1 /* Macros to swap the order of bytes in integer values.
2 Copyright (C) 1997, 1998, 2000, 2002, 2003 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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.
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.
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., 51 Franklin Street, Fifth Floor,
18 Boston, MA 02110-1301, USA.
21 #if !defined _BYTESWAP_H && !defined _NETINET_IN_H
22 # error "Never use <bits/byteswap.h> directly; include <byteswap.h> instead."
25 #ifndef _BITS_BYTESWAP_H
26 #define _BITS_BYTESWAP_H 1
28 /* Swap bytes in 16 bit value. */
29 #define __bswap_constant_16(x) \
30 ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8))
34 # define __bswap_16(x) \
36 ({ register unsigned short int __v, __x = (x); \
37 if (__builtin_constant_p (__x)) \
38 __v = __bswap_constant_16 (__x); \
40 __asm__ ("rorw $8, %w0" \
46 /* This is better than nothing. */
47 # define __bswap_16(x) \
49 ({ register unsigned short int __x = (x); __bswap_constant_16 (__x); }))
52 static __inline
unsigned short int
53 __bswap_16 (unsigned short int __bsx
)
55 return __bswap_constant_16 (__bsx
);
59 /* Swap bytes in 32 bit value. */
60 #define __bswap_constant_32(x) \
61 ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >> 8) | \
62 (((x) & 0x0000ff00) << 8) | (((x) & 0x000000ff) << 24))
66 /* To swap the bytes in a word the i486 processors and up provide the
67 `bswap' opcode. On i386 we have to use three instructions. */
68 # if !defined __i486__ && !defined __pentium__ && !defined __pentiumpro__ \
69 && !defined __pentium4__
70 # define __bswap_32(x) \
72 ({ register unsigned int __v, __x = (x); \
73 if (__builtin_constant_p (__x)) \
74 __v = __bswap_constant_32 (__x); \
76 __asm__ ("rorw $8, %w0;" \
84 # define __bswap_32(x) \
86 ({ register unsigned int __v, __x = (x); \
87 if (__builtin_constant_p (__x)) \
88 __v = __bswap_constant_32 (__x); \
90 __asm__ ("bswap %0" : "=r" (__v) : "0" (__x)); \
94 # define __bswap_32(x) \
96 ({ register unsigned int __x = (x); __bswap_constant_32 (__x); }))
99 static __inline
unsigned int
100 __bswap_32 (unsigned int __bsx
)
102 return __bswap_constant_32 (__bsx
);
107 #if defined __GNUC__ && __GNUC__ >= 2
108 /* Swap bytes in 64 bit value. */
109 #define __bswap_constant_64(x) \
110 ((((x) & 0xff00000000000000ull) >> 56) \
111 | (((x) & 0x00ff000000000000ull) >> 40) \
112 | (((x) & 0x0000ff0000000000ull) >> 24) \
113 | (((x) & 0x000000ff00000000ull) >> 8) \
114 | (((x) & 0x00000000ff000000ull) << 8) \
115 | (((x) & 0x0000000000ff0000ull) << 24) \
116 | (((x) & 0x000000000000ff00ull) << 40) \
117 | (((x) & 0x00000000000000ffull) << 56))
119 # define __bswap_64(x) \
121 ({ union { __extension__ unsigned long long int __ll; \
122 unsigned long int __l[2]; } __w, __r; \
123 if (__builtin_constant_p (x)) \
124 __r.__ll = __bswap_constant_64 (x); \
128 __r.__l[0] = __bswap_32 (__w.__l[1]); \
129 __r.__l[1] = __bswap_32 (__w.__l[0]); \
134 #endif /* _BITS_BYTESWAP_H */