text: /*
   * Copyright 2015-2019 MongoDB, Inc.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  #if (defined(_WIN16) || defined(_WIN32) || defined(_WIN64)) && !defined(__WINDOWS__)
  
  # define __WINDOWS__
  # include <winsock2.h>
  #else
  # include <arpa/inet.h>
  # include <sys/types.h>
  #endif
  
  #define BSON_BIG_ENDIAN    4321
  #define BSON_LITTLE_ENDIAN 1234
  
  #if defined(__sun)
  # include <sys/byteorder.h>
  # if defined(_LITTLE_ENDIAN)
  #  define BSON_BYTE_ORDER 1234
  # else
  #  define BSON_BYTE_ORDER 4321
  # endif
  #endif
  
  /* See a similar check in ruby's sha2.h */
  # ifndef BSON_BYTE_ORDER
  #  ifdef WORDS_BIGENDIAN
  #   define BSON_BYTE_ORDER	BSON_BIG_ENDIAN
  #  else
  #   define BSON_BYTE_ORDER	BSON_LITTLE_ENDIAN
  #  endif
  # endif /* BSON_BYTE_ORDER */
  
  #if defined(__sun)
  # define BSON_UINT16_SWAP_LE_BE(v) __bson_uint16_swap_slow((uint16_t)v)
  # define BSON_UINT32_SWAP_LE_BE(v) __bson_uint32_swap_slow((uint32_t)v)
  # define BSON_UINT64_SWAP_LE_BE(v) __bson_uint64_swap_slow((uint64_t)v)
  #elif defined(__clang__) && defined(__clang_major__) && defined(__clang_minor__) && \
    (__clang_major__ >= 3) && (__clang_minor__ >= 1)
  # if __has_builtin(__builtin_bswap16)
  #  define BSON_UINT16_SWAP_LE_BE(v) __builtin_bswap16(v)
  # endif
  # if __has_builtin(__builtin_bswap32)
  #  define BSON_UINT32_SWAP_LE_BE(v) __builtin_bswap32(v)
  # endif
  # if __has_builtin(__builtin_bswap64)
  #  define BSON_UINT64_SWAP_LE_BE(v) __builtin_bswap64(v)
  # endif
  #elif defined(__GNUC__) && (__GNUC__ >= 4)
  # if __GNUC__ > 4 || (defined (__GNUC_MINOR__) && __GNUC_MINOR__ >= 3)
  #  define BSON_UINT32_SWAP_LE_BE(v) __builtin_bswap32 ((uint32_t)v)
  #  define BSON_UINT64_SWAP_LE_BE(v) __builtin_bswap64 ((uint64_t)v)
  # endif
  #endif
  
  #ifndef BSON_UINT16_SWAP_LE_BE
  # define BSON_UINT16_SWAP_LE_BE(v) __bson_uint16_swap_slow((uint16_t)v)
  #endif
  
  #ifndef BSON_UINT32_SWAP_LE_BE
  # define BSON_UINT32_SWAP_LE_BE(v) __bson_uint32_swap_slow((uint32_t)v)
  #endif
  
  #ifndef BSON_UINT64_SWAP_LE_BE
  # define BSON_UINT64_SWAP_LE_BE(v) __bson_uint64_swap_slow((uint64_t)v)
  #endif
  
  #if BSON_BYTE_ORDER == BSON_LITTLE_ENDIAN
  # define BSON_UINT16_TO_BE(v)    BSON_UINT16_SWAP_LE_BE(v)
  # define BSON_UINT32_FROM_LE(v)  ((uint32_t)v)
  # define BSON_UINT32_TO_LE(v)    ((uint32_t)v)
  # define BSON_UINT32_FROM_BE(v)  BSON_UINT32_SWAP_LE_BE(v)
  # define BSON_UINT32_TO_BE(v)    BSON_UINT32_SWAP_LE_BE(v)
  # define BSON_UINT64_FROM_LE(v)  ((uint64_t)v)
  # define BSON_UINT64_TO_LE(v)    ((uint64_t)v)
  # define BSON_UINT64_FROM_BE(v)  BSON_UINT64_SWAP_LE_BE(v)
  # define BSON_UINT64_TO_BE(v)    BSON_UINT64_SWAP_LE_BE(v)
  # define BSON_DOUBLE_FROM_LE(v)  ((double)v)
  # define BSON_DOUBLE_TO_LE(v)    ((double)v)
  #elif BSON_BYTE_ORDER == BSON_BIG_ENDIAN
  # define BSON_UINT16_TO_BE(v)    ((uint16_t)v)
  # define BSON_UINT32_FROM_LE(v)  BSON_UINT32_SWAP_LE_BE(v)
  # define BSON_UINT32_TO_LE(v)    BSON_UINT32_SWAP_LE_BE(v)
  # define BSON_UINT32_FROM_BE(v)  ((uint32_t)v)
  # define BSON_UINT32_TO_BE(v)    ((uint32_t)v)
  # define BSON_UINT64_FROM_LE(v)  BSON_UINT64_SWAP_LE_BE(v)
  # define BSON_UINT64_TO_LE(v)    BSON_UINT64_SWAP_LE_BE(v)
  # define BSON_UINT64_FROM_BE(v)  ((uint64_t)v)
  # define BSON_UINT64_TO_BE(v)    ((uint64_t)v)
  # define BSON_DOUBLE_FROM_LE(v)  (__bson_double_swap_slow(v))
  # define BSON_DOUBLE_TO_LE(v)    (__bson_double_swap_slow(v))
  #else
  # error "The endianness of target architecture is unknown."
  #endif
  
  /*
   *--------------------------------------------------------------------------
   *
   * __bson_uint16_swap_slow --
   *
   *       Fallback endianness conversion for 16-bit integers.
   *
   * Returns:
   *       The endian swapped version.
   *
   * Side effects:
   *       None.
   *
   *--------------------------------------------------------------------------
   */
  static uint16_t __bson_uint16_swap_slow(uint16_t v)
  {
     return ((v & 0x00FF) << 8) |
            ((v & 0xFF00) >> 8);
  }
  
  /*
   *--------------------------------------------------------------------------
   *
   * __bson_uint32_swap_slow --
   *
   *       Fallback endianness conversion for 32-bit integers.
   *
   * Returns:
   *       The endian swapped version.
   *
   * Side effects:
   *       None.
   *
   *--------------------------------------------------------------------------
   */
  static uint32_t __bson_uint32_swap_slow(uint32_t v)
  {
     return ((v & 0x000000FFU) << 24) |
            ((v & 0x0000FF00U) <<  8) |
            ((v & 0x00FF0000U) >>  8) |
            ((v & 0xFF000000U) >> 24);
  }
  
  
  /*
   *--------------------------------------------------------------------------
   *
   * __bson_uint64_swap_slow --
   *
   *       Fallback endianness conversion for 64-bit integers.
   *
   * Returns:
   *       The endian swapped version.
   *
   * Side effects:
   *       None.
   *
   *--------------------------------------------------------------------------
   */
  static uint64_t __bson_uint64_swap_slow(uint64_t v)
  {
     return ((v & 0x00000000000000FFULL) << 56) |
            ((v & 0x000000000000FF00ULL) << 40) |
            ((v & 0x0000000000FF0000ULL) << 24) |
            ((v & 0x00000000FF000000ULL) <<  8) |
            ((v & 0x000000FF00000000ULL) >>  8) |
            ((v & 0x0000FF0000000000ULL) >> 24) |
            ((v & 0x00FF000000000000ULL) >> 40) |
            ((v & 0xFF00000000000000ULL) >> 56);
  }
  
  /*
   *--------------------------------------------------------------------------
   *
   * __bson_double_swap_slow --
   *
   *       Fallback endianness conversion for double floating point.
   *
   * Returns:
   *       The endian swapped version.
   *
   * Side effects:
   *       None.
   *
   *--------------------------------------------------------------------------
   */
  static double __bson_double_swap_slow(double v)
  {
     uint64_t uv;
  
     memcpy(&uv, &v, sizeof(v));
     uv = BSON_UINT64_SWAP_LE_BE(uv);
     memcpy(&v, &uv, sizeof(v));
  
     return v;
  }
  
  