sysdeps/x86/bits/byteswap.h

   1 /* Macros to swap the order of bytes in integer values.
   2    Copyright (C) 1997-2014 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 */