1 /* Macros to swap the order of bytes in integer values.
2 Copyright (C) 1997,1998,2000,2001,2002,2005 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 <http://www.gnu.org/licenses/>. */
18
19 #if !defined _BYTESWAP_H && !defined _NETINET_IN_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 /* Swap bytes in 16 bit value. */
27 #define __bswap_constant_16(x) \
28 ((((x) >> 8) & 0xffu) | (((x) & 0xffu) << 8))
29
30 #ifndef __bswap_non_constant_16
31 # define __bswap_non_constant_16(x) __bswap_constant_16(x)
32 #endif
33 #ifdef __GNUC__
34 # define __bswap_16(x) \
35 (__extension__ \
36 ({ unsigned short int __bsv, __bsx = (x); \
37 if (__builtin_constant_p (__bsx)) \
38 __bsv = __bswap_constant_16 (__bsx); \
39 else \
40 __bsv = __bswap_non_constant_16 (__bsx); \
41 __bsv; }))
42 #else
43 static __inline unsigned short int
__bswap_16(unsigned short int __bsx)44 __bswap_16 (unsigned short int __bsx)
45 {
46 return __bswap_constant_16 (__bsx);
47 }
48 #endif
49
50 /* Swap bytes in 32 bit value. */
51 #define __bswap_constant_32(x) \
52 ((((x) & 0xff000000u) >> 24) | (((x) & 0x00ff0000u) >> 8) | \
53 (((x) & 0x0000ff00u) << 8) | (((x) & 0x000000ffu) << 24))
54
55 #ifndef __bswap_non_constant_32
56 # define __bswap_non_constant_32(x) __bswap_constant_32(x)
57 #endif
58 #ifdef __GNUC__
59 # define __bswap_32(x) \
60 (__extension__ \
61 ({ unsigned int __bsv, __bsx = (x); \
62 if (__builtin_constant_p (__bsx)) \
63 __bsv = __bswap_constant_32 (__bsx); \
64 else \
65 __bsv = __bswap_non_constant_32 (__bsx); \
66 __bsv; }))
67 #else
68 static __inline unsigned int
__bswap_32(unsigned int __bsx)69 __bswap_32 (unsigned int __bsx)
70 {
71 return __bswap_constant_32 (__bsx);
72 }
73 #endif
74
75 #if defined __GNUC__ && __GNUC__ >= 2
76 /* Swap bytes in 64 bit value. */
77 # define __bswap_constant_64(x) \
78 ((((x) & 0xff00000000000000ull) >> 56) \
79 | (((x) & 0x00ff000000000000ull) >> 40) \
80 | (((x) & 0x0000ff0000000000ull) >> 24) \
81 | (((x) & 0x000000ff00000000ull) >> 8) \
82 | (((x) & 0x00000000ff000000ull) << 8) \
83 | (((x) & 0x0000000000ff0000ull) << 24) \
84 | (((x) & 0x000000000000ff00ull) << 40) \
85 | (((x) & 0x00000000000000ffull) << 56))
86
87 # ifndef __bswap_non_constant_64
88 # define __bswap_non_constant_64(x) \
89 (__extension__ \
90 ({ union { __extension__ unsigned long long int __ll; \
91 unsigned int __l[2]; } __w, __r; \
92 __w.__ll = (x); \
93 __r.__l[0] = __bswap_non_constant_32 (__w.__l[1]); \
94 __r.__l[1] = __bswap_non_constant_32 (__w.__l[0]); \
95 __r.__ll; }))
96 # endif
97 # define __bswap_64(x) \
98 (__extension__ \
99 ({ __extension__ unsigned long long int __ll; \
100 if (__builtin_constant_p (x)) \
101 __ll = __bswap_constant_64 (x); \
102 else \
103 __ll = __bswap_non_constant_64 (x); \
104 __ll; }))
105 #endif
106
107 #endif /* _BITS_BYTESWAP_H */
108