c_cpp Big / Little Endian解压缩整数

Posted 2021-05-14

/********************************************************************************
*
*  Copyright (c) Simon Downey <[e-mail]> <https://github.com/sleepdefic1t>
*
*  The MIT License (MIT)
*
*  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
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*  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.
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*  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
*  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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*  IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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*********************************************************************************/
 
#include <stdint.h>

//////////////////////////////////////////////////////////////////////

uint16_t unpack2LE(uint8_t *src) {
  return ((uint16_t)src[0] & 0xFF)      |
         ((uint16_t)src[1] & 0xFF) << 8U;
}

uint32_t unpack4LE(uint8_t *src) {
  return ((uint32_t)src[0] & 0xFF)                 |
         ((uint32_t)src[1] & 0xFF)          <<  8U |
         ((uint32_t)src[2] & 0xFFFF)        << 16U |
         ((uint32_t)src[3] & 0xFFFFFFFF)    << 24U;
}

uint64_t unpack8LE(uint8_t *src) {
  return ((uint64_t)src[0] & 0xFF)                         |
         ((uint64_t)src[1] & 0xFF)                  <<  8U |
         ((uint64_t)src[2] & 0xFFFF)                << 16U |
         ((uint64_t)src[3] & 0xFFFFFFFF)            << 24U |
         ((uint64_t)src[4] & 0xFFFFFFFF)            << 32U |
         ((uint64_t)src[5] & 0xFFFFFFFFFFFFFFFF)    << 40U |
         ((uint64_t)src[6] & 0xFFFFFFFFFFFFFFFF)    << 48U |
         ((uint64_t)src[7] & 0xFFFFFFFFFFFFFFFF)    << 56U;
}

uint16_t unpack2BE(uint8_t *src) {
  return ((uint16_t)src[1] & 0xFF)  <<  8U |
         ((uint16_t)src[0] & 0xFF);
}

uint32_t unpack4BE(uint8_t *src) {
  return ((uint32_t)src[3] & 0xFFFFFFFF)    << 24U |
         ((uint32_t)src[2] & 0xFFFF)        << 16U |
         ((uint32_t)src[1] & 0xFF)          <<  8U |
         ((uint32_t)src[0] & 0xFF);
}

uint64_t unpack8BE(uint8_t *src) {
  return ((uint64_t)src[7] & 0xFFFFFFFFFFFFFFFF)    << 56U |
         ((uint64_t)src[6] & 0xFFFFFFFFFFFFFFFF)    << 48U |
         ((uint64_t)src[5] & 0xFFFFFFFFFFFFFFFF)    << 40U |
         ((uint64_t)src[4] & 0xFFFFFFFF)            << 32U |
         ((uint64_t)src[3] & 0xFFFFFFFF)            << 24U |
         ((uint64_t)src[2] & 0xFFFF)                << 16U |
         ((uint64_t)src[1] & 0xFF)                  <<  8U |
         ((uint64_t)src[0] & 0xFF);
}

//////////////////////////////////////////////////////////////////////