glibc/bits/byteswap.h

80 lines
3.0 KiB
C

/* Macros to swap the order of bytes in integer values.
Copyright (C) 1997, 1998, 2000 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. */
#ifdef __GNUC__
# define __bswap_16(x) \
(__extension__ \
({ unsigned short int __bsx = (x); \
((((__bsx) >> 8) & 0xff) | (((__bsx) & 0xff) << 8)); }))
#else
static __inline unsigned short int
__bswap_16 (unsigned short int __bsx)
{
return ((((__bsx) >> 8) & 0xff) | (((__bsx) & 0xff) << 8));
}
#endif
/* Swap bytes in 32 bit value. */
#ifdef __GNUC__
# define __bswap_32(x) \
(__extension__ \
({ unsigned int __bsx = (x); \
((((__bsx) & 0xff000000) >> 24) | (((__bsx) & 0x00ff0000) >> 8) | \
(((__bsx) & 0x0000ff00) << 8) | (((__bsx) & 0x000000ff) << 24)); }))
#else
static __inline unsigned int
__bswap_32 (unsigned int __bsx)
{
return ((((__bsx) & 0xff000000) >> 24) | (((__bsx) & 0x00ff0000) >> 8) |
(((__bsx) & 0x0000ff00) << 8) | (((__bsx) & 0x000000ff) << 24));
}
#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