/* 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 */