diff -r 59148e28d9f6 -r 626366955efb toolsandutils/e32tools/elf2e32/source/huffman.cpp
--- a/toolsandutils/e32tools/elf2e32/source/huffman.cpp	Fri Jun 25 18:24:47 2010 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,917 +0,0 @@
-// Copyright (c) 2004-2009 Nokia Corporation and/or its subsidiary(-ies).
-// All rights reserved.
-// This component and the accompanying materials are made available
-// under the terms of "Eclipse Public License v1.0"
-// which accompanies this distribution, and is available
-// at the URL "http://www.eclipse.org/legal/epl-v10.html".
-//
-// Initial Contributors:
-// Nokia Corporation - initial contribution.
-//
-// Contributors:
-//
-// Description:
-// Implementation of the Huffman technique for the elf2e32 tool
-// @internalComponent
-// @released
-// 
-//
-
-#ifdef _MSC_VER
-	#pragma warning(disable: 4710) // function not inlined
-#endif
-
-#include <cassert>
-#include "huffman.h"
-#include "errorhandler.h"
-#include "farray.h"
-
-/**
-Function for overflow
-@internalComponent
-@released
-*/
-void TBitOutput::OverflowL()
-{
-}
-
-/**
-Construct a bit stream output object
-
-Following construction the bit stream is ready for writing bits, but will first call
-OverflowL() as the output buffer is 'full'. A derived class can detect this state as
-Ptr() will return null.
-*/
-TBitOutput::TBitOutput():iCode(0),iBits(-8),iPtr(0),iEnd(0)
-{
-}
-
-/**
-Construct a bit stream output object over a buffer
-
-Data will be written to the 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 "TUint8* aBuf" The buffer for output
-@param "TInt aSize" The size of the buffer in bytes
-*/
-TBitOutput::TBitOutput(TUint8* aBuf,TInt aSize):iCode(0),iBits(-8),iPtr(aBuf),iEnd(aBuf+aSize)
-{
-}
-
-/**
-Write a huffman code
-
-This expects a huffman code value as generated by Huffman::Encoding()
-
-@param "TUint aHuffCode" The huffman code write to the stream
-@leave "OverflowL()" If the output buffer is full, OverflowL() is called
-*/
-void TBitOutput::HuffmanL(TUint aHuffCode)
-{
-	DoWriteL(aHuffCode<<(32-Huffman::KMaxCodeLength),aHuffCode>>Huffman::KMaxCodeLength);
-}
-
-/**
-Write an arbitrary integer value
-
-Write an unsigned integer using the number of bits specified. Only the low order bits of the
-value are written to the output, most significant bit first.
-
-@param "TUint aValue" The value to write to the stream
-@param "TUint aLength" The number of bits to output
-@leave "OverflowL()" If the output buffer is full, OverflowL() is called
-*/
-void TBitOutput::WriteL(TUint aValue,TInt aLength)
-{
-	if (aLength)
-		DoWriteL(aValue<<=32-aLength,aLength);
-}
-
-/**
-Pad the bitstream to the next byte boundary
-
-Terminate the bitstream by padding the last byte with the requested value.
-Following this operation the bitstream can continue to be used, the data will start at the
-next byte.
-
-@param "TUint aPadding" The bit value to pad the final byte with
-@leave "OverflowL()" If the output buffer is full, OverflowL() is called
-*/
-void TBitOutput::PadL(TUint aPadding)
-{
-	if (iBits>-8)
-		WriteL(aPadding?0xffffffffu:0,-iBits);
-}
-
-/**
-Write the higher order bits to the stream
-@internalComponent
-@released
-*/
-void TBitOutput::DoWriteL(TUint aBits,TInt aSize)
-{
-	if (aSize>25)
-	{
-		// cannot process >25 bits in a single pass so do the top 8 bits first
-		assert(aSize<=32);
-		DoWriteL(aBits&0xff000000u,8);
-		aBits<<=8;
-		aSize-=8;
-	}
-
-	TInt bits=iBits;
-	TUint code=iCode|(aBits>>(bits+8));
-	bits+=aSize;
-	if (bits>=0)
-	{
-		TUint8* p=iPtr;
-		do
-		{
-			if (p==iEnd)
-			{
-				// run out of buffer space so invoke the overflow handler
-				iPtr=p;
-				OverflowL();
-				p=iPtr;
-				assert(p!=iEnd);
-			}
-			*p++=TUint8(code>>24);
-			code<<=8;
-			bits-=8;
-		} while (bits>=0);
-		iPtr=p;
-	}
-	iCode=code;
-	iBits=bits;
-}
-
-/**
-Constructor for class TFileOutput
-@internalComponent
-@released
-*/
-TFileOutput::TFileOutput(std::ofstream & os):iOutStream(os)
-{
-	Set(iBuf,KBufSize);
-}
-
-/**
-Function to empty the buffer and reset the pointers
-@internalComponent
-@released
-*/
-void TFileOutput::OverflowL()
-{
-	FlushL();
-	Set(iBuf,KBufSize);
-}
-
-/**
-Function to write out the contents of the buffer
-@internalComponent
-@released
-*/
-void TFileOutput::FlushL()
-{
-	TInt len=Ptr()-iBuf;
-	if (len)
-	{
-		iOutStream.write(reinterpret_cast<char *>(iBuf), len); // write extended header
-		iDataCount += len;
-	}
-}
-
-/**
-Recursive function to calculate the code lengths from the node tree
-@internalComponent
-@released
-*/
-void HuffmanLengthsL(TUint32* aLengths,const TNode* aNodes,TInt aNode,TInt aLen)
-{
-	if (++aLen>Huffman::KMaxCodeLength)
-		throw E32ImageCompressionError(HUFFMANBUFFEROVERFLOWERROR);
-
-	const TNode& node=aNodes[aNode];
-	TUint x=node.iLeft;
-	if (x&KLeaf)
-		aLengths[x&~KLeaf]=aLen;
-	else
-		HuffmanLengthsL(aLengths,aNodes,x,aLen);
-	x=node.iRight;
-	if (x&KLeaf)
-		aLengths[x&~KLeaf]=aLen;
-	else
-		HuffmanLengthsL(aLengths,aNodes,x,aLen);
-}
-
-/**
-Function to Insert the {aCount,aValue} pair into the already sorted array of nodes
-@internalComponent
-@released
-*/
-void InsertInOrder(TNode* aNodes, TInt aSize, TUint aCount, TInt aVal)
-{
-	// Uses Insertion sort following a binary search...
-	TInt l=0, r=aSize;
-	while (l < r)
-	{
-		TInt m = (l+r) >> 1;
-		if (aNodes[m].iCount<aCount)
-			r=m;
-		else
-			l=m+1;
-	}
-	memmove(aNodes+l+1,aNodes+l,sizeof(TNode)*(aSize-l));
-	aNodes[l].iCount=aCount;
-	aNodes[l].iRight=TUint16(aVal);
-}
-
-/**
-Generate a Huffman code.
-
-This generates a Huffman code for a given set of code frequencies. The output is a table of
-code lengths which can be used to build canonincal encoding tables or decoding trees for use
-with the TBitInput and TBitOutput classes.
-
-Entries in the table with a frequency of zero will have a zero code length and thus no
-associated huffman encoding. If each such symbol should have a maximum length encoding, they
-must be given at least a frequency of 1.
-
-For an alphabet of n symbols, this algorithm has a transient memory overhead of 8n, and a
-time complexity of O(n*log(n)).
-
-@param "const TUint32 aFrequency[]" The table of code frequencies
-@param "TInt aNumCodes" The number of codes in the table
-@param "TUint32 aHuffman[]" The table for the output code-length table. This must be the same
-size as the frequency table, and can safely be the same table
-
-@leave "KErrNoMemory" If memory used for code generation cannot be allocated
-@panic "USER ???" If the number of codes exceeds Huffman::KMaxCodes
-*/
-void Huffman::HuffmanL(const TUint32 aFrequency[],TInt aNumCodes,TUint32 aHuffman[])
-{
-	if(TUint(aNumCodes)>TUint(KMaxCodes))
-		throw E32ImageCompressionError(HUFFMANTOOMANYCODESERROR);
-
-	// Sort the values into decreasing order of frequency
-	TNode* nodes = new TNode[aNumCodes];
-
-	TInt lCount=0;
-
-	for (TInt ii=0;ii<aNumCodes;++ii)
-	{
-		TInt c=aFrequency[ii];
-		if (c!=0)
-			InsertInOrder(nodes,lCount++,c,ii|KLeaf);
-	}
-
-	// default code length is zero
-	memset(aHuffman,0,aNumCodes*sizeof(TUint32));
-
-	if (lCount==0)
-	{
-		// no codes with frequency>0. No code has a length
-	}
-	else if (lCount==1)
-	{
-		// special case for a single value (always encode as "0")
-		aHuffman[nodes[0].iRight&~KLeaf]=1;
-	}
-	else
-	{
-		// Huffman algorithm: pair off least frequent nodes and reorder
-		do
-		{
-			--lCount;
-			TUint c=nodes[lCount].iCount + nodes[lCount-1].iCount;
-			nodes[lCount].iLeft=nodes[lCount-1].iRight;
-			// re-order the leaves now to reflect new combined frequency 'c'
-			InsertInOrder(nodes,lCount-1,c,lCount);
-		} while (lCount>1);
-		// generate code lengths in aHuffman[]
-		HuffmanLengthsL(aHuffman,nodes,1,0);
-	}
-
-	delete [] nodes;
-
-	if(!IsValid(aHuffman,aNumCodes))
-		throw E32ImageCompressionError(HUFFMANINVALIDCODINGERROR);
-}
-
-/**
-Validate a Huffman encoding
-
-This verifies that a Huffman coding described by the code lengths is valid. In particular,
-it ensures that no code exceeds the maximum length and that it is possible to generate a
-canonical coding for the specified lengths.
-	
-@param "const TUint32 aHuffman[]" The table of code lengths as generated by Huffman::HuffmanL()
-@param "TInt aNumCodes" The number of codes in the table
-
-@return True if the code is valid, otherwise false
-*/
-TBool Huffman::IsValid(const TUint32 aHuffman[],TInt aNumCodes)
-{
-	// The code is valid if one of the following holds:
-	// (a) the code exactly fills the 'code space'
-	// (b) there is only a single symbol with code length 1
-	// (c) there are no encoded symbols
-	//
-	TUint remain=1<<KMaxCodeLength;
-	TInt totlen=0;
-	for (const TUint32* p=aHuffman+aNumCodes; p>aHuffman;)
-	{
-		TInt len=*--p;
-		if (len>0)
-		{
-			totlen+=len;
-			if (len>KMaxCodeLength)
-				return 0;
-
-			TUint c=1<<(KMaxCodeLength-len);
-			if (c>remain)
-				return 0;
-
-			remain-=c;
-		}
-	}
-
-	return remain==0 || totlen<=1;
-}
-
-/**
-Create a canonical Huffman encoding table
-
-This generates the huffman codes used by TBitOutput::HuffmanL() to write huffman encoded data.
-The input is table of code lengths, as generated by Huffman::HuffmanL() and must represent a
-valid huffman code.
-	
-@param "const TUint32 aHuffman[]" The table of code lengths as generated by Huffman::HuffmanL()
-@param "TInt aNumCodes" The number of codes in the table
-@param "TUint32 aEncodeTable[]" The table for the output huffman codes. This must be the same
-size as the code-length table, and can safely be the same table.
-
-@panic "USER ???" If the provided code is not a valid Huffman coding
-	
-@see IsValid()
-@see HuffmanL()
-*/
-void Huffman::Encoding(const TUint32 aHuffman[],TInt aNumCodes,TUint32 aEncodeTable[])
-{
-	if (!IsValid(aHuffman,aNumCodes)) 
-		throw E32ImageCompressionError(HUFFMANINVALIDCODINGERROR);
-
-	TFixedArray<TInt,KMaxCodeLength> lenCount;
-	lenCount.Reset();
-
-	TInt ii;
-	for (ii=0;ii<aNumCodes;++ii)
-	{
-		TInt len=aHuffman[ii]-1;
-		if (len>=0)
-			++lenCount[len];
-	}
-
-	TFixedArray<TUint,KMaxCodeLength> nextCode;
-	TUint code=0;
-	for (ii=0;ii<KMaxCodeLength;++ii)
-	{
-		code<<=1;
-		nextCode[ii]=code;
-		code+=lenCount[ii];
-	}
-
-	for (ii=0;ii<aNumCodes;++ii)
-	{
-		TInt len=aHuffman[ii];
-		if (len==0)
-			aEncodeTable[ii]=0;
-		else
-		{
-			aEncodeTable[ii] = (nextCode[len-1]<<(KMaxCodeLength-len))|(len<<KMaxCodeLength);
-			++nextCode[len-1];
-		}
-	}
-}
-
-/**
-The encoding table for the externalised code
-@internalComponent
-@released
-*/
-const TUint32 HuffmanEncoding[]=
-{
-	0x10000000,
-	0x1c000000,
-	0x12000000,
-	0x1d000000,
-	0x26000000,
-	0x26800000,
-	0x2f000000,
-	0x37400000,
-	0x37600000,
-	0x37800000,
-	0x3fa00000,
-	0x3fb00000,
-	0x3fc00000,
-	0x3fd00000,
-	0x47e00000,
-	0x47e80000,
-	0x47f00000,
-	0x4ff80000,
-	0x57fc0000,
-	0x5ffe0000,
-	0x67ff0000,
-	0x77ff8000,
-	0x7fffa000,
-	0x7fffb000,
-	0x7fffc000,
-	0x7fffd000,
-	0x7fffe000,
-	0x87fff000,
-	0x87fff800
-};
-
-/**
-Function to encode 0a as '0' and 0b as '1', return number of symbols created
-@internalComponent
-@released
-*/
-void EncodeRunLengthL(TBitOutput& aOutput, TInt aLength)
-{
-	if (aLength>0)
-	{
-		EncodeRunLengthL(aOutput,(aLength-1)>>1);
-		aOutput.HuffmanL(HuffmanEncoding[1-(aLength&1)]);
-	}
-}
-
-/**
-Store a canonical huffman encoding in compact form
-
-As the encoding is canonical, only the code lengths of each code needs to be saved.
-
-Due to the nature of code length tables, these can usually be stored very compactly by
-encoding the encoding itself, hence the use of the bit output stream.
-	
-@param "TBitOutput& aOutput" The output stream for the encoding
-@param "const TUint32 aHuffman[]" The table of code lengths as generated by Huffman::HuffmanL()
-@param "TInt aNumCodes" The number of huffman codes in the table
-
-@leave "TBitOutput::HuffmanL()"
-*/
-void Huffman::ExternalizeL(TBitOutput& aOutput,const TUint32 aHuffman[],TInt aNumCodes)
-{
-	// We assume that the code length table is generated by the huffman generator,
-	// in which case the maxmimum code length is 27 bits.
-	//
-	// We apply three transformations to the data:
-	// 1. the data goes through a move-to-front coder
-	// 2. apply a rle-0 coder which replace runs of '0' with streams of '0a' and '0b'
-	// 3. encode the result using a predefined (average) huffman coding
-	//
-	// This can be done in a single pass over the data, avoiding the need for additional
-	// memory.
-	//
-	// initialise the list for the MTF coder
-	TFixedArray<TUint8,Huffman::KMetaCodes> list;
-	TInt i;
-	for (i=0;i<list.Count();++i)
-		list[i]=TUint8(i);
-	TInt last=0;
-
-	TInt rl=0;
-	const TUint32* p32=aHuffman;
-	const TUint32* e32=p32+aNumCodes;
-	while (p32<e32)
-	{
-		TInt c=*p32++;
-		if (c==last)
-			++rl;	// repeat of last symbol
-		else
-		{
-			// encode run-length
-			EncodeRunLengthL(aOutput,rl);
-			rl=0;
-			// find code in MTF list
-			TInt j;
-			for (j=1;list[j]!=c;++j)
-				;
-			// store this code
-			aOutput.HuffmanL(HuffmanEncoding[j+1]);
-			// adjust list for MTF algorithm
-			while (--j>0)
-				list[j+1]=list[j];
-			list[1]=TUint8(last);
-			last=c;
-		}
-	}
-	// encod any remaining run-length
-	EncodeRunLengthL(aOutput,rl);
-}
-
-const TInt KHuffTerminate=0x0001;
-const TUint32 KBranch1=sizeof(TUint32)<<16;
-
-/**
-Function to write the subtree below aPtr and return the head
-*/
-TUint32* HuffmanSubTree(TUint32* aPtr,const TUint32* aValue,TUint32** aLevel)
-{
-	TUint32* l=*aLevel++;
-	if (l>aValue)
-	{
-		TUint32* sub0=HuffmanSubTree(aPtr,aValue,aLevel);		// 0-tree first
-		aPtr=HuffmanSubTree(sub0,aValue-(aPtr-sub0)-1,aLevel);	// 1-tree
-		TInt branch0=(TUint8*)sub0-(TUint8*)(aPtr-1);
-		*--aPtr=KBranch1|branch0;
-	}
-	else if (l==aValue)
-	{
-		TUint term0=*aValue--;						// 0-term
-		aPtr=HuffmanSubTree(aPtr,aValue,aLevel);	// 1-tree
-		*--aPtr=KBranch1|(term0>>16);
-	}
-	else	// l<iNext
-	{
-		TUint term0=*aValue--;						// 0-term
-		TUint term1=*aValue--;
-		*--aPtr=(term1>>16<<16)|(term0>>16);
-	}
-	return aPtr;
-}
-
-/**
-Create a canonical Huffman decoding tree
-
-This generates the huffman decoding tree used by TBitInput::HuffmanL() to read huffman
-encoded data. The input is table of code lengths, as generated by Huffman::HuffmanL()
-and must represent a valid huffman code.
-	
-@param "const TUint32 aHuffman[]" The table of code lengths as generated by Huffman::HuffmanL()
-@param "TInt aNumCodes" The number of codes in the table
-@param "TUint32 aDecodeTree[]" The space for the decoding tree. This must be the same
-size as the code-length table, and can safely be the same memory
-@param "TInt aSymbolBase" the base value for the output 'symbols' from the decoding tree, by default
-this is zero.
-
-@panic "USER ???" If the provided code is not a valid Huffman coding
-
-@see IsValid()
-@see HuffmanL()
-*/
-void Huffman::Decoding(const TUint32 aHuffman[],TInt aNumCodes,TUint32 aDecodeTree[],TInt aSymbolBase)
-{
-	if(!IsValid(aHuffman,aNumCodes))
-		throw E32ImageCompressionError(HUFFMANINVALIDCODINGERROR);
-
-	TFixedArray<TInt,KMaxCodeLength> counts;
-	counts.Reset();
-	TInt codes=0;
-	TInt ii;
-	for (ii=0;ii<aNumCodes;++ii)
-	{
-		TInt len=aHuffman[ii];
-		aDecodeTree[ii]=len;
-		if (--len>=0)
-		{
-			++counts[len];
-			++codes;
-		}
-	}
-
-	TFixedArray<TUint32*,KMaxCodeLength> level;
-	TUint32* lit=aDecodeTree+codes;
-	for (ii=0;ii<KMaxCodeLength;++ii)
-	{
-		level[ii]=lit;
-		lit-=counts[ii];
-	}
-	
-	aSymbolBase=(aSymbolBase<<17)+(KHuffTerminate<<16);
-	for (ii=0;ii<aNumCodes;++ii)
-	{
-		TUint len=TUint8(aDecodeTree[ii]);
-		if (len)
-			*--level[len-1]|=(ii<<17)+aSymbolBase;
-	}
-	
-	if (codes==1)	// codes==1 special case: tree isn't complete
-	{
-		TUint term=aDecodeTree[0]>>16;
-		aDecodeTree[0]=term|(term<<16); // 0- and 1-terminate at root
-	}
-	else if (codes>1)
-		HuffmanSubTree(aDecodeTree+codes-1,aDecodeTree+codes-1,&level[0]);
-}
-
-/**
-The decoding tree for the externalised code
-*/
-const TUint32 HuffmanDecoding[]=
-{
-	0x0004006c,
-	0x00040064,
-	0x0004005c,
-	0x00040050,
-	0x00040044,
-	0x0004003c,
-	0x00040034,
-	0x00040021,
-	0x00040023,
-	0x00040025,
-	0x00040027,
-	0x00040029,
-	0x00040014,
-	0x0004000c,
-	0x00040035,
-	0x00390037,
-	0x00330031,
-	0x0004002b,
-	0x002f002d,
-	0x001f001d,
-	0x001b0019,
-	0x00040013,
-	0x00170015,
-	0x0004000d,
-	0x0011000f,
-	0x000b0009,
-	0x00070003,
-	0x00050001
-};
-
-
-/**
-Restore a canonical huffman encoding from a bit stream
-
-The encoding must have been stored using Huffman::ExternalizeL(). The resulting
-code-length table can be used to create an encoding table using Huffman::Encoding()
-or a decoding tree using Huffman::Decoding().
-	
-@param "TBitInput& aInput" The input stream with the encoding
-@param "TUint32 aHuffman[]" The internalized code-length table is placed here
-@param "TInt aNumCodes" The number of huffman codes in the table
-
-@leave "TBitInput::HuffmanL()"
-
-@see ExternalizeL()
-See ExternalizeL for a description of the format
-*/
-void Huffman::InternalizeL(TBitInput& aInput,TUint32 aHuffman[],TInt aNumCodes)
-{
-	// initialise move-to-front list
-	TFixedArray<TUint8,Huffman::KMetaCodes> list;
-	for (TInt i=0;i<list.Count();++i)
-		list[i]=TUint8(i);
-
-	TInt last=0;
-	// extract codes, reverse rle-0 and mtf encoding in one pass
-	TUint32* p=aHuffman;
-	const TUint32* end=aHuffman+aNumCodes;
-	TInt rl=0;
-	while (p+rl<end)
-	{
-		TInt c=aInput.HuffmanL(HuffmanDecoding);
-		if (c<2)
-		{
-			// one of the zero codes used by RLE-0
-			// update he run-length
-			rl+=rl+c+1;
-		}
-		else
-		{
-			while (rl>0)
-			{
-				if (p>end)
-				{
-					throw E32ImageCompressionError(HUFFMANINVALIDCODINGERROR);
-				}
-				*p++=last;
-				--rl;
-			}
-			--c;
-			list[0]=TUint8(last);
-			last=list[c];
-			
-			memmove((void * const)&list[1],(const void * const)&list[0],(size_t)c);
-			if (p>end)
-			{
-				throw E32ImageCompressionError(HUFFMANINVALIDCODINGERROR);
-			}
-			*p++=last;
-		}
-	}
-	while (rl>0)
-	{
-		if (p>end)
-		{
-			throw E32ImageCompressionError(HUFFMANINVALIDCODINGERROR);
-		}
-		*p++=last;
-		--rl;
-	}
-}
-
-/**
-bit-stream input class
-Reverse the byte-order of a 32 bit value
-This generates optimal ARM code (4 instructions)
-*/
-inline TUint reverse(TUint aVal)
-{
-	TUint v=(aVal<<16)|(aVal>>16);
-	v^=aVal;
-	v&=0xff00ffff;
-	aVal=(aVal>>8)|(aVal<<24);
-	return aVal^(v>>8);
-}
-
-/**
-Construct a bit stream input object
-
-Following construction the bit stream is ready for reading bits, but will
-immediately call UnderflowL() as the input buffer is empty.
-*/
-TBitInput::TBitInput():iCount(0),iRemain(0)
-{
-
-}
-
-/**
-Construct a bit stream input object over a buffer
-
-Following construction the bit stream is ready for reading bits from the specified buffer.
-
-@param "const TUint8* aPtr" The address of the buffer containing the bit stream
-@param "TInt aLength" The length of the bitstream in bits
-@param "TInt aOffset" The bit offset from the start of the buffer to the bit stream (defaults to zero)
-*/
-TBitInput::TBitInput(const TUint8* aPtr, TInt aLength, TInt aOffset)
-{
-	Set(aPtr,aLength,aOffset);
-}
-
-/**
-Set the memory buffer to use for input.
-
-Bits will be read from this buffer until it is empty, at which point UnderflowL() will be called.
-	
-@param "const TUint8* aPtr" The address of the buffer containing the bit stream
-@param "TInt aLength" The length of the bitstream in bits
-@param "TInt aOffset" The bit offset from the start of the buffer to the bit stream (defaults to zero)
-*/
-void TBitInput::Set(const TUint8* aPtr, TInt aLength, TInt aOffset)
-{
-	TUint p=(TUint)aPtr;
-	p+=aOffset>>3;			// nearest byte to the specified bit offset
-	aOffset&=7;				// bit offset within the byte
-	const TUint32* ptr=(const TUint32*)(p&~3);	// word containing this byte
-	aOffset+=(p&3)<<3;		// bit offset within the word
-	if (aLength==0)
-		iCount=0;
-	else
-	{
-		// read the first few bits of the stream
-		iBits=reverse(*ptr++)<<aOffset;
-		aOffset=32-aOffset;
-		aLength-=aOffset;
-		if (aLength<0)
-			aOffset+=aLength;
-		iCount=aOffset;
-	}
-	iRemain=aLength;
-	iPtr=ptr;
-}
-
-#ifndef __HUFFMAN_MACHINE_CODED__
-
-/**
-Read a single bit from the input
-
-Return the next bit in the input stream. This will call UnderflowL() if there are no more
-bits available.
-
-@return The next bit in the stream
-
-@leave "UnderflowL()" It the bit stream is exhausted more UnderflowL is called to get more
-data
-*/
-TUint TBitInput::ReadL()
-{
-	TInt c=iCount;
-	TUint bits=iBits;
-	if (--c<0)
-		return ReadL(1);
-	iCount=c;
-	iBits=bits<<1;
-	return bits>>31;
-}
-
-/**
-Read a multi-bit value from the input
-
-Return the next few bits as an unsigned integer. The last bit read is the least significant
-bit of the returned value, and the value is zero extended to return a 32-bit result.
-
-A read of zero bits will always reaturn zero.
-	
-This will call UnderflowL() if there are not enough bits available.
-
-@param "TInt aSize" The number of bits to read
-
-@return The bits read from the stream
-
-@leave "UnderflowL()" It the bit stream is exhausted more UnderflowL is called to get more
-data
-*/
-TUint TBitInput::ReadL(TInt aSize)
-{
-	if (!aSize)
-		return 0;
-	TUint val=0;
-	TUint bits=iBits;
-	iCount-=aSize;
-	while (iCount<0)
-	{
-		// need more bits
-#ifdef __CPU_X86
-		// X86 does not allow shift-by-32
-		if (iCount+aSize!=0)
-			val|=bits>>(32-(iCount+aSize))<<(-iCount);	// scrub low order bits
-#else
-		val|=bits>>(32-(iCount+aSize))<<(-iCount);	// scrub low order bits
-#endif
-		aSize=-iCount;	// bits still required
-		if (iRemain>0)
-		{
-			bits=reverse(*iPtr++);
-			iCount+=32;
-			iRemain-=32;
-			if (iRemain<0)
-				iCount+=iRemain;
-		}
-		else
-		{
-			UnderflowL();
-			bits=iBits;
-			iCount-=aSize;
-		}
-	}
-
-#ifdef __CPU_X86
-	// X86 does not allow shift-by-32
-	iBits=aSize==32?0:bits<<aSize;
-#else
-	iBits=bits<<aSize;
-#endif
-
-	return val|(bits>>(32-aSize));
-}
-
-/**
-Read and decode a Huffman Code
-
-Interpret the next bits in the input as a Huffman code in the specified decoding.
-The decoding tree should be the output from Huffman::Decoding().
-
-@param "const TUint32* aTree" The huffman decoding tree
-
-@return The symbol that was decoded
-	
-@leave "UnderflowL()" It the bit stream is exhausted more UnderflowL is called to get more
-data
-*/
-TUint TBitInput::HuffmanL(const TUint32* aTree)
-{
-	TUint huff=0;
-	do
-	{
-		aTree=(const TUint32*)(((TUint8*)aTree)+(huff>>16));
-		huff=*aTree;
-		if (ReadL()==0)
-			huff<<=16;
-	} while ((huff&0x10000u)==0);
-	
-	return huff>>17;
-}
-
-#endif
-
-/**
-Handle an empty input buffer
-
-This virtual function is called when the input buffer is empty and more bits are required.
-It should reset the input buffer with more data using Set().
-
-A derived class can replace this to read the data from a file (for example) before reseting
-the input buffer.
-
-@leave "KErrUnderflow" The default implementation leaves
-*/
-void TBitInput::UnderflowL()
-{
-	throw E32ImageCompressionError(HUFFMANBUFFEROVERFLOWERROR);
-}
-