1 /* Macros to swap the order of bytes in integer values.
2 Copyright (C) 1997-2012 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 && !defined _ENDIAN_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 #include <features.h>
27 #include <bits/types.h>
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 /* Get __bswap_16. */
35 #include <bits/byteswap-16.h>
36
37 /* Swap bytes in 32 bit value. */
38 #define __bswap_constant_32(x) \
39 ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >> 8) | \
40 (((x) & 0x0000ff00) << 8) | (((x) & 0x000000ff) << 24))
41
42 #ifdef __GNUC__
43 # if __GNUC_PREREQ (4, 3)
44 static __inline unsigned int
__bswap_32(unsigned int __bsx)45 __bswap_32 (unsigned int __bsx)
46 {
47 return __builtin_bswap32 (__bsx);
48 }
49 # elif __GNUC__ >= 2
50 # if __WORDSIZE == 64 || (defined __i486__ || defined __pentium__ \
51 || defined __pentiumpro__ || defined __pentium4__ \
52 || defined __k8__ || defined __athlon__ \
53 || defined __k6__ || defined __nocona__ \
54 || defined __core2__ || defined __geode__ \
55 || defined __amdfam10__)
56 /* To swap the bytes in a word the i486 processors and up provide the
57 `bswap' opcode. On i386 we have to use three instructions. */
58 # define __bswap_32(x) \
59 (__extension__ \
60 ({ register unsigned int __v, __x = (x); \
61 if (__builtin_constant_p (__x)) \
62 __v = __bswap_constant_32 (__x); \
63 else \
64 __asm__ ("bswap %0" : "=r" (__v) : "0" (__x)); \
65 __v; }))
66 # else
67 # define __bswap_32(x) \
68 (__extension__ \
69 ({ register unsigned int __v, __x = (x); \
70 if (__builtin_constant_p (__x)) \
71 __v = __bswap_constant_32 (__x); \
72 else \
73 __asm__ ("rorw $8, %w0;" \
74 "rorl $16, %0;" \
75 "rorw $8, %w0" \
76 : "=r" (__v) \
77 : "0" (__x) \
78 : "cc"); \
79 __v; }))
80 # endif
81 # else
82 # define __bswap_32(x) \
83 (__extension__ \
84 ({ register unsigned int __x = (x); __bswap_constant_32 (__x); }))
85 # endif
86 #else
87 static __inline unsigned int
__bswap_32(unsigned int __bsx)88 __bswap_32 (unsigned int __bsx)
89 {
90 return __bswap_constant_32 (__bsx);
91 }
92 #endif
93
94
95 #if __GNUC_PREREQ (2, 0)
96 /* Swap bytes in 64 bit value. */
97 # define __bswap_constant_64(x) \
98 (__extension__ ((((x) & 0xff00000000000000ull) >> 56) \
99 | (((x) & 0x00ff000000000000ull) >> 40) \
100 | (((x) & 0x0000ff0000000000ull) >> 24) \
101 | (((x) & 0x000000ff00000000ull) >> 8) \
102 | (((x) & 0x00000000ff000000ull) << 8) \
103 | (((x) & 0x0000000000ff0000ull) << 24) \
104 | (((x) & 0x000000000000ff00ull) << 40) \
105 | (((x) & 0x00000000000000ffull) << 56)))
106
107 # if __GNUC_PREREQ (4, 3)
108 static __inline __uint64_t
__bswap_64(__uint64_t __bsx)109 __bswap_64 (__uint64_t __bsx)
110 {
111 return __builtin_bswap64 (__bsx);
112 }
113 # elif __WORDSIZE == 64
114 # define __bswap_64(x) \
115 (__extension__ \
116 ({ register __uint64_t __v, __x = (x); \
117 if (__builtin_constant_p (__x)) \
118 __v = __bswap_constant_64 (__x); \
119 else \
120 __asm__ ("bswap %q0" : "=r" (__v) : "0" (__x)); \
121 __v; }))
122 # else
123 # define __bswap_64(x) \
124 (__extension__ \
125 ({ union { __extension__ __uint64_t __ll; \
126 unsigned int __l[2]; } __w, __r; \
127 if (__builtin_constant_p (x)) \
128 __r.__ll = __bswap_constant_64 (x); \
129 else \
130 { \
131 __w.__ll = (x); \
132 __r.__l[0] = __bswap_32 (__w.__l[1]); \
133 __r.__l[1] = __bswap_32 (__w.__l[0]); \
134 } \
135 __r.__ll; }))
136 # endif
137 #elif __GLIBC_HAVE_LONG_LONG
138 # define __bswap_constant_64(x) \
139 ((((x) & 0xff00000000000000ull) >> 56) \
140 | (((x) & 0x00ff000000000000ull) >> 40) \
141 | (((x) & 0x0000ff0000000000ull) >> 24) \
142 | (((x) & 0x000000ff00000000ull) >> 8) \
143 | (((x) & 0x00000000ff000000ull) << 8) \
144 | (((x) & 0x0000000000ff0000ull) << 24) \
145 | (((x) & 0x000000000000ff00ull) << 40) \
146 | (((x) & 0x00000000000000ffull) << 56))
147
148 static __inline __uint64_t
__bswap_64(__uint64_t __bsx)149 __bswap_64 (__uint64_t __bsx)
150 {
151 return __bswap_constant_64 (__bsx);
152 }
153 #endif
154
155 #endif /* _BITS_BYTESWAP_H */
156