--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/symport/e32/include/e32huffman.h	Thu Jun 25 15:59:54 2009 +0100
@@ -0,0 +1,131 @@
+// Copyright (c) 1998-2009 Nokia Corporation and/or its subsidiary(-ies).
+// All rights reserved.
+// This component and the accompanying materials are made available
+// under the terms of the License "Symbian Foundation License v1.0"
+// which accompanies this distribution, and is available
+// at the URL "http://www.symbianfoundation.org/legal/sfl-v10.html".
+//
+// Initial Contributors:
+// Nokia Corporation - initial contribution.
+//
+// Contributors:
+//
+// Description:
+// e32\include\e32huffman.h
+// 
+//
+
+#include <e32std.h>
+
+/** @file
+	@internalTechnology
+*/
+
+/** Bit output stream.
+	Good for writing bit streams for packed, compressed or huffman data algorithms.
+
+	This class must be derived from and OverflowL() reimplemented if the bitstream data
+	cannot be generated into a single memory buffer.
+*/
+class TBitOutput
+	{
+public:
+	IMPORT_C TBitOutput();
+	IMPORT_C TBitOutput(TUint8* aBuf,TInt aSize);
+	inline void Set(TUint8* aBuf,TInt aSize);
+	inline const TUint8* Ptr() const;
+	inline TInt BufferedBits() const;
+//
+	IMPORT_C void WriteL(TUint aValue, TInt aLength);
+	IMPORT_C void HuffmanL(TUint aHuffCode);
+	IMPORT_C void PadL(TUint aPadding);
+private:
+	void DoWriteL(TUint aBits, TInt aSize);
+	virtual void OverflowL();
+private:
+	TUint iCode;		// code in production
+	TInt iBits;
+	TUint8* iPtr;
+	TUint8* iEnd;
+	};
+
+/** Set the memory buffer to use for output
+
+	Data will be written to this buffer until it is full, at which point OverflowL() will
+	be called. This should handle the data and then can Set() again to reset the buffer
+	for further output.
+	
+	@param aBuf The buffer for output
+	@param aSize The size of the buffer in bytes
+*/
+inline void TBitOutput::Set(TUint8* aBuf,TInt aSize)
+	{iPtr=aBuf;iEnd=aBuf+aSize;}
+	
+/** Get the current write position in the output buffer
+
+	In conjunction with the address of the buffer, which should be known to the
+	caller, this describes the data in the bitstream.
+*/
+inline const TUint8* TBitOutput::Ptr() const
+	{return iPtr;}
+	
+/** Get the number of bits that are buffered
+
+	This reports the number of bits that have not yet been written into the
+	output buffer. It will always lie in the range 0..7. Use PadL() to
+	pad the data out to the next byte and write it to the buffer.
+*/
+inline TInt TBitOutput::BufferedBits() const
+	{return iBits+8;}
+
+
+/** Bit input stream. Good for reading bit streams for packed, compressed or huffman
+	data algorithms.
+*/
+class TBitInput
+	{
+public:
+	IMPORT_C TBitInput();
+	IMPORT_C TBitInput(const TUint8* aPtr, TInt aLength, TInt aOffset=0);
+	IMPORT_C void Set(const TUint8* aPtr, TInt aLength, TInt aOffset=0);
+//
+	IMPORT_C TUint ReadL();
+	IMPORT_C TUint ReadL(TInt aSize);
+	IMPORT_C TUint HuffmanL(const TUint32* aTree);
+private:
+	virtual void UnderflowL();
+private:
+	TInt iCount;
+	TUint iBits;
+	TInt iRemain;
+	const TUint32* iPtr;
+	};
+
+/** Huffman code toolkit.
+
+	This class builds a huffman encoding from a frequency table and builds
+	a decoding tree from a code-lengths table
+
+	The encoding generated is based on the rule that given two symbols s1 and s2, with 
+	code length l1 and l2, and huffman codes h1 and h2:
+
+		if l1<l2 then h1<h2 when compared lexicographically
+		if l1==l2 and s1<s2 then h1<h2 ditto
+
+	This allows the encoding to be stored compactly as a table of code lengths
+*/
+class Huffman
+	{
+public:
+	enum {KMaxCodeLength=27};
+	enum {KMetaCodes=KMaxCodeLength+1};
+	enum {KMaxCodes=0x8000};
+public:
+	IMPORT_C static void HuffmanL(const TUint32 aFrequency[],TInt aNumCodes,TUint32 aHuffman[]);
+	IMPORT_C static void Encoding(const TUint32 aHuffman[],TInt aNumCodes,TUint32 aEncodeTable[]);
+	IMPORT_C static void Decoding(const TUint32 aHuffman[],TInt aNumCodes,TUint32 aDecodeTree[],TInt aSymbolBase=0);
+	IMPORT_C static TBool IsValid(const TUint32 aHuffman[],TInt aNumCodes);
+//
+	IMPORT_C static void ExternalizeL(TBitOutput& aOutput,const TUint32 aHuffman[],TInt aNumCodes);
+	IMPORT_C static void InternalizeL(TBitInput& aInput,TUint32 aHuffman[],TInt aNumCodes);
+	};