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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta http-equiv="Content-Type" content="text/html;charset=UTF-8"><title>Crypto++: crc.h Source File</title><link href="doxygen.css" rel="stylesheet" type="text/css"><link href="tabs.css" rel="stylesheet" type="text/css"></head><body><!-- Generated by Doxygen 1.5.2 --><div class="tabs"> <ul> <li><a href="index.html"><span>Main Page</span></a></li> <li><a href="namespaces.html"><span>Namespaces</span></a></li> <li><a href="classes.html"><span>Classes</span></a></li> <li class="current"><a href="files.html"><span>Files</span></a></li> </ul></div><div class="tabs"> <ul> <li><a href="files.html"><span>File List</span></a></li> <li><a href="globals.html"><span>File Members</span></a></li> </ul></div><h1>crc.h</h1><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="preprocessor">#ifndef CRYPTOPP_CRC32_H</span><a name="l00002"></a>00002 <span class="preprocessor"></span><span class="preprocessor">#define CRYPTOPP_CRC32_H</span><a name="l00003"></a>00003 <span class="preprocessor"></span><a name="l00004"></a>00004 <span class="preprocessor">#include "<a class="code" href="cryptlib_8h.html">cryptlib.h</a>"</span><a name="l00005"></a>00005 <a name="l00006"></a>00006 NAMESPACE_BEGIN(CryptoPP)<a name="l00007"></a>00007 <a name="l00008"></a>00008 const word32 CRC32_NEGL = 0xffffffffL;<a name="l00009"></a>00009 <a name="l00010"></a>00010 <span class="preprocessor">#ifdef IS_LITTLE_ENDIAN</span><a name="l00011"></a>00011 <span class="preprocessor"></span><span class="preprocessor">#define CRC32_INDEX(c) (c & 0xff)</span><a name="l00012"></a>00012 <span class="preprocessor"></span><span class="preprocessor">#define CRC32_SHIFTED(c) (c >> 8)</span><a name="l00013"></a>00013 <span class="preprocessor"></span><span class="preprocessor">#else</span><a name="l00014"></a>00014 <span class="preprocessor"></span><span class="preprocessor">#define CRC32_INDEX(c) (c >> 24)</span><a name="l00015"></a>00015 <span class="preprocessor"></span><span class="preprocessor">#define CRC32_SHIFTED(c) (c << 8)</span><a name="l00016"></a>00016 <span class="preprocessor"></span><span class="preprocessor">#endif</span><a name="l00017"></a>00017 <span class="preprocessor"></span><span class="comment"></span><a name="l00018"></a>00018 <span class="comment">//! CRC Checksum Calculation</span><a name="l00019"></a><a class="code" href="class_c_r_c32.html">00019</a> <span class="comment"></span><span class="keyword">class </span><a class="code" href="class_c_r_c32.html" title="CRC Checksum Calculation.">CRC32</a> : <span class="keyword">public</span> <a class="code" href="class_hash_transformation.html" title="interface for hash functions and data processing part of MACs">HashTransformation</a><a name="l00020"></a>00020 {<a name="l00021"></a>00021 <span class="keyword">public</span>:<a name="l00022"></a><a class="code" href="class_c_r_c32.html#35ab46ca0358fe0f3470bfa5f7565d71">00022</a> CRYPTOPP_CONSTANT(<a class="code" href="class_c_r_c32.html#35ab46ca0358fe0f3470bfa5f7565d71">DIGESTSIZE</a> = 4)<a name="l00023"></a>00023 <a class="code" href="class_c_r_c32.html" title="CRC Checksum Calculation.">CRC32</a>();<a name="l00024"></a>00024 <span class="keywordtype">void</span> <a class="code" href="class_c_r_c32.html#bd642abba82cf63edb025461bc1af8c0" title="process more input">Update</a>(const byte *input, <span class="keywordtype">size_t</span> length);<a name="l00025"></a>00025 <span class="keywordtype">void</span> <a class="code" href="class_c_r_c32.html#b6f1523fe38d6f1b690888aab1675982" title="truncated version of Final()">TruncatedFinal</a>(byte *hash, <span class="keywordtype">size_t</span> size);<a name="l00026"></a><a class="code" href="class_c_r_c32.html#0a02cab7e98163326ecf7862dbaff7b9">00026</a> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> <a class="code" href="class_c_r_c32.html#0a02cab7e98163326ecf7862dbaff7b9" title="size of the hash returned by Final()">DigestSize</a>()<span class="keyword"> const </span>{<span class="keywordflow">return</span> <a class="code" href="class_c_r_c32.html#35ab46ca0358fe0f3470bfa5f7565d71">DIGESTSIZE</a>;}<a name="l00027"></a><a class="code" href="class_c_r_c32.html#61c475b1cf49a56e16e9fe4821b15951">00027</a> std::string <a class="code" href="class_c_r_c32.html#61c475b1cf49a56e16e9fe4821b15951" title="returns name of this algorithm, not universally implemented yet">AlgorithmName</a>()<span class="keyword"> const </span>{<span class="keywordflow">return</span> <span class="stringliteral">"CRC32"</span>;}<a name="l00028"></a>00028 <a name="l00029"></a><a class="code" href="class_c_r_c32.html#d1e5051e34441f8cc0d73aac51935424">00029</a> <span class="keywordtype">void</span> <a class="code" href="class_c_r_c32.html#d1e5051e34441f8cc0d73aac51935424">UpdateByte</a>(byte b) {m_crc = m_tab[CRC32_INDEX(m_crc) ^ b] ^ CRC32_SHIFTED(m_crc);}<a name="l00030"></a><a class="code" href="class_c_r_c32.html#18c8ec07e65a2cf1b9eed4e487e4f0bc">00030</a> byte <a class="code" href="class_c_r_c32.html#18c8ec07e65a2cf1b9eed4e487e4f0bc">GetCrcByte</a>(<span class="keywordtype">size_t</span> i)<span class="keyword"> const </span>{<span class="keywordflow">return</span> ((byte *)&(m_crc))[i];}<a name="l00031"></a>00031 <a name="l00032"></a>00032 <span class="keyword">private</span>:<a name="l00033"></a>00033 <span class="keywordtype">void</span> Reset() {m_crc = CRC32_NEGL;}<a name="l00034"></a>00034 <a name="l00035"></a>00035 <span class="keyword">static</span> <span class="keyword">const</span> word32 m_tab[256];<a name="l00036"></a>00036 word32 m_crc;<a name="l00037"></a>00037 };<a name="l00038"></a>00038 <a name="l00039"></a>00039 NAMESPACE_END<a name="l00040"></a>00040 <a name="l00041"></a>00041 <span class="preprocessor">#endif</span></pre></div><hr size="1"><address style="text-align: right;"><small>Generated on Fri Jun 1 11:11:20 2007 for Crypto++ by <a href="http://www.doxygen.org/index.html"><img src="doxygen.png" alt="doxygen" align="middle" border="0"></a> 1.5.2 </small></address></body></html>⌨️ 快捷键说明
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