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7zip/Compress/LZ/LZInWindow.h

@@ -0,0 +1,89 @@
+// LZInWindow.h
+
+// #pragma once
+
+#ifndef __LZ_IN_WINDOW_H
+#define __LZ_IN_WINDOW_H
+
+#include "../../IStream.h"
+
+class CLZInWindow
+{
+  BYTE  *_bufferBase; // pointer to buffer with data
+  ISequentialInStream *_stream;
+  UINT32 _posLimit;  // offset (from _buffer) of first byte when new block reading must be done
+  bool _streamEndWasReached; // if (true) then _streamPos shows real end of stream
+  const BYTE *_pointerToLastSafePosition;
+protected:
+  BYTE  *_buffer;   // Pointer to virtual Buffer begin
+  UINT32 _blockSize;  // Size of Allocated memory block
+  UINT32 _pos;             // offset (from _buffer) of curent byte
+  UINT32 _keepSizeBefore;  // how many BYTEs must be kept in buffer before _pos
+  UINT32 _keepSizeAfter;   // how many BYTEs must be kept buffer after _pos
+  UINT32 _keepSizeReserv;  // how many BYTEs must be kept as reserv
+  UINT32 _streamPos;   // offset (from _buffer) of first not read byte from Stream
+
+  virtual void BeforeMoveBlock() {};
+  virtual void AfterMoveBlock() {};
+  void MoveBlock();
+  virtual HRESULT ReadBlock();
+  void Free();
+public:
+  CLZInWindow(): _bufferBase(0) {}
+  ~CLZInWindow();
+  void Create(UINT32 keepSizeBefore, UINT32 keepSizeAfter, 
+      UINT32 keepSizeReserv = (1<<17));
+
+  HRESULT Init(ISequentialInStream *stream);
+  // void ReleaseStream();
+
+  BYTE *GetBuffer() const { return _buffer; }
+
+  const BYTE *GetPointerToCurrentPos() const { return _buffer + _pos; }
+
+  HRESULT MovePos()
+  {
+    _pos++;
+    if (_pos > _posLimit)
+    {
+      const BYTE *pointerToPostion = _buffer + _pos;
+      if(pointerToPostion > _pointerToLastSafePosition)
+        MoveBlock();
+      return ReadBlock();
+    }
+    else
+      return S_OK;
+  }
+  // BYTE GetCurrentByte()const;
+  BYTE GetIndexByte(UINT32 index)const
+    {  return _buffer[_pos + index]; }
+
+  // UINT32 GetCurPos()const { return _pos;};
+  // BYTE *GetBufferBeg()const { return _buffer;};
+
+  // index + limit have not to exceed _keepSizeAfter;
+  UINT32 GetMatchLen(UINT32 index, UINT32 back, UINT32 limit) const
+  {  
+    if(_streamEndWasReached)
+      if ((_pos + index) + limit > _streamPos)
+        limit = _streamPos - (_pos + index);
+    back++;
+    BYTE *pby = _buffer + _pos + index;
+    UINT32 i;
+    for(i = 0; i < limit && pby[i] == pby[i - back]; i++);
+    return i;
+  }
+
+  UINT32 GetNumAvailableBytes() const { return _streamPos - _pos; }
+
+  void ReduceOffsets(UINT32 subValue)
+  {
+    _buffer += subValue;
+    _posLimit -= subValue;
+    _pos -= subValue;
+    _streamPos -= subValue;
+  }
+
+};
+
+#endif