zinflate_8cpp-source.html

Crypto++是一个非常强大的密码学库,主要是功能全

00441                         }
00442                         m_literalDecoder.<a class="code" href="class_huffman_decoder.html#_huffman_decodera2">Initialize</a>(codeLengths, hlit+257);
00443                         <span class="keywordflow">if</span> (hdist == 0 &amp;&amp; codeLengths[hlit+257] == 0)
00444                         {
00445                                 <span class="keywordflow">if</span> (hlit != 0)  <span class="comment">// a single zero distance code length means all literals</span>
00446                                         <span class="keywordflow">throw</span> BadBlockErr();
00447                         }
00448                         <span class="keywordflow">else</span>
00449                                 m_distanceDecoder.<a class="code" href="class_huffman_decoder.html#_huffman_decodera2">Initialize</a>(codeLengths+hlit+257, hdist+1);
00450                         m_nextDecode = LITERAL;
00451                 }
00452                 <span class="keywordflow">catch</span> (HuffmanDecoder::Err &amp;)
00453                 {
00454                         <span class="keywordflow">throw</span> BadBlockErr();
00455                 }
00456                 <span class="keywordflow">break</span>;
00457                 }
00458         <span class="keywordflow">default</span>:
00459                 <span class="keywordflow">throw</span> BadBlockErr();    <span class="comment">// reserved block type</span>
00460         }
00461         m_state = DECODING_BODY;
00462 }
00463 
00464 <span class="keywordtype">bool</span> Inflator::DecodeBody()
00465 {
00466         <span class="keywordtype">bool</span> blockEnd = <span class="keyword">false</span>;
00467         <span class="keywordflow">switch</span> (m_blockType)
00468         {
00469         <span class="keywordflow">case</span> 0: <span class="comment">// stored</span>
00470                 assert(m_reader.<a class="code" href="class_low_first_bit_reader.html#_low_first_bit_readera2">BitsBuffered</a>() == 0);
00471                 <span class="keywordflow">while</span> (!m_inQueue.<a class="code" href="class_byte_queue.html#_d_e_r_set_encodera16">IsEmpty</a>() &amp;&amp; !blockEnd)
00472                 {
00473                         <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> size;
00474                         <span class="keyword">const</span> byte *block = m_inQueue.<a class="code" href="class_byte_queue.html#_d_e_r_set_encodera20">Spy</a>(size);
00475                         size = STDMIN(size, (<span class="keywordtype">unsigned</span> <span class="keywordtype">int</span>)m_storedLen);
00476                         OutputString(block, size);
00477                         m_inQueue.<a class="code" href="class_buffered_transformation.html#_zlib_decompressorz7_11">Skip</a>(size);
00478                         m_storedLen -= size;
00479                         <span class="keywordflow">if</span> (m_storedLen == 0)
00480                                 blockEnd = <span class="keyword">true</span>;
00481                 }
00482                 <span class="keywordflow">break</span>;
00483         <span class="keywordflow">case</span> 1: <span class="comment">// fixed codes</span>
00484         <span class="keywordflow">case</span> 2: <span class="comment">// dynamic codes</span>
00485                 <span class="keyword">static</span> <span class="keyword">const</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> lengthStarts[] = {
00486                         3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
00487                         35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258};
00488                 <span class="keyword">static</span> <span class="keyword">const</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> lengthExtraBits[] = {
00489                         0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
00490                         3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0};
00491                 <span class="keyword">static</span> <span class="keyword">const</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> distanceStarts[] = {
00492                         1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
00493                         257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
00494                         8193, 12289, 16385, 24577};
00495                 <span class="keyword">static</span> <span class="keyword">const</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> distanceExtraBits[] = {
00496                         0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
00497                         7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
00498                         12, 12, 13, 13};
00499 
00500                 <span class="keywordflow">switch</span> (m_nextDecode)
00501                 {
00502                         <span class="keywordflow">while</span> (<span class="keyword">true</span>)
00503                         {
00504                 <span class="keywordflow">case</span> LITERAL:
00505                                 <span class="keywordflow">if</span> (!m_literalDecoder.<a class="code" href="class_huffman_decoder.html#_huffman_decodera3">Decode</a>(m_reader, m_literal))
00506                                 {
00507                                         m_nextDecode = LITERAL;
00508                                         <span class="keywordflow">break</span>;
00509                                 }
00510                                 <span class="keywordflow">if</span> (m_literal &lt; 256)
00511                                         OutputByte((byte)m_literal);
00512                                 <span class="keywordflow">else</span> <span class="keywordflow">if</span> (m_literal == 256)      <span class="comment">// end of block</span>
00513                                 {
00514                                         blockEnd = <span class="keyword">true</span>;
00515                                         <span class="keywordflow">break</span>;
00516                                 }
00517                                 <span class="keywordflow">else</span>
00518                                 {
00519                                         <span class="keywordflow">if</span> (m_literal &gt; 285)
00520                                                 <span class="keywordflow">throw</span> BadBlockErr();
00521                                         <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> bits;
00522                 <span class="keywordflow">case</span> LENGTH_BITS:
00523                                         bits = lengthExtraBits[m_literal-257];
00524                                         <span class="keywordflow">if</span> (!m_reader.<a class="code" href="class_low_first_bit_reader.html#_low_first_bit_readera4">FillBuffer</a>(bits))
00525                                         {
00526                                                 m_nextDecode = LENGTH_BITS;
00527                                                 <span class="keywordflow">break</span>;
00528                                         }
00529                                         m_literal = m_reader.<a class="code" href="class_low_first_bit_reader.html#_low_first_bit_readera7">GetBits</a>(bits) + lengthStarts[m_literal-257];
00530                 <span class="keywordflow">case</span> DISTANCE:
00531                                         <span class="keywordflow">if</span> (!m_distanceDecoder.<a class="code" href="class_huffman_decoder.html#_huffman_decodera3">Decode</a>(m_reader, m_distance))
00532                                         {
00533                                                 m_nextDecode = DISTANCE;
00534                                                 <span class="keywordflow">break</span>;
00535                                         }
00536                 <span class="keywordflow">case</span> DISTANCE_BITS:
00537                                         bits = distanceExtraBits[m_distance];
00538                                         <span class="keywordflow">if</span> (!m_reader.<a class="code" href="class_low_first_bit_reader.html#_low_first_bit_readera4">FillBuffer</a>(bits))
00539                                         {
00540                                                 m_nextDecode = DISTANCE_BITS;
00541                                                 <span class="keywordflow">break</span>;
00542                                         }
00543                                         m_distance = m_reader.<a class="code" href="class_low_first_bit_reader.html#_low_first_bit_readera7">GetBits</a>(bits) + distanceStarts[m_distance];
00544                                         OutputPast(m_literal, m_distance);
00545                                 }
00546                         }
00547                 }
00548         }
00549         <span class="keywordflow">if</span> (blockEnd)
00550         {
00551                 <span class="keywordflow">if</span> (m_eof)
00552                 {
00553                         FlushOutput();
00554                         m_reader.<a class="code" href="class_low_first_bit_reader.html#_low_first_bit_readera6">SkipBits</a>(m_reader.<a class="code" href="class_low_first_bit_reader.html#_low_first_bit_readera2">BitsBuffered</a>()%8);
00555                         <span class="keywordflow">if</span> (m_reader.<a class="code" href="class_low_first_bit_reader.html#_low_first_bit_readera2">BitsBuffered</a>())
00556                         {
00557                                 <span class="comment">// undo too much lookahead</span>
00558                                 SecBlockWithHint&lt;byte, 4&gt; buffer(m_reader.<a class="code" href="class_low_first_bit_reader.html#_low_first_bit_readera2">BitsBuffered</a>() / 8);
00559                                 <span class="keywordflow">for</span> (<span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> i=0; i&lt;buffer.<a class="code" href="class_sec_block.html#_sec_block_with_hinta13">size</a>(); i++)
00560                                         buffer[i] = (byte)m_reader.<a class="code" href="class_low_first_bit_reader.html#_low_first_bit_readera7">GetBits</a>(8);
00561                                 m_inQueue.<a class="code" href="class_byte_queue.html#_d_e_r_set_encodera18">Unget</a>(buffer, buffer.<a class="code" href="class_sec_block.html#_sec_block_with_hinta13">size</a>());
00562                         }
00563                         m_state = POST_STREAM;
00564                 }
00565                 <span class="keywordflow">else</span>
00566                         m_state = WAIT_HEADER;
00567         }
00568         <span class="keywordflow">return</span> blockEnd;
00569 }
00570 
00571 <span class="keywordtype">void</span> Inflator::FlushOutput()
00572 {
00573         <span class="keywordflow">if</span> (m_state != PRE_STREAM)
00574         {
00575                 assert(m_current &gt;= m_lastFlush);
00576                 ProcessDecompressedData(m_window + m_lastFlush, m_current - m_lastFlush);
00577                 m_lastFlush = m_current;
00578         }
00579 }
00580 
00581 NAMESPACE_END
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