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  • Committer: Bazaar Package Importer
  • Author(s): Hakan Ardo
  • Date: 2006-05-01 12:03:39 UTC
  • mto: (3.1.1 edgy)
  • mto: This revision was merged to the branch mainline in revision 4.
  • Revision ID: james.westby@ubuntu.com-20060501120339-q93dxulpunby36dj
Tags: upstream-1.4.4
Import upstream version 1.4.4

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include/util/parity.h
 
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/* Copyright (c) 2002, Marek Michalkiewicz
 
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   Copyright (c) 2004,2005 Joerg Wunsch
 
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   All rights reserved.
 
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   Redistribution and use in source and binary forms, with or without
 
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   modification, are permitted provided that the following conditions are met:
 
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   * Redistributions of source code must retain the above copyright
 
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     notice, this list of conditions and the following disclaimer.
 
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   * Redistributions in binary form must reproduce the above copyright
 
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     notice, this list of conditions and the following disclaimer in
 
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     the documentation and/or other materials provided with the
 
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     distribution.
 
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   * Neither the name of the copyright holders nor the names of
 
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     contributors may be used to endorse or promote products derived
 
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     from this software without specific prior written permission.
 
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  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 
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  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 
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  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 
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  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 
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  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 
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  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 
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  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 
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  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 
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  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 
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  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 
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  POSSIBILITY OF SUCH DAMAGE. */
 
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/* $Id: parity.h,v 1.1 2005/11/05 22:23:16 joerg_wunsch Exp $ */
 
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#ifndef _UTIL_PARITY_H_
 
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#define _UTIL_PARITY_H_
 
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/** \defgroup util_parity <util/parity.h>: Parity bit generation
 
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    \code #include <util/parity.h> \endcode
 
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    This header file contains optimized assembler code to calculate
 
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    the parity bit for a byte.
 
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*/
 
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/** \def parity_even_bit
 
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    \ingroup util_parity
 
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    \returns 1 if \c val has an odd number of bits set. */
 
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#define parity_even_bit(val)                            \
 
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(__extension__({                                        \
 
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        unsigned char __t;                              \
 
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        __asm__ (                                       \
 
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                "mov __tmp_reg__,%0" "\n\t"             \
 
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                "swap %0" "\n\t"                        \
 
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                "eor %0,__tmp_reg__" "\n\t"             \
 
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                "mov __tmp_reg__,%0" "\n\t"             \
 
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                "lsr %0" "\n\t"                         \
 
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                "lsr %0" "\n\t"                         \
 
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                "eor %0,__tmp_reg__"                    \
 
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                : "=r" (__t)                            \
 
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                : "0" ((unsigned char)(val))            \
 
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                : "r0"                                  \
 
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        );                                              \
 
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        (((__t + 1) >> 1) & 1);                         \
 
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 }))
 
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#endif /* _UTIL_PARITY_H_ */