glibc/sysdeps/m68k/bits/byteswap.h

/* Macros to swap the order of bytes in integer values.  m68k version.
   Copyright (C) 1997 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#if !defined _BYTESWAP_H && !defined _NETINET_IN_H
# error "Never use <bits/byteswap.h> directly; include <byteswap.h> instead."
#endif

/* Swap bytes in 16 bit value.  We don't provide an assembler version
   because GCC is smart enough to generate optimal assembler output, and
   this allows for better cse.  */
#define __bswap_16(x) \
  ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8))

/* Swap bytes in 32 bit value.  */
#define __bswap_constant_32(x) \
  ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) | \
   (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))

#if defined __GNUC__ && __GNUC__ >= 2
# define __bswap_32(x) \
  __extension__					\
  ({ unsigned int __v;				\
     if (__builtin_constant_p (x))		\
       __v = __bswap_constant_32 (x);		\
     else					\
       __asm__ __volatile__ ("ror%.w %#8, %0;"	\
			     "swap %0;"		\
			     "ror%.w %#8, %0"	\
			     : "=d" (__v)	\
			     : "0" (x));	\
     __v; })
#else
# define __bswap_32(x) __bswap_constant_32 (x)
#endif

#if defined __GNUC__ && __GNUC__ >= 2
/* Swap bytes in 64 bit value.  */
# define __bswap_64(x) \
  __extension__						\
  ({ union { unsigned long long int __ll;		\
	     unsigned long int __l[2]; } __v, __r;	\
     __v.__ll = (x);					\
     __r.__l[0] = __bswap_32 (__v.__l[1]);		\
     __r.__l[1] = __bswap_32 (__v.__l[0]);		\
     __r.__ll; })
#endif