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, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
18 02111-1307 USA. */
19
20 #if !defined _BYTESWAP_H && !defined _NETINET_IN_H
21 # error "Never use <bits/byteswap.h> directly; include <byteswap.h> instead."
22 #endif
23
24 #ifndef _BITS_BYTESWAP_H
25 #define _BITS_BYTESWAP_H 1
26
27 /* Swap bytes in 16 bit value. */
28 #define __bswap_constant_16(x) \
29 ((((x) >> 8) & 0xffu) | (((x) & 0xffu) << 8))
30
31 #ifdef __GNUC__
32 # define __bswap_16(x) \
33 (__extension__ \
34 ({ unsigned short int __bsx = (x); __bswap_constant_16 (__bsx); }))
35 #else
36 static __inline unsigned short int
__bswap_16(unsigned short int __bsx)37 __bswap_16 (unsigned short int __bsx)
38 {
39 return __bswap_constant_16 (__bsx);
40 }
41 #endif
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 #ifdef __GNUC__
49 # define __bswap_32(x) \
50 (__extension__ \
51 ({ register unsigned int __bsx = (x); __bswap_constant_32 (__bsx); }))
52 #else
53 static __inline unsigned int
__bswap_32(unsigned int __bsx)54 __bswap_32 (unsigned int __bsx)
55 {
56 return __bswap_constant_32 (__bsx);
57 }
58 #endif
59
60 #if defined __GNUC__ && __GNUC__ >= 2
61 /* Swap bytes in 64 bit value. */
62 # define __bswap_constant_64(x) \
63 ((((x) & 0xff00000000000000ull) >> 56) \
64 | (((x) & 0x00ff000000000000ull) >> 40) \
65 | (((x) & 0x0000ff0000000000ull) >> 24) \
66 | (((x) & 0x000000ff00000000ull) >> 8) \
67 | (((x) & 0x00000000ff000000ull) << 8) \
68 | (((x) & 0x0000000000ff0000ull) << 24) \
69 | (((x) & 0x000000000000ff00ull) << 40) \
70 | (((x) & 0x00000000000000ffull) << 56))
71
72 # define __bswap_64(x) \
73 (__extension__ \
74 ({ union { __extension__ unsigned long long int __ll; \
75 unsigned int __l[2]; } __w, __r; \
76 if (__builtin_constant_p (x)) \
77 __r.__ll = __bswap_constant_64 (x); \
78 else \
79 { \
80 __w.__ll = (x); \
81 __r.__l[0] = __bswap_32 (__w.__l[1]); \
82 __r.__l[1] = __bswap_32 (__w.__l[0]); \
83 } \
84 __r.__ll; }))
85 #endif
86
87 #endif /* _BITS_BYTESWAP_H */
88