diff options
Diffstat (limited to 'CPP/7zip/Compress/Implode/ImplodeHuffmanDecoder.cpp')
-rwxr-xr-x | CPP/7zip/Compress/Implode/ImplodeHuffmanDecoder.cpp | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/CPP/7zip/Compress/Implode/ImplodeHuffmanDecoder.cpp b/CPP/7zip/Compress/Implode/ImplodeHuffmanDecoder.cpp new file mode 100755 index 00000000..ad2061c3 --- /dev/null +++ b/CPP/7zip/Compress/Implode/ImplodeHuffmanDecoder.cpp @@ -0,0 +1,89 @@ +// ImplodeHuffmanDecoder.cpp + +#include "StdAfx.h" + +#include "ImplodeHuffmanDecoder.h" + +namespace NCompress { +namespace NImplode { +namespace NHuffman { + +CDecoder::CDecoder(UInt32 numSymbols): + m_NumSymbols(numSymbols) +{ + m_Symbols = new UInt32[m_NumSymbols]; +} + +CDecoder::~CDecoder() +{ + delete []m_Symbols; +} + +bool CDecoder::SetCodeLengths(const Byte *codeLengths) +{ + // int lenCounts[kNumBitsInLongestCode + 1], tmpPositions[kNumBitsInLongestCode + 1]; + int lenCounts[kNumBitsInLongestCode + 2], tmpPositions[kNumBitsInLongestCode + 1]; + int i; + for(i = 0; i <= kNumBitsInLongestCode; i++) + lenCounts[i] = 0; + UInt32 symbolIndex; + for (symbolIndex = 0; symbolIndex < m_NumSymbols; symbolIndex++) + lenCounts[codeLengths[symbolIndex]]++; + // lenCounts[0] = 0; + + // tmpPositions[0] = m_Positions[0] = m_Limitits[0] = 0; + m_Limitits[kNumBitsInLongestCode + 1] = 0; + m_Positions[kNumBitsInLongestCode + 1] = 0; + lenCounts[kNumBitsInLongestCode + 1] = 0; + + + UInt32 startPos = 0; + static const UInt32 kMaxValue = (1 << kNumBitsInLongestCode); + + for (i = kNumBitsInLongestCode; i > 0; i--) + { + startPos += lenCounts[i] << (kNumBitsInLongestCode - i); + if (startPos > kMaxValue) + return false; + m_Limitits[i] = startPos; + m_Positions[i] = m_Positions[i + 1] + lenCounts[i + 1]; + tmpPositions[i] = m_Positions[i] + lenCounts[i]; + + } + + // if _ZIP_MODE do not throw exception for trees containing only one node + // #ifndef _ZIP_MODE + if (startPos != kMaxValue) + return false; + // #endif + + for (symbolIndex = 0; symbolIndex < m_NumSymbols; symbolIndex++) + if (codeLengths[symbolIndex] != 0) + m_Symbols[--tmpPositions[codeLengths[symbolIndex]]] = symbolIndex; + return true; +} + +UInt32 CDecoder::DecodeSymbol(CInBit *inStream) +{ + UInt32 numBits = 0; + UInt32 value = inStream->GetValue(kNumBitsInLongestCode); + int i; + for(i = kNumBitsInLongestCode; i > 0; i--) + { + if (value < m_Limitits[i]) + { + numBits = i; + break; + } + } + if (i == 0) + return 0xFFFFFFFF; + inStream->MovePos(numBits); + UInt32 index = m_Positions[numBits] + + ((value - m_Limitits[numBits + 1]) >> (kNumBitsInLongestCode - numBits)); + if (index >= m_NumSymbols) + return 0xFFFFFFFF; + return m_Symbols[index]; +} + +}}} |