1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/src/win32/7zip/7z/CPP/7zip/Compress/HuffmanDecoder.h	Sat Mar 03 10:31:27 2012 -0600
     1.3 @@ -0,0 +1,89 @@
     1.4 +// Compress/HuffmanDecoder.h
     1.5 +
     1.6 +#ifndef __COMPRESS_HUFFMAN_DECODER_H
     1.7 +#define __COMPRESS_HUFFMAN_DECODER_H
     1.8 +
     1.9 +#include "../../Common/Types.h"
    1.10 +
    1.11 +namespace NCompress {
    1.12 +namespace NHuffman {
    1.13 +
    1.14 +const int kNumTableBits = 9;
    1.15 +
    1.16 +template <int kNumBitsMax, UInt32 m_NumSymbols>
    1.17 +class CDecoder
    1.18 +{
    1.19 +  UInt32 m_Limits[kNumBitsMax + 1];     // m_Limits[i] = value limit for symbols with length = i
    1.20 +  UInt32 m_Positions[kNumBitsMax + 1];  // m_Positions[i] = index in m_Symbols[] of first symbol with length = i
    1.21 +  UInt32 m_Symbols[m_NumSymbols];
    1.22 +  Byte m_Lengths[1 << kNumTableBits];   // Table oh length for short codes.
    1.23 +
    1.24 +public:
    1.25 +  
    1.26 +  bool SetCodeLengths(const Byte *codeLengths)
    1.27 +  {
    1.28 +    int lenCounts[kNumBitsMax + 1];
    1.29 +    UInt32 tmpPositions[kNumBitsMax + 1];
    1.30 +    int i;
    1.31 +    for(i = 1; i <= kNumBitsMax; i++)
    1.32 +      lenCounts[i] = 0;
    1.33 +    UInt32 symbol;
    1.34 +    for (symbol = 0; symbol < m_NumSymbols; symbol++)
    1.35 +    {
    1.36 +      int len = codeLengths[symbol];
    1.37 +      if (len > kNumBitsMax)
    1.38 +        return false;
    1.39 +      lenCounts[len]++;
    1.40 +      m_Symbols[symbol] = 0xFFFFFFFF;
    1.41 +    }
    1.42 +    lenCounts[0] = 0;
    1.43 +    m_Positions[0] = m_Limits[0] = 0;
    1.44 +    UInt32 startPos = 0;
    1.45 +    UInt32 index = 0;
    1.46 +    const UInt32 kMaxValue = (1 << kNumBitsMax);
    1.47 +    for (i = 1; i <= kNumBitsMax; i++)
    1.48 +    {
    1.49 +      startPos += lenCounts[i] << (kNumBitsMax - i);
    1.50 +      if (startPos > kMaxValue)
    1.51 +        return false;
    1.52 +      m_Limits[i] = (i == kNumBitsMax) ? kMaxValue : startPos;
    1.53 +      m_Positions[i] = m_Positions[i - 1] + lenCounts[i - 1];
    1.54 +      tmpPositions[i] = m_Positions[i];
    1.55 +      if(i <= kNumTableBits)
    1.56 +      {
    1.57 +        UInt32 limit = (m_Limits[i] >> (kNumBitsMax - kNumTableBits));
    1.58 +        for (; index < limit; index++)
    1.59 +          m_Lengths[index] = (Byte)i;
    1.60 +      }
    1.61 +    }
    1.62 +    for (symbol = 0; symbol < m_NumSymbols; symbol++)
    1.63 +    {
    1.64 +      int len = codeLengths[symbol];
    1.65 +      if (len != 0)
    1.66 +        m_Symbols[tmpPositions[len]++] = symbol;
    1.67 +    }
    1.68 +    return true;
    1.69 +  }
    1.70 +
    1.71 +  template <class TBitDecoder>
    1.72 +  UInt32 DecodeSymbol(TBitDecoder *bitStream)
    1.73 +  {
    1.74 +    int numBits;
    1.75 +    UInt32 value = bitStream->GetValue(kNumBitsMax);
    1.76 +    if (value < m_Limits[kNumTableBits])
    1.77 +      numBits = m_Lengths[value >> (kNumBitsMax - kNumTableBits)];
    1.78 +    else
    1.79 +      for (numBits = kNumTableBits + 1; value >= m_Limits[numBits]; numBits++);
    1.80 +    bitStream->MovePos(numBits);
    1.81 +    UInt32 index = m_Positions[numBits] +
    1.82 +      ((value - m_Limits[numBits - 1]) >> (kNumBitsMax - numBits));
    1.83 +    if (index >= m_NumSymbols)
    1.84 +      // throw CDecoderException(); // test it
    1.85 +      return 0xFFFFFFFF;
    1.86 +    return m_Symbols[index];
    1.87 +  }
    1.88 +};
    1.89 +
    1.90 +}}
    1.91 +
    1.92 +#endif