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, 2007, 2008
   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      ((((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 */