src/system/libroot/posix/glibc/include/arch/x86/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 /* Swap bytes in 16 bit value.  */
  28 #define __bswap_constant_16(x) \
  29      ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8))
  30
  31 #ifdef __GNUC__
  32 # if __GNUC__ >= 2
  33 #  define __bswap_16(x) \
  34      (__extension__                                                           \
  35       ({ register unsigned short int __v, __x = (x);                          \
  36          if (__builtin_constant_p (__x))                                      \
  37            __v = __bswap_constant_16 (__x);                                   \
  38          else                                                                 \
  39            __asm__ ("rorw $8, %w0"                                            \
  40                     : "=r" (__v)                                              \
  41                     : "0" (__x)                                               \
  42                     : "cc");                                                  \
  43          __v; }))
  44 # else
  45 /* This is better than nothing.  */
  46 #  define __bswap_16(x) \
  47      (__extension__                                                           \
  48       ({ register unsigned short int __x = (x); __bswap_constant_16 (__x); }))
  49 # endif
  50 #else
  51 static __inline unsigned short int
  52 __bswap_16 (unsigned short int __bsx)
  53 {
  54   return __bswap_constant_16 (__bsx);
  55 }
  56 #endif
  57
  58 /* Swap bytes in 32 bit value.  */
  59 #define __bswap_constant_32(x) \
  60      ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) |               \
  61       (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
  62
  63 #ifdef __GNUC__
  64 # if __GNUC__ >= 2
  65 /* To swap the bytes in a word the i486 processors and up provide the
  66    `bswap' opcode.  On i386 we have to use three instructions.  */
  67 #  if !defined __i486__ && !defined __pentium__ && !defined __pentiumpro__ \
  68       && !defined __pentium4__
  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__ ("rorw $8, %w0;"                                           \
  76                     "rorl $16, %0;"                                           \
  77                     "rorw $8, %w0"                                            \
  78                     : "=r" (__v)                                              \
  79                     : "0" (__x)                                               \
  80                     : "cc");                                                  \
  81          __v; }))
  82 #  else
  83 #   define __bswap_32(x) \
  84      (__extension__                                                           \
  85       ({ register unsigned int __v, __x = (x);                                \
  86          if (__builtin_constant_p (__x))                                      \
  87            __v = __bswap_constant_32 (__x);                                   \
  88          else                                                                 \
  89            __asm__ ("bswap %0" : "=r" (__v) : "0" (__x));                     \
  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 #else
  98 static __inline unsigned int
  99 __bswap_32 (unsigned int __bsx)
 100 {
 101   return __bswap_constant_32 (__bsx);
 102 }
 103 #endif
 104
 105
 106 #if defined __GNUC__ && __GNUC__ >= 2
 107 /* Swap bytes in 64 bit value.  */
 108 #define __bswap_constant_64(x) \
 109      ((((x) & 0xff00000000000000ull) >> 56)                                   \
 110       | (((x) & 0x00ff000000000000ull) >> 40)                                 \
 111       | (((x) & 0x0000ff0000000000ull) >> 24)                                 \
 112       | (((x) & 0x000000ff00000000ull) >> 8)                                  \
 113       | (((x) & 0x00000000ff000000ull) << 8)                                  \
 114       | (((x) & 0x0000000000ff0000ull) << 24)                                 \
 115       | (((x) & 0x000000000000ff00ull) << 40)                                 \
 116       | (((x) & 0x00000000000000ffull) << 56))
 117
 118 # define __bswap_64(x) \
 119      (__extension__                                                           \
 120       ({ union { __extension__ unsigned long long int __ll;                   \
 121                  unsigned long int __l[2]; } __w, __r;                        \
 122          if (__builtin_constant_p (x))                                        \
 123            __r.__ll = __bswap_constant_64 (x);                                \
 124          else                                                                 \
 125            {                                                                  \
 126              __w.__ll = (x);                                                  \
 127              __r.__l[0] = __bswap_32 (__w.__l[1]);                            \
 128              __r.__l[1] = __bswap_32 (__w.__l[0]);                            \
 129            }                                                                  \
 130          __r.__ll; }))
 131 #endif
 132
 133 #endif /* _BITS_BYTESWAP_H */