diff -r c55016431358 -r 0a7b44b10206 symport/e32/euser/us_decode.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/symport/e32/euser/us_decode.cpp	Thu Jun 25 15:59:54 2009 +0100
@@ -0,0 +1,399 @@
+// 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\euser\us_decode.cpp
+// 
+//
+
+#include <e32huffman.h>
+#include <e32base.h>
+#include <e32panic.h>
+#include <cpudefs.h>
+
+const TInt KHuffTerminate=0x0001;
+const TUint32 KBranch1=sizeof(TUint32)<<16;
+_LIT(KCat,"Huffman");
+
+TUint32* HuffmanSubTree(TUint32* aPtr,const TUint32* aValue,TUint32** aLevel)
+//
+// write the subtree below aPtr and return the head
+//
+	{
+	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 aHuffman The table of code lengths as generated by Huffman::HuffmanL()
+	@param aNumCodes The number of codes in the table
+	@param 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  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()
+*/
+EXPORT_C void Huffman::Decoding(const TUint32 aHuffman[],TInt aNumCodes,TUint32 aDecodeTree[],TInt aSymbolBase)
+	{
+	__ASSERT_ALWAYS(IsValid(aHuffman,aNumCodes),User::Panic(KCat,EHuffmanInvalidCoding));
+//
+	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: incomplete tree
+		{
+		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 aInput The input stream with the encoding
+	@param aHuffman The internalized code-length table is placed here
+	@param aNumCodes The number of huffman codes in the table
+
+	@leave TBitInput::HuffmanL()
+
+	@see ExternalizeL()
+*/
+EXPORT_C void Huffman::InternalizeL(TBitInput& aInput,TUint32 aHuffman[],TInt aNumCodes)
+// See ExternalizeL for a description of the format
+	{
+	// 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;
+	TUint rl=0;
+	while (p+rl<end)
+		{
+		TInt c=aInput.HuffmanL(HuffmanDecoding);
+		// c is now 0..28
+		if (c<2)
+			{
+			// one of the zero codes used by RLE-0
+			// update he run-length
+			rl+=rl+c+1;
+			}
+		else
+			{
+			if(rl >= TUint(end-p))
+				User::Leave(KErrCorrupt);
+			while (rl>0)
+				{
+				*p++=last;
+				--rl;
+				}
+			--c; // c is now 1..27
+			list[0]=TUint8(last);
+			last=list[c];
+			Mem::Copy(&list[1],&list[0],c);
+			*p++=last;
+			}
+		}
+
+	while (p<end)
+		*p++=last;
+
+	}
+
+// bit-stream input class
+
+inline TUint reverse(TUint aVal)
+//
+// Reverse the byte-order of a 32 bit value
+// This generates optimal ARM code (4 instructions)
+//
+	{
+	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.
+*/
+EXPORT_C 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 aPtr The address of the buffer containing the bit stream
+	@param aLength The length of the bitstream in bits
+	@param aOffset The bit offset from the start of the buffer to the bit stream (defaults to zero)
+*/
+EXPORT_C 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 aPtr The address of the buffer containing the bit stream
+	@param aLength The length of the bitstream in bits
+	@param aOffset The bit offset from the start of the buffer to the bit stream (defaults to zero)
+*/
+EXPORT_C 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
+*/
+EXPORT_C 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 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
+*/
+EXPORT_C 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 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
+*/
+EXPORT_C TUint TBitInput::HuffmanL(const TUint32* aTree)
+	{
+	TUint huff=0;
+	do
+		{
+		aTree=PtrAdd(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()
+	{
+	User::Leave(KErrUnderflow);
+	}