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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++: zinflate.cpp 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>zinflate.cpp</h1><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">// zinflate.cpp - written and placed in the public domain by Wei Dai</span><a name="l00002"></a>00002 <a name="l00003"></a>00003 <span class="comment">// This is a complete reimplementation of the DEFLATE decompression algorithm.</span><a name="l00004"></a>00004 <span class="comment">// It should not be affected by any security vulnerabilities in the zlib </span><a name="l00005"></a>00005 <span class="comment">// compression library. In particular it is not affected by the double free bug</span><a name="l00006"></a>00006 <span class="comment">// (http://www.kb.cert.org/vuls/id/368819).</span><a name="l00007"></a>00007 <a name="l00008"></a>00008 <span class="preprocessor">#include "pch.h"</span><a name="l00009"></a>00009 <span class="preprocessor">#include "zinflate.h"</span><a name="l00010"></a>00010 <a name="l00011"></a>00011 NAMESPACE_BEGIN(CryptoPP)<a name="l00012"></a>00012 <a name="l00013"></a><a class="code" href="struct_code_less_than.html">00013</a> struct <a class="code" href="struct_code_less_than.html">CodeLessThan</a><a name="l00014"></a>00014 {<a name="l00015"></a><a class="code" href="struct_code_less_than.html#914a1f562d16f80dcc69e0144769a4f9">00015</a> <span class="keyword">inline</span> <span class="keywordtype">bool</span> operator()(CryptoPP::HuffmanDecoder::code_t lhs, <span class="keyword">const</span> CryptoPP::HuffmanDecoder::CodeInfo &rhs)<a name="l00016"></a>00016 {<span class="keywordflow">return</span> lhs < rhs.code;}<a name="l00017"></a>00017 <span class="comment">// needed for MSVC .NET 2005</span><a name="l00018"></a><a class="code" href="struct_code_less_than.html#9aa151d31b39d30a01c6cb1b721e7c7b">00018</a> <span class="keyword">inline</span> <span class="keywordtype">bool</span> operator()(<span class="keyword">const</span> CryptoPP::HuffmanDecoder::CodeInfo &lhs, <span class="keyword">const</span> CryptoPP::HuffmanDecoder::CodeInfo &rhs)<a name="l00019"></a>00019 {<span class="keywordflow">return</span> lhs.code < rhs.code;}<a name="l00020"></a>00020 };<a name="l00021"></a>00021 <a name="l00022"></a><a class="code" href="class_low_first_bit_reader.html#7c2250f093883488eefb6d498aa1c510">00022</a> <span class="keyword">inline</span> <span class="keywordtype">bool</span> <a class="code" href="class_low_first_bit_reader.html#7c2250f093883488eefb6d498aa1c510">LowFirstBitReader::FillBuffer</a>(<span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> length)<a name="l00023"></a>00023 {<a name="l00024"></a>00024 <span class="keywordflow">while</span> (m_bitsBuffered < length)<a name="l00025"></a>00025 {<a name="l00026"></a>00026 byte b;<a name="l00027"></a>00027 <span class="keywordflow">if</span> (!m_store.<a class="code" href="class_buffered_transformation.html#9e1ad913c8fe697d269f408a7d5928fc" title="try to retrieve a single byte">Get</a>(b))<a name="l00028"></a>00028 <span class="keywordflow">return</span> <span class="keyword">false</span>;<a name="l00029"></a>00029 m_buffer |= (<span class="keywordtype">unsigned</span> long)b << m_bitsBuffered;<a name="l00030"></a>00030 m_bitsBuffered += 8;<a name="l00031"></a>00031 }<a name="l00032"></a>00032 assert(m_bitsBuffered <= <span class="keyword">sizeof</span>(<span class="keywordtype">unsigned</span> <span class="keywordtype">long</span>)*8);<a name="l00033"></a>00033 <span class="keywordflow">return</span> <span class="keyword">true</span>;<a name="l00034"></a>00034 }<a name="l00035"></a>00035 <a name="l00036"></a><a class="code" href="class_low_first_bit_reader.html#20e4e0eb1cd259c0447876ae565ec8e0">00036</a> <span class="keyword">inline</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">long</span> <a class="code" href="class_low_first_bit_reader.html#20e4e0eb1cd259c0447876ae565ec8e0">LowFirstBitReader::PeekBits</a>(<span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> length)<a name="l00037"></a>00037 {<a name="l00038"></a>00038 <span class="keywordtype">bool</span> result = <a class="code" href="class_low_first_bit_reader.html#7c2250f093883488eefb6d498aa1c510">FillBuffer</a>(length);<a name="l00039"></a>00039 assert(result);<a name="l00040"></a>00040 <span class="keywordflow">return</span> m_buffer & (((<span class="keywordtype">unsigned</span> long)1 << length) - 1);<a name="l00041"></a>00041 }<a name="l00042"></a>00042 <a name="l00043"></a><a class="code" href="class_low_first_bit_reader.html#7127a720aeefbc1d91dddefc694538c6">00043</a> <span class="keyword">inline</span> <span class="keywordtype">void</span> <a class="code" href="class_low_first_bit_reader.html#7127a720aeefbc1d91dddefc694538c6">LowFirstBitReader::SkipBits</a>(<span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> length)<a name="l00044"></a>00044 {<a name="l00045"></a>00045 assert(m_bitsBuffered >= length);<a name="l00046"></a>00046 m_buffer >>= length;<a name="l00047"></a>00047 m_bitsBuffered -= length;<a name="l00048"></a>00048 }<a name="l00049"></a>00049 <a name="l00050"></a><a class="code" href="class_low_first_bit_reader.html#ecfd76bf8814829b75d9d4f6592a4625">00050</a> <span class="keyword">inline</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">long</span> <a class="code" href="class_low_first_bit_reader.html#ecfd76bf8814829b75d9d4f6592a4625">LowFirstBitReader::GetBits</a>(<span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> length)<a name="l00051"></a>00051 {<a name="l00052"></a>00052 <span class="keywordtype">unsigned</span> <span class="keywordtype">long</span> result = <a class="code" href="class_low_first_bit_reader.html#20e4e0eb1cd259c0447876ae565ec8e0">PeekBits</a>(length);<a name="l00053"></a>00053 <a class="code" href="class_low_first_bit_reader.html#7127a720aeefbc1d91dddefc694538c6">SkipBits</a>(length);<a name="l00054"></a>00054 <span class="keywordflow">return</span> result;<a name="l00055"></a>00055 }<a name="l00056"></a>00056 <a name="l00057"></a>00057 <span class="keyword">inline</span> <a class="code" href="class_huffman_decoder.html#550cd665357c320af58916f992eb8756">HuffmanDecoder::code_t</a> HuffmanDecoder::NormalizeCode(<a class="code" href="class_huffman_decoder.html#550cd665357c320af58916f992eb8756">HuffmanDecoder::code_t</a> code, <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> codeBits)<a name="l00058"></a>00058 {<a name="l00059"></a>00059 <span class="keywordflow">return</span> code << (<a class="code" href="class_huffman_decoder.html#444758e6ef809d2bf568e4e73cd560d7589d91f9fef801b8b978b95c9eef161b">MAX_CODE_BITS</a> - codeBits);<a name="l00060"></a>00060 }<a name="l00061"></a>00061 <a name="l00062"></a><a class="code" href="class_huffman_decoder.html#66275670f30366de75c3bcb506c657f5">00062</a> <span class="keywordtype">void</span> <a class="code" href="class_huffman_decoder.html#66275670f30366de75c3bcb506c657f5">HuffmanDecoder::Initialize</a>(<span class="keyword">const</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> *codeBits, <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> nCodes)<a name="l00063"></a>00063 {<a name="l00064"></a>00064 <span class="comment">// the Huffman codes are represented in 3 ways in this code:</span><a name="l00065"></a>00065 <span class="comment">//</span><a name="l00066"></a>00066 <span class="comment">// 1. most significant code bit (i.e. top of code tree) in the least significant bit position</span><a name="l00067"></a>00067 <span class="comment">// 2. most significant code bit (i.e. top of code tree) in the most significant bit position</span><a name="l00068"></a>00068 <span class="comment">// 3. most significant code bit (i.e. top of code tree) in n-th least significant bit position,</span><a name="l00069"></a>00069 <span class="comment">// where n is the maximum code length for this code tree</span><a name="l00070"></a>00070 <span class="comment">//</span><a name="l00071"></a>00071 <span class="comment">// (1) is the way the codes come in from the deflate stream</span><a name="l00072"></a>00072 <span class="comment">// (2) is used to sort codes so they can be binary searched</span><a name="l00073"></a>00073 <span class="comment">// (3) is used in this function to compute codes from code lengths</span><a name="l00074"></a>00074 <span class="comment">//</span><a name="l00075"></a>00075 <span class="comment">// a code in representation (2) is called "normalized" here</span><a name="l00076"></a>00076 <span class="comment">// The BitReverse() function is used to convert between (1) and (2)</span><a name="l00077"></a>00077 <span class="comment">// The NormalizeCode() function is used to convert from (3) to (2)</span><a name="l00078"></a>00078 <a name="l00079"></a>00079 <span class="keywordflow">if</span> (nCodes == 0)<a name="l00080"></a>00080 <span class="keywordflow">throw</span> <a class="code" href="class_huffman_decoder_1_1_err.html">Err</a>(<span class="stringliteral">"null code"</span>);<a name="l00081"></a>00081 <a name="l00082"></a>00082 m_maxCodeBits = *std::max_element(codeBits, codeBits+nCodes);<a name="l00083"></a>00083 <a name="l00084"></a>00084 <span class="keywordflow">if</span> (m_maxCodeBits > <a class="code" href="class_huffman_decoder.html#444758e6ef809d2bf568e4e73cd560d7589d91f9fef801b8b978b95c9eef161b">MAX_CODE_BITS</a>)<a name="l00085"></a>00085 <span class="keywordflow">throw</span> <a class="code" href="class_huffman_decoder_1_1_err.html">Err</a>(<span class="stringliteral">"code length exceeds maximum"</span>);<a name="l00086"></a>00086 <a name="l00087"></a>00087 <span class="keywordflow">if</span> (m_maxCodeBits == 0)<a name="l00088"></a>00088 <span class="keywordflow">throw</span> <a class="code" href="class_huffman_decoder_1_1_err.html">Err</a>(<span class="stringliteral">"null code"</span>);<a name="l00089"></a>00089 <a name="l00090"></a>00090 <span class="comment">// count number of codes of each length</span><a name="l00091"></a>00091 <a class="code" href="class_sec_block_with_hint.html" title="a SecBlock that preallocates size S statically, and uses the heap when this size...">SecBlockWithHint<unsigned int, 15+1></a> blCount(m_maxCodeBits+1);<a name="l00092"></a>00092 std::fill(blCount.<a class="code" href="class_sec_block.html#11a05906688172579cd3520816799446">begin</a>(), blCount.<a class="code" href="class_sec_block.html#26d88ba73b5da0f5dd4ab87ce6345d8f">end</a>(), 0);<a name="l00093"></a>00093 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> i;<a name="l00094"></a>00094 <span class="keywordflow">for</span> (i=0; i<nCodes; i++)<a name="l00095"></a>00095 blCount[codeBits[i]]++;<a name="l00096"></a>00096 <a name="l00097"></a>00097 <span class="comment">// compute the starting code of each length</span><a name="l00098"></a>00098 <a class="code" href="class_huffman_decoder.html#550cd665357c320af58916f992eb8756">code_t</a> code = 0;<a name="l00099"></a>00099 <a class="code" href="class_sec_block_with_hint.html" title="a SecBlock that preallocates size S statically, and uses the heap when this size...">SecBlockWithHint<code_t, 15+1></a> nextCode(m_maxCodeBits+1);<a name="l00100"></a>00100 nextCode[1] = 0;⌨️ 快捷键说明
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