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/* byteswap.h - Byte swapping
Copyright (C) 2005, 2007, 2009-2024 Free Software Foundation, Inc.
Written by Oskar Liljeblad <oskar@osk.mine.nu>, 2005.
This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
This file is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
#ifndef _GL_BYTESWAP_H
#define _GL_BYTESWAP_H 1
/* This file uses _GL_INLINE. */
#if !_GL_CONFIG_H_INCLUDED
#error "Please include config.h first."
#endif
#include <stdint.h>
_GL_INLINE_HEADER_BEGIN
#ifndef _GL_BYTESWAP_INLINE
# define _GL_BYTESWAP_INLINE _GL_INLINE
#endif
#ifdef __cplusplus
extern "C" {
#endif
#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8)
# define _GL_BYTESWAP_HAS_BUILTIN_BSWAP16 true
#elif defined __has_builtin
# if __has_builtin (__builtin_bswap16)
# define _GL_BYTESWAP_HAS_BUILTIN_BSWAP16 true
# endif
#endif
#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)
# define _GL_BYTESWAP_HAS_BUILTIN_BSWAP32 true
# define _GL_BYTESWAP_HAS_BUILTIN_BSWAP64 true
#elif defined __has_builtin
# if __has_builtin (__builtin_bswap32)
# define _GL_BYTESWAP_HAS_BUILTIN_BSWAP32 true
# endif
# if __has_builtin (__builtin_bswap64)
# define _GL_BYTESWAP_HAS_BUILTIN_BSWAP64 true
# endif
#endif
/* Given an unsigned 16-bit argument X, return the value corresponding to
X with reversed byte order. */
_GL_BYTESWAP_INLINE uint_least16_t
bswap_16 (uint_least16_t x)
{
#ifdef _GL_BYTESWAP_HAS_BUILTIN_BSWAP16
return __builtin_bswap16 (x);
#else
uint_fast16_t mask = 0xff;
return ( (x & mask << 8 * 1) >> 8 * 1
| (x & mask << 8 * 0) << 8 * 1);
#endif
}
/* Given an unsigned 32-bit argument X, return the value corresponding to
X with reversed byte order. */
_GL_BYTESWAP_INLINE uint_least32_t
bswap_32 (uint_least32_t x)
{
#ifdef _GL_BYTESWAP_HAS_BUILTIN_BSWAP32
return __builtin_bswap32 (x);
#else
uint_fast32_t mask = 0xff;
return ( (x & mask << 8 * 3) >> 8 * 3
| (x & mask << 8 * 2) >> 8 * 1
| (x & mask << 8 * 1) << 8 * 1
| (x & mask << 8 * 0) << 8 * 3);
#endif
}
#ifdef UINT_LEAST64_MAX
/* Given an unsigned 64-bit argument X, return the value corresponding to
X with reversed byte order. */
_GL_BYTESWAP_INLINE uint_least64_t
bswap_64 (uint_least64_t x)
{
# ifdef _GL_BYTESWAP_HAS_BUILTIN_BSWAP64
return __builtin_bswap64 (x);
# else
uint_fast64_t mask = 0xff;
return ( (x & mask << 8 * 7) >> 8 * 7
| (x & mask << 8 * 6) >> 8 * 5
| (x & mask << 8 * 5) >> 8 * 3
| (x & mask << 8 * 4) >> 8 * 1
| (x & mask << 8 * 3) << 8 * 1
| (x & mask << 8 * 2) << 8 * 3
| (x & mask << 8 * 1) << 8 * 5
| (x & mask << 8 * 0) << 8 * 7);
# endif
}
#endif
#ifdef __cplusplus
}
#endif
_GL_INLINE_HEADER_END
#endif /* _GL_BYTESWAP_H */
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