1 /* Macros to swap the order of bytes in integer values.
2 Copyright (C) 1997, 1998, 2000, 2002, 2003, 2007, 2008, 2010
3 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, write to the Free
18 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
19 02111-1307 USA. */
20
21 #if !defined _BYTESWAP_H && !defined _NETINET_IN_H && !defined _ENDIAN_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 #include <bits/wordsize.h>
29
30 /* Swap bytes in 16 bit value. */
31 #define __bswap_constant_16(x) \
32 ((unsigned short int) ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8)))
33
34 #if defined __GNUC__ && __GNUC__ >= 2
35 # define __bswap_16(x) \
36 (__extension__ \
37 ({ register unsigned short int __v, __x = (unsigned short int) (x); \
38 if (__builtin_constant_p (__x)) \
39 __v = __bswap_constant_16 (__x); \
40 else \
41 __asm__ ("rorw $8, %w0" \
42 : "=r" (__v) \
43 : "0" (__x) \
44 : "cc"); \
45 __v; }))
46 #else
47 /* This is better than nothing. */
48 # define __bswap_16(x) \
49 (__extension__ \
50 ({ register unsigned short int __x = (unsigned short int) (x); \
51 __bswap_constant_16 (__x); }))
52 #endif
53
54
55 /* Swap bytes in 32 bit value. */
56 #define __bswap_constant_32(x) \
57 ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >> 8) | \
58 (((x) & 0x0000ff00) << 8) | (((x) & 0x000000ff) << 24))
59
60 #if defined __GNUC__ && __GNUC__ >= 2
61 # if __WORDSIZE == 64 || (defined __i486__ || defined __pentium__ \
62 || defined __pentiumpro__ || defined __pentium4__ \
63 || defined __k8__ || defined __athlon__ \
64 || defined __k6__ || defined __nocona__ \
65 || defined __core2__ || defined __geode__ \
66 || defined __amdfam10__)
67 /* To swap the bytes in a word the i486 processors and up provide the
68 `bswap' opcode. On i386 we have to use three instructions. */
69 # define __bswap_32(x) \
70 (__extension__ \
71 ({ register unsigned int __v, __x = (x); \
72 if (__builtin_constant_p (__x)) \
73 __v = __bswap_constant_32 (__x); \
74 else \
75 __asm__ ("bswap %0" : "=r" (__v) : "0" (__x)); \
76 __v; }))
77 # else
78 # define __bswap_32(x) \
79 (__extension__ \
80 ({ register unsigned int __v, __x = (x); \
81 if (__builtin_constant_p (__x)) \
82 __v = __bswap_constant_32 (__x); \
83 else \
84 __asm__ ("rorw $8, %w0;" \
85 "rorl $16, %0;" \
86 "rorw $8, %w0" \
87 : "=r" (__v) \
88 : "0" (__x) \
89 : "cc"); \
90 __v; }))
91 # endif
92 #else
93 # define __bswap_32(x) \
94 (__extension__ \
95 ({ register unsigned int __x = (x); __bswap_constant_32 (__x); }))
96 #endif
97
98
99 #if defined __GNUC__ && __GNUC__ >= 2
100 /* Swap bytes in 64 bit value. */
101 # define __bswap_constant_64(x) \
102 ((((x) & 0xff00000000000000ull) >> 56) \
103 | (((x) & 0x00ff000000000000ull) >> 40) \
104 | (((x) & 0x0000ff0000000000ull) >> 24) \
105 | (((x) & 0x000000ff00000000ull) >> 8) \
106 | (((x) & 0x00000000ff000000ull) << 8) \
107 | (((x) & 0x0000000000ff0000ull) << 24) \
108 | (((x) & 0x000000000000ff00ull) << 40) \
109 | (((x) & 0x00000000000000ffull) << 56))
110
111 # if __WORDSIZE == 64
112 # define __bswap_64(x) \
113 (__extension__ \
114 ({ register unsigned long __v, __x = (x); \
115 if (__builtin_constant_p (__x)) \
116 __v = __bswap_constant_64 (__x); \
117 else \
118 __asm__ ("bswap %q0" : "=r" (__v) : "0" (__x)); \
119 __v; }))
120 # else
121 # define __bswap_64(x) \
122 (__extension__ \
123 ({ union { __extension__ unsigned long long int __ll; \
124 unsigned int __l[2]; } __w, __r; \
125 if (__builtin_constant_p (x)) \
126 __r.__ll = __bswap_constant_64 (x); \
127 else \
128 { \
129 __w.__ll = (x); \
130 __r.__l[0] = __bswap_32 (__w.__l[1]); \
131 __r.__l[1] = __bswap_32 (__w.__l[0]); \
132 } \
133 __r.__ll; }))
134 # endif
135 #endif
136
137 #endif /* _BITS_BYTESWAP_H */
138