text: /*
   * ngtcp2
   *
   * Copyright (c) 2017 ngtcp2 contributors
   *
   * Permission is hereby granted, free of charge, to any person obtaining
   * a copy of this software and associated documentation files (the
   * "Software"), to deal in the Software without restriction, including
   * without limitation the rights to use, copy, modify, merge, publish,
   * distribute, sublicense, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   *
   * The above copyright notice and this permission notice shall be
   * included in all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
   * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
   * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   */
  #include "ngtcp2_conv.h"
  
  #include <string.h>
  #include <assert.h>
  
  #include "ngtcp2_str.h"
  #include "ngtcp2_pkt.h"
  
  uint64_t ngtcp2_get_uint64(const uint8_t *p) {
    uint64_t n;
    memcpy(&n, p, 8);
    return ngtcp2_ntohl64(n);
  }
  
  uint64_t ngtcp2_get_uint48(const uint8_t *p) {
    uint64_t n = 0;
    memcpy(((uint8_t *)&n) + 2, p, 6);
    return ngtcp2_ntohl64(n);
  }
  
  uint32_t ngtcp2_get_uint32(const uint8_t *p) {
    uint32_t n;
    memcpy(&n, p, 4);
    return ntohl(n);
  }
  
  uint32_t ngtcp2_get_uint24(const uint8_t *p) {
    uint32_t n = 0;
    memcpy(((uint8_t *)&n) + 1, p, 3);
    return ntohl(n);
  }
  
  uint16_t ngtcp2_get_uint16(const uint8_t *p) {
    uint16_t n;
    memcpy(&n, p, 2);
    return ntohs(n);
  }
  
  uint64_t ngtcp2_get_varint(size_t *plen, const uint8_t *p) {
    union {
      char b[8];
      uint16_t n16;
      uint32_t n32;
      uint64_t n64;
    } n;
  
    *plen = 1u << (*p >> 6);
  
    switch (*plen) {
    case 1:
      return *p;
    case 2:
      memcpy(&n, p, 2);
      n.b[0] &= 0x3f;
      return ntohs(n.n16);
    case 4:
      memcpy(&n, p, 4);
      n.b[0] &= 0x3f;
      return ntohl(n.n32);
    case 8:
      memcpy(&n, p, 8);
      n.b[0] &= 0x3f;
      return ngtcp2_ntohl64(n.n64);
    }
  
    assert(0);
  }
  
  int64_t ngtcp2_get_pkt_num(const uint8_t *p, size_t pkt_numlen) {
    switch (pkt_numlen) {
    case 1:
      return *p;
    case 2:
      return (int64_t)ngtcp2_get_uint16(p);
    case 3:
      return (int64_t)ngtcp2_get_uint24(p);
    case 4:
      return (int64_t)ngtcp2_get_uint32(p);
    default:
      assert(0);
    }
  }
  
  uint8_t *ngtcp2_put_uint64be(uint8_t *p, uint64_t n) {
    n = ngtcp2_htonl64(n);
    return ngtcp2_cpymem(p, (const uint8_t *)&n, sizeof(n));
  }
  
  uint8_t *ngtcp2_put_uint48be(uint8_t *p, uint64_t n) {
    n = ngtcp2_htonl64(n);
    return ngtcp2_cpymem(p, ((const uint8_t *)&n) + 2, 6);
  }
  
  uint8_t *ngtcp2_put_uint32be(uint8_t *p, uint32_t n) {
    n = htonl(n);
    return ngtcp2_cpymem(p, (const uint8_t *)&n, sizeof(n));
  }
  
  uint8_t *ngtcp2_put_uint24be(uint8_t *p, uint32_t n) {
    n = htonl(n);
    return ngtcp2_cpymem(p, ((const uint8_t *)&n) + 1, 3);
  }
  
  uint8_t *ngtcp2_put_uint16be(uint8_t *p, uint16_t n) {
    n = htons(n);
    return ngtcp2_cpymem(p, (const uint8_t *)&n, sizeof(n));
  }
  
  uint8_t *ngtcp2_put_varint(uint8_t *p, uint64_t n) {
    uint8_t *rv;
    if (n < 64) {
      *p++ = (uint8_t)n;
      return p;
    }
    if (n < 16384) {
      rv = ngtcp2_put_uint16be(p, (uint16_t)n);
      *p |= 0x40;
      return rv;
    }
    if (n < 1073741824) {
      rv = ngtcp2_put_uint32be(p, (uint32_t)n);
      *p |= 0x80;
      return rv;
    }
    assert(n < 4611686018427387904ULL);
    rv = ngtcp2_put_uint64be(p, n);
    *p |= 0xc0;
    return rv;
  }
  
  uint8_t *ngtcp2_put_varint14(uint8_t *p, uint16_t n) {
    uint8_t *rv;
  
    assert(n < 16384);
  
    rv = ngtcp2_put_uint16be(p, n);
    *p |= 0x40;
  
    return rv;
  }
  
  uint8_t *ngtcp2_put_pkt_num(uint8_t *p, int64_t pkt_num, size_t len) {
    switch (len) {
    case 1:
      *p++ = (uint8_t)pkt_num;
      return p;
    case 2:
      ngtcp2_put_uint16be(p, (uint16_t)pkt_num);
      return p + 2;
    case 3:
      ngtcp2_put_uint24be(p, (uint32_t)pkt_num);
      return p + 3;
    case 4:
      ngtcp2_put_uint32be(p, (uint32_t)pkt_num);
      return p + 4;
    default:
      assert(0);
    }
  }
  
  size_t ngtcp2_get_varint_len(const uint8_t *p) { return 1u << (*p >> 6); }
  
  size_t ngtcp2_put_varint_len(uint64_t n) {
    if (n < 64) {
      return 1;
    }
    if (n < 16384) {
      return 2;
    }
    if (n < 1073741824) {
      return 4;
    }
    assert(n < 4611686018427387904ULL);
    return 8;
  }
  
  int64_t ngtcp2_nth_server_bidi_id(uint64_t n) {
    if (n == 0) {
      return 0;
    }
  
    if ((NGTCP2_MAX_VARINT >> 2) < n - 1) {
      return NGTCP2_MAX_SERVER_STREAM_ID_BIDI;
    }
  
    return (int64_t)(((n - 1) << 2) | 0x01);
  }
  
  int64_t ngtcp2_nth_client_bidi_id(uint64_t n) {
    if (n == 0) {
      return 0;
    }
  
    if ((NGTCP2_MAX_VARINT >> 2) < n - 1) {
      return NGTCP2_MAX_CLIENT_STREAM_ID_BIDI;
    }
  
    return (int64_t)((n - 1) << 2);
  }
  
  int64_t ngtcp2_nth_server_uni_id(uint64_t n) {
    if (n == 0) {
      return 0;
    }
  
    if ((NGTCP2_MAX_VARINT >> 2) < n - 1) {
      return NGTCP2_MAX_SERVER_STREAM_ID_UNI;
    }
  
    return (int64_t)(((n - 1) << 2) | 0x03);
  }
  
  int64_t ngtcp2_nth_client_uni_id(uint64_t n) {
    if (n == 0) {
      return 0;
    }
  
    if ((NGTCP2_MAX_VARINT >> 2) < n - 1) {
      return NGTCP2_MAX_CLIENT_STREAM_ID_UNI;
    }
  
    return (int64_t)(((n - 1) << 2) | 0x02);
  }
  
  uint64_t ngtcp2_ord_stream_id(int64_t stream_id) {
    return (uint64_t)(stream_id >> 2) + 1;
  }
  