lz77.h

以前为研究加解密码算法,曾分析了LZ77算法,但觉得所研究的例子压缩文件大小存在限制,所以就着手改进了其算法,使其支持大文件压缩和解压.

// Lz77.h: interface for the CLz77 class.
//
//////////////////////////////////////////////////////////////////////

#if !defined(AFX_LZ77_H__2C25F8DE_69F2_466F_8442_15DFB7166CAC__INCLUDED_)
#define AFX_LZ77_H__2C25F8DE_69F2_466F_8442_15DFB7166CAC__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

#include <windows.h>
#include <conio.h>
#include <stdio.h>
#include <assert.h>

class CLz77  
{
public:
	CLz77();
	CLz77(int offsetCodeLen, int maxWndSize, int offsetMaskCode);
	virtual ~CLz77();
	void CLz77::Compress(PUCHAR pDataBuffer, ULONG ulDataLength, PUCHAR pOutputBuffer, PULONG pulNumberOfBits);
	void CLz77::Decompress(PUCHAR pDataBuffer, ULONG ulNumberOfBits, PUCHAR pOutputBuffer, PULONG pulNumberOfBytes);
private:
	void CLz77::Write1ToBitStream(PUCHAR pBuffer, ULONG ulBitOffset);
	void CLz77::Write0ToBitStream(PUCHAR pBuffer, ULONG ulBitOffset);
	ULONG CLz77::ReadBitFromBitStream(PUCHAR pBuffer, ULONG ulBitOffset);
	ULONG CLz77::WriteGolombCode(ULONG x, PUCHAR pBuffer, ULONG ulBitOffset);
	ULONG CLz77::ReadGolombCode(PULONG pulCodingLength, PUCHAR pBuffer, ULONG ulBitOffset);
	ULONG CLz77::CompareStrings(PUCHAR string1, PUCHAR string2, ULONG length);
	void CLz77::FindLongestSubstring(PUCHAR pSourceString, PUCHAR  pString, ULONG ulSourceStringLength, PULONG pulSubstringOffset, PULONG pulSubstringLength);
	void CLz77::WriteBits(PUCHAR pDataBuffer, ULONG ulOffsetToWrite, ULONG ulBits, ULONG ulBitLength);
	void CLz77::ReadBits(PUCHAR pDataBuffer, ULONG ulOffsetToRead, PULONG pulBits);
private:
	ULONG m;
	int offsetCodeLen;
	int maxWndSize;
	int offsetMaskCode;
};

void WINAPI Lz77Compress(PUCHAR pDataBuffer, ULONG ulDataLength, PUCHAR pOutputBuffer, PULONG pulNumberOfBits);
void WINAPI Lz77Decompress(PUCHAR pDataBuffer, ULONG ulNumberOfBits, PUCHAR pOutputBuffer, PULONG pulNumberOfBytes);

#endif // !defined(AFX_LZ77_H__2C25F8DE_69F2_466F_8442_15DFB7166CAC__INCLUDED_)