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public/tier1/lzss.h

@@ -0,0 +1,71 @@
+//========= Copyright <20> 1996-2007, 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
+
+#if defined( PLAT_LITTLE_ENDIAN )
+#define LZSS_ID				(('S'<<24)|('S'<<16)|('Z'<<8)|('L'))
+#else
+#define LZSS_ID				(('L'<<24)|('Z'<<16)|('S'<<8)|('S'))
+#endif
+
+// 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( unsigned char *pInput, int inputlen, unsigned int *pOutputSize );
+	unsigned char*	CompressNoAlloc( unsigned char *pInput, int inputlen, unsigned char *pOutput, unsigned int *pOutputSize );
+	unsigned int	Uncompress( unsigned char *pInput, unsigned char *pOutput );
+	//unsigned int	Uncompress( unsigned char *pInput, CUtlBuffer &buf );
+	unsigned int	SafeUncompress( unsigned char *pInput, unsigned char *pOutput, unsigned int unBufSize );
+	bool			IsCompressed( unsigned char *pInput );
+	unsigned int	GetActualSize( 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
+	{
+		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( 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
+