1 /* Macros to swap the order of bytes in integer values. 2 Copyright (C) 1997, 1998, 2000, 2002, 2003, 2007, 2008, 2010, 2011 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 (__extension__ ((((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
