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Diffstat (limited to 'sysdeps/i386/bits/byteswap.h')
| -rw-r--r-- | sysdeps/i386/bits/byteswap.h | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/sysdeps/i386/bits/byteswap.h b/sysdeps/i386/bits/byteswap.h new file mode 100644 index 0000000..326962e --- /dev/null +++ b/sysdeps/i386/bits/byteswap.h @@ -0,0 +1,92 @@ +/* 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 */ |