96 lines
3.4 KiB
C
96 lines
3.4 KiB
C
/* Macros to swap the order of bytes in integer values.
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Copyright (C) 1997, 1998 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#if !defined _BYTESWAP_H && !defined _NETINET_IN_H
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# error "Never use <bits/byteswap.h> directly; include <byteswap.h> instead."
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#endif
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/* Swap bytes in 16 bit value. */
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#define __bswap_constant_16(x) \
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((((x) >> 8) & 0xff) | (((x) & 0xff) << 8))
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#if defined __GNUC__ && __GNUC__ >= 2
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# define __bswap_16(x) \
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(__extension__ \
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({ register unsigned short int __v; \
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if (__builtin_constant_p (x)) \
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__v = __bswap_constant_16 (x); \
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else \
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__asm__ __volatile__ ("rorw $8, %w0" \
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: "=r" (__v) \
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: "0" ((unsigned short int) (x)) \
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: "cc"); \
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__v; }))
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#else
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/* This is better than nothing. */
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# define __bswap_16(x) __bswap_constant_16 (x)
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#endif
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/* Swap bytes in 32 bit value. */
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#define __bswap_constant_32(x) \
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((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >> 8) | \
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(((x) & 0x0000ff00) << 8) | (((x) & 0x000000ff) << 24))
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#if defined __GNUC__ && __GNUC__ >= 2
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/* To swap the bytes in a word the i486 processors and up provide the
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`bswap' opcode. On i386 we have to use three instructions. */
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# if !defined __i486__ && !defined __pentium__ && !defined __pentiumpro__
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# define __bswap_32(x) \
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(__extension__ \
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({ register unsigned int __v; \
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if (__builtin_constant_p (x)) \
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__v = __bswap_constant_32 (x); \
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else \
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__asm__ __volatile__ ("rorw $8, %w0;" \
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"rorl $16, %0;" \
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"rorw $8, %w0" \
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: "=r" (__v) \
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: "0" ((unsigned int) (x)) \
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: "cc"); \
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__v; }))
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# else
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# define __bswap_32(x) \
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(__extension__ \
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({ register unsigned int __v; \
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if (__builtin_constant_p (x)) \
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__v = __bswap_constant_32 (x); \
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else \
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__asm__ __volatile__ ("bswap %0" \
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: "=r" (__v) \
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: "0" ((unsigned int) (x))); \
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__v; }))
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# endif
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#else
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# define __bswap_32(x) __bswap_constant_32 (x)
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#endif
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#if defined __GNUC__ && __GNUC__ >= 2
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/* Swap bytes in 64 bit value. */
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# define __bswap_64(x) \
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(__extension__ \
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({ union { __extension__ unsigned long long int __ll; \
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unsigned long int __l[2]; } __w, __r; \
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__w.__ll = (x); \
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__r.__l[0] = __bswap_32 (__w.__l[1]); \
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__r.__l[1] = __bswap_32 (__w.__l[0]); \
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__r.__ll; }))
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#endif
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