Mercurial > vba-clojure
diff src/win32/7zip/7z/CPP/7zip/Compress/ImplodeHuffmanDecoder.cpp @ 1:f9f4f1b99eed
importing src directory
author | Robert McIntyre <rlm@mit.edu> |
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date | Sat, 03 Mar 2012 10:31:27 -0600 |
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1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000 1.2 +++ b/src/win32/7zip/7z/CPP/7zip/Compress/ImplodeHuffmanDecoder.cpp Sat Mar 03 10:31:27 2012 -0600 1.3 @@ -0,0 +1,89 @@ 1.4 +// ImplodeHuffmanDecoder.cpp 1.5 + 1.6 +#include "StdAfx.h" 1.7 + 1.8 +#include "ImplodeHuffmanDecoder.h" 1.9 + 1.10 +namespace NCompress { 1.11 +namespace NImplode { 1.12 +namespace NHuffman { 1.13 + 1.14 +CDecoder::CDecoder(UInt32 numSymbols): 1.15 + m_NumSymbols(numSymbols) 1.16 +{ 1.17 + m_Symbols = new UInt32[m_NumSymbols]; 1.18 +} 1.19 + 1.20 +CDecoder::~CDecoder() 1.21 +{ 1.22 + delete []m_Symbols; 1.23 +} 1.24 + 1.25 +bool CDecoder::SetCodeLengths(const Byte *codeLengths) 1.26 +{ 1.27 + // int lenCounts[kNumBitsInLongestCode + 1], tmpPositions[kNumBitsInLongestCode + 1]; 1.28 + int lenCounts[kNumBitsInLongestCode + 2], tmpPositions[kNumBitsInLongestCode + 1]; 1.29 + int i; 1.30 + for(i = 0; i <= kNumBitsInLongestCode; i++) 1.31 + lenCounts[i] = 0; 1.32 + UInt32 symbolIndex; 1.33 + for (symbolIndex = 0; symbolIndex < m_NumSymbols; symbolIndex++) 1.34 + lenCounts[codeLengths[symbolIndex]]++; 1.35 + // lenCounts[0] = 0; 1.36 + 1.37 + // tmpPositions[0] = m_Positions[0] = m_Limitits[0] = 0; 1.38 + m_Limitits[kNumBitsInLongestCode + 1] = 0; 1.39 + m_Positions[kNumBitsInLongestCode + 1] = 0; 1.40 + lenCounts[kNumBitsInLongestCode + 1] = 0; 1.41 + 1.42 + 1.43 + UInt32 startPos = 0; 1.44 + static const UInt32 kMaxValue = (1 << kNumBitsInLongestCode); 1.45 + 1.46 + for (i = kNumBitsInLongestCode; i > 0; i--) 1.47 + { 1.48 + startPos += lenCounts[i] << (kNumBitsInLongestCode - i); 1.49 + if (startPos > kMaxValue) 1.50 + return false; 1.51 + m_Limitits[i] = startPos; 1.52 + m_Positions[i] = m_Positions[i + 1] + lenCounts[i + 1]; 1.53 + tmpPositions[i] = m_Positions[i] + lenCounts[i]; 1.54 + 1.55 + } 1.56 + 1.57 + // if _ZIP_MODE do not throw exception for trees containing only one node 1.58 + // #ifndef _ZIP_MODE 1.59 + if (startPos != kMaxValue) 1.60 + return false; 1.61 + // #endif 1.62 + 1.63 + for (symbolIndex = 0; symbolIndex < m_NumSymbols; symbolIndex++) 1.64 + if (codeLengths[symbolIndex] != 0) 1.65 + m_Symbols[--tmpPositions[codeLengths[symbolIndex]]] = symbolIndex; 1.66 + return true; 1.67 +} 1.68 + 1.69 +UInt32 CDecoder::DecodeSymbol(CInBit *inStream) 1.70 +{ 1.71 + UInt32 numBits = 0; 1.72 + UInt32 value = inStream->GetValue(kNumBitsInLongestCode); 1.73 + int i; 1.74 + for(i = kNumBitsInLongestCode; i > 0; i--) 1.75 + { 1.76 + if (value < m_Limitits[i]) 1.77 + { 1.78 + numBits = i; 1.79 + break; 1.80 + } 1.81 + } 1.82 + if (i == 0) 1.83 + return 0xFFFFFFFF; 1.84 + inStream->MovePos(numBits); 1.85 + UInt32 index = m_Positions[numBits] + 1.86 + ((value - m_Limitits[numBits + 1]) >> (kNumBitsInLongestCode - numBits)); 1.87 + if (index >= m_NumSymbols) 1.88 + return 0xFFFFFFFF; 1.89 + return m_Symbols[index]; 1.90 +} 1.91 + 1.92 +}}}