sysdeps/x86_64/bits/byteswap.h

   1 /* Macros to swap the order of bytes in integer values.
   2    Copyright (C) 1997, 1998, 2000, 2002, 2003 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #if !defined _BYTESWAP_H && !defined _NETINET_IN_H
  21 # error "Never use <bits/byteswap.h> directly; include <byteswap.h> instead."
  22 #endif
  23
  24 #ifndef _BITS_BYTESWAP_H
  25 #define _BITS_BYTESWAP_H 1
  26
  27 #include <bits/wordsize.h>
  28
  29 /* Swap bytes in 16 bit value.  */
  30 #define __bswap_constant_16(x) \
  31      ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8))
  32
  33 #if defined __GNUC__ && __GNUC__ >= 2
  34 # define __bswap_16(x) \
  35      (__extension__                                                           \
  36       ({ register unsigned short int __v, __x = (x);                          \
  37          if (__builtin_constant_p (__x))                                      \
  38            __v = __bswap_constant_16 (__x);                                   \
  39          else                                                                 \
  40            __asm__ ("rorw $8, %w0"                                            \
  41                     : "=r" (__v)                                              \
  42                     : "0" (__x)                                               \
  43                     : "cc");                                                  \
  44          __v; }))
  45 #else
  46 /* This is better than nothing.  */
  47 # define __bswap_16(x) \
  48      (__extension__                                                           \
  49       ({ register unsigned short int __x = (x); __bswap_constant_16 (__x); }))
  50 #endif
  51
  52
  53 /* Swap bytes in 32 bit value.  */
  54 #define __bswap_constant_32(x) \
  55      ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) |               \
  56       (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
  57
  58 #if defined __GNUC__ && __GNUC__ >= 2
  59 # if __WORDSIZE == 64 || (defined __i486__ || defined __pentium__             \
  60                           || defined __pentiumpro__ || defined __pentium4__   \
  61                           || defined __k8__ || defined __athlon__             \
  62                           || defined __k6__)
  63 /* To swap the bytes in a word the i486 processors and up provide the
  64    `bswap' opcode.  On i386 we have to use three instructions.  */
  65 #  define __bswap_32(x) \
  66      (__extension__                                                           \
  67       ({ register unsigned int __v, __x = (x);                                \
  68          if (__builtin_constant_p (__x))                                      \
  69            __v = __bswap_constant_32 (__x);                                   \
  70          else                                                                 \
  71            __asm__ ("bswap %0" : "=r" (__v) : "0" (__x));                     \
  72          __v; }))
  73 # else
  74 #  define __bswap_32(x)                                                       \
  75      (__extension__                                                           \
  76       ({ register unsigned int __v, __x = (x);                                \
  77          if (__builtin_constant_p (__x))                                      \
  78            __v = __bswap_constant_32 (__x);                                   \
  79          else                                                                 \
  80            __asm__ ("rorw $8, %w0;"                                           \
  81                     "rorl $16, %0;"                                           \
  82                     "rorw $8, %w0"                                            \
  83                     : "=r" (__v)                                              \
  84                     : "0" (__x)                                               \
  85                     : "cc");                                                  \
  86          __v; }))
  87 # endif
  88 #else
  89 # define __bswap_32(x) \
  90      (__extension__                                                           \
  91       ({ register unsigned int __x = (x); __bswap_constant_32 (__x); }))
  92 #endif
  93
  94
  95 #if defined __GNUC__ && __GNUC__ >= 2
  96 /* Swap bytes in 64 bit value.  */
  97 # define __bswap_constant_64(x) \
  98      ((((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 __WORDSIZE == 64
 108 #  define __bswap_64(x) \
 109      (__extension__                                                           \
 110       ({ register unsigned long __v, __x = (x);                               \
 111          if (__builtin_constant_p (__x))                                      \
 112            __v = __bswap_constant_64 (__x);                                   \
 113          else                                                                 \
 114            __asm__ ("bswap %q0" : "=r" (__v) : "0" (__x));                    \
 115          __v; }))
 116 # else
 117 #  define __bswap_64(x) \
 118      (__extension__                                                           \
 119       ({ union { __extension__ unsigned long long int __ll;                   \
 120                  unsigned int __l[2]; } __w, __r;                             \
 121          if (__builtin_constant_p (x))                                        \
 122            __r.__ll = __bswap_constant_64 (x);                                \
 123          else                                                                 \
 124            {                                                                  \
 125              __w.__ll = (x);                                                  \
 126              __r.__l[0] = __bswap_32 (__w.__l[1]);                            \
 127              __r.__l[1] = __bswap_32 (__w.__l[0]);                            \
 128            }                                                                  \
 129          __r.__ll; }))
 130 # endif
 131 #endif
 132
 133 #endif /* _BITS_BYTESWAP_H */