1 /* Macros to swap the order of bytes in integer values. 2 Copyright (C) 1997, 1998, 2000, 2002, 2003, 2007 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 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 ((((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 = (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 = (x); __bswap_constant_16 (__x); })) 51 #endif 52 53 54 /* Swap bytes in 32 bit value. */ 55 #define __bswap_constant_32(x) \ 56 ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >> 8) | \ 57 (((x) & 0x0000ff00) << 8) | (((x) & 0x000000ff) << 24)) 58 59 #if defined __GNUC__ && __GNUC__ >= 2 60 # if __WORDSIZE == 64 || (defined __i486__ || defined __pentium__ \ 61 || defined __pentiumpro__ || defined __pentium4__ \ 62 || defined __k8__ || defined __athlon__ \ 63 || defined __k6__ || defined __nocona__ \ 64 || defined __core2__ || defined __geode__ \ 65 || defined __amdfam10__) 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 # define __bswap_32(x) \ 69 (__extension__ \ 70 ({ register unsigned int __v, __x = (x); \ 71 if (__builtin_constant_p (__x)) \ 72 __v = __bswap_constant_32 (__x); \ 73 else \ 74 __asm__ ("bswap %0" : "=r" (__v) : "0" (__x)); \ 75 __v; })) 76 # else 77 # define __bswap_32(x) \ 78 (__extension__ \ 79 ({ register unsigned int __v, __x = (x); \ 80 if (__builtin_constant_p (__x)) \ 81 __v = __bswap_constant_32 (__x); \ 82 else \ 83 __asm__ ("rorw $8, %w0;" \ 84 "rorl $16, %0;" \ 85 "rorw $8, %w0" \ 86 : "=r" (__v) \ 87 : "0" (__x) \ 88 : "cc"); \ 89 __v; })) 90 # endif 91 #else 92 # define __bswap_32(x) \ 93 (__extension__ \ 94 ({ register unsigned int __x = (x); __bswap_constant_32 (__x); })) 95 #endif 96 97 98 #if defined __GNUC__ && __GNUC__ >= 2 99 /* Swap bytes in 64 bit value. */ 100 # define __bswap_constant_64(x) \ 101 ((((x) & 0xff00000000000000ull) >> 56) \ 102 | (((x) & 0x00ff000000000000ull) >> 40) \ 103 | (((x) & 0x0000ff0000000000ull) >> 24) \ 104 | (((x) & 0x000000ff00000000ull) >> 8) \ 105 | (((x) & 0x00000000ff000000ull) << 8) \ 106 | (((x) & 0x0000000000ff0000ull) << 24) \ 107 | (((x) & 0x000000000000ff00ull) << 40) \ 108 | (((x) & 0x00000000000000ffull) << 56)) 109 110 # if __WORDSIZE == 64 111 # define __bswap_64(x) \ 112 (__extension__ \ 113 ({ register unsigned long __v, __x = (x); \ 114 if (__builtin_constant_p (__x)) \ 115 __v = __bswap_constant_64 (__x); \ 116 else \ 117 __asm__ ("bswap %q0" : "=r" (__v) : "0" (__x)); \ 118 __v; })) 119 # else 120 # define __bswap_64(x) \ 121 (__extension__ \ 122 ({ union { __extension__ unsigned long long int __ll; \ 123 unsigned int __l[2]; } __w, __r; \ 124 if (__builtin_constant_p (x)) \ 125 __r.__ll = __bswap_constant_64 (x); \ 126 else \ 127 { \ 128 __w.__ll = (x); \ 129 __r.__l[0] = __bswap_32 (__w.__l[1]); \ 130 __r.__l[1] = __bswap_32 (__w.__l[0]); \ 131 } \ 132 __r.__ll; })) 133 # endif 134 #endif 135 136 #endif /* _BITS_BYTESWAP_H */ 137
