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//========= Copyright Valve Corporation, All rights reserved. ============//
//
// LZSS Codec. Designed for fast cheap gametime encoding/decoding. Compression results
// are not aggresive as other alogrithms, but gets 2:1 on most arbitrary uncompressed data.
//
//=====================================================================================//
#ifndef _LZSS_H
#define _LZSS_H
#pragma once
#define LZSS_ID uint32( BigLong( ('L'<<24)|('Z'<<16)|('S'<<8)|('S') ) )
#define SNAPPY_ID uint32( BigLong( ('S'<<24)|('N'<<16)|('A'<<8)|('P') ) )
// bind the buffer for correct identification
struct lzss_header_t
{
unsigned int id;
unsigned int actualSize; // always little endian
};
class CUtlBuffer;
#define DEFAULT_LZSS_WINDOW_SIZE 4096
class CLZSS
{
public:
unsigned char* Compress( const unsigned char *pInput, int inputlen, unsigned int *pOutputSize );
unsigned char* CompressNoAlloc( const unsigned char *pInput, int inputlen, unsigned char *pOutput, unsigned int *pOutputSize );
unsigned int Uncompress( const unsigned char *pInput, unsigned char *pOutput );
//unsigned int Uncompress( unsigned char *pInput, CUtlBuffer &buf );
unsigned int SafeUncompress( const unsigned char *pInput, unsigned char *pOutput, unsigned int unBufSize );
static bool IsCompressed( const unsigned char *pInput );
static unsigned int GetActualSize( const unsigned char *pInput );
// windowsize must be a power of two.
FORCEINLINE CLZSS( int nWindowSize = DEFAULT_LZSS_WINDOW_SIZE );
private:
// expected to be sixteen bytes
struct lzss_node_t
{
const unsigned char *pData;
lzss_node_t *pPrev;
lzss_node_t *pNext;
char empty[4];
};
struct lzss_list_t
{
lzss_node_t *pStart;
lzss_node_t *pEnd;
};
void BuildHash( const unsigned char *pData );
lzss_list_t *m_pHashTable;
lzss_node_t *m_pHashTarget;
int m_nWindowSize;
};
FORCEINLINE CLZSS::CLZSS( int nWindowSize )
{
m_nWindowSize = nWindowSize;
}
#endif
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