Blame |
Last modification |
View Log
| RSS feed
/* Macros to swap the order of bytes in integer values.
Copyright (C) 1997, 1998, 2000, 2002 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 Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; 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
#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) \
(__extension__ \
({ register unsigned short int __v; \
if (__builtin_constant_p (x)) \
__v = __bswap_constant_16 (x); \
else \
__asm__ __volatile__ ("rorw $8, %w0" \
: "=r" (__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) \
(__extension__ \
({ 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" \
: "=r" (__v) \
: "0" ((unsigned int) (x)) \
: "cc"); \
__v; }))
# else
# define __bswap_32(x) \
(__extension__ \
({ 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_constant_64(x) \
((((x) & 0xff00000000000000ull) >> 56) \
| (((x) & 0x00ff000000000000ull) >> 40) \
| (((x) & 0x0000ff0000000000ull) >> 24) \
| (((x) & 0x000000ff00000000ull) >> 8) \
| (((x) & 0x00000000ff000000ull) << 8) \
| (((x) & 0x0000000000ff0000ull) << 24) \
| (((x) & 0x000000000000ff00ull) << 40) \
| (((x) & 0x00000000000000ffull) << 56))
# define __bswap_64(x) \
(__extension__ \
({ union { __extension__ unsigned long long int __ll; \
unsigned long int __l[2]; } __w, __r; \
if (__builtin_constant_p (x)) \
__r.__ll = __bswap_constant_64 (x); \
else \
{ \
__w.__ll = (x); \
__r.__l[0] = __bswap_32 (__w.__l[1]); \
__r.__l[1] = __bswap_32 (__w.__l[0]); \
} \
__r.__ll; }))
#endif
#endif /* _BITS_BYTESWAP_H */