spi_read(CYW_SPID_FUNC_BUS, CYW_BUS_SPI_BUSCTRL, &val, sizeof(val));
  val &= ~MG_BIT(7) /* WAKE_UP */; cyw_spi_write(CYW_SPID_FUNC_BUS, CYW_BUS_SPI_BUSCTRL, &val, sizeof(val));
  // Set SPI bus sleep
  val = 0x0f; cyw_spi_write(CYW_SPID_FUNC_CHIP, CYW_CHIP_PULLUP, &val, 1);

  // Clear pullups. NOTE(): ?
  val = 0x00; cyw_spi_write(CYW_SPID_FUNC_CHIP, CYW_CHIP_PULLUP, &val, 1);
  cyw_spi_read(CYW_SPID_FUNC_CHIP, CYW_CHIP_PULLUP, &val, 1);
  // Clear possible data unavailable error
  cyw_spi_read(CYW_SPID_FUNC_BUS, CYW_BUS_SPI_INTEN, &val, sizeof(uint16_t));
  if (val & MG_BIT(0)) cyw_spi_write(CYW_SPID_FUNC_BUS, CYW_BUS_SPI_INTEN, &val, sizeof(uint16_t));

  return true;
}
// clang-format on

// gSPI, CYW43439 DS 4.2.1 Fig.12
#define CYW_SPID_LEN(x) ((x) &0x7FF)             // bits 0-10
#define CYW_SPID_ADDR(x) (((x) &0x1FFFF) << 11)  // bits 11-27,
#define CYW_SPID_FUNC(x) (((x) &3) << 28)        // bits 28-29
#define CYW_SPID_INC MG_BIT(30)
#define CYW_SPID_WR MG_BIT(31)

static bool cyw_spi_write(unsigned int f, uint32_t addr, void *data,
                          uint16_t len) {
  struct mg_tcpip_driver_cyw_data *d =
      (struct mg_tcpip_driver_cyw_data *) s_ifp->driver_data;
  struct mg_tcpip_spi_ *s = (struct mg_tcpip_spi_ *) d->bus;
  uint32_t hdr = CYW_SPID_WR | CYW_SPID_INC | CYW_SPID_FUNC(f) |
                 CYW_SPID_ADDR(addr) | CYW_SPID_LEN(len);  // gSPI header
  // TODO(scaprile): check spin in between and timeout values, return false
  if (f == CYW_SPID_FUNC_WLAN) {
    uint32_t val = 0;
    while ((val & MG_BIT(5)) != MG_BIT(5))  // F2 rx ready (FIFO ready)
      cyw_spi_read(CYW_SPID_FUNC_BUS, CYW_BUS_SPI_STATUS, &val, sizeof(val));
  }
  if (f & CYW_SPI_16bMODE)
    hdr = sw16_2(hdr);  // swap half-words in 16-bit little-endian mode

  s->begin(NULL);
  s->txn(NULL, (uint8_t *) &hdr, NULL, sizeof(hdr));
  if (len <= 4) {
    uint32_t pad = 0;
    memcpy(&pad, data, len);
    s->txn(NULL, (uint8_t *) &pad, NULL, sizeof(pad));
  } else {
    s->txn(NULL, (uint8_t *) data, NULL, len);
  }
  s->end(NULL);
  return true;
}

// will write 32-bit aligned quantities to data if f == CYW_SPID_FUNC_WLAN
static void cyw_spi_read(unsigned int f, uint32_t addr, void *data,
                         uint16_t len) {
  struct mg_tcpip_driver_cyw_data *d =
      (struct mg_tcpip_driver_cyw_data *) s_ifp->driver_data;
  struct mg_tcpip_spi_ *s = (struct mg_tcpip_spi_ *) d->bus;
  uint32_t padding =
      f == CYW_SPID_FUNC_CHIP
          ? 4
          : 0;  // add padding to chip backplane reads as a response delay
  uint32_t hdr = CYW_SPID_INC | CYW_SPID_FUNC(f) | CYW_SPID_ADDR(addr) |
                 CYW_SPID_LEN(len + padding);  // gSPI header
  if (f == CYW_SPID_FUNC_WLAN && (len & 3))
    len = (len + 4) & ~3;  // align WLAN transfers to 32-bit
  if (f & CYW_SPI_16bMODE)
    hdr = sw16_2(hdr);  // swap half-words in 16-bit little-endian mode

  s->begin(NULL);
  s->txn(NULL, (uint8_t *) &hdr, NULL, sizeof(hdr));
  if (f == CYW_SPID_FUNC_CHIP) {
    uint32_t pad;
    s->txn(NULL, NULL, (uint8_t *) &pad, 4);  // read padding back and discard
  }
  s->txn(NULL, NULL, (uint8_t *) data, len);
  s->end(NULL);
}

static bool cyw_bus_specific_init(void) {
  return cyw_spi_init();
}
static size_t cyw_bus_specific_poll(uint32_t *response) {
  return cyw_spi_poll((uint8_t *) response);
}
static size_t cyw_bus_specific_tx(uint32_t *data, uint16_t len) {
  return cyw_spi_tx(data, len);
}
static bool cyw_bus_write(unsigned int f, uint32_t addr, void *data,
                          uint16_t len) {
  if (f == CYW_SPID_FUNC_CHIP && len >= 4) addr |= CYW_CHIP_BCKPLN_ACCSS4B;
  return cyw_spi_write(f, addr, data, len);
}
static bool cyw_bus_read(unsigned int f, uint32_t addr, void *data,
                         uint16_t len) {
  cyw_spi_read(f, addr, data, len);
  return true;
}

#else  // MG_ENABLE_DRIVER_CYW_SDIO



// CYW43 SDIO bus specifics

// CYW4343W and CYW43439 DS 4.1 SDIO v2.0:
//- F0: max block size is  32 bytes
//- F1: max block size is  64 bytes
//- F2: max block size is 512 bytes

// clang-format off
static bool cyw_sdio_transfer(bool write, unsigned int f, uint32_t addr, void *data, uint32_t len) {
  struct mg_tcpip_driver_cyw_data *d = (struct mg_tcpip_driver_cyw_data *) s_ifp->driver_data;
  struct mg_tcpip_sdio *s = (struct mg_tcpip_sdio *) d->bus;
  uint32_t *ptr = (uint32_t *) data; // assume 32-bit aligned data (all except firmware)
  if (write && (size_t) data & 3) {  // missed, source data is not 32-bit aligned
    memcpy(txdata, data, len);       // copy to an aligned buffer, we know it fits
    ptr = txdata;
  } // all possible read destinations are 32-bit aligned
  // mg_sdio_transfer requires 32-bit alignment for > 1 byte transfers
  return mg_sdio_transfer(s, write, f, addr, ptr, len);
}

static size_t cyw_sdio_poll(uint32_t *response) {
  uint32_t res;
  uint16_t *len = (uint16_t *)&res;
  // WHD: internal docs, "tag" hinting a possible packet.
  // This is actually the len / ~len field of a possible struct sdpcm_hdr, if there is a packet available, or 0 if there is none.
  cyw_sdio_transfer(false, CYW_SDIO_FUNC_WLAN, 0, &res, sizeof(res)); // read "the tag"
  if ((len[0] | len[1]) == 0 || (len[0] ^ len[1]) != 0xffff || *len <= 4) return 0;
  response[0] = res; // copy what we already read, then read the rest
  cyw_sdio_transfer(false, CYW_SDIO_FUNC_WLAN, 0, response + 1, *len - sizeof(res));
  return (size_t)*len;
}

static size_t cyw_sdio_tx(uint32_t *data, uint16_t len) {
  return cyw_sdio_transfer(true, CYW_SDIO_FUNC_WLAN, 0, data, len) ? len: 0;
}

static bool cyw_sdio_init() {
  struct mg_tcpip_driver_cyw_data *d = (struct mg_tcpip_driver_cyw_data *) s_ifp->driver_data;
  struct mg_tcpip_sdio *s = (struct mg_tcpip_sdio *) d->bus;
  uint32_t val = 0;
  if (!mg_sdio_init(s)) return false;
  // no block transfers on F0. if (!mg_sdio_set_blksz(s, CYW_SDIO_FUNC_BUS, 32)) return false;
  if (!mg_sdio_set_blksz(s, CYW_SDIO_FUNC_CHIP, 64)) return false;
  if (!mg_sdio_set_blksz(s, CYW_SDIO_FUNC_WLAN, 64)) return false;
  // TODO(scaprile): we don't handle SDIO interrupts, study CCCR INTEN and SDIO support (SDIO 6.3, 8)
  // Enable chip backplane (F1)
  if (!mg_sdio_enable_f(s, CYW_SDIO_FUNC_CHIP)) return false;
  // Wait for F1 to be ready
  if (!mg_sdio_waitready_f(s, CYW_SDIO_FUNC_CHIP)) return false;
  // chip backplane is ready, initialize it
  // request ALP (Active Low Power) clock
  val = MG_BIT(5) | MG_BIT(3) | MG_BIT(0); // HW_CLKREQ_OFF ALP_REQ FORCE_ALP
  cyw_sdio_transfer(true, CYW_SDIO_FUNC_CHIP, CYW_CHIP_CLOCKCSR, &val, 1);
  // BT-ENABLED DEPENDENCY
  unsigned int times = 10;
  while (times--) {
    if(!cyw_sdio_transfer(false, CYW_SDIO_FUNC_CHIP, CYW_CHIP_CLOCKCSR, &val, 1)) return false;
    if (val & MG_BIT(6)) break; // ALP_AVAIL
    mg_delayms(1);
  }
  if (times == (unsigned int) ~0) return false;
  // clear request
  val = 0; cyw_sdio_transfer(true, CYW_SDIO_FUNC_CHIP, CYW_CHIP_CLOCKCSR, &val, 1);
  // Enable WLAN (F2)
  if (!mg_sdio_enable_f(s, CYW_SDIO_FUNC_WLAN)) return false;
  // Clear pullups. NOTE(): ?
  val = 0x00; cyw_sdio_transfer(true, CYW_SDIO_FUNC_CHIP, CYW_CHIP_PULLUP, &val, 1);
  // we don't handle wake nor OOB interrupts; SEP_INT_CTL is a vendor specific SDIO register
  // SDIO interrupts: enable F2 interrupt only

  cyw_set_backplane_window(CYW_CHIP_CHIPCOMMON); // set backplane window to start of CHIPCOMMON area
  cyw_sdio_transfer(false, CYW_SDIO_FUNC_CHIP, (CYW_CHIP_CHIPCOMMON + 0x00) & CYW_CHIP_BCKPLN_ADDRMSK, &val, 2);
  if (val == 43430) val = 4343;
  MG_INFO(("WLAN chip is CYW%u%c", val, val == 4343 ? 'W' : ' '));
  // Load firmware (code and NVRAM)
  if (!cyw_load_firmware(d->fw)) return false;

  // Wait for High Throughput (HT) clock ready
  times = 50;
  while (times--) {
    if(!cyw_sdio_transfer(false, CYW_SDIO_FUNC_CHIP, CYW_CHIP_CLOCKCSR, &val, 1)) return false;
    if (val & MG_BIT(7)) break; // HT_AVAIL
    mg_delayms(1);
  }
  if (times == (unsigned int) ~0) return false;
  // Wait for WLAN ready
  if (!mg_sdio_waitready_f(s, CYW_SDIO_FUNC_WLAN)) return false;

  // CHIP DEPENDENCY
  // Enable save / restore
  // Configure WakeupCtrl, set HT_AVAIL in CLOCK_CSR
  if(!cyw_sdio_transfer(false, CYW_SDIO_FUNC_CHIP, CYW_CHIP_WAKEUPCTL, &val, 1)) return false;
  val |= MG_BIT(1) /* WAKE_TILL_HT_AVAIL */; cyw_sdio_transfer(true, CYW_SDIO_FUNC_CHIP, CYW_CHIP_WAKEUPCTL, &val, 1);
#if 0 // TODO(scaprile): Check if this is actually necessary
  // Set BRCM_CARDCAP to CMD_NODEC. This is a vendor specific SDIO register
  val = MG_BIT(3); cyw_sdio_transfer(true, CYW_SDIO_FUNC_BUS, 0xf0 /* SDIOD_CCCR_BRCM_CARDCAP */, &val, 1);
#endif
  // Force HT request to chip backplane
  val = MG_BIT(1) /* FORCE_HT */; if(!cyw_sdio_transfer(true, CYW_SDIO_FUNC_CHIP, CYW_CHIP_CLOCKCSR, &val, 1)) return false;
  // Enable Keep SDIO On (KSO)
  cyw_sdio_transfer(false, CYW_SDIO_FUNC_CHIP, CYW_CHIP_SLEEPCSR, &val, 1);
  if (!(val & MG_BIT(0))) {
      val |= MG_BIT(0); cyw_sdio_transfer(true, CYW_SDIO_FUNC_CHIP, CYW_CHIP_SLEEPCSR, &val, 1);
  }
  return true;
}

// clang-format on

static bool cyw_bus_specific_init(void) {
  return cyw_sdio_init();
}
static size_t cyw_bus_specific_poll(uint32_t *response) {
  return cyw_sdio_poll(response);
}
static size_t cyw_bus_specific_tx(uint32_t *data, uint16_t len) {
  return cyw_sdio_tx(data, len);
}
static bool cyw_bus_write(unsigned int f, uint32_t addr, void *data,
                          uint16_t len) {
  if (f == CYW_SDIO_FUNC_CHIP && len == 4) addr |= CYW_CHIP_BCKPLN_ACCSS4B;
  return cyw_sdio_transfer(true, f, addr, data, (uint32_t) len);
}
static bool cyw_bus_read(unsigned int f, uint32_t addr, void *data,
                         uint16_t len) {
  return cyw_sdio_transfer(false, f, addr, data, (uint32_t) len);
}

#endif

// Mongoose Wi-Fi API functions

bool mg_wifi_scan(void) {
  return cyw_wifi_scan();
}

bool mg_wifi_connect(struct mg_wifi_data *wifi) {
  s_ifp->ip = s_ip;
  s_ifp->mask = s_mask;
  if (s_ifp->ip == 0) s_ifp->enable_dhcp_client = true;
  s_ifp->enable_dhcp_server = false;
  MG_DEBUG(("Connecting to '%s'", wifi->ssid));
  return cyw_wifi_connect(wifi->ssid, wifi->pass);
}

bool mg_wifi_disconnect(void) {
  return cyw_wifi_disconnect();
}

bool mg_wifi_ap_start(struct mg_wifi_data *wifi) {
  MG_DEBUG(("Starting AP '%s' (%u)", wifi->apssid, wifi->apchannel));
  return cyw_wifi_ap_start(wifi->apssid, wifi->appass, wifi->apchannel);
}

bool mg_wifi_ap_stop(void) {
  return cyw_wifi_ap_stop();
}

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/imxrt.c"
#endif


#if MG_ENABLE_TCPIP && \
  (defined(MG_ENABLE_DRIVER_IMXRT10) && MG_ENABLE_DRIVER_IMXRT10) || \
  (defined(MG_ENABLE_DRIVER_IMXRT11) && MG_ENABLE_DRIVER_IMXRT11) || \
  (defined(MG_ENABLE_DRIVER_MCXE) && MG_ENABLE_DRIVER_MCXE)
struct imxrt_enet {
  volatile uint32_t RESERVED0, EIR, EIMR, RESERVED1, RDAR, TDAR, RESERVED2[3],
      ECR, RESERVED3[6], MMFR, MSCR, RESERVED4[7], MIBC, RESERVED5[7], RCR,
      RESERVED6[15], TCR, RESERVED7[7], PALR, PAUR, OPD, TXIC0, TXIC1, TXIC2,
      RESERVED8, RXIC0, RXIC1, RXIC2, RESERVED9[3], IAUR, IALR, GAUR, GALR,
      RESERVED10[7], TFWR, RESERVED11[14], RDSR, TDSR, MRBR[2], RSFL, RSEM,
      RAEM, RAFL, TSEM, TAEM, TAFL, TIPG, FTRL, RESERVED12[3], TACC, RACC,
      RESERVED13[15], RMON_T_PACKETS, RMON_T_BC_PKT, RMON_T_MC_PKT,
      RMON_T_CRC_ALIGN, RMON_T_UNDERSIZE, RMON_T_OVERSIZE, RMON_T_FRAG,
      RMON_T_JAB, RMON_T_COL, RMON_T_P64, RMON_T_P65TO127, RMON_T_P128TO255,
      RMON_T_P256TO511, RMON_T_P512TO1023, RMON_T_P1024TO2048, RMON_T_GTE2048,
      RMON_T_OCTETS, IEEE_T_DROP, IEEE_T_FRAME_OK, IEEE_T_1COL, IEEE_T_MCOL,
      IEEE_T_DEF, IEEE_T_LCOL, IEEE_T_EXCOL, IEEE_T_MACERR, IEEE_T_CSERR,
      IEEE_T_SQE, IEEE_T_FDXFC, IEEE_T_OCTETS_OK, RESERVED14[3], RMON_R_PACKETS,
      RMON_R_BC_PKT, RMON_R_MC_PKT, RMON_R_CRC_ALIGN, RMON_R_UNDERSIZE,
      RMON_R_OVERSIZE, RMON_R_FRAG, RMON_R_JAB, RESERVED15, RMON_R_P64,
      RMON_R_P65TO127, RMON_R_P128TO255, RMON_R_P256TO511, RMON_R_P512TO1023,
      RMON_R_P1024TO2047, RMON_R_GTE2048, RMON_R_OCTETS, IEEE_R_DROP,
      IEEE_R_FRAME_OK, IEEE_R_CRC, IEEE_R_ALIGN, IEEE_R_MACERR, IEEE_R_FDXFC,
      IEEE_R_OCTETS_OK, RESERVED16[71], ATCR, ATVR, ATOFF, ATPER, ATCOR, ATINC,
      ATSTMP, RESERVED17[122], TGSR, TCSR0, TCCR0, TCSR1, TCCR1, TCSR2, TCCR2,
      TCSR3;
};

#undef ENET
#if defined(MG_ENABLE_DRIVER_IMXRT11) && MG_ENABLE_DRIVER_IMXRT11
#define ENET ((struct imxrt_enet *) (uintptr_t) 0x40424000U)
#define ETH_DESC_CNT 5     // Descriptors count
#elif defined(MG_ENABLE_DRIVER_IMXRT10) && MG_ENABLE_DRIVER_IMXRT10
#define ENET ((struct imxrt_enet *) (uintptr_t) 0x402D8000U)
#define ETH_DESC_CNT 4     // Descriptors count
#else // MG_ENABLE_DRIVER_MCXE
#define ENET ((struct imxrt_enet *) (uintptr_t) 0x40079000U)
#define ETH_DESC_CNT 4     // Descriptor count
#endif

#define ETH_PKT_SIZE 1536  // Max frame size, 64-bit aligned

struct enet_desc {
  uint16_t length;   // Data length
  uint16_t control;  // Control and status
  uint32_t *buffer;  // Data ptr
};

// Descriptors: in non-cached area (TODO(scaprile)), (37.5.1.22.2 37.5.1.23.2)
// Buffers: 64-byte aligned (37.3.14)
static volatile struct enet_desc s_rxdesc[ETH_DESC_CNT] MG_ETH_RAM MG_64BYTE_ALIGNED;
static volatile struct enet_desc s_txdesc[ETH_DESC_CNT] MG_ETH_RAM MG_64BYTE_ALIGNED;
static uint8_t s_rxbuf[ETH_DESC_CNT][ETH_PKT_SIZE] MG_ETH_RAM MG_64BYTE_ALIGNED;
static uint8_t s_txbuf[ETH_DESC_CNT][ETH_PKT_SIZE] MG_ETH_RAM MG_64BYTE_ALIGNED;
static struct mg_tcpip_if *s_ifp;  // MIP interface

static uint16_t enet_read_phy(uint8_t addr, uint8_t reg) {
  ENET->EIR |= MG_BIT(23);  // MII interrupt clear
  ENET->MMFR = (1 << 30) | (2 << 28) | (addr << 23) | (reg << 18) | (2 << 16);
  while ((ENET->EIR & MG_BIT(23)) == 0) (void) 0;
  return ENET->MMFR & 0xffff;
}

static void enet_write_phy(uint8_t addr, uint8_t reg, uint16_t val) {
  ENET->EIR |= MG_BIT(23);  // MII interrupt clear
  ENET->MMFR =
      (1 << 30) | (1 << 28) | (addr << 23) | (reg << 18) | (2 << 16) | val;
  while ((ENET->EIR & MG_BIT(23)) == 0) (void) 0;
}

//  MDC clock is generated from IPS Bus clock (ipg_clk); as per 802.3,
//  it must not exceed 2.5MHz
// The PHY receives the PLL6-generated 50MHz clock
static bool mg_tcpip_driver_imxrt_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_imxrt_data *d =
      (struct mg_tcpip_driver_imxrt_data *) ifp->driver_data;
  s_ifp = ifp;

  // Init RX descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_rxdesc[i].control = MG_BIT(15);              // Own (E)
    s_rxdesc[i].buffer = (uint32_t *) s_rxbuf[i];  // Point to data buffer
  }
  s_rxdesc[ETH_DESC_CNT - 1].control |= MG_BIT(13);  // Wrap last descriptor

  // Init TX descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    // s_txdesc[i].control = MG_BIT(10);  // Own (TC)
    s_txdesc[i].buffer = (uint32_t *) s_txbuf[i];
  }
  s_txdesc[ETH_DESC_CNT - 1].control |= MG_BIT(13);  // Wrap last descriptor

  ENET->ECR = MG_BIT(0);                     // Software reset, disable
  while ((ENET->ECR & MG_BIT(0))) (void) 0;  // Wait until done

  // Set MDC clock divider. If user told us the value, use it.
  // TODO(): Otherwise, guess (currently assuming max freq)
  int cr = (d == NULL || d->mdc_cr < 0) ? 24 : d->mdc_cr;
  ENET->MSCR = (1 << 8) | ((cr & 0x3f) << 1);  // HOLDTIME 2 clks
  struct mg_phy phy = {enet_read_phy, enet_write_phy};
  mg_phy_init(&phy, d->phy_addr, MG_PHY_LEDS_ACTIVE_HIGH); // MAC clocks PHY  
  // Select RMII mode, 100M, keep CRC, set max rx length, disable loop
  ENET->RCR = (1518 << 16) | MG_BIT(8) | MG_BIT(2);
  // ENET->RCR |= MG_BIT(3);     // Receive all
  ENET->TCR = MG_BIT(2);  // Full-duplex
  ENET->RDSR = (uint32_t) (uintptr_t) s_rxdesc;
  ENET->TDSR = (uint32_t) (uintptr_t) s_txdesc;
  ENET->MRBR[0] = ETH_PKT_SIZE;  // Same size for RX/TX buffers
  // MAC address filtering (bytes in reversed order)
  ENET->PAUR = ((uint32_t) ifp->mac[4] << 24U) | (uint32_t) ifp->mac[5] << 16U;
  ENET->PALR = (uint32_t) (ifp->mac[0] << 24U) |
               ((uint32_t) ifp->mac[1] << 16U) |
               ((uint32_t) ifp->mac[2] << 8U) | ifp->mac[3];
  ENET->ECR = MG_BIT(8) | MG_BIT(1);  // Little-endian CPU, Enable
  ENET->EIMR = MG_BIT(25);            // Set interrupt mask
  ENET->RDAR = MG_BIT(24);            // Receive Descriptors have changed
  ENET->TDAR = MG_BIT(24);            // Transmit Descriptors have changed
  // ENET->OPD = 0x10014;
  ENET->IAUR = 0;
  ENET->IALR = 0;
  ENET->GAUR = 0;
  ENET->GALR = 0;
  return true;
}


// Transmit frame
static size_t mg_tcpip_driver_imxrt_tx(const void *buf, size_t len,
                                       struct mg_tcpip_if *ifp) {
  static int s_txno;  // Current descriptor index
  if (len > sizeof(s_txbuf[ETH_DESC_CNT])) {
    MG_ERROR(("Frame too big, %ld", (long) len));
    len = (size_t) -1;  // fail
  } else if ((s_txdesc[s_txno].control & MG_BIT(15))) {
    ifp->nerr++;
    MG_ERROR(("No descriptors available"));
    len = 0;  // retry later
  } else {
    memcpy(s_txbuf[s_txno], buf, len);         // Copy data
    s_txdesc[s_txno].length = (uint16_t) len;  // Set data len
    // Table 37-34, R, L, TC (Ready, last, transmit CRC after frame
    s_txdesc[s_txno].control |=
        (uint16_t) (MG_BIT(15) | MG_BIT(11) | MG_BIT(10));
    ENET->TDAR = MG_BIT(24);  // Descriptor ring updated
    if (++s_txno >= ETH_DESC_CNT) s_txno = 0;
  }
  (void) ifp;
  return len;
}

static void mg_tcpip_driver_imxrt_update_hash_table(struct mg_tcpip_if *ifp) {
  // TODO(): read database, rebuild hash table
  // RM 37.3.4.3.2
  uint32_t hash_table[2] = {0, 0};
  // uint8_t hash64 = ((~mg_crc32(0, mcast_addr, 6)) >> 26) & 0x3f;
  // hash_table[((uint8_t)hash64) >> 5] |= (1 << (hash64 & 0x1f));
  hash_table[1] = MG_BIT(1); // above reduces to this for mDNS addr
  ENET->GAUR = hash_table[1];
  ENET->GALR = hash_table[0];
  (void) ifp;
}

static bool mg_tcpip_driver_imxrt_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (ifp->update_mac_hash_table) {
    mg_tcpip_driver_imxrt_update_hash_table(ifp);
    ifp->update_mac_hash_table = false;
  }
  if (!s1) return false;
  struct mg_tcpip_driver_imxrt_data *d =
      (struct mg_tcpip_driver_imxrt_data *) ifp->driver_data;
  uint8_t speed = MG_PHY_SPEED_10M;
  bool up = false, full_duplex = false;
  struct mg_phy phy = {enet_read_phy, enet_write_phy};
  up = mg_phy_up(&phy, d->phy_addr, &full_duplex, &speed);
  if ((ifp->state == MG_TCPIP_STATE_DOWN) && up) {  // link state just went up
    // tmp = reg with flags set to the most likely situation: 100M full-duplex
    // if(link is slow or half) set flags otherwise
    // reg = tmp
    uint32_t tcr = ENET->TCR | MG_BIT(2);             // Full-duplex
    uint32_t rcr = ENET->RCR & ~MG_BIT(9);            // 100M
    if (speed == MG_PHY_SPEED_10M) rcr |= MG_BIT(9);  // 10M
    if (full_duplex == false) tcr &= ~MG_BIT(2);      // Half-duplex
    ENET->TCR = tcr;  // IRQ handler does not fiddle with these registers
    ENET->RCR = rcr;
    MG_DEBUG(("Link is %uM %s-duplex", rcr & MG_BIT(9) ? 10 : 100,
              tcr & MG_BIT(2) ? "full" : "half"));
  }
  return up;
}

static uint32_t s_rxno;
#if !defined(MG_ENABLE_DRIVER_MCXE)
void ENET_IRQHandler(void);
void ENET_IRQHandler(void) {
#else
void ENET_Receive_IRQHandler(void);
void ENET_Receive_IRQHandler(void) {
#endif
  ENET->EIR = MG_BIT(25);  // Ack IRQ
  // Frame received, loop
  for (uint32_t i = 0; i < 10; i++) {  // read as they arrive but not forever
    uint32_t r = s_rxdesc[s_rxno].control;
    if (r & MG_BIT(15)) break;  // exit when done
    // skip partial/errored frames (Table 37-32)
    if ((r & MG_BIT(11)) &&
        !(r & (MG_BIT(5) | MG_BIT(4) | MG_BIT(2) | MG_BIT(1) | MG_BIT(0)))) {
      size_t len = s_rxdesc[s_rxno].length;
      mg_tcpip_qwrite(s_rxbuf[s_rxno], len > 4 ? len - 4 : len, s_ifp);
    }
    s_rxdesc[s_rxno].control |= MG_BIT(15);
    if (++s_rxno >= ETH_DESC_CNT) s_rxno = 0;
  }
  ENET->RDAR = MG_BIT(24);  // Receive Descriptors have changed
  // If b24 == 0, descriptors were exhausted and probably frames were dropped
}

struct mg_tcpip_driver mg_tcpip_driver_imxrt = {mg_tcpip_driver_imxrt_init,
                                                mg_tcpip_driver_imxrt_tx, NULL,
                                                mg_tcpip_driver_imxrt_poll};

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/nxp_wifi.c"
#endif
#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_NXP_WIFI) && \
    MG_ENABLE_DRIVER_NXP_WIFI



bool __attribute__((weak)) netif_init(struct mg_tcpip_if *ifp) {
  (void) ifp;
  MG_ERROR(("Please link wifi/port/net contents"));
  return false;
}
size_t __attribute__((weak))
netif_tx(const void *bfr, size_t len, struct mg_tcpip_if *ifp) {
  (void) bfr;
  (void) len;
  netif_init(ifp);
  return 0;
}
bool __attribute__((weak)) netif_connect(struct mg_wifi_data *wifi) {
  (void) wifi;
  return netif_init(NULL);
}
bool __attribute__((weak))
netif_poll(struct mg_tcpip_if *ifp, bool s1, mg_tcpip_event_handler_t evcb) {
  (void) ifp;
  (void) s1;
  (void) evcb;
  return false;
}

static struct mg_tcpip_if *s_ifp;
static uint32_t s_ip, s_mask;

static void wifi_cb(struct mg_tcpip_if *ifp, int ev, void *ev_data) {
  struct mg_wifi_data *wifi =
      &((struct mg_tcpip_driver_nxp_wifi_data *) ifp->driver_data)->wifi;
  if (wifi->apmode && ev == MG_TCPIP_EV_ST_CHG &&
      *(uint8_t *) ev_data == MG_TCPIP_STATE_UP) {
    MG_DEBUG(("Access Point started"));
    s_ip = ifp->ip, ifp->ip = wifi->apip;
    s_mask = ifp->mask, ifp->mask = wifi->apmask;
    ifp->enable_dhcp_client = false;
    ifp->enable_dhcp_server = true;
  }
}

static bool nxp_wifi_init(struct mg_tcpip_if *ifp) {
  struct mg_wifi_data *wifi =
      &((struct mg_tcpip_driver_nxp_wifi_data *) ifp->driver_data)->wifi;
  s_ifp = ifp;
  s_ip = ifp->ip;
  s_mask = ifp->mask;
  ifp->pfn = wifi_cb;
  if (!netif_init(ifp)) return false;
  if (wifi->apmode) {
    return mg_wifi_ap_start(wifi);
  } else if (wifi->ssid != NULL && wifi->pass != NULL) {
    return mg_wifi_connect(wifi);
  }
  return true;
}

bool nxp_wifi_poll(struct mg_tcpip_if *ifp, bool s1) {
  return netif_poll(ifp, s1, mg_tcpip_call);
}

struct mg_tcpip_driver mg_tcpip_driver_nxp_wifi = {nxp_wifi_init, netif_tx,
                                                   NULL, nxp_wifi_poll};

bool mg_wifi_connect(struct mg_wifi_data *wifi) {
  s_ifp->ip = s_ip;
  s_ifp->mask = s_mask;
  if (s_ifp->ip == 0) s_ifp->enable_dhcp_client = true;
  s_ifp->enable_dhcp_server = false;
  return netif_connect(wifi);
}

bool __attribute__((weak)) mg_wifi_scan(void) {
  return netif_init(NULL);
}
bool __attribute__((weak)) mg_wifi_disconnect(void) {
  return netif_init(NULL);
}
bool __attribute__((weak)) mg_wifi_ap_start(struct mg_wifi_data *wifi) {
  (void) wifi;
  return netif_init(NULL);
}
bool __attribute__((weak)) mg_wifi_ap_stop(void) {
  return netif_init(NULL);
}

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/phy.c"
#endif


enum {                  // ID1  ID2
  MG_PHY_KSZ8x = 0x22,  // 0022 156x - KSZ8081RNB, KSZ8091RNB
  MG_PHY_DP83x = 0x2000,
  MG_PHY_DP83867 = 0xa231,  // 2000 a231 - TI DP83867I
  MG_PHY_DP83825 = 0xa140,  // 2000 a140 - TI DP83825I
  MG_PHY_DP83848 = 0x5ca2,  // 2000 5ca2 - TI DP83848I
  MG_PHY_LAN87x = 0x7,      // 0007 c0fx - LAN8720
  MG_PHY_RTL82x = 0x1c,
  MG_PHY_RTL8201 = 0xc816,  // 001c c816 - RTL8201F
  MG_PHY_RTL8211 = 0xc916,  // 001c c916 - RTL8211F
  MG_PHY_ICS1894x = 0x15,
  MG_PHY_ICS189432 = 0xf450  // 0015 f450 - ICS1894
};

enum {
  MG_PHY_REG_BCR = 0,
  MG_PHY_REG_BSR = 1,
  MG_PHY_REG_ID1 = 2,
  MG_PHY_REG_ID2 = 3,
  MG_PHY_DP83x_REG_PHYSTS = 16,
  MG_PHY_DP83867_REG_PHYSTS = 17,
  MG_PHY_DP83x_REG_RCSR = 23,
  MG_PHY_DP83x_REG_LEDCR = 24,
  MG_PHY_KSZ8x_REG_PC1R = 30,
  MG_PHY_KSZ8x_REG_PC2R = 31,
  MG_PHY_LAN87x_REG_SCSR = 31,
  MG_PHY_RTL82x_REG_PAGESEL = 31,
  MG_PHY_RTL8201_REG_RMSR = 16,   // in page 7
  MG_PHY_RTL8211_REG_PHYSR = 26,  // in page a43
  MG_PHY_ICS189432_REG_POLL = 17
};

static const char *mg_phy_id_to_str(uint16_t id1, uint16_t id2) {
  switch (id1) {
    case MG_PHY_DP83x:
      switch (id2) {
        case MG_PHY_DP83867:
          return "DP83867";
        case MG_PHY_DP83848:
          return "DP83848";
        case MG_PHY_DP83825:
          return "DP83825";
        default:
          return "DP83x";
      }
    case MG_PHY_KSZ8x:
      return "KSZ8x";
    case MG_PHY_LAN87x:
      return "LAN87x";
    case MG_PHY_RTL82x:
      switch (id2) {
        case MG_PHY_RTL8201:
          return "RTL8201";
        case MG_PHY_RTL8211:
          return "RTL8211";
        default:
          return "RTL82x";
      }
    case MG_PHY_ICS1894x:
      return "ICS1894x";
    default:
      return "unknown";
  }
}

void mg_phy_init(struct mg_phy *phy, uint8_t phy_addr, uint8_t config) {
  uint16_t id1, id2;
  phy->write_reg(phy_addr, MG_PHY_REG_BCR, MG_BIT(15));  // Reset PHY
  while (phy->read_reg(phy_addr, MG_PHY_REG_BCR) & MG_BIT(15)) (void) 0;
  // MG_PHY_REG_BCR[12]: Autonegotiation is default unless hw says otherwise

  id1 = phy->read_reg(phy_addr, MG_PHY_REG_ID1);
  id2 = phy->read_reg(phy_addr, MG_PHY_REG_ID2);
  MG_INFO(("PHY ID: %#04x %#04x (%s)", id1, id2, mg_phy_id_to_str(id1, id2)));

  if (id1 == MG_PHY_DP83x && id2 == MG_PHY_DP83867) {
    phy->write_reg(phy_addr, 0x0d, 0x1f);  // write 0x10d to IO_MUX_CFG (0x0170)
    phy->write_reg(phy_addr, 0x0e, 0x170);
    phy->write_reg(phy_addr, 0x0d, 0x401f);
    phy->write_reg(phy_addr, 0x0e, 0x10d);
  }

  if (config & MG_PHY_CLOCKS_MAC) {
    // Use PHY crystal oscillator (preserve defaults)
    // nothing to do
  } else {  // MAC clocks PHY, PHY has no xtal
    // Enable 50 MHz external ref clock at XI (preserve defaults)
    if (id1 == MG_PHY_DP83x && id2 != MG_PHY_DP83867 && id2 != MG_PHY_DP83848) {
      phy->write_reg(phy_addr, MG_PHY_DP83x_REG_RCSR, MG_BIT(7) | MG_BIT(0));
    } else if (id1 == MG_PHY_KSZ8x) {
      // Disable isolation (override hw, it doesn't make sense at this point)
      // - #2848, some NXP boards set ISO, even though docs say they don't
      phy->write_reg(phy_addr, MG_PHY_REG_BCR,
                     (uint16_t) (phy->read_reg(phy_addr, MG_PHY_REG_BCR) &
                                 (uint16_t) ~MG_BIT(10)));
      // now do clock stuff
      phy->write_reg(phy_addr, MG_PHY_KSZ8x_REG_PC2R,
                     (uint16_t) (MG_BIT(15) | MG_BIT(8) | MG_BIT(7)));
    } else if (id1 == MG_PHY_LAN87x) {
      // nothing to do
    } else if (id1 == MG_PHY_RTL82x && id2 == MG_PHY_RTL8201) {
      // assume PHY has been hardware strapped properly
#if 0
      phy->write_reg(phy_addr, MG_PHY_RTL82x_REG_PAGESEL, 7);  // Select page 7
      phy->write_reg(phy_addr, MG_PHY_RTL8201_REG_RMSR, 0x1ffa);
      phy->write_reg(phy_addr, MG_PHY_RTL82x_REG_PAGESEL, 0);  // Select page 0
#endif
    } else if (id1 == MG_PHY_RTL82x && id2 == MG_PHY_RTL8211) {
      // assume PHY has been hardware strapped properly
    }
  }

  if (config & MG_PHY_LEDS_ACTIVE_HIGH && id1 == MG_PHY_DP83x) {
    phy->write_reg(phy_addr, MG_PHY_DP83x_REG_LEDCR,
                   MG_BIT(9) | MG_BIT(7));  // LED status, active high
  }  // Other PHYs do not support this feature
}

bool mg_phy_up(struct mg_phy *phy, uint8_t phy_addr, bool *full_duplex,
               uint8_t *speed) {
  bool up = false;
  uint16_t bsr = phy->read_reg(phy_addr, MG_PHY_REG_BSR);
  if ((bsr & MG_BIT(5)) && !(bsr & MG_BIT(2)))  // some PHYs latch down events
    bsr = phy->read_reg(phy_addr, MG_PHY_REG_BSR);  // read again
  up = bsr & MG_BIT(2);
  if (up && full_duplex != NULL && speed != NULL) {
    uint16_t id1 = phy->read_reg(phy_addr, MG_PHY_REG_ID1);
    if (id1 == MG_PHY_DP83x) {
      uint16_t id2 = phy->read_reg(phy_addr, MG_PHY_REG_ID2);
      if (id2 == MG_PHY_DP83867) {
        uint16_t physts = phy->read_reg(phy_addr, MG_PHY_DP83867_REG_PHYSTS);
        *full_duplex = physts & MG_BIT(13);
        *speed = (physts & MG_BIT(15))   ? MG_PHY_SPEED_1000M
                 : (physts & MG_BIT(14)) ? MG_PHY_SPEED_100M
                                         : MG_PHY_SPEED_10M;
      } else {
        uint16_t physts = phy->read_reg(phy_addr, MG_PHY_DP83x_REG_PHYSTS);
        *full_duplex = physts & MG_BIT(2);
        *speed = (physts & MG_BIT(1)) ? MG_PHY_SPEED_10M : MG_PHY_SPEED_100M;
      }
    } else if (id1 == MG_PHY_KSZ8x) {
      uint16_t pc1r = phy->read_reg(phy_addr, MG_PHY_KSZ8x_REG_PC1R);
      *full_duplex = pc1r & MG_BIT(2);
      *speed = (pc1r & 3) == 1 ? MG_PHY_SPEED_10M : MG_PHY_SPEED_100M;
    } else if (id1 == MG_PHY_LAN87x) {
      uint16_t scsr = phy->read_reg(phy_addr, MG_PHY_LAN87x_REG_SCSR);
      *full_duplex = scsr & MG_BIT(4);
      *speed = (scsr & MG_BIT(3)) ? MG_PHY_SPEED_100M : MG_PHY_SPEED_10M;
    } else if (id1 == MG_PHY_RTL82x) {
      uint16_t id2 = phy->read_reg(phy_addr, MG_PHY_REG_ID2);
      if (id2 == MG_PHY_RTL8211) {
        uint16_t physr;
        phy->write_reg(phy_addr, MG_PHY_RTL82x_REG_PAGESEL, 0xa43);
        physr = phy->read_reg(phy_addr, MG_PHY_RTL8211_REG_PHYSR);
        phy->write_reg(phy_addr, MG_PHY_RTL82x_REG_PAGESEL, 0);
        *full_duplex = physr & MG_BIT(3);
        *speed = (physr & MG_BIT(5))   ? MG_PHY_SPEED_1000M
                 : (physr & MG_BIT(4)) ? MG_PHY_SPEED_100M
                                       : MG_PHY_SPEED_10M;
      } else {
        uint16_t bcr = phy->read_reg(phy_addr, MG_PHY_REG_BCR);
        *full_duplex = bcr & MG_BIT(8);
        *speed = (bcr & MG_BIT(13)) ? MG_PHY_SPEED_100M : MG_PHY_SPEED_10M;
      }
    } else if (id1 == MG_PHY_ICS1894x) {
      uint16_t poll_reg = phy->read_reg(phy_addr, MG_PHY_ICS189432_REG_POLL);
      *full_duplex = poll_reg & MG_BIT(14);
      *speed = (poll_reg & MG_BIT(15)) ? MG_PHY_SPEED_100M : MG_PHY_SPEED_10M;
    }
  }
  return up;
}

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/pico-w.c"
#endif
#if MG_ENABLE_TCPIP && MG_ARCH == MG_ARCH_PICOSDK && \
    defined(MG_ENABLE_DRIVER_PICO_W) && MG_ENABLE_DRIVER_PICO_W





static struct mg_tcpip_if *s_ifp;
static uint32_t s_ip, s_mask;
static bool s_aplink = false, s_scanning = false;
static bool s_stalink = false, s_connecting = false;

static void wifi_cb(struct mg_tcpip_if *ifp, int ev, void *ev_data) {
  struct mg_wifi_data *wifi =
      &((struct mg_tcpip_driver_pico_w_data *) ifp->driver_data)->wifi;
  if (wifi->apmode && ev == MG_TCPIP_EV_ST_CHG &&
      *(uint8_t *) ev_data == MG_TCPIP_STATE_UP) {
    MG_DEBUG(("Access Point started"));
    s_ip = ifp->ip, ifp->ip = wifi->apip;
    s_mask = ifp->mask, ifp->mask = wifi->apmask;
    ifp->enable_dhcp_client = false;
    ifp->enable_dhcp_server = true;
  }
}

static bool mg_tcpip_driver_pico_w_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_pico_w_data *d =
      (struct mg_tcpip_driver_pico_w_data *) ifp->driver_data;
  struct mg_wifi_data *wifi = &d->wifi;
  s_ifp = ifp;
  s_ip = ifp->ip;
  s_mask = ifp->mask;
  ifp->pfn = wifi_cb;
  if (cyw43_arch_init() != 0)
    return false;  // initialize async_context and WiFi chip
  if (wifi->apmode && wifi->apssid != NULL) {
    if (!mg_wifi_ap_start(wifi)) return false;
    cyw43_wifi_get_mac(&cyw43_state, CYW43_ITF_STA, ifp->mac);  // same MAC
  } else {
    cyw43_arch_enable_sta_mode();
    cyw43_wifi_get_mac(&cyw43_state, CYW43_ITF_STA, ifp->mac);
    if (wifi->ssid != NULL) {
      return mg_wifi_connect(wifi);
    } else {
      cyw43_arch_disable_sta_mode();
    }
  }
  return true;
}

static size_t mg_tcpip_driver_pico_w_tx(const void *buf, size_t len,
                                        struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_pico_w_data *d =
      (struct mg_tcpip_driver_pico_w_data *) ifp->driver_data;
  return cyw43_send_ethernet(&cyw43_state,
                             d->wifi.apmode ? CYW43_ITF_AP : CYW43_ITF_STA, len,
                             buf, false) == 0
             ? len
             : 0;
}

static bool mg_tcpip_driver_pico_w_poll(struct mg_tcpip_if *ifp, bool s1) {
  cyw43_arch_poll();  // not necessary, except when IRQs are disabled (OTA)
  if (s_scanning && !cyw43_wifi_scan_active(&cyw43_state)) {
    MG_VERBOSE(("scan complete"));
    s_scanning = 0;
    mg_tcpip_call(ifp, MG_TCPIP_EV_WIFI_SCAN_END, NULL);
  }
  if (ifp->update_mac_hash_table) {
    // first call to _poll() is after _init(), so this is safe
    cyw43_wifi_update_multicast_filter(&cyw43_state, (uint8_t *) mcast_addr,
                                       true);
    ifp->update_mac_hash_table = false;
  }
  if (!s1) return false;
  struct mg_tcpip_driver_pico_w_data *d =
      (struct mg_tcpip_driver_pico_w_data *) ifp->driver_data;
  if (d->wifi.apmode) return s_aplink;
  int sdkstate = cyw43_wifi_link_status(&cyw43_state, CYW43_ITF_STA);
  MG_VERBOSE(("conn: %c state: %d", s_connecting ? '1' : '0', sdkstate));
  if (sdkstate < 0 && s_connecting) {
    mg_tcpip_call(ifp, MG_TCPIP_EV_WIFI_CONNECT_ERR, &sdkstate);
    s_connecting = false;
  }
  return s_stalink;
}

struct mg_tcpip_driver mg_tcpip_driver_pico_w = {
    mg_tcpip_driver_pico_w_init,
    mg_tcpip_driver_pico_w_tx,
    NULL,
    mg_tcpip_driver_pico_w_poll,
};

// Called once per outstanding frame by async_context
void cyw43_cb_process_ethernet(void *cb_data, int itf, size_t len,
                               const uint8_t *buf) {
  mg_tcpip_qwrite((void *) buf, len, s_ifp);
  (void) cb_data;
}

// Called by async_context
void cyw43_cb_tcpip_set_link_up(cyw43_t *self, int itf) {
  if (itf == CYW43_ITF_AP) {
    s_aplink = true;
  } else {
    s_stalink = true;
    s_connecting = false;
  }
}
void cyw43_cb_tcpip_set_link_down(cyw43_t *self, int itf) {
  if (itf == CYW43_ITF_AP) {
    s_aplink = false;
  } else {
    s_stalink = false;
    // SDK calls this before we check status, don't clear s_connecting here
  }
}

// there's life beyond lwIP
void pbuf_copy_partial(void) {
  (void) 0;
}

static int result_cb(void *arg, const cyw43_ev_scan_result_t *data) {
  struct mg_wifi_scan_bss_data bss;
  bss.SSID = mg_str_n(data->ssid, data->ssid_len);
  bss.BSSID = (char *) data->bssid;
  bss.RSSI = (int8_t) data->rssi;
  bss.has_n = 0;  // SDK ignores this
  bss.channel = (uint8_t) data->channel;
  bss.band = MG_WIFI_BAND_2G;
  // SDK-internal dependency, 2.1.0
  bss.security = data->auth_mode & MG_BIT(0) ? MG_WIFI_SECURITY_WEP
                                             : MG_WIFI_SECURITY_OPEN;
  if (data->auth_mode & MG_BIT(1)) bss.security |= MG_WIFI_SECURITY_WPA;
  if (data->auth_mode & MG_BIT(2)) bss.security |= MG_WIFI_SECURITY_WPA2;
  MG_VERBOSE(("BSS: %.*s (%u) (%M) %d dBm %u", bss.SSID.len, bss.SSID.buf,
              bss.channel, mg_print_mac, bss.BSSID, (int) bss.RSSI,
              bss.security));
  mg_tcpip_call(s_ifp, MG_TCPIP_EV_WIFI_SCAN_RESULT, &bss);
  return 0;
}

bool mg_wifi_scan(void) {
  cyw43_wifi_scan_options_t opts;
  memset(&opts, 0, sizeof(opts));
  bool res = (cyw43_wifi_scan(&cyw43_state, &opts, NULL, result_cb) == 0);
  if (res) s_scanning = true;
  return res;
}

bool mg_wifi_connect(struct mg_wifi_data *wifi) {
  s_ifp->ip = s_ip;
  s_ifp->mask = s_mask;
  if (s_ifp->ip == 0) s_ifp->enable_dhcp_client = true;
  s_ifp->enable_dhcp_server = false;
  cyw43_arch_enable_sta_mode();
  MG_DEBUG(("Connecting to '%s'", wifi->ssid));
  int res = cyw43_arch_wifi_connect_async(wifi->ssid, wifi->pass,
                                          CYW43_AUTH_WPA2_AES_PSK);
  MG_VERBOSE(("res: %d", res));
  if (res == 0) s_connecting = true;
  return (res == 0);
}

bool mg_wifi_disconnect(void) {
  cyw43_arch_disable_sta_mode();
  s_connecting = false;
  return true;
}

bool mg_wifi_ap_start(struct mg_wifi_data *wifi) {
  MG_DEBUG(("Starting AP '%s' (%u)", wifi->apssid, wifi->apchannel));
  cyw43_wifi_ap_set_channel(&cyw43_state, wifi->apchannel);
  cyw43_arch_enable_ap_mode(wifi->apssid, wifi->appass,
                            CYW43_AUTH_WPA2_AES_PSK);
  return true;
}

bool mg_wifi_ap_stop(void) {
  cyw43_arch_disable_ap_mode();
  return true;
}

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/ppp.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_PPP) && MG_ENABLE_DRIVER_PPP

#define MG_PPP_FLAG 0x7e  // PPP frame delimiter
#define MG_PPP_ESC 0x7d   // PPP escape byte for special characters
#define MG_PPP_ADDR 0xff
#define MG_PPP_CTRL 0x03

#define MG_PPP_PROTO_IP 0x0021
#define MG_PPP_PROTO_LCP 0xc021
#define MG_PPP_PROTO_IPCP 0x8021

#define MG_PPP_IPCP_REQ 1
#define MG_PPP_IPCP_ACK 2
#define MG_PPP_IPCP_NACK 3
#define MG_PPP_IPCP_IPADDR 3

#define MG_PPP_LCP_CFG_REQ 1
#define MG_PPP_LCP_CFG_ACK 2
#define MG_PPP_LCP_CFG_NACK 3
#define MG_PPP_LCP_CFG_REJECT 4
#define MG_PPP_LCP_CFG_TERM_REQ 5
#define MG_PPP_LCP_CFG_TERM_ACK 6

#define MG_PPP_AT_TIMEOUT 2000

static size_t print_atcmd(void (*out)(char, void *), void *arg, va_list *ap) {
  struct mg_str s = va_arg(*ap, struct mg_str);
  for (size_t i = 0; i < s.len; i++) out(s.buf[i] < 0x20 ? '.' : s.buf[i], arg);
  return s.len;
}

static void mg_ppp_reset(struct mg_tcpip_driver_ppp_data *dd) {
  dd->script_index = 0;
  dd->deadline = 0;
  if (dd->reset) dd->reset(dd->uart);
}

static bool mg_ppp_atcmd_handle(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_ppp_data *dd =
      (struct mg_tcpip_driver_ppp_data *) ifp->driver_data;
  if (dd->script == NULL || dd->script_index < 0) return true;
  if (dd->deadline == 0) dd->deadline = mg_millis() + MG_PPP_AT_TIMEOUT;
  for (;;) {
    if (dd->script_index % 2 == 0) {  // send AT command
      const char *cmd = dd->script[dd->script_index];
      MG_DEBUG(("send AT[%d]: %M", dd->script_index, print_atcmd, mg_str(cmd)));
      while (*cmd) dd->tx(dd->uart, *cmd++);
      dd->script_index++;
      ifp->recv_queue.head = 0;
    } else {  // check AT command response
      const char *expect = dd->script[dd->script_index];
      struct mg_queue *q = &ifp->recv_queue;
      for (;;) {
        int c;
        int is_timeout = dd->deadline > 0 && mg_millis() > dd->deadline;
        int is_overflow = q->head >= q->size - 1;
        if (is_timeout || is_overflow) {
          MG_ERROR(("AT error: %s, retrying...",
                    is_timeout ? "timeout" : "overflow"));
          mg_ppp_reset(dd);
          return false;  // FAIL: timeout
        }
        if ((c = dd->rx(dd->uart)) < 0) return false;  // no data
        q->buf[q->head++] = c;
        if (mg_match(mg_str_n(q->buf, q->head), mg_str(expect), NULL)) {
          MG_DEBUG(("recv AT[%d]: %M", dd->script_index, print_atcmd,
                    mg_str_n(q->buf, q->head)));
          dd->script_index++;
          q->head = 0;
          break;
        }
      }
    }
    if (dd->script[dd->script_index] == NULL) {
      MG_DEBUG(("finished AT script"));
      dd->script_index = -1;
      return true;
    }
  }
}

static bool mg_ppp_init(struct mg_tcpip_if *ifp) {
  ifp->recv_queue.size = 3000;  // MTU=1500, worst case escaping = 2x
  return true;
}

// Calculate FCS/CRC for PPP frames. Could be implemented faster using lookup
// tables.
static uint32_t fcs_do(uint32_t fcs, uint8_t x) {
  for (int i = 0; i < 8; i++) {
    fcs = ((fcs ^ x) & 1) ? (fcs >> 1) ^ 0x8408 : fcs >> 1;
    x >>= 1;
  }
  return fcs;
}

static bool mg_ppp_poll(struct mg_tcpip_if *ifp, bool s1) {
  (void) s1;
  return ifp->driver_data != NULL;
}

// Transmit a single byte as part of the PPP frame (escaped, if needed)
static void mg_ppp_tx_byte(struct mg_tcpip_driver_ppp_data *dd, uint8_t b) {
  if ((b < 0x20) || (b == MG_PPP_ESC) || (b == MG_PPP_FLAG)) {
    dd->tx(dd->uart, MG_PPP_ESC);
    dd->tx(dd->uart, b ^ 0x20);
  } else {
    dd->tx(dd->uart, b);
  }
}

// Transmit a single PPP frame for the given protocol
static void mg_ppp_tx_frame(struct mg_tcpip_driver_ppp_data *dd, uint16_t proto,
                            uint8_t *data, size_t datasz) {
  uint16_t crc;
  uint32_t fcs = 0xffff;

  dd->tx(dd->uart, MG_PPP_FLAG);
  mg_ppp_tx_byte(dd, MG_PPP_ADDR);
  mg_ppp_tx_byte(dd, MG_PPP_CTRL);
  mg_ppp_tx_byte(dd, proto >> 8);
  mg_ppp_tx_byte(dd, proto & 0xff);
  fcs = fcs_do(fcs, MG_PPP_ADDR);
  fcs = fcs_do(fcs, MG_PPP_CTRL);
  fcs = fcs_do(fcs, proto >> 8);
  fcs = fcs_do(fcs, proto & 0xff);
  for (unsigned int i = 0; i < datasz; i++) {
    mg_ppp_tx_byte(dd, data[i]);
    fcs = fcs_do(fcs, data[i]);
  }
  crc = fcs & 0xffff;
  mg_ppp_tx_byte(dd, ~crc);  // send CRC, note the byte order
  mg_ppp_tx_byte(dd, ~crc >> 8);
  dd->tx(dd->uart, MG_PPP_FLAG);  // end of frame
}

// Send Ethernet frame as PPP frame
static size_t mg_ppp_tx(const void *buf, size_t len, struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_ppp_data *dd =
      (struct mg_tcpip_driver_ppp_data *) ifp->driver_data;
  if (ifp->state != MG_TCPIP_STATE_READY) return 0;
  // XXX: what if not an IP protocol?
  mg_ppp_tx_frame(dd, MG_PPP_PROTO_IP, (uint8_t *) buf + 14, len - 14);
  return len;
}

// Given a full PPP frame, unescape it in place and verify FCS, returns actual
// data size on success or 0 on error.
static size_t mg_ppp_verify_frame(uint8_t *buf, size_t bufsz) {
  int unpack = 0;
  uint16_t crc;
  size_t pktsz = 0;
  uint32_t fcs = 0xffff;
  for (unsigned int i = 0; i < bufsz; i++) {
    if (unpack == 0) {
      if (buf[i] == 0x7d) {
        unpack = 1;
      } else {
        buf[pktsz] = buf[i];
        fcs = fcs_do(fcs, buf[pktsz]);
        pktsz++;
      }
    } else {
      unpack = 0;
      buf[pktsz] = buf[i] ^ 0x20;
      fcs = fcs_do(fcs, buf[pktsz]);
      pktsz++;
    }
  }
  crc = fcs & 0xffff;
  if (crc != 0xf0b8) {
    MG_DEBUG(("bad crc: %04x", crc));
    return 0;
  }
  if (pktsz < 6 || buf[0] != MG_PPP_ADDR || buf[1] != MG_PPP_CTRL) {
    return 0;
  }
  return pktsz - 2;  // strip FCS
}

// fetch as much data as we can, until a single PPP frame is received
static size_t mg_ppp_rx_frame(struct mg_tcpip_driver_ppp_data *dd,
                              struct mg_queue *q) {
  while (q->head < q->size) {
    int c;
    if ((c = dd->rx(dd->uart)) < 0) {
      return 0;
    }
    if (c == MG_PPP_FLAG) {
      if (q->head > 0) {
        break;
      } else {
        continue;
      }
    }
    q->buf[q->head++] = c;
  }

  size_t n = mg_ppp_verify_frame((uint8_t *) q->buf, q->head);
  if (n == 0) {
    MG_DEBUG(("invalid PPP frame of %d bytes", q->head));
    q->head = 0;
    return 0;
  }
  q->head = n;
  return q->head;
}

static void mg_ppp_handle_lcp(struct mg_tcpip_if *ifp, uint8_t *lcp,
                              size_t lcpsz) {
  uint8_t id;
  uint16_t len;
  struct mg_tcpip_driver_ppp_data *dd =
      (struct mg_tcpip_driver_ppp_data *) ifp->driver_data;
  if (lcpsz < 4) return;
  id = lcp[1];
  len = (((uint16_t) lcp[2]) << 8) | (lcp[3]);
  switch (lcp[0]) {
    case MG_PPP_LCP_CFG_REQ: {
      if (len == 4) {
        MG_DEBUG(("LCP config request of %d bytes, acknowledging...", len));
        lcp[0] = MG_PPP_LCP_CFG_ACK;
        mg_ppp_tx_frame(dd, MG_PPP_PROTO_LCP, lcp, len);
        lcp[0] = MG_PPP_LCP_CFG_REQ;
        mg_ppp_tx_frame(dd, MG_PPP_PROTO_LCP, lcp, len);
      } else {
        MG_DEBUG(("LCP config request of %d bytes, rejecting...", len));
        lcp[0] = MG_PPP_LCP_CFG_REJECT;
        mg_ppp_tx_frame(dd, MG_PPP_PROTO_LCP, lcp, len);
      }
    } break;
    case MG_PPP_LCP_CFG_TERM_REQ: {
      uint8_t ack[4] = {MG_PPP_LCP_CFG_TERM_ACK, id, 0, 4};
      MG_DEBUG(("LCP termination request, acknowledging..."));
      mg_ppp_tx_frame(dd, MG_PPP_PROTO_LCP, ack, sizeof(ack));
      mg_ppp_reset(dd);
      ifp->state = MG_TCPIP_STATE_UP;
      if (dd->reset) dd->reset(dd->uart);
    } break;
  }
}

static void mg_ppp_handle_ipcp(struct mg_tcpip_if *ifp, uint8_t *ipcp,
                               size_t ipcpsz) {
  struct mg_tcpip_driver_ppp_data *dd =
      (struct mg_tcpip_driver_ppp_data *) ifp->driver_data;
  uint16_t len;
  uint8_t id;
  uint8_t req[] = {
      MG_PPP_IPCP_REQ, 0, 0, 10, MG_PPP_IPCP_IPADDR, 6, 0, 0, 0, 0};
  if (ipcpsz < 4) return;
  id = ipcp[1];
  len = (((uint16_t) ipcp[2]) << 8) | (ipcp[3]);
  switch (ipcp[0]) {
    case MG_PPP_IPCP_REQ:
      MG_DEBUG(("got IPCP config request, acknowledging..."));
      if (len >= 10 && ipcp[4] == MG_PPP_IPCP_IPADDR) {
        uint8_t *ip = ipcp + 6;
        MG_DEBUG(("host ip: %d.%d.%d.%d", ip[0], ip[1], ip[2], ip[3]));
      }
      ipcp[0] = MG_PPP_IPCP_ACK;
      mg_ppp_tx_frame(dd, MG_PPP_PROTO_IPCP, ipcp, len);
      req[1] = id;
      // Request IP address 0.0.0.0
      mg_ppp_tx_frame(dd, MG_PPP_PROTO_IPCP, req, sizeof(req));
      break;
    case MG_PPP_IPCP_ACK:
      // This usually does not happen, as our "preferred" IP address is invalid
      MG_DEBUG(("got IPCP config ack, link is online now"));
      ifp->state = MG_TCPIP_STATE_READY;
      break;
    case MG_PPP_IPCP_NACK:
      MG_DEBUG(("got IPCP config nack"));
      // NACK contains our "suggested" IP address, use it
      if (len >= 10 && ipcp[4] == MG_PPP_IPCP_IPADDR) {
        uint8_t *ip = ipcp + 6;
        MG_DEBUG(("ipcp ack, ip: %d.%d.%d.%d", ip[0], ip[1], ip[2], ip[3]));
        ipcp[0] = MG_PPP_IPCP_REQ;
        mg_ppp_tx_frame(dd, MG_PPP_PROTO_IPCP, ipcp, len);
        ifp->ip = ifp->mask = MG_IPV4(ip[0], ip[1], ip[2], ip[3]);
        ifp->state = MG_TCPIP_STATE_READY;
      }
      break;
  }
}

static size_t mg_ppp_rx(void *ethbuf, size_t ethlen, struct mg_tcpip_if *ifp) {
  uint8_t *eth = ethbuf;
  size_t ethsz = 0;
  struct mg_tcpip_driver_ppp_data *dd =
      (struct mg_tcpip_driver_ppp_data *) ifp->driver_data;
  uint8_t *buf = (uint8_t *) ifp->recv_queue.buf;

  if (!mg_ppp_atcmd_handle(ifp)) return 0;

  size_t bufsz = mg_ppp_rx_frame(dd, &ifp->recv_queue);
  if (!bufsz) return 0;
  uint16_t proto = (((uint16_t) buf[2]) << 8) | (uint16_t) buf[3];
  switch (proto) {
    case MG_PPP_PROTO_LCP: mg_ppp_handle_lcp(ifp, buf + 4, bufsz - 4); break;
    case MG_PPP_PROTO_IPCP: mg_ppp_handle_ipcp(ifp, buf + 4, bufsz - 4); break;
    case MG_PPP_PROTO_IP:
      MG_VERBOSE(("got IP packet of %d bytes", bufsz - 4));
      memmove(eth + 14, buf + 4, bufsz - 4);
      memmove(eth, ifp->mac, 6);
      memmove(eth + 6, "\xff\xff\xff\xff\xff\xff", 6);
      eth[12] = 0x08;
      eth[13] = 0x00;
      ethsz = bufsz - 4 + 14;
      ifp->recv_queue.head = 0;
      return ethsz;
#if 0
    default:
      MG_DEBUG(("unknown PPP frame:"));
      mg_hexdump(ppp->buf, ppp->bufsz);
#endif
  }
  ifp->recv_queue.head = 0;
  return 0;
  (void) ethlen;
}

struct mg_tcpip_driver mg_tcpip_driver_ppp = {mg_ppp_init, mg_ppp_tx, mg_ppp_rx,
                                              mg_ppp_poll};

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/ra.c"
#endif


#if MG_ENABLE_TCPIP && \
  (defined(MG_ENABLE_DRIVER_RA6) && MG_ENABLE_DRIVER_RA6) || \
  (defined(MG_ENABLE_DRIVER_RA8) && MG_ENABLE_DRIVER_RA8)
struct ra_etherc {
  volatile uint32_t ECMR, RESERVED, RFLR, RESERVED1, ECSR, RESERVED2, ECSIPR,
      RESERVED3, PIR, RESERVED4, PSR, RESERVED5[5], RDMLR, RESERVED6[3], IPGR,
      APR, MPR, RESERVED7, RFCF, TPAUSER, TPAUSECR, BCFRR, RESERVED8[20], MAHR,
      RESERVED9, MALR, RESERVED10, TROCR, CDCR, LCCR, CNDCR, RESERVED11, CEFCR,
      FRECR, TSFRCR, TLFRCR, RFCR, MAFCR;
};

struct ra_edmac {
  volatile uint32_t EDMR, RESERVED, EDTRR, RESERVED1, EDRRR, RESERVED2, TDLAR,
      RESERVED3, RDLAR, RESERVED4, EESR, RESERVED5, EESIPR, RESERVED6, TRSCER,
      RESERVED7, RMFCR, RESERVED8, TFTR, RESERVED9, FDR, RESERVED10, RMCR,
      RESERVED11[2], TFUCR, RFOCR, IOSR, FCFTR, RESERVED12, RPADIR, TRIMD,
      RESERVED13[18], RBWAR, RDFAR, RESERVED14, TBRAR, TDFAR;
};

#undef ETHERC
#undef EDMAC
#undef RASYSC
#undef ICU_IELSR
#if defined(MG_ENABLE_DRIVER_RA8) && MG_ENABLE_DRIVER_RA8
#define ETHERC ((struct ra_etherc *) (uintptr_t) 0x40354100U)
#define EDMAC ((struct ra_edmac *) (uintptr_t) 0x40354000U)
#define RASYSC ((uint32_t *) (uintptr_t) 0x4001E000U)
#define ICU_IELSR ((uint32_t *) (uintptr_t) 0x4000C300U)
#else
#define ETHERC ((struct ra_etherc *) (uintptr_t) 0x40114100U)
#define EDMAC ((struct ra_edmac *) (uintptr_t) 0x40114000U)
#define RASYSC ((uint32_t *) (uintptr_t) 0x4001E000U)
#define ICU_IELSR ((uint32_t *) (uintptr_t) 0x40006300U)
#endif

#define ETH_PKT_SIZE 1536  // Max frame size, multiple of 32
#define ETH_DESC_CNT 4     // Descriptors count

// Descriptors: 16-byte aligned
// Buffers: 32-byte aligned (27.3.1)
static volatile uint32_t s_rxdesc[ETH_DESC_CNT][4] MG_ETH_RAM MG_16BYTE_ALIGNED;
static volatile uint32_t s_txdesc[ETH_DESC_CNT][4] MG_ETH_RAM MG_16BYTE_ALIGNED;
static uint8_t s_rxbuf[ETH_DESC_CNT][ETH_PKT_SIZE] MG_ETH_RAM MG_32BYTE_ALIGNED;
static uint8_t s_txbuf[ETH_DESC_CNT][ETH_PKT_SIZE] MG_ETH_RAM MG_32BYTE_ALIGNED;
static struct mg_tcpip_if *s_ifp;  // MIP interface

// fastest is 3 cycles (SUB + BNE) on a 3-stage pipeline or equivalent
static inline void raspin(volatile uint32_t count) {
  while (count--) (void) 0;
}
// count to get the 200ns SMC semi-cycle period (2.5MHz) calling raspin():
// SYS_FREQUENCY * 200ns / 3 = SYS_FREQUENCY / 15000000
static uint32_t s_smispin;

// Bit-banged SMI
static void smi_preamble(void) {
  unsigned int i = 32;
  uint32_t pir = MG_BIT(1) | MG_BIT(2);  // write, mdio = 1, mdc = 0
  ETHERC->PIR = pir;
  while (i--) {
    pir &= ~MG_BIT(0);  // mdc = 0
    ETHERC->PIR = pir;
    raspin(s_smispin);
    pir |= MG_BIT(0);  // mdc = 1
    ETHERC->PIR = pir;
    raspin(s_smispin);
  }
}
static void smi_wr(uint16_t header, uint16_t data) {
  uint32_t word = (header << 16) | data;
  smi_preamble();
  unsigned int i = 32;
  while (i--) {
    uint32_t pir = MG_BIT(1) |
                   (word & 0x80000000 ? MG_BIT(2) : 0);  // write, mdc = 0, data
    ETHERC->PIR = pir;
    raspin(s_smispin);
    pir |= MG_BIT(0);  // mdc = 1
    ETHERC->PIR = pir;
    raspin(s_smispin);
    word <<= 1;
  }
}
static uint16_t smi_rd(uint16_t header) {
  smi_preamble();
  unsigned int i = 16;  // 2 LSb as turnaround
  uint32_t pir;
  while (i--) {
    pir = (i > 1 ? MG_BIT(1) : 0) |
          (header & 0x8000
               ? MG_BIT(2)
               : 0);  // mdc = 0, header, set read direction at turnaround
    ETHERC->PIR = pir;
    raspin(s_smispin);
    pir |= MG_BIT(0);  // mdc = 1
    ETHERC->PIR = pir;
    raspin(s_smispin);
    header <<= 1;
  }
  i = 16;
  uint16_t data = 0;
  while (i--) {
    data <<= 1;
    pir = 0;  // read, mdc = 0
    ETHERC->PIR = pir;
    raspin(s_smispin / 2);  // 1/4 clock period, 300ns max access time
    data |= (uint16_t) (ETHERC->PIR & MG_BIT(3) ? 1 : 0);  // read mdio
    raspin(s_smispin / 2);                                 // 1/4 clock period
    pir |= MG_BIT(0);                                      // mdc = 1
    ETHERC->PIR = pir;
    raspin(s_smispin);
  }
  return data;
}

static uint16_t raeth_read_phy(uint8_t addr, uint8_t reg) {
  return smi_rd(
      (uint16_t) ((1 << 14) | (2 << 12) | (addr << 7) | (reg << 2) | (2 << 0)));
}

static void raeth_write_phy(uint8_t addr, uint8_t reg, uint16_t val) {
  smi_wr(
      (uint16_t) ((1 << 14) | (1 << 12) | (addr << 7) | (reg << 2) | (2 << 0)),
      val);
}

// MDC clock is generated manually; as per 802.3, it must not exceed 2.5MHz
static bool mg_tcpip_driver_ra_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_ra_data *d =
      (struct mg_tcpip_driver_ra_data *) ifp->driver_data;
  s_ifp = ifp;

  // Init SMI clock timing. If user told us the clock value, use it.
  // TODO(): Otherwise, guess
  s_smispin = d->clock / 15000000;

  // Init RX descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_rxdesc[i][0] = MG_BIT(31);             // RACT
    s_rxdesc[i][1] = ETH_PKT_SIZE << 16;     // RBL
    s_rxdesc[i][2] = (uint32_t) s_rxbuf[i];  // Point to data buffer
  }
  s_rxdesc[ETH_DESC_CNT - 1][0] |= MG_BIT(30);  // Wrap last descriptor

  // Init TX descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    // TACT = 0
    s_txdesc[i][2] = (uint32_t) s_txbuf[i];
  }
  s_txdesc[ETH_DESC_CNT - 1][0] |= MG_BIT(30);  // Wrap last descriptor

  EDMAC->EDMR = MG_BIT(0);  // Software reset, wait 64 PCLKA clocks (27.2.1)
  uint32_t sckdivcr = RASYSC[8];  // get divisors from SCKDIVCR (8.2.2)
  uint32_t ick = 1 << ((sckdivcr >> 24) & 7);   // sys_clock div
  uint32_t pcka = 1 << ((sckdivcr >> 12) & 7);  // pclka div
  raspin((64U * pcka) / (3U * ick));
  EDMAC->EDMR = MG_BIT(6);  // Initialize, little-endian (27.2.1)

  MG_DEBUG(("PHY addr: %d, smispin: %d", d->phy_addr, s_smispin));
  struct mg_phy phy = {raeth_read_phy, raeth_write_phy};
  mg_phy_init(&phy, d->phy_addr, MG_PHY_CLOCKS_MAC);

  // Select RMII mode,
  ETHERC->ECMR = MG_BIT(2) | MG_BIT(1);  // 100M, Full-duplex, CRC
  // ETHERC->ECMR |= MG_BIT(0);             // Receive all
  ETHERC->RFLR = 1518;  // Set max rx length

  EDMAC->RDLAR = (uint32_t) (uintptr_t) s_rxdesc;
  EDMAC->TDLAR = (uint32_t) (uintptr_t) s_txdesc;
  // MAC address filtering (bytes in reversed order)
  ETHERC->MAHR = (uint32_t) (ifp->mac[0] << 24U) |
                 ((uint32_t) ifp->mac[1] << 16U) |
                 ((uint32_t) ifp->mac[2] << 8U) | ifp->mac[3];
  ETHERC->MALR = ((uint32_t) ifp->mac[4] << 8U) | ifp->mac[5];

  EDMAC->TFTR = 0;                        // Store and forward (27.2.10)
  EDMAC->FDR = 0x070f;                    // (27.2.11)
  EDMAC->RMCR = MG_BIT(0);                // (27.2.12)
  ETHERC->ECMR |= MG_BIT(6) | MG_BIT(5);  // TE RE
  EDMAC->EESIPR = MG_BIT(18);  // FR: Enable Rx (frame) IRQ
  EDMAC->EDRRR = MG_BIT(0);  // Receive Descriptors have changed
  EDMAC->EDTRR = MG_BIT(0);  // Transmit Descriptors have changed
  return true;
}

// Transmit frame
static size_t mg_tcpip_driver_ra_tx(const void *buf, size_t len,
                                    struct mg_tcpip_if *ifp) {
  static int s_txno;  // Current descriptor index
  if (len > sizeof(s_txbuf[ETH_DESC_CNT])) {
    MG_ERROR(("Frame too big, %ld", (long) len));
    len = (size_t) -1;  // fail
  } else if ((s_txdesc[s_txno][0] & MG_BIT(31))) {
    ifp->nerr++;
    MG_ERROR(("No descriptors available"));
    len = 0;  // retry later
  } else {
    memcpy(s_txbuf[s_txno], buf, len);            // Copy data
    s_txdesc[s_txno][1] = len << 16;              // Set data len
    s_txdesc[s_txno][0] |= MG_BIT(31) | 3 << 28;  // (27.3.1.1) mark valid
    EDMAC->EDTRR = MG_BIT(0);                     // Transmit request
    if (++s_txno >= ETH_DESC_CNT) s_txno = 0;
  }
  return len;
}

static bool mg_tcpip_driver_ra_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (ifp->update_mac_hash_table) {
    EDMAC->EESIPR = MG_BIT(18) | MG_BIT(7);  // FR, RMAF: Frame and mcast IRQ
    ifp->update_mac_hash_table = false;
  }
  if (!s1) return false;
  struct mg_tcpip_driver_ra_data *d =
      (struct mg_tcpip_driver_ra_data *) ifp->driver_data;
  uint8_t speed = MG_PHY_SPEED_10M;
  bool up = false, full_duplex = false;
  struct mg_phy phy = {raeth_read_phy, raeth_write_phy};
  up = mg_phy_up(&phy, d->phy_addr, &full_duplex, &speed);
  if ((ifp->state == MG_TCPIP_STATE_DOWN) && up) {  // link state just went up
    // tmp = reg with flags set to the most likely situation: 100M full-duplex
    // if(link is slow or half) set flags otherwise
    // reg = tmp
    uint32_t ecmr = ETHERC->ECMR | MG_BIT(2) | MG_BIT(1);  // 100M Full-duplex
    if (speed == MG_PHY_SPEED_10M) ecmr &= ~MG_BIT(2);     // 10M
    if (full_duplex == false) ecmr &= ~MG_BIT(1);          // Half-duplex
    ETHERC->ECMR = ecmr;  // IRQ handler does not fiddle with these registers
    MG_DEBUG(("Link is %uM %s-duplex", ecmr & MG_BIT(2) ? 100 : 10,
              ecmr & MG_BIT(1) ? "full" : "half"));
  }
  return up;
}

void EDMAC_IRQHandler(void);
static uint32_t s_rxno;
void EDMAC_IRQHandler(void) {
  struct mg_tcpip_driver_ra_data *d =
      (struct mg_tcpip_driver_ra_data *) s_ifp->driver_data;
  EDMAC->EESR = MG_BIT(18) | MG_BIT(7);  // Ack IRQ in EDMAC 1st
  ICU_IELSR[d->irqno] &= ~MG_BIT(16);  // Ack IRQ in ICU last
  // Frame received, loop
  for (uint32_t i = 0; i < 10; i++) {  // read as they arrive but not forever
    uint32_t r = s_rxdesc[s_rxno][0];
    if (r & MG_BIT(31)) break;  // exit when done
    // skip partial/errored frames (27.3.1.2)
    if ((r & (MG_BIT(29) | MG_BIT(28)) && !(r & MG_BIT(27)))) {
      size_t len = s_rxdesc[s_rxno][1] & 0xffff;
      mg_tcpip_qwrite(s_rxbuf[s_rxno], len, s_ifp);  // CRC already stripped
    }
    s_rxdesc[s_rxno][0] |= MG_BIT(31);
    if (++s_rxno >= ETH_DESC_CNT) s_rxno = 0;
  }
  EDMAC->EDRRR = MG_BIT(0);  // Receive Descriptors have changed
  // If b0 == 0, descriptors were exhausted and probably frames were dropped,
  // (27.2.9 RMFCR counts them)
}

struct mg_tcpip_driver mg_tcpip_driver_ra = {mg_tcpip_driver_ra_init,
                                             mg_tcpip_driver_ra_tx, NULL,
                                             mg_tcpip_driver_ra_poll};

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/rw612.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_RW612) && MG_ENABLE_DRIVER_RW612

struct ENET_Type {
  volatile uint32_t RESERVED_0[1], EIR, EIMR, RESERVED_1[1], RDAR, TDAR,
      RESERVED_2[3], ECR, RESERVED_3[6], MMFR, MSCR, RESERVED_4[7], MIBC,
      RESERVED_5[7], RCR, RESERVED_6[15], TCR, RESERVED_7[7], PALR, PAUR, OPD,
      TXIC[1], RESERVED_8[3], RXIC[1], RESERVED_9[5], IAUR, IALR, GAUR, GALR,
      RESERVED_10[7], TFWR, RESERVED_11[14], RDSR, TDSR, MRBR, RESERVED_12[1],
      RSFL, RSEM, RAEM, RAFL, TSEM, TAEM, TAFL, TIPG, FTRL, RESERVED_13[3],
      TACC, RACC, RESERVED_14[15], RMON_T_PACKETS, RMON_T_BC_PKT, RMON_T_MC_PKT,
      RMON_T_CRC_ALIGN, RMON_T_UNDERSIZE, RMON_T_OVERSIZE, RMON_T_FRAG,
      RMON_T_JAB, RMON_T_COL, RMON_T_P64, RMON_T_P65TO127, RMON_T_P128TO255,
      RMON_T_P256TO511, RMON_T_P512TO1023, RMON_T_P1024TO2047, RMON_T_P_GTE2048,
      RMON_T_OCTETS, IEEE_T_DROP, IEEE_T_FRAME_OK, IEEE_T_1COL, IEEE_T_MCOL,
      IEEE_T_DEF, IEEE_T_LCOL, IEEE_T_EXCOL, IEEE_T_MACERR, IEEE_T_CSERR,
      IEEE_T_SQE, IEEE_T_FDXFC, IEEE_T_OCTETS_OK, RESERVED_15[3],
      RMON_R_PACKETS, RMON_R_BC_PKT, RMON_R_MC_PKT, RMON_R_CRC_ALIGN,
      RMON_R_UNDERSIZE, RMON_R_OVERSIZE, RMON_R_FRAG, RMON_R_JAB,
      RESERVED_16[1], RMON_R_P64, RMON_R_P65TO127, RMON_R_P128TO255,
      RMON_R_P256TO511, RMON_R_P512TO1023, RMON_R_P1024TO2047, RMON_R_P_GTE2048,
      RMON_R_OCTETS, IEEE_R_DROP, IEEE_R_FRAME_OK, IEEE_R_CRC, IEEE_R_ALIGN,
      IEEE_R_MACERR, IEEE_R_FDXFC, IEEE_R_OCTETS_OK, RESERVED_17[71], ATCR,
      ATVR, ATOFF, ATPER, ATCOR, ATINC, ATSTMP, RESERVED_18[122], TGSR,
      CHANNEL_TCSR[4], CHANNEL_TCCR[4];
};

#undef ENET
#define ENET ((struct ENET_Type *) 0x40138000)

#define ETH_PKT_SIZE 1536  // Max frame size
#define ETH_DESC_CNT 4     // Descriptors count
#define ETH_DS 2           // Descriptor size (words)

static uint8_t s_rxbuf[ETH_DESC_CNT][ETH_PKT_SIZE] MG_ETH_RAM MG_8BYTE_ALIGNED;
static uint8_t s_txbuf[ETH_DESC_CNT][ETH_PKT_SIZE] MG_ETH_RAM MG_8BYTE_ALIGNED;
static uint32_t s_rxdesc[ETH_DESC_CNT][ETH_DS] MG_ETH_RAM MG_8BYTE_ALIGNED;
static uint32_t s_txdesc[ETH_DESC_CNT][ETH_DS] MG_ETH_RAM MG_8BYTE_ALIGNED;
static uint8_t s_txno;  // Current TX descriptor
static uint8_t s_rxno;  // Current RX descriptor

static struct mg_tcpip_if *s_ifp;  // MIP interface

static uint16_t eth_read_phy(uint8_t addr, uint8_t reg) {
  ENET->MMFR = MG_BIT(30) |  // Start of frame delimiter
               MG_BIT(29) |  // Opcode
               ((addr & 0x1f) << 23) | ((reg & 0x1f) << 18) | MG_BIT(17);
  while ((ENET->EIR & MG_BIT(23)) == 0) (void) 0;
  ENET->EIR |= MG_BIT(23);
  return ENET->MMFR & 0xffff;
}

static void eth_write_phy(uint8_t addr, uint8_t reg, uint16_t val) {
  ENET->MMFR = MG_BIT(30) |  // Start of frame delimiter
               MG_BIT(28) |  // Opcode
               ((addr & 0x1f) << 23) | ((reg & 0x1f) << 18) | MG_BIT(17) | val;
  while ((ENET->EIR & MG_BIT(23)) == 0) (void) 0;
  ENET->EIR |= MG_BIT(23);
}

static bool mg_tcpip_driver_rw612_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_rw612_data *d =
      (struct mg_tcpip_driver_rw612_data *) ifp->driver_data;
  s_ifp = ifp;
  ENET->MSCR = ((d->mdc_cr & 0x3f) << 1) | ((d->mdc_holdtime & 7) << 8);
  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  mg_phy_init(&phy, d->phy_addr, 0);
  ENET->ECR |= MG_BIT(0);  // reset ETH

  // initialize descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_rxdesc[i][1] = (uint32_t) s_rxbuf[i];
    s_rxdesc[i][0] = MG_BIT(31);  // OWN
    if (i == ETH_DESC_CNT - 1) {
      s_rxdesc[i][0] |= MG_BIT(29);  // mark last descriptor
    }
    s_txdesc[i][1] = (uint32_t) s_txbuf[i];
    if (i == ETH_DESC_CNT - 1) {
      s_txdesc[i][0] |= MG_BIT(29);  // mark last descriptor
    }
  }

  ENET->RCR = (ENET->RCR & (0xffff << 16)) | MG_BIT(14) | MG_BIT(8) | MG_BIT(2);
  ENET->TCR = MG_BIT(2);  // full duplex
  ENET->TDSR = (uint32_t) &s_txdesc[0][0];
  ENET->RDSR = (uint32_t) &s_rxdesc[0][0];
  ENET->MRBR = ETH_PKT_SIZE;
  ENET->PALR =
      ifp->mac[0] << 24 | ifp->mac[1] << 16 | ifp->mac[2] << 8 | ifp->mac[3];
  ENET->PAUR |= (ifp->mac[4] << 24 | ifp->mac[5] << 16);
  ENET->IALR = 0;
  ENET->IAUR = 0;
  ENET->GALR = 0;
  ENET->GAUR = 0;
  ENET->MSCR = ((d->mdc_cr & 0x3f) << 1) | ((d->mdc_holdtime & 7) << 8);
  ENET->EIMR = MG_BIT(25);             // Enable RX interrupt
  ENET->ECR |= MG_BIT(8) | MG_BIT(1);  // DBSWP, Enable
  ENET->RDAR = 0;                      // activate RX descriptors ring
  return true;
}

static size_t mg_tcpip_driver_rw612_tx(const void *buf, size_t len,
                                       struct mg_tcpip_if *ifp) {
  if (len > sizeof(s_txbuf[s_txno])) {
    MG_ERROR(("Frame too big, %ld", (long) len));
    len = 0;  // Frame is too big
  } else if (((s_txdesc[s_txno][0] & MG_BIT(31)) != 0)) {
    ifp->nerr++;
    MG_ERROR(("No free descriptors"));
    len = 0;  // All descriptors are busy, fail
  } else {
    memcpy(s_txbuf[s_txno], buf, len);
    s_txdesc[s_txno][0] = len | MG_BIT(27) | MG_BIT(26);  // last buffer, crc
    if (s_txno == ETH_DESC_CNT - 1) {
      s_txdesc[s_txno][0] |= MG_BIT(29);  // wrap
    }
    s_txdesc[s_txno][0] |= MG_BIT(31);  // release ownership
    MG_DSB();
    ENET->TDAR = 0;
    // MG_INFO(("s_txdesc[%d][0]: 0x%x", s_txno, s_txdesc[s_txno][0]));
    if (++s_txno >= ETH_DESC_CNT) s_txno = 0;
  }

  return len;
}


static void mg_tcpip_driver_rw612_update_hash_table(struct mg_tcpip_if *ifp) {
  // TODO(): read database, rebuild hash table
  ENET->GAUR = MG_BIT(1); // see imxrt, it reduces to this for mDNS
  (void) ifp;
}

static bool mg_tcpip_driver_rw612_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (ifp->update_mac_hash_table) {
    mg_tcpip_driver_rw612_update_hash_table(ifp);
    ifp->update_mac_hash_table = false;
  }
  if (!s1) return false;
  struct mg_tcpip_driver_rw612_data *d =
      (struct mg_tcpip_driver_rw612_data *) ifp->driver_data;
  uint8_t speed = MG_PHY_SPEED_10M;
  bool up = false, full_duplex = false;
  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  up = mg_phy_up(&phy, d->phy_addr, &full_duplex, &speed);
  if ((ifp->state == MG_TCPIP_STATE_DOWN) && up) {  // link state just went up
    // tmp = reg with flags set to the most likely situation: 100M full-duplex
    // if(link is slow or half) set flags otherwise
    // reg = tmp
    if (speed == MG_PHY_SPEED_100M && (ENET->RCR & MG_BIT(9))) {
      ENET->RCR &= ~MG_BIT(9);
    } else if (speed == MG_PHY_SPEED_10M && (ENET->RCR & MG_BIT(9)) == 0) {
      ENET->RCR |= MG_BIT(9);
    }
    if (full_duplex && (ENET->TCR & MG_BIT(2)) == 0) {
      ENET->ECR &= ~MG_BIT(1);
      ENET->TCR |= MG_BIT(2);
      ENET->ECR |= MG_BIT(1);
    } else if (!full_duplex && (ENET->TCR & MG_BIT(2))) {
      ENET->ECR &= ~MG_BIT(1);
      ENET->TCR &= ~MG_BIT(2);
      ENET->ECR |= MG_BIT(1);
    }
    MG_INFO(("Link is %uM %s-duplex",
             speed == MG_PHY_SPEED_10M
                 ? 10
                 : (speed == MG_PHY_SPEED_100M ? 100 : 1000),
             full_duplex ? "full" : "half"));
  }
  return up;
}

void ENET_IRQHandler(void) {
  if (ENET->EIR & MG_BIT(25)) {
    ENET->EIR = MG_BIT(25);              // Ack RX
    for (uint32_t i = 0; i < 10; i++) {  // read as they arrive but not forever
      if ((s_rxdesc[s_rxno][0] & MG_BIT(31)) != 0) break;  // exit when done
      // skip partial/errored frames
      if ((s_rxdesc[s_rxno][0] & MG_BIT(27)) &&
          !(s_rxdesc[s_rxno][0] &
            (MG_BIT(21) | MG_BIT(20) | MG_BIT(18) | MG_BIT(17) | MG_BIT(16)))) {
        size_t len = s_rxdesc[s_rxno][0] & 0xffff;
        mg_tcpip_qwrite(s_rxbuf[s_rxno], len, s_ifp);
        s_rxdesc[s_rxno][0] |= MG_BIT(31);  // OWN bit: handle control to DMA
        MG_DSB();
        ENET->RDAR = 0;
        if (++s_rxno >= ETH_DESC_CNT) s_rxno = 0;
      }
    }
  }
}

struct mg_tcpip_driver mg_tcpip_driver_rw612 = {mg_tcpip_driver_rw612_init,
                                                mg_tcpip_driver_rw612_tx, NULL,
                                                mg_tcpip_driver_rw612_poll};
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/same54.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_SAME54) && \
    MG_ENABLE_DRIVER_SAME54

struct GMAC_REGS_ {
  uint32_t GMAC_NCR, GMAC_NCFGR, GMAC_NSR, GMAC_UR, GMAC_DCFGR, GMAC_TSR,
      GMAC_RBQB, GMAC_TBQB, GMAC_RSR, GMAC_ISR, GMAC_IER, GMAC_IDR, GMAC_IMR,
      GMAC_MAN, GMAC_RPQ, GMAC_TPQ, GMAC_TPSF, GMAC_RPSF, GMAC_RJFML,
      Reserved1[13], GMAC_HRB, GMAC_HRT, GMAC_SAB0, GMAC_SAT0, GMAC_SAB1,
      GMAC_SAT1, GMAC_SAB2, GMAC_SAT2, GMAC_SAB3, GMAC_SAT3, GMAC_TIDM[4],
      GMAC_WOL, GMAC_IPGS, GMAC_SVLAN, GMAC_TPFCP, GMAC_SAMB1, GMAC_SAMT1,
      Reserved2[3], GMAC_NSC, GMAC_SCL, GMAC_SCH, GMAC_EFTSH, GMAC_EFRSH,
      GMAC_PEFTSH, GMAC_PEFRSH, Reserved3[2], GMAC_OTLO, GMAC_OTHI, GMAC_FT,
      GMAC_BCFT, GMAC_MFT, GMAC_PFT, GMAC_BFT64, GMAC_TBFT127, GMAC_TBFT255,
      GMAC_TBFT511, GMAC_TBFT1023, GMAC_TBFT1518, GMAC_GTBFT1518, GMAC_TUR,
      GMAC_SCF, GMAC_MCF, GMAC_EC, GMAC_LC, GMAC_DTF, GMAC_CSE, GMAC_ORLO,
      GMAC_ORHI, GMAC_FR, GMAC_BCFR, GMAC_MFR, GMAC_PFR, GMAC_BFR64,
      GMAC_TBFR127, GMAC_TBFR255, GMAC_TBFR511, GMAC_TBFR1023, GMAC_TBFR1518,
      GMAC_TMXBFR, GMAC_UFR, GMAC_OFR, GMAC_JR, GMAC_FCSE, GMAC_LFFE, GMAC_RSE,
      GMAC_AE, GMAC_RRE, GMAC_ROE, GMAC_IHCE, GMAC_TCE, GMAC_UCE, Reserved4[2],
      GMAC_TISUBN, GMAC_TSH, Reserved5, GMAC_TSSSL, GMAC_TSSN, GMAC_TSL,
      GMAC_TN, GMAC_TA, GMAC_TI, GMAC_EFTSL, GMAC_EFTN, GMAC_EFRSL, GMAC_EFRN,
      GMAC_PEFTSL, GMAC_PEFTN, GMAC_PEFRSL, GMAC_PEFRN, Reserved6[28],
      GMAC_RLPITR, GMAC_RLPITI, GMAC_TLPITR, GMAC_TLPITI;
};

struct GCLK_REGS_ {
  uint32_t GCLK_CTRLA_RESERVED, GCLK_SYNCBUSY, Reserved2[6], GCLK_GENCTRL[12],
      Reserved3[12], GCLK_PCHCTRL[48];
};

#define GMAC_REGS ((struct GMAC_REGS_ *) 0x42000800)
#define GCLK_REGS ((struct GCLK_REGS_ *) 0x40001c00)

#define ETH_PKT_SIZE 1536  // Max frame size
#define ETH_DESC_CNT 4     // Descriptors count
#define ETH_DS 2           // Descriptor size (words)

static uint8_t s_rxbuf[ETH_DESC_CNT][ETH_PKT_SIZE];
static uint8_t s_txbuf[ETH_DESC_CNT][ETH_PKT_SIZE];
static uint32_t s_rxdesc[ETH_DESC_CNT][ETH_DS];  // RX descriptors
static uint32_t s_txdesc[ETH_DESC_CNT][ETH_DS];  // TX descriptors
static uint8_t s_txno;                           // Current TX descriptor
static uint8_t s_rxno;                           // Current RX descriptor

static struct mg_tcpip_if *s_ifp;  // MIP interface

static uint16_t eth_read_phy(uint8_t addr, uint8_t reg) {
  GMAC_REGS->GMAC_MAN = MG_BIT(30) |  // Clause 22
                        MG_BIT(29) |  // Setting the read operation
                        MG_BIT(17) | ((addr & 0x1f) << 23) |  // PHY address
                        ((reg & 0x1f) << 18);  // Setting the register
  while (!(GMAC_REGS->GMAC_NSR & MG_BIT(2))) (void) 0;
  return GMAC_REGS->GMAC_MAN & 0xffff;  // Getting the read value
}

static void eth_write_phy(uint8_t addr, uint8_t reg, uint16_t val) {
  GMAC_REGS->GMAC_MAN = MG_BIT(30) |
                        MG_BIT(28) |  // Setting the write operation
                        MG_BIT(17) | ((addr & 0x1f) << 23) |  // PHY address
                        ((reg & 0x1f) << 18) | val;  // Setting the register
  while (!(GMAC_REGS->GMAC_NSR & MG_BIT(2)))
    ;  // Waiting until the write op is complete
}

uint32_t get_clock_rate(struct mg_tcpip_driver_same54_data *d) {
  if (d && d->mdc_cr >= 0 && d->mdc_cr <= 5) {
    return d->mdc_cr;
  } else {
    // get MCLK from GCLK_GENERATOR 0
    uint32_t div = 512;
    uint32_t mclk;
    if (!(GCLK_REGS->GCLK_GENCTRL[0] & MG_BIT(12))) {
      div = ((GCLK_REGS->GCLK_GENCTRL[0] & 0x00FF0000) >> 16);
      if (div == 0) div = 1;
    }
    switch (GCLK_REGS->GCLK_GENCTRL[0] & 0xF) {
      case 0:               // GCLK_GENCTRL_SRC_XOSC0_Val
        mclk = 32000000UL;  // 32MHz
        break;
      case 1:               // GCLK_GENCTRL_SRC_XOSC1_Val
        mclk = 32000000UL;  // 32MHz
        break;
      case 4:            // GCLK_GENCTRL_SRC_OSCULP32K_Val
        mclk = 32000UL;  // 32Khz
        break;
      case 5:            // GCLK_GENCTRL_SRC_XOSC32K_Val
        mclk = 32000UL;  // 32Khz
        break;
      case 6:               // GCLK_GENCTRL_SRC_DFLL_Val
        mclk = 48000000UL;  // 48MHz
        break;
      case 7:                // GCLK_GENCTRL_SRC_DPLL0_Val:
        mclk = 200000000UL;  // 200MHz
        break;
      case 8:                // GCLK_GENCTRL_SRC_DPLL1_Val
        mclk = 200000000UL;  // 200MHz
        break;
      default:
        mclk = 200000000UL;  // 200MHz
    }

    mclk /= div;
    uint8_t crs[] = {0, 1, 2, 3, 4, 5};            // GMAC->NCFGR::CLK values
    uint8_t dividers[] = {8, 16, 32, 48, 64, 96};  // Respective CLK dividers
    for (int i = 0; i < 6; i++) {
      if (mclk / dividers[i] <= 2375000UL) {  // 2.5MHz - 5%
        return crs[i];
      }
    }

    return 5;
  }
}

static bool mg_tcpip_driver_same54_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_same54_data *d =
      (struct mg_tcpip_driver_same54_data *) ifp->driver_data;
  s_ifp = ifp;

  GMAC_REGS->GMAC_NCFGR = get_clock_rate(d) << 18;  // Set MDC divider
  GMAC_REGS->GMAC_NCR = 0;                          // Disable RX & TX
  GMAC_REGS->GMAC_NCR |= MG_BIT(4);                 // Enable MDC & MDIO

  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  mg_phy_init(&phy, d->phy_addr, 0);

  for (int i = 0; i < ETH_DESC_CNT; i++) {   // Init TX descriptors
    s_txdesc[i][0] = (uint32_t) s_txbuf[i];  // Point to data buffer
    s_txdesc[i][1] = MG_BIT(31);             // OWN bit
  }
  s_txdesc[ETH_DESC_CNT - 1][1] |= MG_BIT(30);  // Last tx descriptor - wrap

  GMAC_REGS->GMAC_DCFGR = (0x18 << 16) |     // DMA recv buf 1536
                          (3 << 8) |         // RXBMS
                          MG_BIT(10);        // See #2487
  for (int i = 0; i < ETH_DESC_CNT; i++) {   // Init RX descriptors
    s_rxdesc[i][0] = (uint32_t) s_rxbuf[i];  // Address of the data buffer
    s_rxdesc[i][1] = 0;                      // Clear status
  }
  s_rxdesc[ETH_DESC_CNT - 1][0] |= MG_BIT(1);  // Last rx descriptor - wrap

  GMAC_REGS->GMAC_TBQB = (uint32_t) s_txdesc;  // about the descriptor addresses
  GMAC_REGS->GMAC_RBQB = (uint32_t) s_rxdesc;  // Let the controller know

  GMAC_REGS->GMAC_SAB0 =
      MG_U32(ifp->mac[3], ifp->mac[2], ifp->mac[1], ifp->mac[0]);
  GMAC_REGS->GMAC_SAT0 = MG_U32(0, 0, ifp->mac[5], ifp->mac[4]);

  GMAC_REGS->GMAC_UR &= ~MG_BIT(0);                 // Disable MII, use RMII
  GMAC_REGS->GMAC_NCFGR |= MG_BIT(8) | MG_BIT(6) |  // MAXFX, MTIHEN
                           MG_BIT(25) | MG_BIT(4);  // EFRHD, CAF
  GMAC_REGS->GMAC_TSR = 0x17f;                      // all transmit statuses
  GMAC_REGS->GMAC_RSR = 0xf;                        // all recv statuses
  GMAC_REGS->GMAC_IDR = ~0U;  // Disable interrupts, then enable required
  GMAC_REGS->GMAC_IER = MG_BIT(11) | MG_BIT(10) |  // HRESP, ROVR
                        MG_BIT(7) | MG_BIT(6) |    // TCOMP, TFC
                        MG_BIT(5) | MG_BIT(4) |    // RLEX, TUR
                        MG_BIT(2) | MG_BIT(1);     // RXUBR, RCOMP
  GMAC_REGS->GMAC_NCR |= MG_BIT(3) | MG_BIT(2);    // TXEN, RXEN

  return true;
}

static size_t mg_tcpip_driver_same54_tx(const void *buf, size_t len,
                                        struct mg_tcpip_if *ifp) {
  if (len > sizeof(s_txbuf[s_txno])) {
    MG_ERROR(("Frame too big, %ld", (long) len));
    len = 0;  // Frame is too big
  } else if ((s_txdesc[s_txno][1] & MG_BIT(31)) == 0) {
    ifp->nerr++;
    MG_ERROR(("No free descriptors"));
    len = 0;  // All descriptors are busy, fail
  } else {
    uint32_t status = len | MG_BIT(15);  // Frame length, last chunk
    if (s_txno == ETH_DESC_CNT - 1) status |= MG_BIT(30);  // wrap
    memcpy(s_txbuf[s_txno], buf, len);                     // Copy data
    s_txdesc[s_txno][1] = status;
    if (++s_txno >= ETH_DESC_CNT) s_txno = 0;
  }
  MG_DSB();                          // Ensure descriptors have been written
  GMAC_REGS->GMAC_NCR |= MG_BIT(9);  // Enable transmission
  return len;
}

static void mg_tcpip_driver_same54_update_hash_table(struct mg_tcpip_if *ifp) {
  // TODO(): read database, rebuild hash table
  // Setting Hash Index for 01:00:5e:00:00:fb (multicast)
  // 24.6.9 Hash addressing
  // computed hash is 55, which means bit 23 (55 - 32) in
  // HRT register must be set
  GMAC_REGS->GMAC_HRT = MG_BIT(23);
  GMAC_REGS->GMAC_NCFGR |= MG_BIT(6);  // enable multicast hash filtering
  (void) ifp;
}

static bool mg_tcpip_driver_same54_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (ifp->update_mac_hash_table) {
    mg_tcpip_driver_same54_update_hash_table(ifp);
    ifp->update_mac_hash_table = false;
  }

  bool up = false;
  if (s1) {
    uint8_t speed = MG_PHY_SPEED_10M;
    bool full_duplex = false;
    struct mg_phy phy = {eth_read_phy, eth_write_phy};
    up = mg_phy_up(&phy, 0, &full_duplex, &speed);

    // If PHY is ready, update NCFGR accordingly
    if (ifp->state == MG_TCPIP_STATE_DOWN && up) {
      GMAC_REGS->GMAC_NCFGR =
          (GMAC_REGS->GMAC_NCFGR & ~(MG_BIT(0) | MG_BIT(1))) | (speed & 1) |
          (full_duplex << 1);
    }
  }
  return up;
}

void GMAC_Handler(void);
void GMAC_Handler(void) {
  uint32_t isr = GMAC_REGS->GMAC_ISR;
  uint32_t rsr = GMAC_REGS->GMAC_RSR;
  uint32_t tsr = GMAC_REGS->GMAC_TSR;
  if (isr & MG_BIT(1)) {
    if (rsr & MG_BIT(1)) {
      for (uint8_t i = 0; i < ETH_DESC_CNT; i++) {
        if ((s_rxdesc[s_rxno][0] & MG_BIT(0)) == 0) break;
        size_t len = s_rxdesc[s_rxno][1] & (MG_BIT(13) - 1);
        mg_tcpip_qwrite(s_rxbuf[s_rxno], len, s_ifp);
        s_rxdesc[s_rxno][0] &= ~MG_BIT(0);  // Disown
        if (++s_rxno >= ETH_DESC_CNT) s_rxno = 0;
      }
    }
  }

  if (tsr != 0) {
    // MG_INFO((" --> %#x %#x", s_txdesc[s_txno][1], tsr));
    if (!(s_txdesc[s_txno][1] & MG_BIT(31))) s_txdesc[s_txno][1] |= MG_BIT(31);
  }

  GMAC_REGS->GMAC_RSR = rsr;
  GMAC_REGS->GMAC_TSR = tsr;
}

struct mg_tcpip_driver mg_tcpip_driver_same54 = {
    mg_tcpip_driver_same54_init, mg_tcpip_driver_same54_tx, NULL,
    mg_tcpip_driver_same54_poll};
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/sdio.c"
#endif


#if MG_ENABLE_TCPIP && \
    (defined(MG_ENABLE_DRIVER_CYW_SDIO) && MG_ENABLE_DRIVER_CYW_SDIO)

// SDIO 6.9 Table 6-1 CCCR (Common Card Control Registers)
#define MG_SDIO_CCCR_SDIOREV 0x000
#define MG_SDIO_CCCR_SDREV 0x001
#define MG_SDIO_CCCR_IOEN 0x002
#define MG_SDIO_CCCR_IORDY 0x003
#define MG_SDIO_CCCR_INTEN 0x004
#define MG_SDIO_CCCR_BIC 0x007
#define MG_SDIO_CCCR_CCAP 0x008
#define MG_SDIO_CCCR_CCIS 0x009     // 3 registers
#define MG_SDIO_CCCR_F0BLKSZ 0x010  // 2 registers
#define MG_SDIO_CCCR_HISPD 0x013
// SDIO 6.10 Table 6-3 FBR (Function Basic Registers)
#define MG_SDIO_FBR_FnBLKSZ(n) (((n) &7) * 0x100 + 0x10)  // 2 registers

// SDIO 5.1 IO_RW_DIRECT Command (CMD52)
#define MG_SDIO_DATA(x) ((x) &0xFF)            // bits 0-7
#define MG_SDIO_ADDR(x) (((x) &0x1FFFF) << 9)  // bits 9-25
#define MG_SDIO_FUNC(x) (((x) &3) << 28)       // bits 28-30 (30 unused here)
#define MG_SDIO_WR MG_BIT(31)

// SDIO 5.3 IO_RW_EXTENDED Command (CMD53)
#define MG_SDIO_LEN(x) ((x) &0x1FF)  // bits 0-8
#define MG_SDIO_OPINC MG_BIT(26)
#define MG_SDIO_BLKMODE MG_BIT(27)

// - Drivers set blocksize, drivers request transfers. Requesting a read
// transfer > blocksize means block transfer will be used.
// - To simplify the use of DMA transfers and avoid intermediate buffers,
// drivers must have room to accomodate a whole block transfer, e.g.: blocksize
// = 64, read 65 => 2 blocks = 128 bytes
// - Transfers of more than 1 byte assume (uint32_t *) data. 1-byte transfers
// use (uint8_t *) data
// - 'len' is the number of _bytes_ to transfer
bool mg_sdio_transfer(struct mg_tcpip_sdio *sdio, bool write, unsigned int f,
                      uint32_t addr, void *data, uint32_t len) {
  uint32_t arg, val = 0;
  unsigned int blksz = 64;  // TODO(): mg_sdio_set_blksz() stores in an array,
                            // index on f, skip if 0
  if (len == 1) {
    arg = (write ? MG_SDIO_WR : 0) | MG_SDIO_FUNC(f) | MG_SDIO_ADDR(addr) |
          (write ? MG_SDIO_DATA(*(uint8_t *) data) : 0);
    bool res = sdio->txn(sdio, 52, arg, &val);  // IO_RW_DIRECT
    if (!write) *(uint8_t *) data = (uint8_t) val;
    return res;
  }
  // IO_RW_EXTENDED
  arg = (write ? MG_SDIO_WR : 0) | MG_SDIO_OPINC | MG_SDIO_FUNC(f) |
        MG_SDIO_ADDR(addr);
  if (len > 512 || (blksz != 0 && len > blksz)) {  // SDIO 5.3 512 -> len=0
    unsigned int blkcnt;
    if (blksz == 0) return false;  // > 512 requires block size set
    blkcnt = (len + blksz - 1) / blksz;
    if (blkcnt > 511) return false;  // we don't support "infinite" blocks
    arg |= MG_SDIO_BLKMODE | MG_SDIO_LEN(blkcnt);  // block transfer
    len = blksz * blkcnt;
  } else {
    arg |= MG_SDIO_LEN(len);  // multi-byte transfer
  }
  return sdio->xfr(sdio, write, arg,
                   (arg & MG_SDIO_BLKMODE) ? (uint16_t) blksz : 0,
                   (uint32_t *) data, len, &val);
}

bool mg_sdio_set_blksz(struct mg_tcpip_sdio *sdio, unsigned int f,
                       uint16_t blksz) {
  uint32_t val = blksz & 0xff;
  if (!mg_sdio_transfer(sdio, true, 0, MG_SDIO_FBR_FnBLKSZ(f), &val, 1))
    return false;
  val = (blksz >> 8) & 0x0f;  // SDIO 6.10 Table 6-4, max 2048
  if (!mg_sdio_transfer(sdio, true, 0, MG_SDIO_FBR_FnBLKSZ(f) + 1, &val, 1))
    return false;
  // TODO(): store in an array, index on f. Static 8-element array
  MG_VERBOSE(("F%c block size set", (f & 7) + '0'));
  return true;
}

// Enable Fx
bool mg_sdio_enable_f(struct mg_tcpip_sdio *sdio, unsigned int f) {
  uint8_t bit = 1U << (f & 7), bits;
  uint32_t val = 0;
  if (!mg_sdio_transfer(sdio, false, 0, MG_SDIO_CCCR_IOEN, &val, 1))
    return false;
  bits = (uint8_t) val | bit;
  unsigned int times = 501;
  while (times--) {
    val = bits; /* IOEf */
    ;
    if (!mg_sdio_transfer(sdio, true, 0, MG_SDIO_CCCR_IOEN, &val, 1))
      return false;
    mg_delayms(1);
    val = 0;
    if (!mg_sdio_transfer(sdio, false, 0, MG_SDIO_CCCR_IOEN, &val, 1))
      return false;
    if (val & bit) break;
  }
  if (times == (unsigned int) ~0) return false;
  MG_VERBOSE(("F%c enabled", (f & 7) + '0'));
  return true;
}

// Wait for Fx to be ready
bool mg_sdio_waitready_f(struct mg_tcpip_sdio *sdio, unsigned int f) {
  uint8_t bit = 1U << (f & 7);
  unsigned int times = 501;
  while (times--) {
    uint32_t val;
    if (!mg_sdio_transfer(sdio, false, 0, MG_SDIO_CCCR_IORDY, &val, 1))
      return false;
    if (val & bit) break;  // IORf
    mg_delayms(1);
  }
  if (times == (unsigned int) ~0) return false;
  MG_VERBOSE(("F%c ready", (f & 7) + '0'));
  return true;
}

// SDIO 6.14 Bus State Diagram
bool mg_sdio_init(struct mg_tcpip_sdio *sdio) {
  uint32_t val = 0;
  if (!sdio->txn(sdio, 0, 0, NULL)) return false;  // GO_IDLE_STATE
  sdio->txn(sdio, 5, 0, &val);                     // IO_SEND_OP_COND, no CRC
  MG_VERBOSE(("IO Functions: %u, Memory: %c", 1 + ((val >> 28) & 7),
              (val & MG_BIT(27)) ? 'Y' : 'N'));
  if (!sdio->txn(sdio, 3, 0, &val)) return false;  // SEND_RELATIVE_ADDR
  val = ((uint32_t) val) >> 16;                    // RCA
  if (!sdio->txn(sdio, 7, val << 16, &val))
    return false;  // SELECT/DESELECT_CARD
  mg_sdio_transfer(sdio, false, 0, MG_SDIO_CCCR_SDIOREV, &val, 1);
  MG_DEBUG(("CCCR: %u.%u, SDIO: %u.%u", 1 + ((val >> 2) & 3), (val >> 0) & 3,
            1 + ((val >> 6) & 3), (val >> 4) & 3));
  mg_sdio_transfer(sdio, false, 0, MG_SDIO_CCCR_SDREV, &val, 1);
  MG_VERBOSE(("SD: %u.%u", 1 + ((val >> 2) & 3), (val >> 0) & 3));
  mg_sdio_transfer(sdio, false, 0, MG_SDIO_CCCR_BIC, &val, 1);
  MG_SET_BITS(val, 3,
              MG_BIT(7) | MG_BIT(1));  // SDIO 6.9 Tables 6-1 6-2, 4-bit bus
  mg_sdio_transfer(sdio, true, 0, MG_SDIO_CCCR_BIC, &val, 1);
  // All Full-Speed SDIO cards support a 4-bit bus. Skip for Low-Speed SDIO
  // cards, we don't provide separate low-level functions for width and speed
  sdio->cfg(sdio, 0);  // set DS;
  if (!mg_sdio_transfer(sdio, false, 0, MG_SDIO_CCCR_HISPD, &val, 1))
    return false;
  if (val & MG_BIT(0) /* SHS */) {
    val = MG_BIT(1); /* EHS */
    if (!mg_sdio_transfer(sdio, true, 0, MG_SDIO_CCCR_HISPD, &val, 1))
      return false;
    sdio->cfg(sdio, 1);  // set HS;
    MG_VERBOSE(("Bus set to 4-bit @50MHz"));
  } else {
    MG_VERBOSE(("Bus set to 4-bit @25MHz"));
  }
  return true;
}

// - 6.11 Card Information Structure (CIS): 0x0001000-0x017FF; for card common
// and all functions
// - 16.5 SDIO Card Metaformat
// - 16.7.2 CISTPL_FUNCE (0x22): Function Extension Tuple, provides standard
// information about the card (common) and each individual function. One
// CISTPL_FUNCE in each function’s CIS, immediately following the CISTPL_FUNCID
// tuple
// - 16.7.3 CISTPL_FUNCE Tuple for Function 0 (common)
// - 16.7.4 CISTPL_FUNCE Tuple for Function 1-7

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/st67w6.c"
#endif



#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_ST67W6) && \
    MG_ENABLE_DRIVER_ST67W6

static struct mg_tcpip_if *s_ifp;
static uint32_t s_ip, s_mask;
static bool s_link = false, s_connecting = false;

static void wifi_cb(struct mg_tcpip_if *ifp, int ev, void *ev_data) {
  struct mg_wifi_data *wifi =
      &((struct mg_tcpip_driver_st67w6_data *) ifp->driver_data)->wifi;
  if (wifi->apmode && ev == MG_TCPIP_EV_ST_CHG &&
      *(uint8_t *) ev_data == MG_TCPIP_STATE_UP) {
    MG_DEBUG(("Access Point started"));
    s_ip = ifp->ip, ifp->ip = wifi->apip;
    s_mask = ifp->mask, ifp->mask = wifi->apmask;
    ifp->enable_dhcp_client = false;
    ifp->enable_dhcp_server = true;
  }
}

static bool st67w6_init(uint8_t *mac);
static void st67w6_poll(bool is_at);

static bool mg_tcpip_driver_st67w6_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_st67w6_data *d =
      (struct mg_tcpip_driver_st67w6_data *) ifp->driver_data;
  struct mg_wifi_data *wifi = &d->wifi;
  if (MG_BIG_ENDIAN) {
    MG_ERROR(("Big-endian host"));
    return false;
  }
  if (d->is_ready == NULL) return false;
  s_ifp = ifp;
  s_ip = ifp->ip;
  s_mask = ifp->mask;
  s_link = false;
  ifp->pfn = wifi_cb;
  if (!st67w6_init(ifp->mac)) return false;

  if (d->send_queue.size == 0) d->send_queue.size = 8192;
  d->send_queue.buf = (char *) mg_calloc(1, d->send_queue.size);
  if (d->send_queue.buf == NULL) {
    MG_ERROR(("OOM"));
    return false;
  }

  if (wifi->apmode) {
    return mg_wifi_ap_start(wifi);
  } else if (wifi->ssid != NULL && wifi->pass != NULL) {
    return mg_wifi_connect(wifi);
  }
  return true;
}

// Decouple; module access depends on it being RDY. See st67w6_poll()
size_t mg_tcpip_driver_st67w6_output(const void *buf, size_t len,
                                     struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_st67w6_data *d =
      (struct mg_tcpip_driver_st67w6_data *) ifp->driver_data;
  char *p;
  if (mg_queue_book(&d->send_queue, &p, len) < len) return 0;
  memcpy(p, buf, len);
  mg_queue_add(&d->send_queue, len);
  return len;
}

static bool mg_tcpip_driver_st67w6_poll(struct mg_tcpip_if *ifp, bool s1) {
  struct mg_tcpip_driver_st67w6_data *d =
      (struct mg_tcpip_driver_st67w6_data *) ifp->driver_data;
  if (d->is_ready == NULL) return false;
  st67w6_poll(false);
  if (!s1) return false;
  return s_link;
}

struct mg_tcpip_driver mg_tcpip_driver_st67w6 = {
    mg_tcpip_driver_st67w6_init, mg_tcpip_driver_st67w6_output, NULL,
    mg_tcpip_driver_st67w6_poll};

//  AT | STA | AP | HCI | OT
// --------------------------
//       framing             <-- includes rx stall indication
// --------------------------
//         SPI               <-- padded to 32-bit
//
// Transactions take place when the module signals RDY, 'tx' and 'write'
// functions actually just write to memory
// - AT: handles configuration and events (unsolicited +foo:). Responses may
// come as:
//   - 1 frame: just OK or ERROR
//   - 2 frames: 1 text line each, a response and OK
//   - 3 frames: 2 text lines: 1 frame with text and no CR/LF, 1 frame with
//   binary and CR/LF, 1 text line with OK
// - STA and AP contain plain Ethernet frames to/from the STA and AP networks,
// respectively
// - HCI: BLE stuff
// - OT: ?

#pragma pack(push, 1)
// little endian

struct spi_hdr {
  uint16_t magic;
  uint16_t len;
  uint8_t vflags;  // version :2, rx_stall :1, flags :5
  uint8_t type;
  uint16_t reserved;
};

#define ST67W6_SPI_TYPE_AT 0
#define ST67W6_SPI_TYPE_STA 1
#define ST67W6_SPI_TYPE_AP 2
#define ST67W6_SPI_TYPE_HCI 3
#define ST67W6_SPI_TYPE_OT 4

#pragma pack(pop)

static uint32_t txdata[2048 / 4], rxdata[2048 / 4];
static uint8_t at_resp[300];

static bool s_at_ok, s_at_err;
static size_t s_at_resp_len;
static void st67w6_handle_wifi_evnt(char *, size_t len);
static void st67w6_handle_scan_result(char *, size_t len);

static size_t st67w6_spi_poll(uint8_t *write, uint8_t *read);
static void st67w6_write(unsigned int f, void *data, uint16_t len);
static void st67w6_update_hash_table(void);

// High-level comm stuff

static void st67w6_poll(bool is_at) {
  struct mg_tcpip_driver_st67w6_data *d =
      (struct mg_tcpip_driver_st67w6_data *) s_ifp->driver_data;
  struct spi_hdr *h = (struct spi_hdr *) rxdata;
  unsigned int type;
  uint8_t *txsource = (uint8_t *) txdata;
  if (s_ifp->update_mac_hash_table) {
    // first call to _poll() is after _init(), so this is safe
    st67w6_update_hash_table();
    s_ifp->update_mac_hash_table = false;
  }
  if (!is_at) {  // send outstanding WLAN frames in the queue
    char *buf;
    size_t len;
    // NOTE(): have traffic-dependent queues or queue traffic type with data
    if ((len = mg_queue_next(&d->send_queue, &buf)) > 0) {
      st67w6_write(d->wifi.apmode ? ST67W6_SPI_TYPE_AP : ST67W6_SPI_TYPE_STA,
                   buf, (uint16_t) len);
      mg_queue_del(&d->send_queue, len);
    } else {  // nothing to send
      txsource = NULL;
    }
  }
  if (st67w6_spi_poll(txsource, (uint8_t *) rxdata) == 0) return;
  if (h->len == 0) return;
  type = h->type;
  if (type == ST67W6_SPI_TYPE_AT) {
    char *p = (char *) (h + 1);
    size_t len = h->len;
    if (len > 7 && strncmp(p, "+CWLAP:", 7) == 0) {  // scan result
      st67w6_handle_scan_result(p + 7, len - 7);
    } else if (len > 4 && strncmp(p, "+CW:", 4) == 0) {
      st67w6_handle_wifi_evnt(p + 4, len - 4);
    } else {
      MG_VERBOSE(("AT partial: %.*s", (int) len, p));
      if (s_at_resp_len + len >= sizeof(at_resp))
        s_at_resp_len = 0;  // truncate response, error will be caught later
      memcpy(at_resp + s_at_resp_len, p, len);
      s_at_resp_len += len;
      if (mg_match(mg_str_n((char *) at_resp, s_at_resp_len),
                   mg_str_n("*ERROR*", 7), NULL)) {
        s_at_err = true;
      } else if (mg_match(mg_str_n((char *) at_resp, s_at_resp_len),
                          mg_str_n("*OK*", 4), NULL)) {
        s_at_ok = true;
      }
    }
  } else if (type == ST67W6_SPI_TYPE_STA || type == ST67W6_SPI_TYPE_AP) {
    // WLAN frame reception
    mg_tcpip_qwrite(h + 1, h->len, s_ifp);
  }  // else silently discard
}

// WLAN event handling

// - Do not call any AT functions here, otherwise revise st67w6_at_wait()
// - The module likes to send ERROR along with other events
static void st67w6_handle_wifi_evnt(char *p, size_t len) {
  struct mg_str data[2];
  MG_VERBOSE(("event: %.*s", (int) len, p));
  if (len > 9 && strncmp(p, "CONNECTED", 9) == 0) {
    s_link = true;
    s_connecting = false;
  } else if (len > 12 && strncmp(p, "DISCONNECTED", 12) == 0) {
    s_link = false;
    s_connecting = false;  // should not be needed
  } else if (s_connecting && len > 6 &&
             mg_match(mg_str_n(p, len), mg_str_n("ERROR,*\r\n*", 10), data)) {
    size_t reason = 0;
    bool ok = mg_to_size_t(data[0], &reason);
    s_connecting = false;
    MG_ERROR(("CONNECT FAILED"));
    mg_tcpip_call(s_ifp, MG_TCPIP_EV_WIFI_CONNECT_ERR, ok ? &reason : NULL);
  } else if (len > 9 && strncmp(p, "SCAN_DONE", 9) == 0) {
    MG_VERBOSE(("scan complete"));
    mg_tcpip_call(s_ifp, MG_TCPIP_EV_WIFI_SCAN_END, NULL);
  }  // else silently discard: CONNECTING; STA_CONNECTED,"MAC";
     // STA_DISCONNECTED,"MAC"; DIST_STA_IP,"MAC","IP"
}

static bool st67w6_at_cmd(char *cmd, size_t len);

// Wi-Fi network stuff

static bool st67w6_wifi_connect(char *ssid, char *pass) {
  char cmd[90];  // ssid + pass + AT
  size_t cmd_len;
  if (!st67w6_at_cmd("AT+CWMODE=1,0\r\n", 15)) return false;
  cmd_len = mg_snprintf(cmd, sizeof(cmd), "AT+CWJAP=\"%s\",\"%s\",,0\r\n", ssid,
                        pass);  // takes >700ms
  if (!st67w6_at_cmd(cmd, cmd_len)) return false;
  st67w6_at_cmd("AT+CWRECONNCFG=0,0\r\n", 20);  // disregard error, connecting
  s_connecting = true;
  return true;
}

static bool st67w6_wifi_disconnect(void) {
  s_connecting = false;
  if (!st67w6_at_cmd("AT+CWQAP=0\r\n", 12)) return false;  // takes >800ms
  return st67w6_at_cmd("AT+CWMODE=0,0\r\n", 15);           // takes >550ms
}

static bool st67w6_wifi_ap_start(char *ssid, char *pass, unsigned int channel) {
  char cmd[90];  // ssid + pass + AT
  size_t cmd_len;
  if (!st67w6_at_cmd("AT+CWMODE=2,0\r\n", 15)) return false;  // takes >800ms
  cmd_len = mg_snprintf(
      cmd, sizeof(cmd), "AT+CWSAP=\"%s\",\"%s\",%u,3,2,0\r\n", ssid, pass,
      channel);  // 3: WPA2_PSK; 2: max stations  // takes >350ms
  s_link = true;
  return st67w6_at_cmd(cmd, cmd_len);
}

static bool st67w6_wifi_ap_stop(void) {
  s_link = false;
  return st67w6_at_cmd("AT+CWMODE=0,0\r\n", 15);  // takes >550ms
}

// WLAN scan handling

// +CWLAP:(security,"SSID",RSSI,"BSSID",channel,cipher,proto,wps)\r\n
// security: OPEN, WEP, WPA, WPA2, WPA-WPA2, WPA-EAP, WPA3-SAE, WPA2-WPA3-SAE
// cipher: NONE, WEP, AES/CCMP, TKIP, TKIP and AES/CCMP
// proto: 4-bit bitmap AX,N,G,B; all set from right to left

static bool st67w6_wifi_scan(void) {
  return st67w6_at_cmd("AT+CWLAPOPT=1,1695,-100,255,50\r\n", 32) &&
         st67w6_at_cmd("AT+CWLAP=0,,,0\r\n", 16);
}

static void st67w6_handle_scan_result(char *data, size_t len) {
  struct mg_wifi_scan_bss_data bss;
  struct mg_str fields[2];
  char mac[6];
  uint8_t val;
  unsigned int i;
  MG_VERBOSE(("scan result event: %.*s", (int) len, data));
  ++data, --len;  // skip '('
  if (!mg_span(mg_str_n(data, len), &fields[0], &fields[1], ',') ||
      !mg_str_to_num(fields[0], 10, &val, 1))
    return;
  bss.security =
      (val == 0) ? MG_WIFI_SECURITY_OPEN : (uint8_t) MG_WIFI_SECURITY_WEP;
  if (val == 2 || val == 4) bss.security |= MG_WIFI_SECURITY_WPA;
  if (val == 3 || val == 4 || val == 7) bss.security |= MG_WIFI_SECURITY_WPA2;
  if (val == 6 || val == 7) bss.security |= MG_WIFI_SECURITY_WPA3;
  if (val == 5) bss.security |= MG_WIFI_SECURITY_WPA_ENTERPRISE;
  if (!mg_span(fields[1], &fields[0], &fields[1], ',')) return;
  bss.SSID.buf = fields[0].buf + 1, bss.SSID.len = fields[0].len - 2;
  if (!mg_span(fields[1], &fields[0], &fields[1], ',')) return;
  while (fields[0].buf[0] == ' ') ++fields[0].buf, --fields[0].len;
  if (fields[0].buf[0] != '-') return;  // positive RSSI would be great
  ++fields[0].buf, --fields[0].len;
  if (!mg_str_to_num(fields[0], 10, &val, 1)) return;
  bss.RSSI = (int8_t) - (int8_t) val;
  if (!mg_span(fields[1], &fields[0], &fields[1], ',')) return;
  if (fields[0].len < 19) return;
  ++fields[0].buf, --fields[0].len;  // skip '"'
  for (i = 0; i < 6; i++) {
    struct mg_str str;
    str.buf = fields[0].buf + 3 * i;
    str.len = 2;
    if (!mg_str_to_num(str, 16, &mac[i], 1)) return;
  }
  bss.BSSID = mac;
  if (!mg_span(fields[1], &fields[0], &fields[1], ',') ||
      !mg_str_to_num(fields[0], 10, &bss.channel, 1))
    return;
  if (!mg_span(fields[1], &fields[0], &fields[1], ',') ||
      !mg_str_to_num(fields[0], 10, &val, 1))
    return;
  // ignore cypher
  if (!mg_span(fields[1], &fields[0], &fields[1], ',') ||
      !mg_str_to_num(fields[0], 10, &val, 1))
    return;
  bss.has_n = (val & 4) != 0;
  bss.has_ax = (val & 8) != 0;
  bss.band = MG_WIFI_BAND_2G;  // NOT INFORMED with default options, no docs
  MG_VERBOSE(("BSS: %.*s (%u) (%M) %d dBm %u", bss.SSID.len, bss.SSID.buf,
              bss.channel, mg_print_mac, bss.BSSID, (int) bss.RSSI,
              bss.security));
  mg_tcpip_call(s_ifp, MG_TCPIP_EV_WIFI_SCAN_RESULT, &bss);
}

// AT stuff

static inline bool delayms(unsigned int ms) {
  mg_delayms(ms);
  return true;
}

// send AT command, wait for a response or timeout, meanwhile delivering
// received frames and events

static bool st67w6_at_cmd(char *cmd, size_t len) {
  bool is_at = true;
  unsigned int times = 1000;
  s_at_resp_len = 0;
  st67w6_write(ST67W6_SPI_TYPE_AT, cmd, (uint16_t) len);
  s_at_ok = false, s_at_err = false;
  do {  // AT response processing does not call any other AT function
    st67w6_poll(is_at);  // otherwise we can't allow them to pile up here
    is_at = false;       // avoid repeating, allow queued WLAN frames to be sent
    // network frames will be pushed to the queue so that is safe
  } while (!s_at_ok && !s_at_err && times-- > 0 && delayms(1));
  MG_VERBOSE(("AT response:\n%.*s", s_at_resp_len, at_resp));
  MG_VERBOSE(("ok: %c, err: %c, times: %d", s_at_ok ? '1' : '0',
              s_at_err ? '1' : '0', (int) times));
  return s_at_ok;
}

static bool st67w6_spi_init(void);
bool mg_to_size_t(struct mg_str str, size_t *val);

static bool st67w6_init(uint8_t *mac) {
  //  struct mg_tcpip_driver_st67w6_data *d = (struct
  //  mg_tcpip_driver_st67w6_data *) s_ifp->driver_data;
  struct mg_str data[3];
  size_t val;
  bool is_b = false;
  if (!st67w6_spi_init()) return false;
  if (!st67w6_at_cmd("AT\r\n", 4)) return false;
  if (!st67w6_at_cmd("AT+CWNETMODE?\r\n", 15) ||
      !mg_match(mg_str_n((char *) at_resp, s_at_resp_len),
                mg_str_n("*:*\r\n*", 6), data) ||
      !mg_to_size_t(data[1], &val))
    return false;
  if (val != 0) {
    MG_ERROR(("Wrong firmware, T02 is needed"));
    return false;
  }
  // set clock, who cares ???
  if (!st67w6_at_cmd("AT+GET_CLOCK\r\n", 14)) return false;
  MG_DEBUG(("%.*s", s_at_resp_len, at_resp));  // TODO(scaprile): --> VERBOSE
  // BT-ENABLED DEPENDENCY

  // MODULE DEPENDENCY
  if (!st67w6_at_cmd("AT+EFUSE-R=24,\"0x100\"\r\n", 23) ||
      !mg_match(mg_str_n((char *) at_resp, s_at_resp_len), mg_str_n("*,*", 3),
                data))
    return false;
  if (data[1].buf[0] == 'C' && data[1].buf[1] == '6') is_b = true;
  MG_DEBUG(("WLAN module is %sB type", is_b ? "" : "not"));  // --> VERBOSE
  if (is_b) {
    // Disable the antenna diversity pin
    if (!st67w6_at_cmd("AT+IORST=0\r\n", 12)) return false;
    // Apparently they intend to disable some antenna ...
    if (!st67w6_at_cmd("AT+CWANTENABLE?\r\n", 17)) return false;
    MG_DEBUG(("%.*s", s_at_resp_len, at_resp));  // --> VERBOSE
  }

  // Do not set wake-up pin (AT+SLWKIO)
  // Disable power save mode
  // NOTE(scaprile): (no response if in hibernate mode, though I guess we
  // wouldn't have reached this point in that case either)
  if (!st67w6_at_cmd("AT+PWR=0\r\n", 12)) return false;
  // set Wi-Fi
  // set country code
  if (!st67w6_at_cmd("AT+CWCOUNTRY=0,\"00\"\r\n", 21)) return false;
#if 0
	// set DTIM
  if (!st67w6_at_cmd("AT+SLWKDTIM=1\r\n", 15)) return false;
#endif
  // Read only default MAC, ignore set bit count (data[6] & 0x3F). Custom MACs
  // reside at @0x64 and 0x70
  if (st67w6_at_cmd("AT+EFUSE-R=7,\"0x014\"\r\n", 22) &&
      mg_match(mg_str_n((char *) at_resp, s_at_resp_len), mg_str_n("*,*", 3),
               data)) {
    int i;
    for (i = 0; i < 6; i++) mac[i] = data[1].buf[5 - i];
    MG_DEBUG(("MAC: %M", mg_print_mac, mac));
  } else {
    MG_ERROR(("read MAC failed"));
  }
  return true;
}

static void st67w6_update_hash_table(void) {
  // TODO(): read database, rebuild hash table
  //  uint32_t val = 0;
  //  val = 1;
  //  st67w6_at_iovar_set2_(0, "mcast_list", (uint8_t *) &val, sizeof(val),
  //  (uint8_t *) mcast_addr, sizeof(mcast_addr)); mg_delayms(50);
}

// SPI specifics

#define ST67W6_SPI_MAGIC 0x55AA
// #define ST67W6_SPI_VERSION(x), IS_STALL, FLAGS(x), ...

static const uint8_t idlehdr[sizeof(struct spi_hdr)] = {0xaa, 0x55, 0, 0,
                                                        0,    0,    0, 0};

static void st67w6_write(unsigned int f, void *data, uint16_t len) {
  struct spi_hdr *h = (struct spi_hdr *) txdata;
  h->magic = ST67W6_SPI_MAGIC;
  h->type = (uint8_t) f;
  h->vflags = 0;
  h->len = len;
  h->reserved = 0;
  memmove(h + 1, data, len);
}

static size_t st67w6_spi_poll(uint8_t *write, uint8_t *read) {
  struct mg_tcpip_driver_st67w6_data *d =
      (struct mg_tcpip_driver_st67w6_data *) s_ifp->driver_data;
  struct spi_hdr *th, *rh = (struct spi_hdr *) read;
  struct mg_tcpip_spi_ *s = (struct mg_tcpip_spi_ *) d->spi;
  size_t padded;
  unsigned int times;

  th = (write != NULL) ? (struct spi_hdr *) write : (struct spi_hdr *) idlehdr;
  s->begin(s->spi);
  times = 50;
  while (times--) {
    if (d->is_ready()) break;
    if (times == 0) {
      MG_ERROR(("RDY TIMEOUT"));
      s->end(s->spi);
      return 0;
    }
    mg_delayms(1);
  }

  padded = (th->len + 3) & ~3;
  s->txn(s->spi, (uint8_t *) th, (uint8_t *) rh, sizeof(*th) + padded);
  if (rh->magic == ST67W6_SPI_MAGIC && rh->len > padded) {
    size_t remaining_padded = (rh->len - padded + 3) & ~3;
    if (remaining_padded > (2048 - sizeof(*rh) - padded))
      remaining_padded = 2048 - sizeof(*rh) - padded;
    s->txn(s->spi, NULL, read + sizeof(*rh) + padded, remaining_padded);
  }
  times = 50;
  while (times--) {
    if (!d->is_ready()) break;
    if (times == 0) {
      MG_ERROR(("!RDY TIMEOUT"));
      break;
    }
    mg_delayms(1);
  }
  s->end(s->spi);
  return (size_t) rh->len;
}

static bool st67w6_spi_init(void) {
  struct mg_tcpip_driver_st67w6_data *d =
      (struct mg_tcpip_driver_st67w6_data *) s_ifp->driver_data;
  size_t len;
  unsigned int times = 1000;
  while (times--) {
    if (d->is_ready()) break;
    if (times == 0) return false;
    mg_delayms(1);
  }
  if (((len = st67w6_spi_poll(NULL, (uint8_t *) rxdata)) == 0) ||
      !mg_match(mg_str_n(((char *) rxdata) + sizeof(struct spi_hdr), len),
                mg_str_n("*ready*", 7), NULL))
    return false;
  return true;
}

// Mongoose Wi-Fi API functions

bool mg_wifi_scan(void) {
  return st67w6_wifi_scan();
}

bool mg_wifi_connect(struct mg_wifi_data *wifi) {
  s_ifp->ip = s_ip;
  s_ifp->mask = s_mask;
  if (s_ifp->ip == 0) s_ifp->enable_dhcp_client = true;
  s_ifp->enable_dhcp_server = false;
  MG_DEBUG(("Connecting to '%s'", wifi->ssid));
  return st67w6_wifi_connect(wifi->ssid, wifi->pass);
}

bool mg_wifi_disconnect(void) {
  return st67w6_wifi_disconnect();
}

bool mg_wifi_ap_start(struct mg_wifi_data *wifi) {
  MG_DEBUG(("Starting AP '%s' (%u)", wifi->apssid, wifi->apchannel));
  return st67w6_wifi_ap_start(wifi->apssid, wifi->appass, wifi->apchannel);
}

bool mg_wifi_ap_stop(void) {
  return st67w6_wifi_ap_stop();
}

#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/stm32f.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_STM32F) && \
    MG_ENABLE_DRIVER_STM32F
struct stm32f_eth {
  volatile uint32_t MACCR, MACFFR, MACHTHR, MACHTLR, MACMIIAR, MACMIIDR, MACFCR,
      MACVLANTR, RESERVED0[2], MACRWUFFR, MACPMTCSR, RESERVED1, MACDBGR, MACSR,
      MACIMR, MACA0HR, MACA0LR, MACA1HR, MACA1LR, MACA2HR, MACA2LR, MACA3HR,
      MACA3LR, RESERVED2[40], MMCCR, MMCRIR, MMCTIR, MMCRIMR, MMCTIMR,
      RESERVED3[14], MMCTGFSCCR, MMCTGFMSCCR, RESERVED4[5], MMCTGFCR,
      RESERVED5[10], MMCRFCECR, MMCRFAECR, RESERVED6[10], MMCRGUFCR,
      RESERVED7[334], PTPTSCR, PTPSSIR, PTPTSHR, PTPTSLR, PTPTSHUR, PTPTSLUR,
      PTPTSAR, PTPTTHR, PTPTTLR, RESERVED8, PTPTSSR, PTPPPSCR, RESERVED9[564],
      DMABMR, DMATPDR, DMARPDR, DMARDLAR, DMATDLAR, DMASR, DMAOMR, DMAIER,
      DMAMFBOCR, DMARSWTR, RESERVED10[8], DMACHTDR, DMACHRDR, DMACHTBAR,
      DMACHRBAR;
};
#undef ETH
#define ETH ((struct stm32f_eth *) (uintptr_t) 0x40028000)

#define ETH_PKT_SIZE 1540  // Max frame size
#define ETH_DESC_CNT 4     // Descriptors count
#define ETH_DS 4           // Descriptor size (words)

static uint32_t s_rxdesc[ETH_DESC_CNT][ETH_DS] MG_ETH_RAM;      // RX descriptors
static uint32_t s_txdesc[ETH_DESC_CNT][ETH_DS] MG_ETH_RAM;      // TX descriptors
static uint8_t s_rxbuf[ETH_DESC_CNT][ETH_PKT_SIZE] MG_ETH_RAM;  // RX ethernet buffers
static uint8_t s_txbuf[ETH_DESC_CNT][ETH_PKT_SIZE] MG_ETH_RAM;  // TX ethernet buffers
static uint8_t s_txno;                               // Current TX descriptor
static uint8_t s_rxno;                               // Current RX descriptor

static struct mg_tcpip_if *s_ifp;  // MIP interface

static uint16_t eth_read_phy(uint8_t addr, uint8_t reg) {
  ETH->MACMIIAR &= (7 << 2);
  ETH->MACMIIAR |= ((uint32_t) addr << 11) | ((uint32_t) reg << 6);
  ETH->MACMIIAR |= MG_BIT(0);
  while (ETH->MACMIIAR & MG_BIT(0)) (void) 0;
  return ETH->MACMIIDR & 0xffff;
}

static void eth_write_phy(uint8_t addr, uint8_t reg, uint16_t val) {
  ETH->MACMIIDR = val;
  ETH->MACMIIAR &= (7 << 2);
  ETH->MACMIIAR |= ((uint32_t) addr << 11) | ((uint32_t) reg << 6) | MG_BIT(1);
  ETH->MACMIIAR |= MG_BIT(0);
  while (ETH->MACMIIAR & MG_BIT(0)) (void) 0;
}

static uint32_t get_hclk(void) {
  struct rcc {
    volatile uint32_t CR, PLLCFGR, CFGR;
  } *rcc = (struct rcc *) 0x40023800;
  uint32_t clk = 0, hsi = 16000000 /* 16 MHz */, hse = 8000000 /* 8MHz */;

  if (rcc->CFGR & (1 << 2)) {
    clk = hse;
  } else if (rcc->CFGR & (1 << 3)) {
    uint32_t vco, m, n, p;
    m = (rcc->PLLCFGR & (0x3f << 0)) >> 0;
    n = (rcc->PLLCFGR & (0x1ff << 6)) >> 6;
    p = (((rcc->PLLCFGR & (3 << 16)) >> 16) + 1) * 2;
    clk = (rcc->PLLCFGR & (1 << 22)) ? hse : hsi;
    vco = (uint32_t) ((uint64_t) clk * n / m);
    clk = vco / p;
  } else {
    clk = hsi;
  }
  uint32_t hpre = (rcc->CFGR & (15 << 4)) >> 4;
  if (hpre < 8) return clk;

  uint8_t ahbptab[8] = {1, 2, 3, 4, 6, 7, 8, 9};  // log2(div)
  return ((uint32_t) clk) >> ahbptab[hpre - 8];
}

//  Guess CR from HCLK. MDC clock is generated from HCLK (AHB); as per 802.3,
//  it must not exceed 2.5MHz As the AHB clock can be (and usually is) derived
//  from the HSI (internal RC), and it can go above specs, the datasheets
//  specify a range of frequencies and activate one of a series of dividers to
//  keep the MDC clock safely below 2.5MHz. We guess a divider setting based on
//  HCLK with a +5% drift. If the user uses a different clock from our
//  defaults, needs to set the macros on top Valid for STM32F74xxx/75xxx
//  (38.8.1) and STM32F42xxx/43xxx (33.8.1) (both 4.5% worst case drift)
static int guess_mdc_cr(void) {
  uint8_t crs[] = {2, 3, 0, 1, 4, 5};          // ETH->MACMIIAR::CR values
  uint8_t div[] = {16, 26, 42, 62, 102, 124};  // Respective HCLK dividers
  uint32_t hclk = get_hclk();                  // Guess system HCLK
  int result = -1;                             // Invalid CR value
  if (hclk < 25000000) {
    MG_ERROR(("HCLK too low"));
  } else {
    for (int i = 0; i < 6; i++) {
      if (hclk / div[i] <= 2375000UL /* 2.5MHz - 5% */) {
        result = crs[i];
        break;
      }
    }
    if (result < 0) MG_ERROR(("HCLK too high"));
  }
  MG_DEBUG(("HCLK: %u, CR: %d", hclk, result));
  return result;
}

static bool mg_tcpip_driver_stm32f_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_stm32f_data *d =
      (struct mg_tcpip_driver_stm32f_data *) ifp->driver_data;
  uint8_t phy_addr = d == NULL ? 0 : d->phy_addr;
  s_ifp = ifp;

  // Init RX descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_rxdesc[i][0] = MG_BIT(31);                         // Own
    s_rxdesc[i][1] = sizeof(s_rxbuf[i]) | MG_BIT(14);    // 2nd address chained
    s_rxdesc[i][2] = (uint32_t) (uintptr_t) s_rxbuf[i];  // Point to data buffer
    s_rxdesc[i][3] =
        (uint32_t) (uintptr_t) s_rxdesc[(i + 1) % ETH_DESC_CNT];  // Chain
  }

  // Init TX descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_txdesc[i][2] = (uint32_t) (uintptr_t) s_txbuf[i];  // Buf pointer
    s_txdesc[i][3] =
        (uint32_t) (uintptr_t) s_txdesc[(i + 1) % ETH_DESC_CNT];  // Chain
  }

  ETH->DMABMR |= MG_BIT(0);                         // Software reset
  while ((ETH->DMABMR & MG_BIT(0)) != 0) (void) 0;  // Wait until done

  // Set MDC clock divider. If user told us the value, use it. Otherwise, guess
  int cr = (d == NULL || d->mdc_cr < 0) ? guess_mdc_cr() : d->mdc_cr;
  ETH->MACMIIAR = ((uint32_t) cr & 7) << 2;

  // NOTE(cpq): we do not use extended descriptor bit 7, and do not use
  // hardware checksum. Therefore, descriptor size is 4, not 8
  // ETH->DMABMR = MG_BIT(13) | MG_BIT(16) | MG_BIT(22) | MG_BIT(23) |
  // MG_BIT(25);
  ETH->MACIMR = MG_BIT(3) | MG_BIT(9);  // Mask timestamp & PMT IT
  ETH->MACFCR = MG_BIT(7);              // Disable zero quarta pause
  ETH->MACFFR = MG_BIT(10);             // Perfect filtering
  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  mg_phy_init(&phy, phy_addr, MG_PHY_CLOCKS_MAC);
  ETH->DMARDLAR = (uint32_t) (uintptr_t) s_rxdesc;  // RX descriptors
  ETH->DMATDLAR = (uint32_t) (uintptr_t) s_txdesc;  // RX descriptors
  ETH->DMAIER = MG_BIT(6) | MG_BIT(16);             // RIE, NISE
  ETH->MACCR =
      MG_BIT(2) | MG_BIT(3) | MG_BIT(11) | MG_BIT(14);  // RE, TE, Duplex, Fast
  ETH->DMAOMR =
      MG_BIT(1) | MG_BIT(13) | MG_BIT(21) | MG_BIT(25);  // SR, ST, TSF, RSF

  // MAC address filtering
  ETH->MACA0HR = ((uint32_t) ifp->mac[5] << 8U) | ifp->mac[4];
  ETH->MACA0LR = (uint32_t) (ifp->mac[3] << 24) |
                 ((uint32_t) ifp->mac[2] << 16) |
                 ((uint32_t) ifp->mac[1] << 8) | ifp->mac[0];
  return true;
}

static size_t mg_tcpip_driver_stm32f_tx(const void *buf, size_t len,
                                        struct mg_tcpip_if *ifp) {
  if (len > sizeof(s_txbuf[s_txno])) {
    MG_ERROR(("Frame too big, %ld", (long) len));
    len = 0;  // Frame is too big
  } else if ((s_txdesc[s_txno][0] & MG_BIT(31))) {
    ifp->nerr++;
    MG_ERROR(("No free descriptors"));
    // printf("D0 %lx SR %lx\n", (long) s_txdesc[0][0], (long) ETH->DMASR);
    len = 0;  // All descriptors are busy, fail
  } else {
    memcpy(s_txbuf[s_txno], buf, len);                           // Copy data
    s_txdesc[s_txno][1] = (uint32_t) len;                        // Set data len
    s_txdesc[s_txno][0] = MG_BIT(20) | MG_BIT(28) | MG_BIT(29);  // Chain,FS,LS
    s_txdesc[s_txno][0] |= MG_BIT(31);  // Set OWN bit - let DMA take over
    if (++s_txno >= ETH_DESC_CNT) s_txno = 0;
  }
  MG_DSB();                            // ensure descriptors have been written
  ETH->DMASR = MG_BIT(2) | MG_BIT(5);  // Clear any prior TBUS/TUS
  ETH->DMATPDR = 0;                    // and resume
  return len;
}

static void mg_tcpip_driver_stm32f_update_hash_table(struct mg_tcpip_if *ifp) {
  // TODO(): read database, rebuild hash table
  ETH->MACA1LR = (uint32_t) mcast_addr[3] << 24 |
                 (uint32_t) mcast_addr[2] << 16 |
                 (uint32_t) mcast_addr[1] << 8 | (uint32_t) mcast_addr[0];
  ETH->MACA1HR = (uint32_t) mcast_addr[5] << 8 | (uint32_t) mcast_addr[4];
  ETH->MACA1HR |= MG_BIT(31);  // AE
  (void) ifp;
}

static bool mg_tcpip_driver_stm32f_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (ifp->update_mac_hash_table) {
    mg_tcpip_driver_stm32f_update_hash_table(ifp);
    ifp->update_mac_hash_table = false;
  }
  if (!s1) return false;
  struct mg_tcpip_driver_stm32f_data *d =
      (struct mg_tcpip_driver_stm32f_data *) ifp->driver_data;
  uint8_t phy_addr = d == NULL ? 0 : d->phy_addr;
  uint8_t speed = MG_PHY_SPEED_10M;
  bool up = false, full_duplex = false;
  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  up = mg_phy_up(&phy, phy_addr, &full_duplex, &speed);
  if ((ifp->state == MG_TCPIP_STATE_DOWN) && up) {  // link state just went up
    // tmp = reg with flags set to the most likely situation: 100M full-duplex
    // if(link is slow or half) set flags otherwise
    // reg = tmp
    uint32_t maccr = ETH->MACCR | MG_BIT(14) | MG_BIT(11);  // 100M, Full-duplex
    if (speed == MG_PHY_SPEED_10M) maccr &= ~MG_BIT(14);    // 10M
    if (full_duplex == false) maccr &= ~MG_BIT(11);         // Half-duplex
    ETH->MACCR = maccr;  // IRQ handler does not fiddle with this register
    MG_DEBUG(("Link is %uM %s-duplex", maccr & MG_BIT(14) ? 100 : 10,
              maccr & MG_BIT(11) ? "full" : "half"));
  }
  return up;
}

#ifdef __riscv
__attribute__((interrupt()))  // For RISCV CH32V307, which share the same MAC
#endif
void ETH_IRQHandler(void);
void ETH_IRQHandler(void) {
  if (ETH->DMASR & MG_BIT(6)) {           // Frame received, loop
    ETH->DMASR = MG_BIT(16) | MG_BIT(6);  // Clear flag
    for (uint32_t i = 0; i < 10; i++) {   // read as they arrive but not forever
      if (s_rxdesc[s_rxno][0] & MG_BIT(31)) break;  // exit when done
      if (((s_rxdesc[s_rxno][0] & (MG_BIT(8) | MG_BIT(9))) ==
           (MG_BIT(8) | MG_BIT(9))) &&
          !(s_rxdesc[s_rxno][0] & MG_BIT(15))) {  // skip partial/errored frames
        uint32_t len = ((s_rxdesc[s_rxno][0] >> 16) & (MG_BIT(14) - 1));
        //  printf("%lx %lu %lx %.8lx\n", s_rxno, len, s_rxdesc[s_rxno][0],
        //  ETH->DMASR);
        mg_tcpip_qwrite(s_rxbuf[s_rxno], len > 4 ? len - 4 : len, s_ifp);
      }
      s_rxdesc[s_rxno][0] = MG_BIT(31);
      if (++s_rxno >= ETH_DESC_CNT) s_rxno = 0;
    }
  }
  // Cleanup flags
  ETH->DMASR = MG_BIT(16)    // NIS, normal interrupt summary
               | MG_BIT(7);  // Clear possible RBUS while processing
  ETH->DMARPDR = 0;          // and resume RX
}

struct mg_tcpip_driver mg_tcpip_driver_stm32f = {
    mg_tcpip_driver_stm32f_init, mg_tcpip_driver_stm32f_tx, NULL,
    mg_tcpip_driver_stm32f_poll};
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/stm32h.c"
#endif


#if MG_ENABLE_TCPIP && (MG_ENABLE_DRIVER_STM32H || MG_ENABLE_DRIVER_MCXN || \
                        MG_ENABLE_DRIVER_STM32N)
// STM32H: vendor modded single-queue Synopsys v4.2
// STM32N: dual-queue GbE Synopsys v5.2 with no hash table option, 64-bit AXI
// MCXNx4x: dual-queue Synopsys v5.2 with no hash table option
// RT1170: ENET_QOS: quad-queue Synopsys v5.1
#if MG_ENABLE_DRIVER_STM32H
#define SYNOPSYS_ENET_V5 0
#define SYNOPSYS_ENET_SINGLEQ 1
#define SYNOPSYS_ENET_NOHASHTABLE 0
#define SYNOPSYS_ENET_GbE 0
#elif MG_ENABLE_DRIVER_STM32N
#define SYNOPSYS_ENET_V5 1
#define SYNOPSYS_ENET_SINGLEQ 0
#define SYNOPSYS_ENET_NOHASHTABLE 1
#define SYNOPSYS_ENET_GbE 1
#elif MG_ENABLE_DRIVER_MCXN
#define SYNOPSYS_ENET_V5 1
#define SYNOPSYS_ENET_SINGLEQ 0
#define SYNOPSYS_ENET_NOHASHTABLE 1
#define SYNOPSYS_ENET_GbE 0
#endif

struct synopsys_enet_qos {
  volatile uint32_t MACCR, MACECR, MACPFR, MACWTR, MACHT0R, MACHT1R,
      RESERVED1[14], MACVTR, RESERVED2, MACVHTR, RESERVED3, MACVIR, MACIVIR,
      RESERVED4[2], MACTFCR, RESERVED5[7], MACRFCR, RESERVED6[7], MACISR,
      MACIER, MACRXTXSR, RESERVED7, MACPCSR, MACRWKPFR, RESERVED8[2], MACLCSR,
      MACLTCR, MACLETR, MAC1USTCR, RESERVED9[12], MACVR, MACDR, RESERVED10,
      MACHWF0R, MACHWF1R, MACHWF2R, RESERVED11[54], MACMDIOAR, MACMDIODR,
      RESERVED12[2], MACARPAR, RESERVED13[59], MACA0HR, MACA0LR, MACA1HR,
      MACA1LR, MACA2HR, MACA2LR, MACA3HR, MACA3LR, RESERVED14[248], MMCCR,
      MMCRIR, MMCTIR, MMCRIMR, MMCTIMR, RESERVED15[14], MMCTSCGPR, MMCTMCGPR,
      RESERVED16[5], MMCTPCGR, RESERVED17[10], MMCRCRCEPR, MMCRAEPR,
      RESERVED18[10], MMCRUPGR, RESERVED19[9], MMCTLPIMSTR, MMCTLPITCR,
      MMCRLPIMSTR, MMCRLPITCR, RESERVED20[65], MACL3L4C0R, MACL4A0R,
      RESERVED21[2], MACL3A0R0R, MACL3A1R0R, MACL3A2R0R, MACL3A3R0R,
      RESERVED22[4], MACL3L4C1R, MACL4A1R, RESERVED23[2], MACL3A0R1R,
      MACL3A1R1R, MACL3A2R1R, MACL3A3R1R, RESERVED24[108], MACTSCR, MACSSIR,
      MACSTSR, MACSTNR, MACSTSUR, MACSTNUR, MACTSAR, RESERVED25, MACTSSR,
      RESERVED26[3], MACTTSSNR, MACTTSSSR, RESERVED27[2], MACACR, RESERVED28,
      MACATSNR, MACATSSR, MACTSIACR, MACTSEACR, MACTSICNR, MACTSECNR,
      RESERVED29[4], MACPPSCR, RESERVED30[3], MACPPSTTSR, MACPPSTTNR, MACPPSIR,
      MACPPSWR, RESERVED31[12], MACPOCR, MACSPI0R, MACSPI1R, MACSPI2R, MACLMIR,
      RESERVED32[11], MTLOMR, RESERVED33[7], MTLISR, RESERVED34[55], MTLTQOMR,
      MTLTQUR, MTLTQDR, RESERVED35[8], MTLQICSR, MTLRQOMR, MTLRQMPOCR, MTLRQDR,
      RESERVED36[177], DMAMR, DMASBMR, DMAISR, DMADSR, RESERVED37[60], DMACCR,
      DMACTCR, DMACRCR, RESERVED38[2], DMACTDLAR, RESERVED39, DMACRDLAR,
      DMACTDTPR, RESERVED40, DMACRDTPR, DMACTDRLR, DMACRDRLR, DMACIER,
      DMACRIWTR, DMACSFCSR, RESERVED41, DMACCATDR, RESERVED42, DMACCARDR,
      RESERVED43, DMACCATBR, RESERVED44, DMACCARBR, DMACSR, RESERVED45[2],
      DMACMFCR;
};
#undef ETH
#if MG_ENABLE_DRIVER_STM32H
#define ETH ((struct synopsys_enet_qos *) (uintptr_t) 0x40028000UL)
#elif MG_ENABLE_DRIVER_STM32N
#define ETH ((struct synopsys_enet_qos *) (uintptr_t) 0x48036000UL)
#elif MG_ENABLE_DRIVER_MCXN
#define ETH ((struct synopsys_enet_qos *) (uintptr_t) 0x40100000UL)
#endif

#define ETH_PKT_SIZE 1540  // Max frame size
#define ETH_DESC_CNT 4     // Descriptors count
#define ETH_DS 4           // Descriptor size (words)

#if MG_ENABLE_DRIVER_STM32H || MG_ENABLE_DRIVER_STM32N
#define CACHE_LINESZ 32  // must be a whole number of (d)words (see DESC_SZW)
#ifndef SCB
struct m7_scb {
  volatile uint32_t CPUID, RESERVED1[4], CCR, RESERVED2[145], DCIMVAC, DCISW,
      DCCMVAU, DCCMVAC, DCCSW, DCCIMVAC, DCCISW, RESERVED3[10], CACR,
      RESERVED4[3];
};
#define SCB ((struct m7_scb *) (uintptr_t) 0xE000ED00UL)
#endif
// ending ISB is not needed because we don't cache instructions in data space
static inline void MG_CACHE_INVAL(uint8_t *addr, int32_t len) {
#if MG_ENABLE_DRIVER_STM32H
  if ((SCB->CPUID & 0xfff0) != 0xc270) return;  // not a Cortex-M7 => not an H7
#endif
  if ((SCB->CCR & MG_BIT(16)) == 0) return;     // cache not enabled
  MG_DSB();
  while (len > 0) {
    SCB->DCIMVAC = (uint32_t) addr;
    addr += CACHE_LINESZ;
    len -= CACHE_LINESZ;
  }
  MG_DSB();
}
static inline void MG_CACHE_FLUSH(uint8_t *addr, int32_t len) {
#if MG_ENABLE_DRIVER_STM32H
  if ((SCB->CPUID & 0xfff0) != 0xc270) return;  // not a Cortex-M7 => not an H7
#endif
  if ((SCB->CCR & MG_BIT(16)) == 0) return;     // cache not enabled
  MG_DSB();
  while (len > 0) {
    SCB->DCCMVAC = (uint32_t) addr;
    addr += CACHE_LINESZ;
    len -= CACHE_LINESZ;
  }
  MG_DSB();
}
#define ETH_RAM_ALIGNED MG_32BYTE_ALIGNED  // depends on CACHE_LINESZ and ETH
#define CACHE_ALIGN(x) \
  ((((size_t) (x)) + CACHE_LINESZ - 1) & ~(CACHE_LINESZ - 1))
#define DESC_SZ CACHE_ALIGN(4 * ETH_DS)  // grow descriptors to fit a line
#define DESC_SZW (DESC_SZ / 4)
#define BUFF_SZ CACHE_ALIGN(ETH_PKT_SIZE)  // grow buffers to fit n lines
#if MG_ENABLE_DRIVER_STM32H
#define DESC_SKIPW (DESC_SZW - ETH_DS)  // tell DMA the descriptor size, words
#else
// MG_ENABLE_DRIVER_STM32N, DMA is AXI and specs skip in 64-bit double-words
#define DESC_SKIPW ((DESC_SZW - ETH_DS) / 2)
#endif
#else
#define MG_CACHE_FLUSH(a, b)
#define MG_CACHE_INVAL(a, b)
#define ETH_RAM_ALIGNED MG_8BYTE_ALIGNED  // depends on ETH DMA alone
#define DESC_SZ 0
#define DESC_SZW ETH_DS
#define BUFF_SZ ETH_PKT_SIZE
#define DESC_SKIPW 0  // no need to skip, as we're not aligning to cache lines
#endif

// array[rows][cols] = coldata coldata ... for all rows, keeps alignment
static volatile uint32_t s_rxdesc[ETH_DESC_CNT][DESC_SZW] MG_ETH_RAM
    ETH_RAM_ALIGNED;
static volatile uint32_t s_txdesc[ETH_DESC_CNT][DESC_SZW] MG_ETH_RAM
    ETH_RAM_ALIGNED;
static uint8_t s_rxbuf[ETH_DESC_CNT][BUFF_SZ] MG_ETH_RAM ETH_RAM_ALIGNED;
static uint8_t s_txbuf[ETH_DESC_CNT][BUFF_SZ] MG_ETH_RAM ETH_RAM_ALIGNED;

static struct mg_tcpip_if *s_ifp;  // MIP interface

static uint16_t eth_read_phy(uint8_t addr, uint8_t reg) {
  ETH->MACMDIOAR &= (0xF << 8);
  ETH->MACMDIOAR |= ((uint32_t) addr << 21) | ((uint32_t) reg << 16) | 3 << 2;
  ETH->MACMDIOAR |= MG_BIT(0);
  while (ETH->MACMDIOAR & MG_BIT(0)) (void) 0;
  return (uint16_t) ETH->MACMDIODR;
}

static void eth_write_phy(uint8_t addr, uint8_t reg, uint16_t val) {
  ETH->MACMDIODR = val;
  ETH->MACMDIOAR &= (0xF << 8);
  ETH->MACMDIOAR |= ((uint32_t) addr << 21) | ((uint32_t) reg << 16) | 1 << 2;
  ETH->MACMDIOAR |= MG_BIT(0);
  while (ETH->MACMDIOAR & MG_BIT(0)) (void) 0;
}

static bool mg_tcpip_driver_stm32h_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_stm32h_data *d =
      (struct mg_tcpip_driver_stm32h_data *) ifp->driver_data;
  s_ifp = ifp;
  uint8_t phy_addr = d == NULL ? 0 : d->phy_addr;
  uint8_t phy_conf = d == NULL ? MG_PHY_CLOCKS_MAC : d->phy_conf;

  // Init RX descriptors
  memset((char *) s_rxdesc, 0, sizeof(s_rxdesc));  // manual init
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_rxdesc[i][0] = (uint32_t) (uintptr_t) s_rxbuf[i];  // Point to data buffer
    s_rxdesc[i][3] = MG_BIT(31) | MG_BIT(30) | MG_BIT(24);  // OWN, IOC, BUF1V
  }
  MG_CACHE_FLUSH((uint8_t *) s_rxdesc, sizeof(s_rxdesc));

  // Init TX descriptors
  memset((char *) s_txdesc, 0, sizeof(s_txdesc));  // manual init
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_txdesc[i][0] = (uint32_t) (uintptr_t) s_txbuf[i];  // Buf pointer
  }
  MG_CACHE_FLUSH((uint8_t *) s_txdesc, sizeof(s_txdesc));

  ETH->DMAMR |= MG_BIT(0);  // Software reset
  for (int i = 0; i < 4; i++)
    (void) 0;  // wait at least 4 clocks before reading
  while ((ETH->DMAMR & MG_BIT(0)) != 0) (void) 0;  // Wait until done

  // Set MDC clock divider. Get user value, else, assume max freq
  int cr = (d == NULL || d->mdc_cr < 0) ? 7 : d->mdc_cr;
  ETH->MACMDIOAR = ((uint32_t) cr & 0xF) << 8;

  // NOTE(scaprile): We do not use timing facilities so the DMA engine does not
  // re-write buffer address
  ETH->DMAMR = 0 << 16;        // use interrupt mode 0 (58.8.1) (reset value)
  ETH->DMASBMR |= MG_BIT(12);  // AAL NOTE(scaprile): is this actually needed
  ETH->MACIER = 0;  // Do not enable additional irq sources (reset value)
  ETH->MACTFCR = MG_BIT(7);  // Disable zero-quanta pause
#if !SYNOPSYS_ENET_V5
  ETH->MACPFR = MG_BIT(10);  // Perfect filtering
#endif
  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  mg_phy_init(&phy, phy_addr, phy_conf);
  ETH->DMACRDLAR =
      (uint32_t) (uintptr_t) s_rxdesc;  // RX descriptors start address
  ETH->DMACRDRLR = ETH_DESC_CNT - 1;    // ring length
  ETH->DMACRDTPR =
      (uint32_t) (uintptr_t) &s_rxdesc[ETH_DESC_CNT -
                                       1];  // last valid descriptor address
  ETH->DMACTDLAR =
      (uint32_t) (uintptr_t) s_txdesc;  // TX descriptors start address
  ETH->DMACTDRLR = ETH_DESC_CNT - 1;    // ring length
  ETH->DMACTDTPR =
      (uint32_t) (uintptr_t) s_txdesc;  // first available descriptor address
  ETH->DMACCR = DESC_SKIPW << 18;  // DSL (contiguous/sparse descriptor table)
#if SYNOPSYS_ENET_V5
  MG_SET_BITS(ETH->DMACTCR, 0x3F << 16, MG_BIT(16));
  MG_SET_BITS(ETH->DMACRCR, 0x3F << 16, MG_BIT(16));
#endif
  ETH->DMACIER = MG_BIT(6) | MG_BIT(15);  // RIE, NIE
  ETH->MACCR = MG_BIT(0) | MG_BIT(1) | MG_BIT(13) | MG_BIT(14) |
               MG_BIT(15);  // RE, TE, Duplex, Fast, (10/100)/Reserved
#if SYNOPSYS_ENET_SINGLEQ
  ETH->MTLTQOMR |= MG_BIT(1);  // TSF
  ETH->MTLRQOMR |= MG_BIT(5);  // RSF
#else
  ETH->MTLTQOMR |= (7 << 16) | MG_BIT(3) | MG_BIT(1);  // 2KB Q0, TSF
  ETH->MTLRQOMR |= (7 << 20) | MG_BIT(5);              // 2KB Q, RSF
  MG_SET_BITS(ETH->RESERVED6[3], 3, 2);  // Enable RxQ0 (MAC_RXQ_CTRL0)
#endif
  ETH->DMACTCR |= MG_BIT(0);  // ST
  ETH->DMACRCR |= MG_BIT(0);  // SR

  // MAC address filtering
  ETH->MACA0HR = ((uint32_t) ifp->mac[5] << 8U) | ifp->mac[4];
  ETH->MACA0LR = (uint32_t) (ifp->mac[3] << 24) |
                 ((uint32_t) ifp->mac[2] << 16) |
                 ((uint32_t) ifp->mac[1] << 8) | ifp->mac[0];
  return true;
}

static uint32_t s_txno;
static size_t mg_tcpip_driver_stm32h_tx(const void *buf, size_t len,
                                        struct mg_tcpip_if *ifp) {
  if (len > sizeof(s_txbuf[s_txno])) {
    MG_ERROR(("Frame too big, %ld", (long) len));
    return 0;  // Frame is too big
  }
  MG_CACHE_INVAL((uint8_t *) &s_txdesc[s_txno], DESC_SZ);
  if ((s_txdesc[s_txno][3] & MG_BIT(31))) {
    ifp->nerr++;
    MG_ERROR(("No free descriptors: %u %08X %08X %08X", s_txno,
              s_txdesc[s_txno][3], ETH->DMACSR, ETH->DMACTCR));
    MG_CACHE_INVAL((uint8_t *) s_txdesc, sizeof(s_txdesc));
    for (int i = 0; i < ETH_DESC_CNT; i++) MG_ERROR(("%08X", s_txdesc[i][3]));
    len = 0;  // All descriptors are busy, fail
  } else {
    memcpy(s_txbuf[s_txno], buf, len);  // Copy data
    MG_CACHE_FLUSH((uint8_t *) &s_txbuf[s_txno], BUFF_SZ);
    s_txdesc[s_txno][2] = (uint32_t) len;           // Set data len
    s_txdesc[s_txno][3] = MG_BIT(28) | MG_BIT(29);  // FD, LD
    s_txdesc[s_txno][3] |= MG_BIT(31);  // Set OWN bit - let DMA take over
    MG_CACHE_FLUSH((uint8_t *) &s_txdesc[s_txno], DESC_SZ);
    if (++s_txno >= ETH_DESC_CNT) s_txno = 0;
  }
  ETH->DMACSR |= MG_BIT(2) | MG_BIT(1);  // Clear any prior TBU, TPS
  ETH->DMACTDTPR = (uint32_t) (uintptr_t) &s_txdesc[s_txno];  // and resume
  return len;
  (void) ifp;
}

static void mg_tcpip_driver_stm32h_update_hash_table(struct mg_tcpip_if *ifp) {
#if SYNOPSYS_ENET_NOHASHTABLE
  ETH->MACPFR = MG_BIT(4);  // Pass Multicast (pass all multicast frames)
#else
  // TODO(): read database, rebuild hash table
  // add mDNS / DNS-SD multicast address
  ETH->MACA1LR = (uint32_t) mcast_addr[3] << 24 |
                 (uint32_t) mcast_addr[2] << 16 |
                 (uint32_t) mcast_addr[1] << 8 | (uint32_t) mcast_addr[0];
  ETH->MACA1HR = (uint32_t) mcast_addr[5] << 8 | (uint32_t) mcast_addr[4];
  ETH->MACA1HR |= MG_BIT(31);  // AE
#endif
  (void) ifp;
}

static bool mg_tcpip_driver_stm32h_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (ifp->update_mac_hash_table) {
    mg_tcpip_driver_stm32h_update_hash_table(ifp);
    ifp->update_mac_hash_table = false;
  }
  if (!s1) return false;
  struct mg_tcpip_driver_stm32h_data *d =
      (struct mg_tcpip_driver_stm32h_data *) ifp->driver_data;
  uint8_t phy_addr = d == NULL ? 0 : d->phy_addr;
  uint8_t speed = MG_PHY_SPEED_10M;
  bool up = false, full_duplex = false;
  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  up = mg_phy_up(&phy, phy_addr, &full_duplex, &speed);
  if ((ifp->state == MG_TCPIP_STATE_DOWN) && up) {  // link state just went up
    // tmp = reg with flags set to the most likely situation: 100M full-duplex
    // if(link is slow or half) set flags otherwise
    // reg = tmp
    uint32_t maccr = ETH->MACCR | MG_BIT(14) | MG_BIT(13);  // 100M, Full-duplex
#if SYNOPSYS_ENET_GbE
    if (speed == MG_PHY_SPEED_1000M) maccr &= ~MG_BIT(15);  // 1000M
#endif
    if (speed == MG_PHY_SPEED_10M) maccr &= ~MG_BIT(14);  // 10M
    if (full_duplex == false) maccr &= ~MG_BIT(13);       // Half-duplex
    ETH->MACCR = maccr;  // IRQ handler does not fiddle with this register
    MG_DEBUG(("Link is %uM %s-duplex", maccr & MG_BIT(14) ? 100 : 10,
              maccr & MG_BIT(13) ? "full" : "half"));
  }
  return up;
}

static uint32_t s_rxno;
#if MG_ENABLE_DRIVER_MCXN
void ETHERNET_IRQHandler(void);
void ETHERNET_IRQHandler(void) {
#elif MG_ENABLE_DRIVER_STM32H
void ETH_IRQHandler(void);
void ETH_IRQHandler(void) {
#else
void ETH1_IRQHandler(void);
void ETH1_IRQHandler(void) {
#endif
  if (ETH->DMACSR & MG_BIT(6)) {           // Frame received, loop
    ETH->DMACSR = MG_BIT(15) | MG_BIT(6);  // Clear flag
    for (uint32_t i = 0; i < 10; i++) {  // read as they arrive but not forever
      MG_CACHE_INVAL((uint8_t *) &s_rxdesc[s_rxno], DESC_SZ);
      if (s_rxdesc[s_rxno][3] & MG_BIT(31)) break;  // exit when done
      if (((s_rxdesc[s_rxno][3] & (MG_BIT(28) | MG_BIT(29))) ==
           (MG_BIT(28) | MG_BIT(29))) &&
          !(s_rxdesc[s_rxno][3] & MG_BIT(15))) {  // skip partial/errored frames
        uint32_t len = s_rxdesc[s_rxno][3] & (MG_BIT(15) - 1);
        // MG_DEBUG(("%lx %lu %lx %08lx", s_rxno, len, s_rxdesc[s_rxno][3],
        // ETH->DMACSR));
        MG_CACHE_INVAL((uint8_t *) &s_rxbuf[s_rxno], BUFF_SZ);
        mg_tcpip_qwrite(s_rxbuf[s_rxno], len > 4 ? len - 4 : len, s_ifp);
      }
      s_rxdesc[s_rxno][3] =
          MG_BIT(31) | MG_BIT(30) | MG_BIT(24);  // OWN, IOC, BUF1V
      MG_CACHE_FLUSH((uint8_t *) &s_rxdesc[s_rxno], DESC_SZ);
      if (++s_rxno >= ETH_DESC_CNT) s_rxno = 0;
    }
  }
  ETH->DMACSR =
      MG_BIT(7) | MG_BIT(8);  // Clear possible RBU RPS while processing
  ETH->DMACRDTPR =
      (uint32_t) (uintptr_t) &s_rxdesc[ETH_DESC_CNT - 1];  // and resume RX
}

struct mg_tcpip_driver mg_tcpip_driver_stm32h = {
    mg_tcpip_driver_stm32h_init, mg_tcpip_driver_stm32h_tx, NULL,
    mg_tcpip_driver_stm32h_poll};
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/tm4c.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_TM4C) && MG_ENABLE_DRIVER_TM4C
struct tm4c_emac {
  volatile uint32_t EMACCFG, EMACFRAMEFLTR, EMACHASHTBLH, EMACHASHTBLL,
      EMACMIIADDR, EMACMIIDATA, EMACFLOWCTL, EMACVLANTG, RESERVED0, EMACSTATUS,
      EMACRWUFF, EMACPMTCTLSTAT, RESERVED1[2], EMACRIS, EMACIM, EMACADDR0H,
      EMACADDR0L, EMACADDR1H, EMACADDR1L, EMACADDR2H, EMACADDR2L, EMACADDR3H,
      EMACADDR3L, RESERVED2[31], EMACWDOGTO, RESERVED3[8], EMACMMCCTRL,
      EMACMMCRXRIS, EMACMMCTXRIS, EMACMMCRXIM, EMACMMCTXIM, RESERVED4,
      EMACTXCNTGB, RESERVED5[12], EMACTXCNTSCOL, EMACTXCNTMCOL, RESERVED6[4],
      EMACTXOCTCNTG, RESERVED7[6], EMACRXCNTGB, RESERVED8[4], EMACRXCNTCRCERR,
      EMACRXCNTALGNERR, RESERVED9[10], EMACRXCNTGUNI, RESERVED10[239],
      EMACVLNINCREP, EMACVLANHASH, RESERVED11[93], EMACTIMSTCTRL, EMACSUBSECINC,
      EMACTIMSEC, EMACTIMNANO, EMACTIMSECU, EMACTIMNANOU, EMACTIMADD,
      EMACTARGSEC, EMACTARGNANO, EMACHWORDSEC, EMACTIMSTAT, EMACPPSCTRL,
      RESERVED12[12], EMACPPS0INTVL, EMACPPS0WIDTH, RESERVED13[294],
      EMACDMABUSMOD, EMACTXPOLLD, EMACRXPOLLD, EMACRXDLADDR, EMACTXDLADDR,
      EMACDMARIS, EMACDMAOPMODE, EMACDMAIM, EMACMFBOC, EMACRXINTWDT,
      RESERVED14[8], EMACHOSTXDESC, EMACHOSRXDESC, EMACHOSTXBA, EMACHOSRXBA,
      RESERVED15[218], EMACPP, EMACPC, EMACCC, RESERVED16, EMACEPHYRIS,
      EMACEPHYIM, EMACEPHYIMSC;
};
#undef EMAC
#define EMAC ((struct tm4c_emac *) (uintptr_t) 0x400EC000)

#define ETH_PKT_SIZE 1540  // Max frame size
#define ETH_DESC_CNT 4     // Descriptors count
#define ETH_DS 4           // Descriptor size (words)

static uint32_t s_rxdesc[ETH_DESC_CNT][ETH_DS];      // RX descriptors
static uint32_t s_txdesc[ETH_DESC_CNT][ETH_DS];      // TX descriptors
static uint8_t s_rxbuf[ETH_DESC_CNT][ETH_PKT_SIZE];  // RX ethernet buffers
static uint8_t s_txbuf[ETH_DESC_CNT][ETH_PKT_SIZE];  // TX ethernet buffers
static struct mg_tcpip_if *s_ifp;                    // MIP interface
enum {
  EPHY_ADDR = 0,
  EPHYBMCR = 0,
  EPHYBMSR = 1,
  EPHYSTS = 16
};  // PHY constants

static inline void tm4cspin(volatile uint32_t count) {
  while (count--) (void) 0;
}

static uint32_t emac_read_phy(uint8_t addr, uint8_t reg) {
  EMAC->EMACMIIADDR &= (0xf << 2);
  EMAC->EMACMIIADDR |= ((uint32_t) addr << 11) | ((uint32_t) reg << 6);
  EMAC->EMACMIIADDR |= MG_BIT(0);
  while (EMAC->EMACMIIADDR & MG_BIT(0)) tm4cspin(1);
  return EMAC->EMACMIIDATA;
}

static void emac_write_phy(uint8_t addr, uint8_t reg, uint32_t val) {
  EMAC->EMACMIIDATA = val;
  EMAC->EMACMIIADDR &= (0xf << 2);
  EMAC->EMACMIIADDR |=
      ((uint32_t) addr << 11) | ((uint32_t) reg << 6) | MG_BIT(1);
  EMAC->EMACMIIADDR |= MG_BIT(0);
  while (EMAC->EMACMIIADDR & MG_BIT(0)) tm4cspin(1);
}

static uint32_t get_sysclk(void) {
  struct sysctl {
    volatile uint32_t DONTCARE0[44], RSCLKCFG, DONTCARE1[43], PLLFREQ0,
        PLLFREQ1;
  } *sysctl = (struct sysctl *) 0x400FE000;
  uint32_t clk = 0, piosc = 16000000 /* 16 MHz */, mosc = 25000000 /* 25MHz */;
  if (sysctl->RSCLKCFG & (1 << 28)) {  // USEPLL
    uint32_t fin, vco, mdiv, n, q, psysdiv;
    uint32_t pllsrc = (sysctl->RSCLKCFG & (0xf << 24)) >> 24;
    if (pllsrc == 0) {
      clk = piosc;
    } else if (pllsrc == 3) {
      clk = mosc;
    } else {
      MG_ERROR(("Unsupported clock source"));
    }
    q = (sysctl->PLLFREQ1 & (0x1f << 8)) >> 8;
    n = (sysctl->PLLFREQ1 & (0x1f << 0)) >> 0;
    fin = clk / ((q + 1) * (n + 1));
    mdiv = (sysctl->PLLFREQ0 & (0x3ff << 0)) >>
           0;  // mint + (mfrac / 1024); MFRAC not supported
    psysdiv = (sysctl->RSCLKCFG & (0x3f << 0)) >> 0;
    vco = (uint32_t) ((uint64_t) fin * mdiv);
    return vco / (psysdiv + 1);
  }
  uint32_t oscsrc = (sysctl->RSCLKCFG & (0xf << 20)) >> 20;
  if (oscsrc == 0) {
    clk = piosc;
  } else if (oscsrc == 3) {
    clk = mosc;
  } else {
    MG_ERROR(("Unsupported clock source"));
  }
  uint32_t osysdiv = (sysctl->RSCLKCFG & (0xf << 16)) >> 16;
  return clk / (osysdiv + 1);
}

//  Guess CR from SYSCLK. MDC clock is generated from SYSCLK (AHB); as per
//  802.3, it must not exceed 2.5MHz (also 20.4.2.6) As the AHB clock can be
//  derived from the PIOSC (internal RC), and it can go above  specs, the
//  datasheets specify a range of frequencies and activate one of a series of
//  dividers to keep the MDC clock safely below 2.5MHz. We guess a divider
//  setting based on SYSCLK with a +5% drift. If the user uses a different clock
//  from our defaults, needs to set the macros on top Valid for TM4C129x (20.7)
//  (4.5% worst case drift)
// The PHY receives the main oscillator (MOSC) (20.3.1)
static int guess_mdc_cr(void) {
  uint8_t crs[] = {2, 3, 0, 1};      // EMAC->MACMIIAR::CR values
  uint8_t div[] = {16, 26, 42, 62};  // Respective HCLK dividers
  uint32_t sysclk = get_sysclk();    // Guess system SYSCLK
  int i, result = -1;                // Invalid CR value
  if (sysclk < 25000000) {
    MG_ERROR(("SYSCLK too low"));
  } else {
    for (i = 0; i < 4; i++) {
      if (sysclk / div[i] <= 2375000UL /* 2.5MHz - 5% */) {
        result = crs[i];
        break;
      }
    }
    if (result < 0) MG_ERROR(("SYSCLK too high"));
  }
  MG_DEBUG(("SYSCLK: %u, CR: %d", sysclk, result));
  return result;
}

static bool mg_tcpip_driver_tm4c_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_tm4c_data *d =
      (struct mg_tcpip_driver_tm4c_data *) ifp->driver_data;
  int i;
  s_ifp = ifp;

  // Init RX descriptors
  for (i = 0; i < ETH_DESC_CNT; i++) {
    s_rxdesc[i][0] = MG_BIT(31);                         // Own
    s_rxdesc[i][1] = sizeof(s_rxbuf[i]) | MG_BIT(14);    // 2nd address chained
    s_rxdesc[i][2] = (uint32_t) (uintptr_t) s_rxbuf[i];  // Point to data buffer
    s_rxdesc[i][3] =
        (uint32_t) (uintptr_t) s_rxdesc[(i + 1) % ETH_DESC_CNT];  // Chain
    // MG_DEBUG(("%d %p", i, s_rxdesc[i]));
  }

  // Init TX descriptors
  for (i = 0; i < ETH_DESC_CNT; i++) {
    s_txdesc[i][2] = (uint32_t) (uintptr_t) s_txbuf[i];  // Buf pointer
    s_txdesc[i][3] =
        (uint32_t) (uintptr_t) s_txdesc[(i + 1) % ETH_DESC_CNT];  // Chain
  }

  EMAC->EMACDMABUSMOD |= MG_BIT(0);  // Software reset
  while ((EMAC->EMACDMABUSMOD & MG_BIT(0)) != 0)
    tm4cspin(1);  // Wait until done

  // Set MDC clock divider. If user told us the value, use it. Otherwise, guess
  int cr = (d == NULL || d->mdc_cr < 0) ? guess_mdc_cr() : d->mdc_cr;
  EMAC->EMACMIIADDR = ((uint32_t) cr & 0xf) << 2;

  // NOTE(cpq): we do not use extended descriptor bit 7, and do not use
  // hardware checksum. Therefore, descriptor size is 4, not 8
  // EMAC->EMACDMABUSMOD = MG_BIT(13) | MG_BIT(16) | MG_BIT(22) | MG_BIT(23) |
  // MG_BIT(25);
  EMAC->EMACIM = MG_BIT(3) | MG_BIT(9);  // Mask timestamp & PMT IT
  EMAC->EMACFLOWCTL = MG_BIT(7);         // Disable zero-quanta pause
  EMAC->EMACFRAMEFLTR = MG_BIT(10);      // Perfect filtering
  // EMAC->EMACPC defaults to internal PHY (EPHY) in MMI mode
  emac_write_phy(EPHY_ADDR, EPHYBMCR, MG_BIT(15));  // Reset internal PHY (EPHY)
  emac_write_phy(EPHY_ADDR, EPHYBMCR, MG_BIT(12));  // Set autonegotiation
  EMAC->EMACRXDLADDR = (uint32_t) (uintptr_t) s_rxdesc;  // RX descriptors
  EMAC->EMACTXDLADDR = (uint32_t) (uintptr_t) s_txdesc;  // TX descriptors
  EMAC->EMACDMAIM = MG_BIT(6) | MG_BIT(16);              // RIE, NIE
  EMAC->EMACCFG =
      MG_BIT(2) | MG_BIT(3) | MG_BIT(11) | MG_BIT(14);  // RE, TE, Duplex, Fast
  EMAC->EMACDMAOPMODE =
      MG_BIT(1) | MG_BIT(13) | MG_BIT(21) | MG_BIT(25);  // SR, ST, TSF, RSF
  EMAC->EMACADDR0H = ((uint32_t) ifp->mac[5] << 8U) | ifp->mac[4];
  EMAC->EMACADDR0L = (uint32_t) (ifp->mac[3] << 24) |
                     ((uint32_t) ifp->mac[2] << 16) |
                     ((uint32_t) ifp->mac[1] << 8) | ifp->mac[0];
  return true;
}

static uint32_t s_txno;
static size_t mg_tcpip_driver_tm4c_tx(const void *buf, size_t len,
                                      struct mg_tcpip_if *ifp) {
  if (len > sizeof(s_txbuf[s_txno])) {
    MG_ERROR(("Frame too big, %ld", (long) len));
    len = 0;  // fail
  } else if ((s_txdesc[s_txno][0] & MG_BIT(31))) {
    ifp->nerr++;
    MG_ERROR(("No descriptors available"));
    // printf("D0 %lx SR %lx\n", (long) s_txdesc[0][0], (long)
    // EMAC->EMACDMARIS);
    len = 0;  // fail
  } else {
    memcpy(s_txbuf[s_txno], buf, len);     // Copy data
    s_txdesc[s_txno][1] = (uint32_t) len;  // Set data len
    s_txdesc[s_txno][0] =
        MG_BIT(20) | MG_BIT(28) | MG_BIT(29) | MG_BIT(30);  // Chain,FS,LS,IC
    s_txdesc[s_txno][0] |= MG_BIT(31);  // Set OWN bit - let DMA take over
    if (++s_txno >= ETH_DESC_CNT) s_txno = 0;
  }
  EMAC->EMACDMARIS = MG_BIT(2) | MG_BIT(5);  // Clear any prior TU/UNF
  EMAC->EMACTXPOLLD = 0;                     // and resume
  return len;
}

static void mg_tcpip_driver_tm4c_update_hash_table(struct mg_tcpip_if *ifp) {
  // TODO(): read database, rebuild hash table
  // add mDNS / DNS-SD multicast address
  EMAC->EMACADDR1L = (uint32_t) mcast_addr[3] << 24 |
                     (uint32_t) mcast_addr[2] << 16 |
                     (uint32_t) mcast_addr[1] << 8 | (uint32_t) mcast_addr[0];
  EMAC->EMACADDR1H = (uint32_t) mcast_addr[5] << 8 | (uint32_t) mcast_addr[4];
  EMAC->EMACADDR1H |= MG_BIT(31);  // AE
  (void) ifp;
}

static bool mg_tcpip_driver_tm4c_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (ifp->update_mac_hash_table) {
    mg_tcpip_driver_tm4c_update_hash_table(ifp);
    ifp->update_mac_hash_table = false;
  }
  if (!s1) return false;
  uint32_t bmsr = emac_read_phy(EPHY_ADDR, EPHYBMSR);
  bool up = (bmsr & MG_BIT(2)) ? 1 : 0;
  if ((ifp->state == MG_TCPIP_STATE_DOWN) && up) {  // link state just went up
    uint32_t sts = emac_read_phy(EPHY_ADDR, EPHYSTS);
    // tmp = reg with flags set to the most likely situation: 100M full-duplex
    // if(link is slow or half) set flags otherwise
    // reg = tmp
    uint32_t emaccfg =
        EMAC->EMACCFG | MG_BIT(14) | MG_BIT(11);         // 100M, Full-duplex
    if (sts & MG_BIT(1)) emaccfg &= ~MG_BIT(14);         // 10M
    if ((sts & MG_BIT(2)) == 0) emaccfg &= ~MG_BIT(11);  // Half-duplex
    EMAC->EMACCFG = emaccfg;  // IRQ handler does not fiddle with this register
    MG_DEBUG(("Link is %uM %s-duplex", emaccfg & MG_BIT(14) ? 100 : 10,
              emaccfg & MG_BIT(11) ? "full" : "half"));
  }
  return up;
}

void EMAC0_IRQHandler(void);
static uint32_t s_rxno;
void EMAC0_IRQHandler(void) {
  int i;
  if (EMAC->EMACDMARIS & MG_BIT(6)) {           // Frame received, loop
    EMAC->EMACDMARIS = MG_BIT(16) | MG_BIT(6);  // Clear flag
    for (i = 0; i < 10; i++) {  // read as they arrive but not forever
      if (s_rxdesc[s_rxno][0] & MG_BIT(31)) break;  // exit when done
      if (((s_rxdesc[s_rxno][0] & (MG_BIT(8) | MG_BIT(9))) ==
           (MG_BIT(8) | MG_BIT(9))) &&
          !(s_rxdesc[s_rxno][0] & MG_BIT(15))) {  // skip partial/errored frames
        uint32_t len = ((s_rxdesc[s_rxno][0] >> 16) & (MG_BIT(14) - 1));
        //  printf("%lx %lu %lx %.8lx\n", s_rxno, len, s_rxdesc[s_rxno][0],
        //  EMAC->EMACDMARIS);
        mg_tcpip_qwrite(s_rxbuf[s_rxno], len > 4 ? len - 4 : len, s_ifp);
      }
      s_rxdesc[s_rxno][0] = MG_BIT(31);
      if (++s_rxno >= ETH_DESC_CNT) s_rxno = 0;
    }
  }
  EMAC->EMACDMARIS = MG_BIT(7);  // Clear possible RU while processing
  EMAC->EMACRXPOLLD = 0;         // and resume RX
}

struct mg_tcpip_driver mg_tcpip_driver_tm4c = {mg_tcpip_driver_tm4c_init,
                                               mg_tcpip_driver_tm4c_tx, NULL,
                                               mg_tcpip_driver_tm4c_poll};
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/tms570.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_TMS570) && MG_ENABLE_DRIVER_TMS570
struct tms570_emac_ctrl {
  volatile uint32_t REVID, SOFTRESET, RESERVED1[1], INTCONTROL, C0RXTHRESHEN,
  C0RXEN, C0TXEN, C0MISCEN, RESERVED2[8],
  C0RXTHRESHSTAT, C0RXSTAT, C0TXSTAT, C0MISCSTAT,
  RESERVED3[8],
  C0RXIMAX, C0TXIMAX;
};
struct tms570_emac {
  volatile uint32_t TXREVID, TXCONTROL, TXTEARDOWN, RESERVED1[1], RXREVID,
  RXCONTROL, RXTEARDOWN, RESERVED2[25], TXINTSTATRAW,TXINTSTATMASKED,
  TXINTMASKSET, TXINTMASKCLEAR, MACINVECTOR, MACEOIVECTOR, RESERVED8[2], RXINTSTATRAW,
  RXINTSTATMASKED, RXINTMASKSET, RXINTMASKCLEAR, MACINTSTATRAW, MACINTSTATMASKED,
  MACINTMASKSET, MACINTMASKCLEAR, RESERVED3[16], RXMBPENABLE, RXUNICASTSET,
  RXUNICASTCLEAR, RXMAXLEN, RXBUFFEROFFSET, RXFILTERLOWTHRESH, RESERVED9[2], RXFLOWTHRESH[8],
  RXFREEBUFFER[8], MACCONTROL, MACSTATUS, EMCONTROL, FIFOCONTROL, MACCONFIG,
  SOFTRESET, RESERVED4[22], MACSRCADDRLO, MACSRCADDRHI, MACHASH1, MACHASH2,
  BOFFTEST, TPACETEST, RXPAUSE, TXPAUSE, RESERVED5[4], RXGOODFRAMES, RXBCASTFRAMES,
  RXMCASTFRAMES, RXPAUSEFRAMES, RXCRCERRORS, RXALIGNCODEERRORS, RXOVERSIZED,
  RXJABBER, RXUNDERSIZED, RXFRAGMENTS, RXFILTERED, RXQOSFILTERED, RXOCTETS,
  TXGOODFRAMES, TXBCASTFRAMES, TXMCASTFRAMES, TXPAUSEFRAMES, TXDEFERRED,
  TXCOLLISION, TXSINGLECOLL, TXMULTICOLL, TXEXCESSIVECOLL, TXLATECOLL,
  TXUNDERRUN, TXCARRIERSENSE, TXOCTETS, FRAME64, FRAME65T127, FRAME128T255,
  FRAME256T511, FRAME512T1023, FRAME1024TUP, NETOCTETS, RXSOFOVERRUNS,
  RXMOFOVERRUNS, RXDMAOVERRUNS, RESERVED6[156], MACADDRLO, MACADDRHI,
  MACINDEX, RESERVED7[61], TXHDP[8], RXHDP[8], TXCP[8], RXCP[8];
};
struct tms570_mdio {
  volatile uint32_t REVID, CONTROL, ALIVE, LINK, LINKINTRAW, LINKINTMASKED,
  RESERVED1[2], USERINTRAW, USERINTMASKED, USERINTMASKSET, USERINTMASKCLEAR,
  RESERVED2[20], USERACCESS0, USERPHYSEL0, USERACCESS1, USERPHYSEL1;
};
#define SWAP32(x) ( (((x) & 0x000000FF) << 24) | \
                              (((x) & 0x0000FF00) << 8)  | \
                              (((x) & 0x00FF0000) >> 8)  | \
                              (((x) & 0xFF000000) >> 24) )
#undef EMAC
#undef EMAC_CTRL
#undef MDIO
#define EMAC ((struct tms570_emac *) (uintptr_t) 0xFCF78000)
#define EMAC_CTRL ((struct tms570_emac_ctrl *) (uintptr_t) 0xFCF78800)
#define MDIO ((struct tms570_mdio *) (uintptr_t) 0xFCF78900)
#define ETH_PKT_SIZE 1540  // Max frame size
#define ETH_DESC_CNT 4     // Descriptors count
#define ETH_DS 4           // Descriptor size (words)
static uint32_t s_txdesc[ETH_DESC_CNT][ETH_DS] 
  __attribute__((section(".ETH_CPPI"), aligned(4)));      // TX descriptors
static uint32_t s_rxdesc[ETH_DESC_CNT][ETH_DS] 
  __attribute__((section(".ETH_CPPI"), aligned(4)));      // RX descriptors
static uint8_t s_rxbuf[ETH_DESC_CNT][ETH_PKT_SIZE] 
  __attribute__((aligned(4)));  // RX ethernet buffers
static uint8_t s_txbuf[ETH_DESC_CNT][ETH_PKT_SIZE] 
  __attribute__((aligned(4)));  // TX ethernet buffers
static struct mg_tcpip_if *s_ifp;                    // MIP interface
static uint16_t emac_read_phy(uint8_t addr, uint8_t reg) {
  while(MDIO->USERACCESS0 & MG_BIT(31)) (void) 0;
  MDIO->USERACCESS0 = MG_BIT(31) | ((reg & 0x1f) << 21) |
                      ((addr & 0x1f) << 16);
  while(MDIO->USERACCESS0 & MG_BIT(31)) (void) 0;
  return MDIO->USERACCESS0 & 0xffff;
}
static void emac_write_phy(uint8_t addr, uint8_t reg, uint16_t val) {
  while(MDIO->USERACCESS0 & MG_BIT(31)) (void) 0;
  MDIO->USERACCESS0 = MG_BIT(31) | MG_BIT(30) | ((reg & 0x1f) << 21) |
                      ((addr & 0x1f) << 16) | (val & 0xffff);
  while(MDIO->USERACCESS0 & MG_BIT(31)) (void) 0;
}
static bool mg_tcpip_driver_tms570_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_tms570_data *d =
      (struct mg_tcpip_driver_tms570_data *) ifp->driver_data;
  s_ifp = ifp;
  EMAC_CTRL->SOFTRESET = MG_BIT(0); // Reset the EMAC Control Module
  while(EMAC_CTRL->SOFTRESET & MG_BIT(0)) (void) 0; // wait
  EMAC->SOFTRESET = MG_BIT(0); // Reset the EMAC Module
  while(EMAC->SOFTRESET & MG_BIT(0)) (void) 0;
  EMAC->MACCONTROL = 0;
  EMAC->RXCONTROL = 0;
  EMAC->TXCONTROL = 0;
  // Initialize all the header descriptor pointer registers
  uint32_t i;
  for(i =  0; i < ETH_DESC_CNT; i++) {
    EMAC->RXHDP[i] = 0;
    EMAC->TXHDP[i] = 0;
    EMAC->RXCP[i] = 0;
    EMAC->TXCP[i] = 0;
    ///EMAC->RXFREEBUFFER[i] = 0xff;
  }
  // Clear the interrupt enable for all the channels
  EMAC->TXINTMASKCLEAR = 0xff;
  EMAC->RXINTMASKCLEAR = 0xff;
  EMAC->MACHASH1 = 0;
  EMAC->MACHASH2 = 0;
  EMAC->RXBUFFEROFFSET = 0;
  EMAC->RXUNICASTCLEAR = 0xff;
  EMAC->RXUNICASTSET = 0;
  EMAC->RXMBPENABLE = 0;
  // init MDIO
  // MDIO_CLK frequency = VCLK3/(CLKDIV + 1). (MDIO must be between 1.0 - 2.5Mhz)
  uint32_t clkdiv = 75; // VCLK is configured to 75Mhz
  // CLKDIV, ENABLE, PREAMBLE, FAULTENB
  MDIO->CONTROL = (clkdiv - 1) | MG_BIT(30) | MG_BIT(20) | MG_BIT(18);
  volatile int delay = 0xfff;
  while (delay-- != 0) (void) 0;
  struct mg_phy phy = {emac_read_phy, emac_write_phy};
  mg_phy_init(&phy, d->phy_addr, MG_PHY_CLOCKS_MAC);
  uint32_t channel;
  for (channel = 0; channel < 8; channel++) {
    EMAC->MACINDEX = channel;
    EMAC->MACADDRHI = ifp->mac[0] | (ifp->mac[1] << 8) | (ifp->mac[2] << 16) |
                       (ifp->mac[3] << 24);
    EMAC->MACADDRLO = ifp->mac[4] | (ifp->mac[5] << 8) | MG_BIT(20) |
                      MG_BIT(19) | (channel << 16);
  }
  EMAC->RXUNICASTSET = 1; // accept unicast frames;

  EMAC->RXMBPENABLE |= MG_BIT(30) | MG_BIT(13); // CRC, broadcast

  // Initialize the descriptors
  for (i = 0; i < ETH_DESC_CNT; i++) {
    if (i < ETH_DESC_CNT - 1) {
      s_txdesc[i][0] = 0;
      s_rxdesc[i][0] = SWAP32(((uint32_t) &s_rxdesc[i + 1][0]));
    }
    s_txdesc[i][1] = SWAP32(((uint32_t) s_txbuf[i]));
    s_rxdesc[i][1] = SWAP32(((uint32_t) s_rxbuf[i]));
    s_txdesc[i][2] = 0;
    s_rxdesc[i][2] = SWAP32(ETH_PKT_SIZE);
    s_txdesc[i][3] = 0;
    s_rxdesc[i][3] = SWAP32(MG_BIT(29)); // OWN
  }
  s_txdesc[ETH_DESC_CNT - 1][0] = 0;
  s_rxdesc[ETH_DESC_CNT - 1][0] = 0;
  
  EMAC->MACCONTROL = MG_BIT(5) | MG_BIT(0); // Enable MII, Full-duplex
  //EMAC->TXINTMASKSET = 1; // Enable TX interrupt
  EMAC->RXINTMASKSET = 1; // Enable RX interrupt
  //EMAC_CTRL->C0TXEN = 1; // TX completion interrupt
  EMAC_CTRL->C0RXEN = 1; // RX completion interrupt
  EMAC->TXCONTROL = 1; // TXEN
  EMAC->RXCONTROL = 1; // RXEN
  EMAC->RXHDP[0] = (uint32_t) &s_rxdesc[0][0];
  return true;
}
static uint32_t s_txno;
static size_t mg_tcpip_driver_tms570_tx(const void *buf, size_t len,
                                      struct mg_tcpip_if *ifp) {
  if (len > sizeof(s_txbuf[s_txno])) {
    MG_ERROR(("Frame too big, %ld", (long) len));
    len = 0;  // fail
  } else if ((s_txdesc[s_txno][3] & SWAP32(MG_BIT(29)))) {
    ifp->nerr++;
    MG_ERROR(("No descriptors available"));
    len = 0;  // fail
  } else {
    memcpy(s_txbuf[s_txno], buf, len);     // Copy data
    if (len < 128) len = 128;
    s_txdesc[s_txno][2] = SWAP32((uint32_t) len);  // Set data len
    s_txdesc[s_txno][3] =
        SWAP32(MG_BIT(31) | MG_BIT(30) | MG_BIT(29) | len);  // SOP, EOP, OWN, length
    
    while(EMAC->TXHDP[0] != 0) (void) 0;
    EMAC->TXHDP[0] = (uint32_t) &s_txdesc[s_txno][0];
    if(++s_txno == ETH_DESC_CNT) {
      s_txno = 0;
    }
  }
  return len;
  (void) ifp;
}

static void mg_tcpip_driver_tms570_update_hash_table(struct mg_tcpip_if *ifp) {
  // TODO(): read database, rebuild hash table
  // Setting Hash Index for 01:00:5e:00:00:fb (multicast)
  // using TMS570 XOR method (32.5.37).
  // computed hash is 55, which means bit 23 (55 - 32) in
  // HASH2 register must be set
  EMAC->MACHASH2 = MG_BIT(23);
  EMAC->RXMBPENABLE = MG_BIT(5); // enable hash filtering
  (void) ifp;
}

static bool mg_tcpip_driver_tms570_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (ifp->update_mac_hash_table) {
    mg_tcpip_driver_tms570_update_hash_table(ifp);
    ifp->update_mac_hash_table = false;
  }
  if (!s1) return false;
  struct mg_tcpip_driver_tms570_data *d =
      (struct mg_tcpip_driver_tms570_data *) ifp->driver_data;
  uint8_t speed = MG_PHY_SPEED_10M;
  bool up = false, full_duplex = false;
  struct mg_phy phy = {emac_read_phy, emac_write_phy};
  if (!s1) return false;
  up = mg_phy_up(&phy, d->phy_addr, &full_duplex, &speed);
  if ((ifp->state == MG_TCPIP_STATE_DOWN) && up) {
    // link state just went up
    MG_DEBUG(("Link is %uM %s-duplex", speed == MG_PHY_SPEED_10M ? 10 : 100,
              full_duplex ? "full" : "half"));
  }
  return up;
}

#pragma CODE_STATE(EMAC_TX_IRQHandler, 32)
#pragma INTERRUPT(EMAC_TX_IRQHandler, IRQ)
void EMAC_TX_IRQHandler(void) {
  uint32_t status = EMAC_CTRL->C0TXSTAT;
  if (status & 1) { // interrupt caused on channel 0
    while(s_txdesc[s_txno][3] & SWAP32(MG_BIT(29))) (void) 0;
    EMAC->TXCP[0] = (uint32_t) &s_txdesc[s_txno][0];
  }
  //Write the DMA end of interrupt vector
  EMAC->MACEOIVECTOR = 2;
}
static uint32_t s_rxno;
#pragma CODE_STATE(EMAC_RX_IRQHandler, 32)
#pragma INTERRUPT(EMAC_RX_IRQHandler, IRQ)
void EMAC_RX_IRQHandler(void) {
  uint32_t status = EMAC_CTRL->C0RXSTAT;
  if (status & 1) { // Frame received, loop
    uint32_t i;
    //MG_INFO(("RX interrupt"));
    for (i = 0; i < 10; i++) {   // read as they arrive but not forever
      if (s_rxdesc[s_rxno][3] & SWAP32(MG_BIT(29))) break;
      uint32_t len = SWAP32(s_rxdesc[s_rxno][3]) & 0xffff;
      //MG_INFO(("recv len: %d", len));
      //mg_hexdump(s_rxbuf[s_rxno], len);
      mg_tcpip_qwrite(s_rxbuf[s_rxno], len > 4 ? len - 4 : len, s_ifp);
      uint32_t flags = s_rxdesc[s_rxno][3];
      s_rxdesc[s_rxno][3] = SWAP32(MG_BIT(29));
      s_rxdesc[s_rxno][2] = SWAP32(ETH_PKT_SIZE);
      EMAC->RXCP[0] = (uint32_t) &s_rxdesc[s_rxno][0];
      if (flags & SWAP32(MG_BIT(28))) {
        //MG_INFO(("EOQ detected"));
        EMAC->RXHDP[0] = (uint32_t) &s_rxdesc[0][0];
      }
      if (++s_rxno >= ETH_DESC_CNT) s_rxno = 0;
    }
  }
  //Write the DMA end of interrupt vector
  EMAC->MACEOIVECTOR = 1;
}
struct mg_tcpip_driver mg_tcpip_driver_tms570 = {mg_tcpip_driver_tms570_init,
                                               mg_tcpip_driver_tms570_tx, NULL,
                                               mg_tcpip_driver_tms570_poll};
#endif


#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/w5100.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_W5100) && MG_ENABLE_DRIVER_W5100

static void w5100_txn(struct mg_tcpip_spi *s, uint16_t addr, bool wr, void *buf,
                      size_t len) {
  size_t i;
  uint8_t *p = (uint8_t *) buf;
  uint8_t control = wr ? 0xF0 : 0x0F;
  uint8_t cmd[] = {control, (uint8_t) (addr >> 8), (uint8_t) (addr & 255)};
  s->begin(s->spi);
  for (i = 0; i < sizeof(cmd); i++) s->txn(s->spi, cmd[i]);
  for (i = 0; i < len; i++) {
    uint8_t r = s->txn(s->spi, p[i]);
    if (!wr) p[i] = r;
  }
  s->end(s->spi);
}

// clang-format off
static  void w5100_wn(struct mg_tcpip_spi *s, uint16_t addr, void *buf, size_t len) { w5100_txn(s, addr, true, buf, len); }
static  void w5100_w1(struct mg_tcpip_spi *s, uint16_t addr, uint8_t val) { w5100_wn(s, addr, &val, 1); }
static  void w5100_w2(struct mg_tcpip_spi *s, uint16_t addr, uint16_t val) { uint8_t buf[2] = {(uint8_t) (val >> 8), (uint8_t) (val & 255)}; w5100_wn(s, addr, buf, sizeof(buf)); }
static  void w5100_rn(struct mg_tcpip_spi *s, uint16_t addr, void *buf, size_t len) { w5100_txn(s, addr, false, buf, len); }
static  uint8_t w5100_r1(struct mg_tcpip_spi *s, uint16_t addr) { uint8_t r = 0; w5100_rn(s, addr, &r, 1); return r; }
static  uint16_t w5100_r2(struct mg_tcpip_spi *s, uint16_t addr) { uint8_t buf[2] = {0, 0}; w5100_rn(s, addr, buf, sizeof(buf)); return (uint16_t) ((buf[0] << 8) | buf[1]); }
// clang-format on

static size_t w5100_rx(void *buf, size_t buflen, struct mg_tcpip_if *ifp) {
  struct mg_tcpip_spi *s = (struct mg_tcpip_spi *) ifp->driver_data;
  uint16_t r = 0, n = 0, len = (uint16_t) buflen, n2;  // Read recv len
  while ((n2 = w5100_r2(s, 0x426)) > n) n = n2;        // Until it is stable
  if (n > 0) {
    uint16_t ptr = w5100_r2(s, 0x428);  // Get read pointer
    if (n <= len + 2 && n > 1) {
      r = (uint16_t) (n - 2);
    }
    uint16_t rxbuf_size = (1 << (w5100_r1(s, 0x1a) & 3)) * 1024;
    uint16_t rxbuf_addr = 0x6000;
    uint16_t ptr_ofs = (ptr + 2) & (rxbuf_size - 1);
    if (ptr_ofs + r < rxbuf_size) {
      w5100_rn(s, rxbuf_addr + ptr_ofs, buf, r);
    } else {
      uint16_t remaining_len = rxbuf_size - ptr_ofs;
      w5100_rn(s, rxbuf_addr + ptr_ofs, buf, remaining_len);
      w5100_rn(s, rxbuf_addr, buf + remaining_len, n - remaining_len);
    }
    w5100_w2(s, 0x428, (uint16_t) (ptr + n));
    w5100_w1(s, 0x401, 0x40);  // Sock0 CR -> RECV
  }
  return r;
}

static size_t w5100_tx(const void *buf, size_t buflen,
                       struct mg_tcpip_if *ifp) {
  struct mg_tcpip_spi *s = (struct mg_tcpip_spi *) ifp->driver_data;
  uint16_t i, n = 0, ptr = 0, len = (uint16_t) buflen;
  while (n < len) n = w5100_r2(s, 0x420);  // Wait for space
  ptr = w5100_r2(s, 0x424);                // Get write pointer
  uint16_t txbuf_size = (1 << (w5100_r1(s, 0x1b) & 3)) * 1024;
  uint16_t ptr_ofs = ptr & (txbuf_size - 1);
  uint16_t txbuf_addr = 0x4000;
  if (ptr_ofs + len > txbuf_size) {
    uint16_t size = txbuf_size - ptr_ofs;
    w5100_wn(s, txbuf_addr + ptr_ofs, (char *) buf, size);
    w5100_wn(s, txbuf_addr, (char *) buf + size, len - size);
  } else {
    w5100_wn(s, txbuf_addr + ptr_ofs, (char *) buf, len);
  }
  w5100_w2(s, 0x424, (uint16_t) (ptr + len));  // Advance write pointer
  w5100_w1(s, 0x401, 0x20);                    // Sock0 CR -> SEND
  for (i = 0; i < 40; i++) {
    uint8_t ir = w5100_r1(s, 0x402);  // Read S0 IR
    if (ir == 0) continue;
    // printf("IR %d, len=%d, free=%d, ptr %d\n", ir, (int) len, (int) n, ptr);
    w5100_w1(s, 0x402, ir);    // Write S0 IR: clear it!
    if (ir & 8) len = 0;       // Timeout. Report error
    if (ir & (16 | 8)) break;  // Stop on SEND_OK or timeout
  }
  return len;
}

static bool w5100_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_spi *s = (struct mg_tcpip_spi *) ifp->driver_data;
  s->end(s->spi);
  w5100_w1(s, 0, 0x80);               // Reset chip: CR -> 0x80
  w5100_w1(s, 0x72, 0x53);            // CR PHYLCKR -> unlock PHY
  w5100_w1(s, 0x46, 0);               // CR PHYCR0 -> autonegotiation
  w5100_w1(s, 0x47, 0);               // CR PHYCR1 -> reset
  w5100_w1(s, 0x72, 0x00);            // CR PHYLCKR -> lock PHY
  w5100_wn(s, 0x09, ifp->mac, 6);     // SHAR
  w5100_w1(s, 0x1a, 6);               // Sock0 RX buf size - 4KB
  w5100_w1(s, 0x1b, 6);               // Sock0 TX buf size - 4KB
  w5100_w1(s, 0x400, 0x44);           // Sock0 MR -> MACRAW, MAC filter
  w5100_w1(s, 0x401, 1);              // Sock0 CR -> OPEN
  return w5100_r1(s, 0x403) == 0x42;  // Sock0 SR == MACRAW
}

static bool w5100_poll(struct mg_tcpip_if *ifp, bool s1) {
  struct mg_tcpip_spi *spi = (struct mg_tcpip_spi *) ifp->driver_data;
  return s1 ? w5100_r1(spi, 0x3c /* PHYSR */) & 1
            : false;  // Bit 0 of PHYSR is LNK (0 - down, 1 - up)
}

struct mg_tcpip_driver mg_tcpip_driver_w5100 = {w5100_init, w5100_tx, w5100_rx,
                                                w5100_poll};
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/w5500.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_W5500) && MG_ENABLE_DRIVER_W5500

enum { W5500_CR = 0, W5500_S0 = 1, W5500_TX0 = 2, W5500_RX0 = 3 };

static void w5500_txn(struct mg_tcpip_spi *s, uint8_t block, uint16_t addr,
                      bool wr, void *buf, size_t len) {
  size_t i;
  uint8_t *p = (uint8_t *) buf;
  uint8_t cmd[] = {(uint8_t) (addr >> 8), (uint8_t) (addr & 255),
                   (uint8_t) ((block << 3) | (wr ? 4 : 0))};
  s->begin(s->spi);
  for (i = 0; i < sizeof(cmd); i++) s->txn(s->spi, cmd[i]);
  for (i = 0; i < len; i++) {
    uint8_t r = s->txn(s->spi, p[i]);
    if (!wr) p[i] = r;
  }
  s->end(s->spi);
}

// clang-format off
static  void w5500_wn(struct mg_tcpip_spi *s, uint8_t block, uint16_t addr, void *buf, size_t len) { w5500_txn(s, block, addr, true, buf, len); }
static  void w5500_w1(struct mg_tcpip_spi *s, uint8_t block, uint16_t addr, uint8_t val) { w5500_wn(s, block, addr, &val, 1); }
static  void w5500_w2(struct mg_tcpip_spi *s, uint8_t block, uint16_t addr, uint16_t val) { uint8_t buf[2] = {(uint8_t) (val >> 8), (uint8_t) (val & 255)}; w5500_wn(s, block, addr, buf, sizeof(buf)); }
static  void w5500_rn(struct mg_tcpip_spi *s, uint8_t block, uint16_t addr, void *buf, size_t len) { w5500_txn(s, block, addr, false, buf, len); }
static  uint8_t w5500_r1(struct mg_tcpip_spi *s, uint8_t block, uint16_t addr) { uint8_t r = 0; w5500_rn(s, block, addr, &r, 1); return r; }
static  uint16_t w5500_r2(struct mg_tcpip_spi *s, uint8_t block, uint16_t addr) { uint8_t buf[2] = {0, 0}; w5500_rn(s, block, addr, buf, sizeof(buf)); return (uint16_t) ((buf[0] << 8) | buf[1]); }
// clang-format on

static size_t w5500_rx(void *buf, size_t buflen, struct mg_tcpip_if *ifp) {
  struct mg_tcpip_spi *s = (struct mg_tcpip_spi *) ifp->driver_data;
  uint16_t r = 0, n = 0, len = (uint16_t) buflen, n2;     // Read recv len
  while ((n2 = w5500_r2(s, W5500_S0, 0x26)) > n) n = n2;  // Until it is stable
  // printf("RSR: %d\n", (int) n);
  if (n > 0) {
    uint16_t ptr = w5500_r2(s, W5500_S0, 0x28);  // Get read pointer
    n = w5500_r2(s, W5500_RX0, ptr);             // Read frame length
    if (n <= len + 2 && n > 1) {
      r = (uint16_t) (n - 2);
      w5500_rn(s, W5500_RX0, (uint16_t) (ptr + 2), buf, r);
    }
    w5500_w2(s, W5500_S0, 0x28, (uint16_t) (ptr + n));  // Advance read pointer
    w5500_w1(s, W5500_S0, 1, 0x40);                     // Sock0 CR -> RECV
    // printf("  RX_RD: tot=%u n=%u r=%u\n", n2, n, r);
  }
  return r;
}

static size_t w5500_tx(const void *buf, size_t buflen,
                       struct mg_tcpip_if *ifp) {
  struct mg_tcpip_spi *s = (struct mg_tcpip_spi *) ifp->driver_data;
  uint16_t i, ptr, n = 0, len = (uint16_t) buflen;
  while (n < len) n = w5500_r2(s, W5500_S0, 0x20);      // Wait for space
  ptr = w5500_r2(s, W5500_S0, 0x24);                    // Get write pointer
  w5500_wn(s, W5500_TX0, ptr, (void *) buf, len);       // Write data
  w5500_w2(s, W5500_S0, 0x24, (uint16_t) (ptr + len));  // Advance write pointer
  w5500_w1(s, W5500_S0, 1, 0x20);                       // Sock0 CR -> SEND
  for (i = 0; i < 40; i++) {
    uint8_t ir = w5500_r1(s, W5500_S0, 2);  // Read S0 IR
    if (ir == 0) continue;
    // printf("IR %d, len=%d, free=%d, ptr %d\n", ir, (int) len, (int) n, ptr);
    w5500_w1(s, W5500_S0, 2, ir);  // Write S0 IR: clear it!
    if (ir & 8) len = 0;           // Timeout. Report error
    if (ir & (16 | 8)) break;      // Stop on SEND_OK or timeout
  }
  return len;
}

static bool w5500_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_spi *s = (struct mg_tcpip_spi *) ifp->driver_data;
  s->end(s->spi);
  w5500_w1(s, W5500_CR, 0, 0x80);     // Reset chip: CR -> 0x80
  w5500_w1(s, W5500_CR, 0x2e, 0);     // CR PHYCFGR -> reset
  w5500_w1(s, W5500_CR, 0x2e, 0xf8);  // CR PHYCFGR -> set
  // w5500_wn(s, W5500_CR, 9, s->mac, 6);      // Set source MAC
  w5500_w1(s, W5500_S0, 0x1e, 16);          // Sock0 RX buf size
  w5500_w1(s, W5500_S0, 0x1f, 16);          // Sock0 TX buf size
  w5500_w1(s, W5500_S0, 0, 4);              // Sock0 MR -> MACRAW
  w5500_w1(s, W5500_S0, 1, 1);              // Sock0 CR -> OPEN
  return w5500_r1(s, W5500_S0, 3) == 0x42;  // Sock0 SR == MACRAW
}

static bool w5500_poll(struct mg_tcpip_if *ifp, bool s1) {
  struct mg_tcpip_spi *spi = (struct mg_tcpip_spi *) ifp->driver_data;
  return s1 ? w5500_r1(spi, W5500_CR, 0x2e /* PHYCFGR */) & 1
            : false;  // Bit 0 of PHYCFGR is LNK (0 - down, 1 - up)
}

struct mg_tcpip_driver mg_tcpip_driver_w5500 = {w5500_init, w5500_tx, w5500_rx,
                                                w5500_poll};
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/xmc.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_XMC) && MG_ENABLE_DRIVER_XMC

struct ETH_GLOBAL_TypeDef {
  volatile uint32_t MAC_CONFIGURATION, MAC_FRAME_FILTER, HASH_TABLE_HIGH,
      HASH_TABLE_LOW, GMII_ADDRESS, GMII_DATA, FLOW_CONTROL, VLAN_TAG, VERSION,
      DEBUG, REMOTE_WAKE_UP_FRAME_FILTER, PMT_CONTROL_STATUS, RESERVED[2],
      INTERRUPT_STATUS, INTERRUPT_MASK, MAC_ADDRESS0_HIGH, MAC_ADDRESS0_LOW,
      MAC_ADDRESS1_HIGH, MAC_ADDRESS1_LOW, MAC_ADDRESS2_HIGH, MAC_ADDRESS2_LOW,
      MAC_ADDRESS3_HIGH, MAC_ADDRESS3_LOW, RESERVED1[40], MMC_CONTROL,
      MMC_RECEIVE_INTERRUPT, MMC_TRANSMIT_INTERRUPT, MMC_RECEIVE_INTERRUPT_MASK,
      MMC_TRANSMIT_INTERRUPT_MASK, TX_STATISTICS[26], RESERVED2,
      RX_STATISTICS_1[26], RESERVED3[6], MMC_IPC_RECEIVE_INTERRUPT_MASK,
      RESERVED4, MMC_IPC_RECEIVE_INTERRUPT, RESERVED5, RX_STATISTICS_2[30],
      RESERVED7[286], TIMESTAMP_CONTROL, SUB_SECOND_INCREMENT,
      SYSTEM_TIME_SECONDS, SYSTEM_TIME_NANOSECONDS, SYSTEM_TIME_SECONDS_UPDATE,
      SYSTEM_TIME_NANOSECONDS_UPDATE, TIMESTAMP_ADDEND, TARGET_TIME_SECONDS,
      TARGET_TIME_NANOSECONDS, SYSTEM_TIME_HIGHER_WORD_SECONDS,
      TIMESTAMP_STATUS, PPS_CONTROL, RESERVED8[564], BUS_MODE,
      TRANSMIT_POLL_DEMAND, RECEIVE_POLL_DEMAND,
      RECEIVE_DESCRIPTOR_LIST_ADDRESS, TRANSMIT_DESCRIPTOR_LIST_ADDRESS, STATUS,
      OPERATION_MODE, INTERRUPT_ENABLE,
      MISSED_FRAME_AND_BUFFER_OVERFLOW_COUNTER,
      RECEIVE_INTERRUPT_WATCHDOG_TIMER, RESERVED9, AHB_STATUS, RESERVED10[6],
      CURRENT_HOST_TRANSMIT_DESCRIPTOR, CURRENT_HOST_RECEIVE_DESCRIPTOR,
      CURRENT_HOST_TRANSMIT_BUFFER_ADDRESS, CURRENT_HOST_RECEIVE_BUFFER_ADDRESS,
      HW_FEATURE;
};

#undef ETH0
#define ETH0 ((struct ETH_GLOBAL_TypeDef *) 0x5000C000UL)

#define ETH_PKT_SIZE 1536  // Max frame size
#define ETH_DESC_CNT 4     // Descriptors count
#define ETH_DS 4           // Descriptor size (words)

static uint8_t s_rxbuf[ETH_DESC_CNT][ETH_PKT_SIZE] MG_ETH_RAM;
static uint8_t s_txbuf[ETH_DESC_CNT][ETH_PKT_SIZE] MG_ETH_RAM;
static uint32_t s_rxdesc[ETH_DESC_CNT]
                        [ETH_DS] MG_ETH_RAM;  // RX descriptors
static uint32_t s_txdesc[ETH_DESC_CNT]
                        [ETH_DS] MG_ETH_RAM;  // TX descriptors
static uint8_t s_txno;                             // Current TX descriptor
static uint8_t s_rxno;                             // Current RX descriptor

static struct mg_tcpip_if *s_ifp;  // MIP interface
enum { MG_PHY_ADDR = 0, MG_PHYREG_BCR = 0, MG_PHYREG_BSR = 1 };

static uint16_t eth_read_phy(uint8_t addr, uint8_t reg) {
  ETH0->GMII_ADDRESS = (ETH0->GMII_ADDRESS & 0x3c) | ((uint32_t) addr << 11) |
                       ((uint32_t) reg << 6) | 1;
  while ((ETH0->GMII_ADDRESS & 1) != 0) (void) 0;
  return (uint16_t) (ETH0->GMII_DATA & 0xffff);
}

static void eth_write_phy(uint8_t addr, uint8_t reg, uint16_t val) {
  ETH0->GMII_DATA = val;
  ETH0->GMII_ADDRESS = (ETH0->GMII_ADDRESS & 0x3c) | ((uint32_t) addr << 11) |
                       ((uint32_t) reg << 6) | 3;
  while ((ETH0->GMII_ADDRESS & 1) != 0) (void) 0;
}

static uint32_t get_clock_rate(struct mg_tcpip_driver_xmc_data *d) {
  if (d->mdc_cr == -1) {
    // assume ETH clock is 60MHz by default
    // then according to 13.2.8.1, we need to set value 3
    return 3;
  }

  return d->mdc_cr;
}

static bool mg_tcpip_driver_xmc_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_xmc_data *d =
      (struct mg_tcpip_driver_xmc_data *) ifp->driver_data;
  s_ifp = ifp;

  // reset MAC
  ETH0->BUS_MODE |= 1;
  while (ETH0->BUS_MODE & 1) (void) 0;

  // set clock rate
  ETH0->GMII_ADDRESS = get_clock_rate(d) << 2;

  // init phy
  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  mg_phy_init(&phy, d->phy_addr, MG_PHY_CLOCKS_MAC);

  // configure MAC: DO, DM, FES, TC
  ETH0->MAC_CONFIGURATION = MG_BIT(13) | MG_BIT(11) | MG_BIT(14) | MG_BIT(24);

  // set the MAC address
  ETH0->MAC_ADDRESS0_HIGH = MG_U32(0, 0, ifp->mac[5], ifp->mac[4]);
  ETH0->MAC_ADDRESS0_LOW =
      MG_U32(ifp->mac[3], ifp->mac[2], ifp->mac[1], ifp->mac[0]);

  // Configure the receive filter
  ETH0->MAC_FRAME_FILTER = MG_BIT(10);  // Perfect filter
  // Disable flow control
  ETH0->FLOW_CONTROL = 0;
  // Enable store and forward mode
  ETH0->OPERATION_MODE = MG_BIT(25) | MG_BIT(21);  // RSF, TSF

  // Configure DMA bus mode (AAL, USP, RPBL, PBL)
  ETH0->BUS_MODE = MG_BIT(25) | MG_BIT(23) | (32 << 17) | (32 << 8);

  // init RX descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_rxdesc[i][0] = MG_BIT(31);  // OWN descriptor
    s_rxdesc[i][1] = MG_BIT(14) | ETH_PKT_SIZE;
    s_rxdesc[i][2] = (uint32_t) s_rxbuf[i];
    if (i == ETH_DESC_CNT - 1) {
      s_rxdesc[i][3] = (uint32_t) &s_rxdesc[0][0];
    } else {
      s_rxdesc[i][3] = (uint32_t) &s_rxdesc[i + 1][0];
    }
  }
  ETH0->RECEIVE_DESCRIPTOR_LIST_ADDRESS = (uint32_t) &s_rxdesc[0][0];

  // init TX descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_txdesc[i][0] = MG_BIT(30) | MG_BIT(20);
    s_txdesc[i][2] = (uint32_t) s_txbuf[i];
    if (i == ETH_DESC_CNT - 1) {
      s_txdesc[i][3] = (uint32_t) &s_txdesc[0][0];
    } else {
      s_txdesc[i][3] = (uint32_t) &s_txdesc[i + 1][0];
    }
  }
  ETH0->TRANSMIT_DESCRIPTOR_LIST_ADDRESS = (uint32_t) &s_txdesc[0][0];

  // Clear interrupts
  ETH0->STATUS = 0xFFFFFFFF;

  // Disable MAC interrupts
  ETH0->MMC_TRANSMIT_INTERRUPT_MASK = 0xFFFFFFFF;
  ETH0->MMC_RECEIVE_INTERRUPT_MASK = 0xFFFFFFFF;
  ETH0->MMC_IPC_RECEIVE_INTERRUPT_MASK = 0xFFFFFFFF;
  ETH0->INTERRUPT_MASK = MG_BIT(9) | MG_BIT(3);  // TSIM, PMTIM

  // Enable interrupts (NIE, RIE, TIE)
  ETH0->INTERRUPT_ENABLE = MG_BIT(16) | MG_BIT(6) | MG_BIT(0);

  // Enable MAC transmission and reception (TE, RE)
  ETH0->MAC_CONFIGURATION |= MG_BIT(3) | MG_BIT(2);
  // Enable DMA transmission and reception (ST, SR)
  ETH0->OPERATION_MODE |= MG_BIT(13) | MG_BIT(1);
  return true;
}

static size_t mg_tcpip_driver_xmc_tx(const void *buf, size_t len,
                                     struct mg_tcpip_if *ifp) {
  if (len > sizeof(s_txbuf[s_txno])) {
    MG_ERROR(("Frame too big, %ld", (long) len));
    len = 0;  // Frame is too big
  } else if ((s_txdesc[s_txno][0] & MG_BIT(31))) {
    ifp->nerr++;
    MG_ERROR(("No free descriptors"));
    len = 0;  // All descriptors are busy, fail
  } else {
    memcpy(s_txbuf[s_txno], buf, len);
    s_txdesc[s_txno][1] = len;
    // Table 13-19 Transmit Descriptor Word 0 (IC, LS, FS, TCH)
    s_txdesc[s_txno][0] = MG_BIT(30) | MG_BIT(29) | MG_BIT(28) | MG_BIT(20);
    s_txdesc[s_txno][0] |= MG_BIT(31);  // OWN bit: handle control to DMA
    if (++s_txno >= ETH_DESC_CNT) s_txno = 0;
  }

  // Resume processing
  ETH0->STATUS = MG_BIT(2);  // clear Transmit unavailable
  ETH0->TRANSMIT_POLL_DEMAND = 0;
  return len;
}

static void mg_tcpip_driver_xmc_update_hash_table(struct mg_tcpip_if *ifp) {
  // TODO(): read database, rebuild hash table
  // set the multicast address filter
  ETH0->MAC_ADDRESS1_HIGH =
      MG_U32(0, 0, mcast_addr[5], mcast_addr[4]) | MG_BIT(31);
  ETH0->MAC_ADDRESS1_LOW =
      MG_U32(mcast_addr[3], mcast_addr[2], mcast_addr[1], mcast_addr[0]);
  (void) ifp;
}

static bool mg_tcpip_driver_xmc_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (ifp->update_mac_hash_table) {
    mg_tcpip_driver_xmc_update_hash_table(ifp);
    ifp->update_mac_hash_table = false;
  }
  if (!s1) return false;
  struct mg_tcpip_driver_xmc_data *d =
      (struct mg_tcpip_driver_xmc_data *) ifp->driver_data;
  uint8_t speed = MG_PHY_SPEED_10M;
  bool up = false, full_duplex = false;
  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  up = mg_phy_up(&phy, d->phy_addr, &full_duplex, &speed);
  if ((ifp->state == MG_TCPIP_STATE_DOWN) && up) {  // link state just went up
    MG_DEBUG(("Link is %uM %s-duplex", speed == MG_PHY_SPEED_10M ? 10 : 100,
              full_duplex ? "full" : "half"));
  }
  return up;
}

void ETH0_0_IRQHandler(void);
void ETH0_0_IRQHandler(void) {
  uint32_t irq_status = ETH0->STATUS;

  // check if a frame was received
  if (irq_status & MG_BIT(6)) {
    for (uint8_t i = 0; i < 10; i++) {  // read as they arrive, but not forever
      if (s_rxdesc[s_rxno][0] & MG_BIT(31)) break;
      size_t len = (s_rxdesc[s_rxno][0] & 0x3fff0000) >> 16;
      mg_tcpip_qwrite(s_rxbuf[s_rxno], len, s_ifp);
      s_rxdesc[s_rxno][0] = MG_BIT(31);  // OWN bit: handle control to DMA
      // Resume processing
      ETH0->STATUS = MG_BIT(7) | MG_BIT(6);  // clear RU and RI
      ETH0->RECEIVE_POLL_DEMAND = 0;
      if (++s_rxno >= ETH_DESC_CNT) s_rxno = 0;
    }
    ETH0->STATUS = MG_BIT(6);
  }

  // clear Successful transmission interrupt
  if (irq_status & 1) {
    ETH0->STATUS = 1;
  }

  // clear normal interrupt
  if (irq_status & MG_BIT(16)) {
    ETH0->STATUS = MG_BIT(16);
  }
}

struct mg_tcpip_driver mg_tcpip_driver_xmc = {mg_tcpip_driver_xmc_init,
                                              mg_tcpip_driver_xmc_tx, NULL,
                                              mg_tcpip_driver_xmc_poll};
#endif

#ifdef MG_ENABLE_LINES
#line 1 "src/drivers/xmc7.c"
#endif


#if MG_ENABLE_TCPIP && defined(MG_ENABLE_DRIVER_XMC7) && MG_ENABLE_DRIVER_XMC7

struct ETH_Type {
  volatile uint32_t CTL, STATUS, RESERVED[1022], NETWORK_CONTROL,
      NETWORK_CONFIG, NETWORK_STATUS, USER_IO_REGISTER, DMA_CONFIG,
      TRANSMIT_STATUS, RECEIVE_Q_PTR, TRANSMIT_Q_PTR, RECEIVE_STATUS,
      INT_STATUS, INT_ENABLE, INT_DISABLE, INT_MASK, PHY_MANAGEMENT, PAUSE_TIME,
      TX_PAUSE_QUANTUM, PBUF_TXCUTTHRU, PBUF_RXCUTTHRU, JUMBO_MAX_LENGTH,
      EXTERNAL_FIFO_INTERFACE, RESERVED1, AXI_MAX_PIPELINE, RSC_CONTROL,
      INT_MODERATION, SYS_WAKE_TIME, RESERVED2[7], HASH_BOTTOM, HASH_TOP,
      SPEC_ADD1_BOTTOM, SPEC_ADD1_TOP, SPEC_ADD2_BOTTOM, SPEC_ADD2_TOP,
      SPEC_ADD3_BOTTOM, SPEC_ADD3_TOP, SPEC_ADD4_BOTTOM, SPEC_ADD4_TOP,
      SPEC_TYPE1, SPEC_TYPE2, SPEC_TYPE3, SPEC_TYPE4, WOL_REGISTER,
      STRETCH_RATIO, STACKED_VLAN, TX_PFC_PAUSE, MASK_ADD1_BOTTOM,
      MASK_ADD1_TOP, DMA_ADDR_OR_MASK, RX_PTP_UNICAST, TX_PTP_UNICAST,
      TSU_NSEC_CMP, TSU_SEC_CMP, TSU_MSB_SEC_CMP, TSU_PTP_TX_MSB_SEC,
      TSU_PTP_RX_MSB_SEC, TSU_PEER_TX_MSB_SEC, TSU_PEER_RX_MSB_SEC,
      DPRAM_FILL_DBG, REVISION_REG, OCTETS_TXED_BOTTOM, OCTETS_TXED_TOP,
      FRAMES_TXED_OK, BROADCAST_TXED, MULTICAST_TXED, PAUSE_FRAMES_TXED,
      FRAMES_TXED_64, FRAMES_TXED_65, FRAMES_TXED_128, FRAMES_TXED_256,
      FRAMES_TXED_512, FRAMES_TXED_1024, FRAMES_TXED_1519, TX_UNDERRUNS,
      SINGLE_COLLISIONS, MULTIPLE_COLLISIONS, EXCESSIVE_COLLISIONS,
      LATE_COLLISIONS, DEFERRED_FRAMES, CRS_ERRORS, OCTETS_RXED_BOTTOM,
      OCTETS_RXED_TOP, FRAMES_RXED_OK, BROADCAST_RXED, MULTICAST_RXED,
      PAUSE_FRAMES_RXED, FRAMES_RXED_64, FRAMES_RXED_65, FRAMES_RXED_128,
      FRAMES_RXED_256, FRAMES_RXED_512, FRAMES_RXED_1024, FRAMES_RXED_1519,
      UNDERSIZE_FRAMES, EXCESSIVE_RX_LENGTH, RX_JABBERS, FCS_ERRORS,
      RX_LENGTH_ERRORS, RX_SYMBOL_ERRORS, ALIGNMENT_ERRORS, RX_RESOURCE_ERRORS,
      RX_OVERRUNS, RX_IP_CK_ERRORS, RX_TCP_CK_ERRORS, RX_UDP_CK_ERRORS,
      AUTO_FLUSHED_PKTS, RESERVED3, TSU_TIMER_INCR_SUB_NSEC, TSU_TIMER_MSB_SEC,
      TSU_STROBE_MSB_SEC, TSU_STROBE_SEC, TSU_STROBE_NSEC, TSU_TIMER_SEC,
      TSU_TIMER_NSEC, TSU_TIMER_ADJUST, TSU_TIMER_INCR, TSU_PTP_TX_SEC,
      TSU_PTP_TX_NSEC, TSU_PTP_RX_SEC, TSU_PTP_RX_NSEC, TSU_PEER_TX_SEC,
      TSU_PEER_TX_NSEC, TSU_PEER_RX_SEC, TSU_PEER_RX_NSEC, PCS_CONTROL,
      PCS_STATUS, RESERVED4[2], PCS_AN_ADV, PCS_AN_LP_BASE, PCS_AN_EXP,
      PCS_AN_NP_TX, PCS_AN_LP_NP, RESERVED5[6], PCS_AN_EXT_STATUS, RESERVED6[8],
      TX_PAUSE_QUANTUM1, TX_PAUSE_QUANTUM2, TX_PAUSE_QUANTUM3, RESERVED7,
      RX_LPI, RX_LPI_TIME, TX_LPI, TX_LPI_TIME, DESIGNCFG_DEBUG1,
      DESIGNCFG_DEBUG2, DESIGNCFG_DEBUG3, DESIGNCFG_DEBUG4, DESIGNCFG_DEBUG5,
      DESIGNCFG_DEBUG6, DESIGNCFG_DEBUG7, DESIGNCFG_DEBUG8, DESIGNCFG_DEBUG9,
      DESIGNCFG_DEBUG10, RESERVED8[22], SPEC_ADD5_BOTTOM, SPEC_ADD5_TOP,
      RESERVED9[60], SPEC_ADD36_BOTTOM, SPEC_ADD36_TOP, INT_Q1_STATUS,
      INT_Q2_STATUS, INT_Q3_STATUS, RESERVED10[11], INT_Q15_STATUS, RESERVED11,
      TRANSMIT_Q1_PTR, TRANSMIT_Q2_PTR, TRANSMIT_Q3_PTR, RESERVED12[11],
      TRANSMIT_Q15_PTR, RESERVED13, RECEIVE_Q1_PTR, RECEIVE_Q2_PTR,
      RECEIVE_Q3_PTR, RESERVED14[3], RECEIVE_Q7_PTR, RESERVED15,
      DMA_RXBUF_SIZE_Q1, DMA_RXBUF_SIZE_Q2, DMA_RXBUF_SIZE_Q3, RESERVED16[3],
      DMA_RXBUF_SIZE_Q7, CBS_CONTROL, CBS_IDLESLOPE_Q_A, CBS_IDLESLOPE_Q_B,
      UPPER_TX_Q_BASE_ADDR, TX_BD_CONTROL, RX_BD_CONTROL, UPPER_RX_Q_BASE_ADDR,
      RESERVED17[2], HIDDEN_REG0, HIDDEN_REG1, HIDDEN_REG2, HIDDEN_REG3,
      RESERVED18[2], HIDDEN_REG4, HIDDEN_REG5;
};

#define ETH0 ((struct ETH_Type *) 0x40490000)

#define ETH_PKT_SIZE 1536  // Max frame size
#define ETH_DESC_CNT 4     // Descriptors count
#define ETH_DS 2           // Descriptor size (words)

static uint8_t s_rxbuf[ETH_DESC_CNT][ETH_PKT_SIZE] MG_ETH_RAM;
static uint8_t s_txbuf[ETH_DESC_CNT][ETH_PKT_SIZE] MG_ETH_RAM;
static uint32_t s_rxdesc[ETH_DESC_CNT][ETH_DS] MG_ETH_RAM MG_8BYTE_ALIGNED;
static uint32_t s_txdesc[ETH_DESC_CNT][ETH_DS] MG_ETH_RAM MG_8BYTE_ALIGNED;
static uint8_t s_txno;  // Current TX descriptor
static uint8_t s_rxno;  // Current RX descriptor

static struct mg_tcpip_if *s_ifp;  // MIP interface
enum { MG_PHY_ADDR = 0, MG_PHYREG_BCR = 0, MG_PHYREG_BSR = 1 };

static uint16_t eth_read_phy(uint8_t addr, uint8_t reg) {
  // WRITE1, READ OPERATION, PHY, REG, WRITE10
  ETH0->PHY_MANAGEMENT = MG_BIT(30) | MG_BIT(29) | ((addr & 0xf) << 24) |
                         ((reg & 0x1f) << 18) | MG_BIT(17);
  while ((ETH0->NETWORK_STATUS & MG_BIT(2)) == 0) (void) 0;
  return ETH0->PHY_MANAGEMENT & 0xffff;
}

static void eth_write_phy(uint8_t addr, uint8_t reg, uint16_t val) {
  ETH0->PHY_MANAGEMENT = MG_BIT(30) | MG_BIT(28) | ((addr & 0xf) << 24) |
                         ((reg & 0x1f) << 18) | MG_BIT(17) | val;
  while ((ETH0->NETWORK_STATUS & MG_BIT(2)) == 0) (void) 0;
}

static uint32_t get_clock_rate(struct mg_tcpip_driver_xmc7_data *d) {
  // see ETH0 -> NETWORK_CONFIG register
  (void) d;
  return 3;
}

static bool mg_tcpip_driver_xmc7_init(struct mg_tcpip_if *ifp) {
  struct mg_tcpip_driver_xmc7_data *d =
      (struct mg_tcpip_driver_xmc7_data *) ifp->driver_data;
  s_ifp = ifp;

  // enable controller, set RGMII mode
  ETH0->CTL = MG_BIT(31) | (4 << 8) | 2;

  uint32_t cr = get_clock_rate(d);
  // set NSP change, ignore RX FCS, data bus width, clock rate
  // frame length 1536, full duplex, speed
  ETH0->NETWORK_CONFIG = MG_BIT(29) | MG_BIT(26) | MG_BIT(21) |
                         ((cr & 7) << 18) | MG_BIT(8) | MG_BIT(1) | MG_BIT(0);

  // config DMA settings: Force TX burst, Discard on Error, set RX buffer size
  // to 1536, TX_PBUF_SIZE, RX_PBUF_SIZE, AMBA_BURST_LENGTH
  ETH0->DMA_CONFIG =
      MG_BIT(26) | MG_BIT(24) | (0x18 << 16) | MG_BIT(10) | (3 << 8) | 4;

  // initialize descriptors
  for (int i = 0; i < ETH_DESC_CNT; i++) {
    s_rxdesc[i][0] = (uint32_t) s_rxbuf[i];
    if (i == ETH_DESC_CNT - 1) {
      s_rxdesc[i][0] |= MG_BIT(1);  // mark last descriptor
    }

    s_txdesc[i][0] = (uint32_t) s_txbuf[i];
    s_txdesc[i][1] = MG_BIT(31);  // OWN descriptor
    if (i == ETH_DESC_CNT - 1) {
      s_txdesc[i][1] |= MG_BIT(30);  // mark last descriptor
    }
  }
  ETH0->RECEIVE_Q_PTR = (uint32_t) s_rxdesc;
  ETH0->TRANSMIT_Q_PTR = (uint32_t) s_txdesc;

  // disable other queues
  ETH0->TRANSMIT_Q2_PTR = 1;
  ETH0->TRANSMIT_Q1_PTR = 1;
  ETH0->RECEIVE_Q2_PTR = 1;
  ETH0->RECEIVE_Q1_PTR = 1;

  // enable interrupts (RX complete)
  ETH0->INT_ENABLE = MG_BIT(1);

  // set MAC address
  ETH0->SPEC_ADD1_BOTTOM =
      ifp->mac[3] << 24 | ifp->mac[2] << 16 | ifp->mac[1] << 8 | ifp->mac[0];
  ETH0->SPEC_ADD1_TOP = ifp->mac[5] << 8 | ifp->mac[4];

  // enable MDIO, TX, RX
  ETH0->NETWORK_CONTROL = MG_BIT(4) | MG_BIT(3) | MG_BIT(2);

  // start transmission
  ETH0->NETWORK_CONTROL |= MG_BIT(9);

  // init phy
  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  mg_phy_init(&phy, d->phy_addr, MG_PHY_CLOCKS_MAC);

  (void) d;
  return true;
}

static size_t mg_tcpip_driver_xmc7_tx(const void *buf, size_t len,
                                      struct mg_tcpip_if *ifp) {
  if (len > sizeof(s_txbuf[s_txno])) {
    MG_ERROR(("Frame too big, %ld", (long) len));
    len = 0;  // Frame is too big
  } else if (((s_txdesc[s_txno][1] & MG_BIT(31)) == 0)) {
    ifp->nerr++;
    MG_ERROR(("No free descriptors"));
    len = 0;  // All descriptors are busy, fail
  } else {
    memcpy(s_txbuf[s_txno], buf, len);
    s_txdesc[s_txno][1] = (s_txno == ETH_DESC_CNT - 1 ? MG_BIT(30) : 0) |
                          MG_BIT(15) | len;  // Last buffer and length

    ETH0->NETWORK_CONTROL |= MG_BIT(9);  // enable transmission
    if (++s_txno >= ETH_DESC_CNT) s_txno = 0;
  }

  MG_DSB();
  ETH0->TRANSMIT_STATUS = ETH0->TRANSMIT_STATUS;
  ETH0->NETWORK_CONTROL |= MG_BIT(9);  // enable transmission

  return len;
}

static void mg_tcpip_driver_xmc7_update_hash_table(struct mg_tcpip_if *ifp) {
  // TODO(): read database, rebuild hash table
  // set multicast MAC address
  ETH0->SPEC_ADD2_BOTTOM = mcast_addr[3] << 24 | mcast_addr[2] << 16 |
                           mcast_addr[1] << 8 | mcast_addr[0];
  ETH0->SPEC_ADD2_TOP = mcast_addr[5] << 8 | mcast_addr[4];
  (void) ifp;
}

static bool mg_tcpip_driver_xmc7_poll(struct mg_tcpip_if *ifp, bool s1) {
  if (ifp->update_mac_hash_table) {
    mg_tcpip_driver_xmc7_update_hash_table(ifp);
    ifp->update_mac_hash_table = false;
  }
  if (!s1) return false;
  struct mg_tcpip_driver_xmc7_data *d =
      (struct mg_tcpip_driver_xmc7_data *) ifp->driver_data;
  uint8_t speed = MG_PHY_SPEED_10M;
  bool up = false, full_duplex = false;
  struct mg_phy phy = {eth_read_phy, eth_write_phy};
  up = mg_phy_up(&phy, d->phy_addr, &full_duplex, &speed);
  if ((ifp->state == MG_TCPIP_STATE_DOWN) && up) {  // link state just went up
    // tmp = reg with flags set to the most likely situation: 100M full-duplex
    // if(link is slow or half) set flags otherwise
    // reg = tmp
    uint32_t netconf = ETH0->NETWORK_CONFIG;
    MG_SET_BITS(netconf, MG_BIT(10),
                MG_BIT(1) | MG_BIT(0));  // 100M, Full-duplex
    uint32_t ctl = ETH0->CTL;
    MG_SET_BITS(ctl, 0xFF00, 4 << 8);  // /5 for 25M clock
    if (speed == MG_PHY_SPEED_1000M) {
      netconf |= MG_BIT(10);        // 1000M
      MG_SET_BITS(ctl, 0xFF00, 0);  // /1 for 125M clock TODO() IS THIS NEEDED ?
    } else if (speed == MG_PHY_SPEED_10M) {
      netconf &= ~MG_BIT(0);         // 10M
      MG_SET_BITS(ctl, 0xFF00, 49);  // /50 for 2.5M clock
    }
    if (full_duplex == false) netconf &= ~MG_BIT(1);  // Half-duplex
    ETH0->NETWORK_CONFIG = netconf;  // IRQ handler does not fiddle with these
    ETH0->CTL = ctl;
    MG_DEBUG(("Link is %uM %s-duplex",
              speed == MG_PHY_SPEED_10M
                  ? 10
                  : (speed == MG_PHY_SPEED_100M ? 100 : 1000),
              full_duplex ? "full" : "half"));
  }
  return up;
}

void ETH_IRQHandler(void) {
  uint32_t irq_status = ETH0->INT_STATUS;
  if (irq_status & MG_BIT(1)) {
    for (uint8_t i = 0; i < 10; i++) {  // read as they arrive, but not forever
      if ((s_rxdesc[s_rxno][0] & MG_BIT(0)) == 0) break;
      size_t len = s_rxdesc[s_rxno][1] & (MG_BIT(13) - 1);
      mg_tcpip_qwrite(s_rxbuf[s_rxno], len, s_ifp);
      s_rxdesc[s_rxno][0] &= ~MG_BIT(0);  // OWN bit: handle control to DMA
      if (++s_rxno >= ETH_DESC_CNT) s_rxno = 0;
    }
  }

  ETH0->INT_STATUS = irq_status;
}

struct mg_tcpip_driver mg_tcpip_driver_xmc7 = {mg_tcpip_driver_xmc7_init,
                                               mg_tcpip_driver_xmc7_tx, NULL,
                                               mg_tcpip_driver_xmc7_poll};
#endif
