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byteswap1.h
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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.
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., 51 Franklin Street, Fifth Floor,
18 Boston, MA 02110-1301, USA.
19*/
20
21#if !defined _BYTESWAP_H && !defined _NETINET_IN_H
22# error "Never use <bits/byteswap.h> directly; include <byteswap.h> instead."
23#endif
24
25#ifndef _BITS_BYTESWAP_H
26#define _BITS_BYTESWAP_H 1
27
28/* Swap bytes in 16 bit value. */
29#define __bswap_constant_16(x) \
30 ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8))
31
32#ifdef __GNUC__
33# if __GNUC__ >= 2
34# define __bswap_16(x) \
35 (__extension__ \
36 ({ register unsigned short int __v, __x = (x); \
37 if (__builtin_constant_p (__x)) \
38 __v = __bswap_constant_16 (__x); \
39 else \
40 __asm__ ("rorw $8, %w0" \
41 : "=r" (__v) \
42 : "0" (__x) \
43 : "cc"); \
44 __v; }))
45# else
46/* This is better than nothing. */
47# define __bswap_16(x) \
48 (__extension__ \
49 ({ register unsigned short int __x = (x); __bswap_constant_16 (__x); }))
50# endif
51#else
52static __inline unsigned short int
53__bswap_16 (unsigned short int __bsx)
54{
55 return __bswap_constant_16 (__bsx);
56}
57#endif
58
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))
63
64#ifdef __GNUC__
65# if __GNUC__ >= 2
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) \
71 (__extension__ \
72 ({ register unsigned int __v, __x = (x); \
73 if (__builtin_constant_p (__x)) \
74 __v = __bswap_constant_32 (__x); \
75 else \
76 __asm__ ("rorw $8, %w0;" \
77 "rorl $16, %0;" \
78 "rorw $8, %w0" \
79 : "=r" (__v) \
80 : "0" (__x) \
81 : "cc"); \
82 __v; }))
83# else
84# define __bswap_32(x) \
85 (__extension__ \
86 ({ register unsigned int __v, __x = (x); \
87 if (__builtin_constant_p (__x)) \
88 __v = __bswap_constant_32 (__x); \
89 else \
90 __asm__ ("bswap %0" : "=r" (__v) : "0" (__x)); \
91 __v; }))
92# endif
93# else
94# define __bswap_32(x) \
95 (__extension__ \
96 ({ register unsigned int __x = (x); __bswap_constant_32 (__x); }))
97# endif
98#else
99static __inline unsigned int
100__bswap_32 (unsigned int __bsx)
101{
102 return __bswap_constant_32 (__bsx);
103}
104#endif
105
106
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))
118
119# define __bswap_64(x) \
120 (__extension__ \
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); \
125 else \
126 { \
127 __w.__ll = (x); \
128 __r.__l[0] = __bswap_32 (__w.__l[1]); \
129 __r.__l[1] = __bswap_32 (__w.__l[0]); \
130 } \
131 __r.__ll; }))
132#endif
133
134#endif /* _BITS_BYTESWAP_H */
static __inline unsigned short int __bswap_16(unsigned short int __bsx)
Definition: byteswap1.h:53
#define __bswap_constant_16(x)
Definition: byteswap1.h:29
#define __bswap_constant_32(x)
Definition: byteswap1.h:60
static __inline unsigned int __bswap_32(unsigned int __bsx)
Definition: byteswap1.h:100