123

CryNetwork/StaticCharCompressor.h

@@ -0,0 +1,98 @@
+// for ASCII strings up to 255 character
+// character with priority 0 remain available
+
+// References:
+//    http://www.howtodothings.com/showarticle.asp?article=313
+//    http://dogma.net/markn/articles/bwt/bwt.htm   (this might perform worse for small strings)
+
+#include <vector>						// STL vector<>
+
+//
+class CStaticCharCompressor
+{
+public:
+	//! constructor
+	CStaticCharCompressor();
+
+	//! \param indwPriority table of the priorites of the character set
+	void InitFromStatistics( const DWORD indwPriority[256] );
+
+	//! \return stream error
+	bool Write( CStream &outStream, const unsigned char inChar );
+
+	//! \return stream error
+	bool Read( CStream &inStream, unsigned char &outChar );
+
+
+private: // ---------------------------------------------------------
+
+	struct SNode
+	{
+		//! constructor for a leaf
+		SNode( const unsigned char inValue )
+			:m_Value(inValue)
+		{
+			m_dwIndexZero=0xffffffff;m_dwIndexOne=0xffffffff;		// unused
+		}
+
+		//! constructor for a node
+		SNode( const DWORD indwIndexZero, const DWORD indwIndexOne )
+			:m_dwIndexZero(indwIndexZero),m_dwIndexOne(indwIndexOne)
+		{
+			m_Value=0;																					// unused
+		}
+
+		DWORD							m_dwIndexZero;			//!< 0xffffffff or index to the subtree for bit = 0
+		DWORD							m_dwIndexOne;				//!< 0xffffffff or index to the subtree for bit = 1
+
+		unsigned char			m_Value;						//!< is only valid for Leafes
+
+		bool IsLeaf()
+		{
+			return m_dwIndexZero==0xffffffff && m_dwIndexOne==0xffffffff;
+		}
+	};
+	
+	// ------------------------------------------------------------------
+
+	struct SPriIndex
+	{
+		//! constructor
+		SPriIndex( const DWORD indwIndex, const DWORD indwPriority ) 
+			:m_dwIndex(indwIndex),m_dwPriority(indwPriority)
+		{
+		}
+
+		DWORD								m_dwIndex;					//!<
+		DWORD								m_dwPriority;				//!<
+
+		//! used for sorting (from low to hight values)
+		bool operator<( const SPriIndex &inRhs ) const
+		{
+			return m_dwPriority<inRhs.m_dwPriority;
+		}
+	};
+
+	// ------------------------------------------------------------------
+
+	struct SBitToChar
+	{
+		//! constructor
+		SBitToChar()
+		{
+			m_Bitfield=0;m_BitCount=0;
+		}
+
+		unsigned short			m_Bitfield;					//!<
+		unsigned short			m_BitCount;					//!<
+	};
+
+	// ------------------------------------------------------------------
+
+	DWORD									m_dwRootIndex;			//!< 0 if the instance was not initiated - tree is build out of elements from m_NodeMemory
+	std::vector<SNode>		m_Nodes;						//!<
+	SBitToChar						m_CharToBit[256];		//!<
+
+	bool GetCharFromBits_slow( const unsigned char inVal, const DWORD indwIndex, SBitToChar &outDat );
+};
+