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// LzInWindow.cs↩
↩
using System;↩
↩
namespace SevenZip.Compression.LZ↩
{↩
public class InWindow↩
{↩
public Byte[] _bufferBase = null; // pointer to buffer with data↩
System.IO.Stream _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↩
↩
UInt32 _pointerToLastSafePosition;↩
↩
public UInt32 _bufferOffset;↩
↩
public UInt32 _blockSize; // Size of Allocated memory block↩
public 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↩
public UInt32 _streamPos; // offset (from _buffer) of first not read byte from Stream↩
↩
public void MoveBlock()↩
{↩
UInt32 offset = (UInt32)(_bufferOffset) + _pos - _keepSizeBefore;↩
// we need one additional byte, since MovePos moves on 1 byte.↩
if (offset > 0)↩
offset--;↩
↩
UInt32 numBytes = (UInt32)(_bufferOffset) + _streamPos - offset;↩
↩
// check negative offset ????↩
for (UInt32 i = 0; i < numBytes; i++)↩
_bufferBase[i] = _bufferBase[offset + i];↩
_bufferOffset -= offset;↩
}↩
↩
public virtual void ReadBlock()↩
{↩
if (_streamEndWasReached)↩
return;↩
while (true)↩
{↩
int size = (int)((0 - _bufferOffset) + _blockSize - _streamPos);↩
if (size == 0)↩
return;↩
int numReadBytes = _stream.Read(_bufferBase, (int)(_bufferOffset + _streamPos), size);↩
if (numReadBytes == 0)↩
{↩
_posLimit = _streamPos;↩
UInt32 pointerToPostion = _bufferOffset + _posLimit;↩
if (pointerToPostion > _pointerToLastSafePosition)↩
_posLimit = (UInt32)(_pointerToLastSafePosition - _bufferOffset);↩
↩
_streamEndWasReached = true;↩
return;↩
}↩
_streamPos += (UInt32)numReadBytes;↩
if (_streamPos >= _pos + _keepSizeAfter)↩
_posLimit = _streamPos - _keepSizeAfter;↩
}↩
}↩
↩
void Free() { _bufferBase = null; }↩
↩
public void Create(UInt32 keepSizeBefore, UInt32 keepSizeAfter, UInt32 keepSizeReserv)↩
{↩
_keepSizeBefore = keepSizeBefore;↩
_keepSizeAfter = keepSizeAfter;↩
UInt32 blockSize = keepSizeBefore + keepSizeAfter + keepSizeReserv;↩
if (_bufferBase == null || _blockSize != blockSize)↩
{↩
Free();↩
_blockSize = blockSize;↩
_bufferBase = new Byte[_blockSize];↩
}↩
_pointerToLastSafePosition = _blockSize - keepSizeAfter;↩
}↩
↩
public void SetStream(System.IO.Stream stream) { _stream = stream; }↩
public void ReleaseStream() { _stream = null; }↩
↩
public void Init()↩
{↩
_bufferOffset = 0;↩
_pos = 0;↩
_streamPos = 0;↩
_streamEndWasReached = false;↩
ReadBlock();↩
}↩
↩
public void MovePos()↩
{↩
_pos++;↩
if (_pos > _posLimit)↩
{↩
UInt32 pointerToPostion = _bufferOffset + _pos;↩
if (pointerToPostion > _pointerToLastSafePosition)↩
MoveBlock();↩
ReadBlock();↩
}↩
}↩
↩
public Byte GetIndexByte(Int32 index) { return _bufferBase[_bufferOffset + _pos + index]; }↩
↩
// index + limit have not to exceed _keepSizeAfter;↩
public UInt32 GetMatchLen(Int32 index, UInt32 distance, UInt32 limit)↩
{↩
if (_streamEndWasReached)↩
if ((_pos + index) + limit > _streamPos)↩
limit = _streamPos - (UInt32)(_pos + index);↩
distance++;↩
// Byte *pby = _buffer + (size_t)_pos + index;↩
UInt32 pby = _bufferOffset + _pos + (UInt32)index;↩
↩
UInt32 i;↩
for (i = 0; i < limit && _bufferBase[pby + i] == _bufferBase[pby + i - distance]; i++);↩
return i;↩
}↩
↩
public UInt32 GetNumAvailableBytes() { return _streamPos - _pos; }↩
↩
public void ReduceOffsets(Int32 subValue)↩
{↩
_bufferOffset += (UInt32)subValue;↩
_posLimit -= (UInt32)subValue;↩
_pos -= (UInt32)subValue;↩
_streamPos -= (UInt32)subValue;↩
}↩
}↩
}↩