1 /* Macros to swap the order of bytes in integer values. 2 Copyright (C) 1997-2015 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 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 ({ 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 ({ 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 ({ unsigned int __x = (x); __bswap_constant_32 (__x); })) 85 # endif 86 #else 87 static __inline unsigned int 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 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 ({ __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 #else 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 149 __bswap_64 (__uint64_t __bsx) 150 { 151 return __bswap_constant_64 (__bsx); 152 } 153 #endif 154 155 #endif /* _BITS_BYTESWAP_H */ 156