curl/lib/curl_endian.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at https://curl.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ***************************************************************************/

#include "curl_setup.h"

#include "curl_endian.h"

/*
 * Curl_read16_le()
 *
 * This function converts a 16-bit integer from the little endian format, as
 * used in the incoming package to whatever endian format we're using
 * natively.
 *
 * Parameters:
 *
 * buf      [in]     - A pointer to a 2 byte buffer.
 *
 * Returns the integer.
 */
unsigned short Curl_read16_le(const unsigned char *buf)
{
  return (unsigned short)(((unsigned short)buf[0]) |
                          ((unsigned short)buf[1] << 8));
}

/*
 * Curl_read32_le()
 *
 * This function converts a 32-bit integer from the little endian format, as
 * used in the incoming package to whatever endian format we're using
 * natively.
 *
 * Parameters:
 *
 * buf      [in]     - A pointer to a 4 byte buffer.
 *
 * Returns the integer.
 */
unsigned int Curl_read32_le(const unsigned char *buf)
{
  return ((unsigned int)buf[0]) | ((unsigned int)buf[1] << 8) |
         ((unsigned int)buf[2] << 16) | ((unsigned int)buf[3] << 24);
}

/*
 * Curl_read16_be()
 *
 * This function converts a 16-bit integer from the big endian format, as
 * used in the incoming package to whatever endian format we're using
 * natively.
 *
 * Parameters:
 *
 * buf      [in]     - A pointer to a 2 byte buffer.
 *
 * Returns the integer.
 */
unsigned short Curl_read16_be(const unsigned char *buf)
{
  return (unsigned short)(((unsigned short)buf[0] << 8) |
                          ((unsigned short)buf[1]));
}

#if (CURL_SIZEOF_CURL_OFF_T > 4)
/*
 * write32_le()
 *
 * This function converts a 32-bit integer from the native endian format,
 * to little endian format ready for sending down the wire.
 *
 * Parameters:
 *
 * value    [in]     - The 32-bit integer value.
 * buffer   [in]     - A pointer to the output buffer.
 */
static void write32_le(const int value, unsigned char *buffer)
{
  buffer[0] = (char)(value & 0x000000FF);
  buffer[1] = (char)((value & 0x0000FF00) >> 8);
  buffer[2] = (char)((value & 0x00FF0000) >> 16);
  buffer[3] = (char)((value & 0xFF000000) >> 24);
}

/*
 * Curl_write64_le()
 *
 * This function converts a 64-bit integer from the native endian format,
 * to little endian format ready for sending down the wire.
 *
 * Parameters:
 *
 * value    [in]     - The 64-bit integer value.
 * buffer   [in]     - A pointer to the output buffer.
 */
#if defined(HAVE_LONGLONG)
void Curl_write64_le(const long long value, unsigned char *buffer)
#else
void Curl_write64_le(const __int64 value, unsigned char *buffer)
#endif
{
  write32_le((int)value, buffer);
  write32_le((int)(value >> 32), buffer + 4);
}
#endif /* CURL_SIZEOF_CURL_OFF_T > 4 */