ppmddecoder.h

7z一个高压缩比的压缩程序源代码,重要的是里面的算法值得学习

// PpmdDecoder.h

#ifndef __COMPRESS_PPMD_DECODER_H
#define __COMPRESS_PPMD_DECODER_H

#include "../../Common/MyCom.h"

#include "../ICoder.h"

#include "../Common/OutBuffer.h"

#include "PpmdDecode.h"
#include "RangeCoder.h"

namespace NCompress {
namespace NPpmd {

class CDecoder :
  public ICompressCoder,
  public ICompressSetDecoderProperties2,
  #ifndef NO_READ_FROM_CODER
  public ICompressSetInStream,
  public ICompressSetOutStreamSize,
  public ISequentialInStream,
  #endif
  public CMyUnknownImp
{
  CRangeDecoder _rangeDecoder;

  COutBuffer _outStream;

  CDecodeInfo _info;

  Byte _order;
  UInt32 _usedMemorySize;

  int _remainLen;
  UInt64 _outSize;
  bool _outSizeDefined;
  UInt64 _processedSize;

  HRESULT CodeSpec(UInt32 num, Byte *memStream);

public:

  #ifndef NO_READ_FROM_CODER
  MY_UNKNOWN_IMP4(
      ICompressSetDecoderProperties2,
      ICompressSetInStream,
      ICompressSetOutStreamSize,
      ISequentialInStream)
  #else
  MY_UNKNOWN_IMP1(
      ICompressSetDecoderProperties2)
  #endif

  void ReleaseStreams()
  {
    ReleaseInStream();
    _outStream.ReleaseStream();
  }

  HRESULT Flush() { return _outStream.Flush(); }

  STDMETHOD(CodeReal)(ISequentialInStream *inStream, ISequentialOutStream *outStream,
      const UInt64 *inSize, const UInt64 *outSize, ICompressProgressInfo *progress);

  STDMETHOD(Code)(ISequentialInStream *inStream, ISequentialOutStream *outStream,
      const UInt64 *inSize, const UInt64 *outSize, ICompressProgressInfo *progress);

  STDMETHOD(SetDecoderProperties2)(const Byte *data, UInt32 size);

  STDMETHOD(SetInStream)(ISequentialInStream *inStream);
  STDMETHOD(ReleaseInStream)();
  STDMETHOD(SetOutStreamSize)(const UInt64 *outSize);

  #ifndef NO_READ_FROM_CODER
  STDMETHOD(Read)(void *data, UInt32 size, UInt32 *processedSize);
  #endif

  CDecoder(): _outSizeDefined(false) {}
};

}}

#endif