bzip2decoder.cpp

7-Zip 是一款号称有着现今最高压缩比的压缩软件

      randToGo--;
    }
    
    if (numReps == kRleModeRepSize)
    {
      for (; b > 0; b--)
      {
        crc.UpdateByte(prevByte);
        m_OutStream.WriteByte((Byte)prevByte);
      }
      numReps = 0;
      continue;
    }
    if (b != prevByte)
      numReps = 0;
    numReps++;
    prevByte = b;
    crc.UpdateByte(b);
    m_OutStream.WriteByte((Byte)b);
  }
  while(--blockSize != 0);
  return crc.GetDigest();
}

#ifdef COMPRESS_BZIP2_MT

CDecoder::CDecoder():
  m_States(0)
{
  m_NumThreadsPrev = 0;
  NumThreads = 1;
}

CDecoder::~CDecoder()
{
  Free();
}

#define RINOK_THREAD(x) { WRes __result_ = (x); if(__result_ != 0) return __result_; }

HRESULT CDecoder::Create()
{
  RINOK_THREAD(CanProcessEvent.CreateIfNotCreated());
  RINOK_THREAD(CanStartWaitingEvent.CreateIfNotCreated());
  if (m_States != 0 && m_NumThreadsPrev == NumThreads)
    return S_OK;
  Free();
  MtMode = (NumThreads > 1);
  m_NumThreadsPrev = NumThreads;
  try
  {
    m_States = new CState[NumThreads];
    if (m_States == 0)
      return E_OUTOFMEMORY;
  }
  catch(...) { return E_OUTOFMEMORY; }
  for (UInt32 t = 0; t < NumThreads; t++)
  {
    CState &ti = m_States[t];
    ti.Decoder = this;
    if (MtMode)
    {
      HRESULT res = ti.Create();
      if (res != S_OK)
      {
        NumThreads = t;
        Free();
        return res;
      }
    }
  }
  return S_OK;
}

void CDecoder::Free()
{
  if (!m_States)
    return;
  CloseThreads = true;
  CanProcessEvent.Set();
  for (UInt32 t = 0; t < NumThreads; t++)
  {
    CState &s = m_States[t];
    if (MtMode)
      s.Thread.Wait();
    s.Free();
  }
  delete []m_States;
  m_States = 0;
}
#endif

HRESULT CDecoder::ReadSignatures(bool &wasFinished, UInt32 &crc)
{
  wasFinished = false;
  Byte s[6];
  for (int i = 0; i < 6; i++)
    s[i] = ReadByte();
  crc = ReadCRC();
  if (s[0] == kFinSig0)
  {
    if (s[1] != kFinSig1 ||
        s[2] != kFinSig2 ||
        s[3] != kFinSig3 ||
        s[4] != kFinSig4 ||
        s[5] != kFinSig5)
      return S_FALSE;
    
    wasFinished = true;
    return (crc == CombinedCRC.GetDigest()) ? S_OK : S_FALSE;
  }
  if (s[0] != kBlockSig0 ||
      s[1] != kBlockSig1 ||
      s[2] != kBlockSig2 ||
      s[3] != kBlockSig3 ||
      s[4] != kBlockSig4 ||
      s[5] != kBlockSig5)
    return S_FALSE;
  CombinedCRC.Update(crc);
  return S_OK;
}

HRESULT CDecoder::DecodeFile(bool &isBZ, ICompressProgressInfo *progress)
{
  #ifdef COMPRESS_BZIP2_MT
  Progress = progress;
  RINOK(Create());
  for (UInt32 t = 0; t < NumThreads; t++)
  {
    CState &s = m_States[t];
    if (!s.Alloc())
      return E_OUTOFMEMORY;
    if (MtMode)
    {
      RINOK(s.StreamWasFinishedEvent.Reset());
      RINOK(s.WaitingWasStartedEvent.Reset());
      RINOK(s.CanWriteEvent.Reset());
    }
  }
  #else
  if (!m_States[0].Alloc())
    return E_OUTOFMEMORY;
  #endif

  isBZ = false;
  Byte s[6];
  int i;
  for (i = 0; i < 4; i++)
    s[i] = ReadByte();
  if (s[0] != kArSig0 ||
      s[1] != kArSig1 ||
      s[2] != kArSig2 ||
      s[3] <= kArSig3 ||
      s[3] > kArSig3 + kBlockSizeMultMax)
    return S_OK;
  isBZ = true;
  UInt32 dicSize = (UInt32)(s[3] - kArSig3) * kBlockSizeStep;

  CombinedCRC.Init();
  #ifdef COMPRESS_BZIP2_MT
  if (MtMode)
  {
    NextBlockIndex = 0;
    StreamWasFinished1 = StreamWasFinished2 = false;
    CloseThreads = false;
    CanStartWaitingEvent.Reset();
    m_States[0].CanWriteEvent.Set();
    BlockSizeMax = dicSize;
    Result1 = Result2 = S_OK;
    CanProcessEvent.Set();
    UInt32 t;
    for (t = 0; t < NumThreads; t++)
      m_States[t].StreamWasFinishedEvent.Lock();
    CanProcessEvent.Reset();
    CanStartWaitingEvent.Set();
    for (t = 0; t < NumThreads; t++)
      m_States[t].WaitingWasStartedEvent.Lock();
    CanStartWaitingEvent.Reset();
    RINOK(Result2);
    RINOK(Result1);
  }
  else
  #endif
  {
    CState &state = m_States[0];
    for (;;)
    {
      if (progress)
      {
        UInt64 packSize = m_InStream.GetProcessedSize();
        UInt64 unpackSize = m_OutStream.GetProcessedSize();
        RINOK(progress->SetRatioInfo(&packSize, &unpackSize));
      }
      bool wasFinished;
      UInt32 crc;
      RINOK(ReadSignatures(wasFinished, crc));
      if (wasFinished)
        return S_OK;

      UInt32 blockSize, origPtr;
      bool randMode;
      RINOK(ReadBlock(&m_InStream, state.Counters, dicSize,
        m_Selectors, m_HuffmanDecoders,
        &blockSize, &origPtr, &randMode));
      DecodeBlock1(state.Counters, blockSize);
      if ((randMode ?
          DecodeBlock2Rand(state.Counters + 256, blockSize, origPtr, m_OutStream) :
          DecodeBlock2(state.Counters + 256, blockSize, origPtr, m_OutStream)) != crc)
        return S_FALSE;
    }
  }
  return S_OK;
}

HRESULT CDecoder::CodeReal(ISequentialInStream *inStream,
    ISequentialOutStream *outStream, const UInt64 * /* inSize */, const UInt64 * /* outSize */,
    ICompressProgressInfo *progress)
{
  if (!m_InStream.Create(kBufferSize))
    return E_OUTOFMEMORY;
  if (!m_OutStream.Create(kBufferSize))
    return E_OUTOFMEMORY;

  m_InStream.SetStream(inStream);
  m_InStream.Init();

  m_OutStream.SetStream(outStream);
  m_OutStream.Init();

  CDecoderFlusher flusher(this);

  bool isBZ;
  RINOK(DecodeFile(isBZ, progress));
  return isBZ ? S_OK: S_FALSE;
}

STDMETHODIMP CDecoder::Code(ISequentialInStream *inStream,
    ISequentialOutStream *outStream, const UInt64 *inSize, const UInt64 *outSize,
    ICompressProgressInfo *progress)
{
  try { return CodeReal(inStream, outStream, inSize, outSize, progress); }
  catch(const CInBufferException &e)  { return e.ErrorCode; }
  catch(const COutBufferException &e) { return e.ErrorCode; }
  catch(...) { return E_FAIL; }
}

STDMETHODIMP CDecoder::GetInStreamProcessedSize(UInt64 *value)
{
  if (value == NULL)
    return E_INVALIDARG;
  *value = m_InStream.GetProcessedSize();
  return S_OK;
}

#ifdef COMPRESS_BZIP2_MT

static THREAD_FUNC_DECL MFThread(void *p) { ((CState *)p)->ThreadFunc(); return 0; }

HRESULT CState::Create()
{
  RINOK_THREAD(StreamWasFinishedEvent.CreateIfNotCreated());
  RINOK_THREAD(WaitingWasStartedEvent.CreateIfNotCreated());
  RINOK_THREAD(CanWriteEvent.CreateIfNotCreated());
  RINOK_THREAD(Thread.Create(MFThread, this));
  return S_OK;
}

void CState::FinishStream()
{
  Decoder->StreamWasFinished1 = true;
  StreamWasFinishedEvent.Set();
  Decoder->CS.Leave();
  Decoder->CanStartWaitingEvent.Lock();
  WaitingWasStartedEvent.Set();
}

void CState::ThreadFunc()
{
  for (;;)
  {
    Decoder->CanProcessEvent.Lock();
    Decoder->CS.Enter();
    if (Decoder->CloseThreads)
    {
      Decoder->CS.Leave();
      return;
    }
    if (Decoder->StreamWasFinished1)
    {
      FinishStream();
      continue;
    }
    HRESULT res = S_OK;

    UInt32 blockIndex = Decoder->NextBlockIndex;
    UInt32 nextBlockIndex = blockIndex + 1;
    if (nextBlockIndex == Decoder->NumThreads)
      nextBlockIndex = 0;
    Decoder->NextBlockIndex = nextBlockIndex;
    UInt32 crc;
    UInt64 packSize;
    UInt32 blockSize = 0, origPtr = 0;
    bool randMode = false;

    try
    {
      bool wasFinished;
      res = Decoder->ReadSignatures(wasFinished, crc);
      if (res != S_OK)
      {
        Decoder->Result1 = res;
        FinishStream();
        continue;
      }
      if (wasFinished)
      {
        Decoder->Result1 = res;
        FinishStream();
        continue;
      }

      res = ReadBlock(&Decoder->m_InStream, Counters, Decoder->BlockSizeMax,
          Decoder->m_Selectors, Decoder->m_HuffmanDecoders,
          &blockSize, &origPtr, &randMode);
      if (res != S_OK)
      {
        Decoder->Result1 = res;
        FinishStream();
        continue;
      }
      packSize = Decoder->m_InStream.GetProcessedSize();
    }
    catch(const CInBufferException &e) { res = e.ErrorCode;  if (res != S_OK) res = E_FAIL; }
    catch(...) { res = E_FAIL; }
    if (res != S_OK)
    {
      Decoder->Result1 = res;
      FinishStream();
      continue;
    }

    Decoder->CS.Leave();

    DecodeBlock1(Counters, blockSize);

    bool needFinish = true;
    try
    {
      Decoder->m_States[blockIndex].CanWriteEvent.Lock();
      needFinish = Decoder->StreamWasFinished2;
      if (!needFinish)
      {
        if ((randMode ?
          DecodeBlock2Rand(Counters + 256, blockSize, origPtr, Decoder->m_OutStream) :
          DecodeBlock2(Counters + 256, blockSize, origPtr, Decoder->m_OutStream)) == crc)
        {
          if (Decoder->Progress)
          {
            UInt64 unpackSize = Decoder->m_OutStream.GetProcessedSize();
            res = Decoder->Progress->SetRatioInfo(&packSize, &unpackSize);
          }
        }
        else
          res = S_FALSE;
      }
    }
    catch(const COutBufferException &e) { res = e.ErrorCode; if (res != S_OK) res = E_FAIL; }
    catch(...) { res = E_FAIL; }
    if (res != S_OK)
    {
      Decoder->Result2 = res;
      Decoder->StreamWasFinished2 = true;
    }
    Decoder->m_States[nextBlockIndex].CanWriteEvent.Set();
    if (res != S_OK || needFinish)
    {
      StreamWasFinishedEvent.Set();
      Decoder->CanStartWaitingEvent.Lock();
      WaitingWasStartedEvent.Set();
    }
  }
}

STDMETHODIMP CDecoder::SetNumberOfThreads(UInt32 numThreads)
{
  NumThreads = numThreads;
  if (NumThreads < 1)
    NumThreads = 1;
  if (NumThreads > kNumThreadsMax)
    NumThreads = kNumThreadsMax;
  return S_OK;
}
#endif

}}