lzmadecode.c

lzma的压缩算法再嵌入式系统上的实现

/*
LzmaDecode.c
LZMA Decoder
LZMA SDK 4.01 Copyright (c) 1999-2004 Igor Pavlov (2004-02-15)
*/

#include "LzmaDecode.h"

#ifndef Byte
#define Byte unsigned char
#endif

#define kNumTopBits 24
#define kTopValue ((UInt32)1 << kNumTopBits)

#define kNumBitModelTotalBits 11
#define kBitModelTotal (1 << kNumBitModelTotalBits)
#define kNumMoveBits 5

typedef struct _CRangeDecoder
{
  Byte *Buffer;
  Byte *BufferLim;
  UInt32 Range;
  UInt32 Code;
  #ifdef _LZMA_IN_CB
  ILzmaInCallback *InCallback;
  int Result;
  #endif
  int ExtraBytes;
} CRangeDecoder;

Byte RangeDecoderReadByte(CRangeDecoder *rd)
{
  if (rd->Buffer == rd->BufferLim)
  {
    #ifdef _LZMA_IN_CB
    UInt32 size;
    rd->Result = rd->InCallback->Read(rd->InCallback, &rd->Buffer, &size);
    rd->BufferLim = rd->Buffer + size;
    if (size == 0)
    #endif
    {
      rd->ExtraBytes = 1;
      return 0xFF;
    }
  }
  return (*rd->Buffer++);
}

/* #define ReadByte (*rd->Buffer++) */
#define ReadByte (RangeDecoderReadByte(rd))

void RangeDecoderInit(CRangeDecoder *rd,
  #ifdef _LZMA_IN_CB
    ILzmaInCallback *inCallback
  #else
    Byte *stream, UInt32 bufferSize
  #endif
    )
{
  int i;
  #ifdef _LZMA_IN_CB
  rd->InCallback = inCallback;
  rd->Buffer = rd->BufferLim = 0;
  #else
  rd->Buffer = stream;
  rd->BufferLim = stream + bufferSize;
  #endif
  rd->ExtraBytes = 0;
  rd->Code = 0;
  rd->Range = (0xFFFFFFFF);
  for(i = 0; i < 5; i++)
    rd->Code = (rd->Code << 8) | ReadByte;
}

#define RC_INIT_VAR UInt32 range = rd->Range; UInt32 code = rd->Code;        
#define RC_FLUSH_VAR rd->Range = range; rd->Code = code;
#define RC_NORMALIZE if (range < kTopValue) { range <<= 8; code = (code << 8) | ReadByte; }

UInt32 RangeDecoderDecodeDirectBits(CRangeDecoder *rd, int numTotalBits)
{
  RC_INIT_VAR
  UInt32 result = 0;
  int i;
  for (i = numTotalBits; i > 0; i--)
  {
    /* UInt32 t; */
    range >>= 1;

    result <<= 1;
    if (code >= range)
    {
      code -= range;
      result |= 1;
    }
    /*
    t = (code - range) >> 31;
    t &= 1;
    code -= range & (t - 1);
    result = (result + result) | (1 - t);
    */
    RC_NORMALIZE
  }
  RC_FLUSH_VAR
  return result;
}

int RangeDecoderBitDecode(CProb *prob, CRangeDecoder *rd)
{
  UInt32 bound = (rd->Range >> kNumBitModelTotalBits) * *prob;
  if (rd->Code < bound)
  {
    rd->Range = bound;
    *prob += (kBitModelTotal - *prob) >> kNumMoveBits;
    if (rd->Range < kTopValue)
    {
      rd->Code = (rd->Code << 8) | ReadByte;
      rd->Range <<= 8;
    }
    return 0;
  }
  else
  {
    rd->Range -= bound;
    rd->Code -= bound;
    *prob -= (*prob) >> kNumMoveBits;
    if (rd->Range < kTopValue)
    {
      rd->Code = (rd->Code << 8) | ReadByte;
      rd->Range <<= 8;
    }
    return 1;
  }
}

#define RC_GET_BIT2(prob, mi, A0, A1) \
  UInt32 bound = (range >> kNumBitModelTotalBits) * *prob; \
  if (code < bound) \
    { A0; range = bound; *prob += (kBitModelTotal - *prob) >> kNumMoveBits; mi <<= 1; } \
  else \
    { A1; range -= bound; code -= bound; *prob -= (*prob) >> kNumMoveBits; mi = (mi + mi) + 1; } \
  RC_NORMALIZE

#define RC_GET_BIT(prob, mi) RC_GET_BIT2(prob, mi, ; , ;)               

int RangeDecoderBitTreeDecode(CProb *probs, int numLevels, CRangeDecoder *rd)
{
  int mi = 1;
  int i;
  #ifdef _LZMA_LOC_OPT
  RC_INIT_VAR
  #endif
  for(i = numLevels; i > 0; i--)
  {
    #ifdef _LZMA_LOC_OPT
    CProb *prob = probs + mi;
    RC_GET_BIT(prob, mi)
    #else
    mi = (mi + mi) + RangeDecoderBitDecode(probs + mi, rd);
    #endif
  }
  #ifdef _LZMA_LOC_OPT
  RC_FLUSH_VAR
  #endif
  return mi - (1 << numLevels);
}

int RangeDecoderReverseBitTreeDecode(CProb *probs, int numLevels, CRangeDecoder *rd)
{
  int mi = 1;
  int i;
  int symbol = 0;
  #ifdef _LZMA_LOC_OPT
  RC_INIT_VAR
  #endif
  for(i = 0; i < numLevels; i++)
  {
    #ifdef _LZMA_LOC_OPT
    CProb *prob = probs + mi;
    RC_GET_BIT2(prob, mi, ; , symbol |= (1 << i))
    #else
    int bit = RangeDecoderBitDecode(probs + mi, rd);
    mi = mi + mi + bit;
    symbol |= (bit << i);
    #endif
  }
  #ifdef _LZMA_LOC_OPT
  RC_FLUSH_VAR
  #endif
  return symbol;
}

Byte LzmaLiteralDecode(CProb *probs, CRangeDecoder *rd)
{ 
  int symbol = 1;
  #ifdef _LZMA_LOC_OPT
  RC_INIT_VAR
  #endif
  do
  {
    #ifdef _LZMA_LOC_OPT
    CProb *prob = probs + symbol;
    RC_GET_BIT(prob, symbol)
    #else
    symbol = (symbol + symbol) | RangeDecoderBitDecode(probs + symbol, rd);
    #endif
  }
  while (symbol < 0x100);
  #ifdef _LZMA_LOC_OPT
  RC_FLUSH_VAR
  #endif
  return symbol;
}

Byte LzmaLiteralDecodeMatch(CProb *probs, CRangeDecoder *rd, Byte matchByte)
{ 
  int symbol = 1;
  #ifdef _LZMA_LOC_OPT
  RC_INIT_VAR
  #endif
  do
  {
    int bit;
    int matchBit = (matchByte >> 7) & 1;
    matchByte <<= 1;
    #ifdef _LZMA_LOC_OPT
    {
      CProb *prob = probs + ((1 + matchBit) << 8) + symbol;
      RC_GET_BIT2(prob, symbol, bit = 0, bit = 1)
    }
    #else
    bit = RangeDecoderBitDecode(probs + ((1 + matchBit) << 8) + symbol, rd);
    symbol = (symbol << 1) | bit;
    #endif
    if (matchBit != bit)
    {
      while (symbol < 0x100)
      {
        #ifdef _LZMA_LOC_OPT
        CProb *prob = probs + symbol;
        RC_GET_BIT(prob, symbol)
        #else
        symbol = (symbol + symbol) | RangeDecoderBitDecode(probs + symbol, rd);
        #endif
      }
      break;
    }
  }
  while (symbol < 0x100);
  #ifdef _LZMA_LOC_OPT
  RC_FLUSH_VAR
  #endif
  return symbol;
}

#define kNumPosBitsMax 4
#define kNumPosStatesMax (1 << kNumPosBitsMax)

#define kLenNumLowBits 3
#define kLenNumLowSymbols (1 << kLenNumLowBits)
#define kLenNumMidBits 3
#define kLenNumMidSymbols (1 << kLenNumMidBits)
#define kLenNumHighBits 8
#define kLenNumHighSymbols (1 << kLenNumHighBits)

#define LenChoice 0
#define LenChoice2 (LenChoice + 1)
#define LenLow (LenChoice2 + 1)
#define LenMid (LenLow + (kNumPosStatesMax << kLenNumLowBits))
#define LenHigh (LenMid + (kNumPosStatesMax << kLenNumMidBits))
#define kNumLenProbs (LenHigh + kLenNumHighSymbols) 

int LzmaLenDecode(CProb *p, CRangeDecoder *rd, int posState)
{
  if(RangeDecoderBitDecode(p + LenChoice, rd) == 0)
    return RangeDecoderBitTreeDecode(p + LenLow +
        (posState << kLenNumLowBits), kLenNumLowBits, rd);
  if(RangeDecoderBitDecode(p + LenChoice2, rd) == 0)
    return kLenNumLowSymbols + RangeDecoderBitTreeDecode(p + LenMid +
        (posState << kLenNumMidBits), kLenNumMidBits, rd);
  return kLenNumLowSymbols + kLenNumMidSymbols + 
      RangeDecoderBitTreeDecode(p + LenHigh, kLenNumHighBits, rd);
}

#define kNumStates 12

#define kStartPosModelIndex 4
#define kEndPosModelIndex 14
#define kNumFullDistances (1 << (kEndPosModelIndex >> 1))

#define kNumPosSlotBits 6
#define kNumLenToPosStates 4

#define kNumAlignBits 4
#define kAlignTableSize (1 << kNumAlignBits)

#define kMatchMinLen 2

#define IsMatch 0
#define IsRep (IsMatch + (kNumStates << kNumPosBitsMax))
#define IsRepG0 (IsRep + kNumStates)
#define IsRepG1 (IsRepG0 + kNumStates)
#define IsRepG2 (IsRepG1 + kNumStates)
#define IsRep0Long (IsRepG2 + kNumStates)
#define PosSlot (IsRep0Long + (kNumStates << kNumPosBitsMax))
#define SpecPos (PosSlot + (kNumLenToPosStates << kNumPosSlotBits))
#define Align (SpecPos + kNumFullDistances - kEndPosModelIndex)
#define LenCoder (Align + kAlignTableSize)
#define RepLenCoder (LenCoder + kNumLenProbs)
#define Literal (RepLenCoder + kNumLenProbs)

#if Literal != LZMA_BASE_SIZE
StopCompilingDueBUG
#endif

#ifdef _LZMA_OUT_READ

typedef struct _LzmaVarState
{
  CRangeDecoder RangeDecoder;
  Byte *Dictionary;
  UInt32 DictionarySize;
  UInt32 DictionaryPos;
  UInt32 GlobalPos;