glibc (2.38)
1 /* Macros and inline functions to swap the order of bytes in integer values.
2 Copyright (C) 1997-2023 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
33 static __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
48 static __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 */
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