sysdeps/m68k/bits/byteswap.h

   1 /* Macros to swap the order of bytes in integer values.  m68k version.
   2    Copyright (C) 1997, 2002 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.  We don't provide an assembler version
  28    because GCC is smart enough to generate optimal assembler output, and
  29    this allows for better cse.  */
  30 #define __bswap_16(x) \
  31   ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8))
  32
  33 /* Swap bytes in 32 bit value.  */
  34 #define __bswap_constant_32(x) \
  35   ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) | \
  36    (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
  37
  38 #if defined __GNUC__ && __GNUC__ >= 2
  39 # define __bswap_32(x) \
  40   __extension__                                                 \
  41   ({ unsigned int __bswap_32_v;                                 \
  42      if (__builtin_constant_p (x))                              \
  43        __bswap_32_v = __bswap_constant_32 (x);                  \
  44      else                                                       \
  45        __asm__ __volatile__ ("ror%.w %#8, %0;"                  \
  46                              "swap %0;"                         \
  47                              "ror%.w %#8, %0"                   \
  48                              : "=d" (__bswap_32_v)              \
  49                              : "0" ((unsigned int) (x)));       \
  50      __bswap_32_v; })
  51 #else
  52 # define __bswap_32(x) __bswap_constant_32 (x)
  53 #endif
  54
  55 #if defined __GNUC__ && __GNUC__ >= 2
  56 /* Swap bytes in 64 bit value.  */
  57 # define __bswap_64(x) \
  58   __extension__                                                         \
  59   ({ union { unsigned long long int __ll;                               \
  60              unsigned long int __l[2]; } __bswap_64_v, __bswap_64_r;    \
  61      __bswap_64_v.__ll = (x);                                           \
  62      __bswap_64_r.__l[0] = __bswap_32 (__bswap_64_v.__l[1]);            \
  63      __bswap_64_r.__l[1] = __bswap_32 (__bswap_64_v.__l[0]);            \
  64      __bswap_64_r.__ll; })
  65 #endif
  66
  67 #endif /* _BITS_BYTESWAP_H */