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<h1>parity.h</h1> </div>
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<a href="parity_8h.html">Go to the documentation of this file.</a><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">/* Copyright (c) 2002, Marek Michalkiewicz</span>
<a name="l00002"></a>00002 <span class="comment"> Copyright (c) 2004,2005,2007 Joerg Wunsch</span>
<a name="l00003"></a>00003 <span class="comment"> All rights reserved.</span>
<a name="l00004"></a>00004 <span class="comment"></span>
<a name="l00005"></a>00005 <span class="comment"> Redistribution and use in source and binary forms, with or without</span>
<a name="l00006"></a>00006 <span class="comment"> modification, are permitted provided that the following conditions are met:</span>
<a name="l00007"></a>00007 <span class="comment"></span>
<a name="l00008"></a>00008 <span class="comment"> * Redistributions of source code must retain the above copyright</span>
<a name="l00009"></a>00009 <span class="comment"> notice, this list of conditions and the following disclaimer.</span>
<a name="l00010"></a>00010 <span class="comment"></span>
<a name="l00011"></a>00011 <span class="comment"> * Redistributions in binary form must reproduce the above copyright</span>
<a name="l00012"></a>00012 <span class="comment"> notice, this list of conditions and the following disclaimer in</span>
<a name="l00013"></a>00013 <span class="comment"> the documentation and/or other materials provided with the</span>
<a name="l00014"></a>00014 <span class="comment"> distribution.</span>
<a name="l00015"></a>00015 <span class="comment"></span>
<a name="l00016"></a>00016 <span class="comment"> * Neither the name of the copyright holders nor the names of</span>
<a name="l00017"></a>00017 <span class="comment"> contributors may be used to endorse or promote products derived</span>
<a name="l00018"></a>00018 <span class="comment"> from this software without specific prior written permission.</span>
<a name="l00019"></a>00019 <span class="comment"></span>
<a name="l00020"></a>00020 <span class="comment"> THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"</span>
<a name="l00021"></a>00021 <span class="comment"> AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE</span>
<a name="l00022"></a>00022 <span class="comment"> IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE</span>
<a name="l00023"></a>00023 <span class="comment"> ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE</span>
<a name="l00024"></a>00024 <span class="comment"> LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR</span>
<a name="l00025"></a>00025 <span class="comment"> CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF</span>
<a name="l00026"></a>00026 <span class="comment"> SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS</span>
<a name="l00027"></a>00027 <span class="comment"> INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN</span>
<a name="l00028"></a>00028 <span class="comment"> CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)</span>
<a name="l00029"></a>00029 <span class="comment"> ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE</span>
<a name="l00030"></a>00030 <span class="comment"> POSSIBILITY OF SUCH DAMAGE. */</span>
<a name="l00031"></a>00031
<a name="l00032"></a>00032 <span class="comment">/* $Id: parity.h 1196 2007-01-23 15:34:58Z joerg_wunsch $ */</span>
<a name="l00033"></a>00033
<a name="l00034"></a>00034 <span class="preprocessor">#ifndef _UTIL_PARITY_H_</span>
<a name="l00035"></a>00035 <span class="preprocessor"></span><span class="preprocessor">#define _UTIL_PARITY_H_</span>
<a name="l00036"></a>00036 <span class="preprocessor"></span><span class="comment"></span>
<a name="l00037"></a>00037 <span class="comment">/** \file */</span><span class="comment"></span>
<a name="l00038"></a>00038 <span class="comment">/** \defgroup util_parity <util/parity.h>: Parity bit generation</span>
<a name="l00039"></a>00039 <span class="comment"> \code #include <util/parity.h> \endcode</span>
<a name="l00040"></a>00040 <span class="comment"></span>
<a name="l00041"></a>00041 <span class="comment"> This header file contains optimized assembler code to calculate</span>
<a name="l00042"></a>00042 <span class="comment"> the parity bit for a byte.</span>
<a name="l00043"></a>00043 <span class="comment">*/</span><span class="comment"></span>
<a name="l00044"></a>00044 <span class="comment">/** \def parity_even_bit</span>
<a name="l00045"></a>00045 <span class="comment"> \ingroup util_parity</span>
<a name="l00046"></a>00046 <span class="comment"> \returns 1 if \c val has an odd number of bits set. */</span>
<a name="l00047"></a><a class="code" href="group__util__parity.html#ga4180eaa9b8f27f8efc589f3a3ba1724c">00047</a> <span class="preprocessor">#define parity_even_bit(val) \</span>
<a name="l00048"></a>00048 <span class="preprocessor">(__extension__({ \</span>
<a name="l00049"></a>00049 <span class="preprocessor"> unsigned char __t; \</span>
<a name="l00050"></a>00050 <span class="preprocessor"> __asm__ ( \</span>
<a name="l00051"></a>00051 <span class="preprocessor"> "mov __tmp_reg__,%0" "\n\t" \</span>
<a name="l00052"></a>00052 <span class="preprocessor"> "swap %0" "\n\t" \</span>
<a name="l00053"></a>00053 <span class="preprocessor"> "eor %0,__tmp_reg__" "\n\t" \</span>
<a name="l00054"></a>00054 <span class="preprocessor"> "mov __tmp_reg__,%0" "\n\t" \</span>
<a name="l00055"></a>00055 <span class="preprocessor"> "lsr %0" "\n\t" \</span>
<a name="l00056"></a>00056 <span class="preprocessor"> "lsr %0" "\n\t" \</span>
<a name="l00057"></a>00057 <span class="preprocessor"> "eor %0,__tmp_reg__" \</span>
<a name="l00058"></a>00058 <span class="preprocessor"> : "=r" (__t) \</span>
<a name="l00059"></a>00059 <span class="preprocessor"> : "0" ((unsigned char)(val)) \</span>
<a name="l00060"></a>00060 <span class="preprocessor"> : "r0" \</span>
<a name="l00061"></a>00061 <span class="preprocessor"> ); \</span>
<a name="l00062"></a>00062 <span class="preprocessor"> (((__t + 1) >> 1) & 1); \</span>
<a name="l00063"></a>00063 <span class="preprocessor"> }))</span>
<a name="l00064"></a>00064 <span class="preprocessor"></span>
<a name="l00065"></a>00065 <span class="preprocessor">#endif </span><span class="comment">/* _UTIL_PARITY_H_ */</span>
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