1/* Macros and inline functions to swap the order of bytes in integer values.
2 Copyright (C) 1997-2020 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#if !defined _BYTESWAP_H && !defined _NETINET_IN_H && !defined _ENDIAN_H
20# error "Never use <bits/byteswap.h> directly; include <byteswap.h> instead."
21#endif
22
23#ifndef _BITS_BYTESWAP_H
24#define _BITS_BYTESWAP_H 1
25
26#include <features.h>
27#include <bits/types.h>
28
29/* Swap bytes in 16-bit value. */
30#define __bswap_constant_16(x) \
31 ((__uint16_t) ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8)))
32
33static __inline __uint16_t
34__bswap_16 (__uint16_t __bsx)
35{
36#if __GNUC_PREREQ (4, 8)
37 return __builtin_bswap16 (__bsx);
38#else
39 return __bswap_constant_16 (__bsx);
40#endif
41}
42
43/* Swap bytes in 32-bit value. */
44#define __bswap_constant_32(x) \
45 ((((x) & 0xff000000u) >> 24) | (((x) & 0x00ff0000u) >> 8) \
46 | (((x) & 0x0000ff00u) << 8) | (((x) & 0x000000ffu) << 24))
47
48static __inline __uint32_t
49__bswap_32 (__uint32_t __bsx)
50{
51#if __GNUC_PREREQ (4, 3)
52 return __builtin_bswap32 (__bsx);
53#else
54 return __bswap_constant_32 (__bsx);
55#endif
56}
57
58/* Swap bytes in 64-bit value. */
59#define __bswap_constant_64(x) \
60 ((((x) & 0xff00000000000000ull) >> 56) \
61 | (((x) & 0x00ff000000000000ull) >> 40) \
62 | (((x) & 0x0000ff0000000000ull) >> 24) \
63 | (((x) & 0x000000ff00000000ull) >> 8) \
64 | (((x) & 0x00000000ff000000ull) << 8) \
65 | (((x) & 0x0000000000ff0000ull) << 24) \
66 | (((x) & 0x000000000000ff00ull) << 40) \
67 | (((x) & 0x00000000000000ffull) << 56))
68
69__extension__ static __inline __uint64_t
70__bswap_64 (__uint64_t __bsx)
71{
72#if __GNUC_PREREQ (4, 3)
73 return __builtin_bswap64 (__bsx);
74#else
75 return __bswap_constant_64 (__bsx);
76#endif
77}
78
79#endif /* _BITS_BYTESWAP_H */
80

source code of include/x86_64-linux-gnu/bits/byteswap.h