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/* Macros to swap the order of bytes in integer values.
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. */
#ifndef _BITS_BYTESWAP_H
#define _BITS_BYTESWAP_H 1
/* Swap bytes in 16 bit value. */
#define __bswap_constant_16(x) \
((((x) >> 8) & 0xff) | (((x) & 0xff) << 8))
#if defined __GNUC__ && __GNUC__ >= 2
# define __bswap_16(x) \
({ register unsigned short int __v; \
if (__builtin_constant_p (x)) \
__v = __bswap_constant_16 (x); \
else \
__asm__ __volatile__ ("rorw $8, %w0" \
: "=q" (__v) \
: "0" ((unsigned short int) (x)) \
: "cc"); \
__v; })
#else
/* This is better than nothing. */
# define __bswap_16(x) __bswap_constant_16 (x)
#endif
/* 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
/* To swap the bytes in a word the i486 processors and up provide the
`bswap' opcode. On i386 we have to use three instructions. */
# if !defined __i486__ && !defined __pentium__ && !defined __pentiumpro__
# define __bswap_32(x) \
({ register unsigned int __v; \
if (__builtin_constant_p (x)) \
__v = __bswap_constant_32 (x); \
else \
__asm__ __volatile__ ("rorw $8, %w0;" \
"rorl $16, %0;" \
"rorw $8, %w0" \
: "=q" (__v) \
: "0" ((unsigned int) (x)) \
: "cc"); \
__v; })
# else
# define __bswap_32(x) \
({ register unsigned int __v; \
if (__builtin_constant_p (x)) \
__v = __bswap_constant_32 (x); \
else \
__asm__ __volatile__ ("bswap %0" \
: "=r" (__v) \
: "0" ((unsigned int) (x))); \
__v; })
# endif
#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) \
({ 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
#endif /* bits/byteswap.h */
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