/*

* 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 "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: 

* e32tools\petran\Szip\inflate.cpp

*

*/

#include "deflate.h"

#include "panic.h"

#include "h_utl.h"

// Class RInflater

//

// The inflation algorithm, complete with huffman decoding

inline CInflater::CInflater(TBitInput& aInput)

	:iBits(&aInput),iEncoding(0),iOut(0)

	{}

void CInflater::ConstructL()

	{

	iEncoding=new TEncoding;

	if(iEncoding==NULL)

		Panic(EHuffmanOutOfMemory);

	InitL();

	iLen=0;

	iOut=new TUint8[KDeflateMaxDistance];

	if(iOut==NULL)

		Panic(EHuffmanOutOfMemory);

	iAvail=iLimit=iOut;

	}

CInflater* CInflater::NewLC(TBitInput& aInput)

	{

	CInflater* self=new CInflater(aInput);

	if(self==NULL)

		Panic(EHuffmanOutOfMemory);

	self->ConstructL();

	return self;

	}

CInflater::~CInflater()

	{

	delete iEncoding;

	delete [] iOut;

	}

TInt CInflater::ReadL(TUint8* aBuffer,TInt aLength)

	{

	TInt tfr=0;

	for (;;)

		{

		TInt len=Min(aLength,iLimit-iAvail);

		if (len && aBuffer)

			{

			HMem::Copy(aBuffer,iAvail,len);

			aBuffer+=len;

			}

		aLength-=len;

		iAvail+=len;

		tfr+=len;

		if (aLength==0)

			return tfr;

		len=InflateL();

		if (len==0)

			return tfr;

		iAvail=iOut;

		iLimit=iAvail+len;

		}

	}

TInt CInflater::SkipL(TInt aLength)

	{

	return ReadL(0,aLength);

	}

void CInflater::InitL()

	{

// read the encoding

	Huffman::InternalizeL(*iBits,iEncoding->iLitLen,KDeflationCodes);

// validate the encoding

	if (!Huffman::IsValid(iEncoding->iLitLen,TEncoding::ELitLens) ||

		!Huffman::IsValid(iEncoding->iDistance,TEncoding::EDistances))

		Panic(EHuffmanCorruptFile);

// convert the length tables into huffman decoding trees

	Huffman::Decoding(iEncoding->iLitLen,TEncoding::ELitLens,iEncoding->iLitLen);

	Huffman::Decoding(iEncoding->iDistance,TEncoding::EDistances,iEncoding->iDistance,KDeflateDistCodeBase);

	}

TInt CInflater::InflateL()

//

// consume all data lag in the history buffer, then decode to fill up the output buffer

// return the number of available bytes in the output buffer. This is only ever less than

// the buffer size if the end of stream marker has been read

//

	{

// empty the history buffer into the output

	TUint8* out=iOut;

	TUint8* const end=out+KDeflateMaxDistance;

	const TUint32* tree=iEncoding->iLitLen;

	if (iLen<0)	// EOF

		return 0;

	if (iLen>0)

		goto useHistory;

//

	while (out<end)

		{

		// get a huffman code

		{

		TInt val=iBits->HuffmanL(tree)-TEncoding::ELiterals;

		if (val<0)

			{

			*out++=TUint8(val);

			continue;			// another literal/length combo

			}

		if (val==TEncoding::EEos-TEncoding::ELiterals)

			{	// eos marker. we're done

			iLen=-1;

			break;

			}

		// get the extra bits for the code

		TInt code=val&0xff;

		if (code>=8)

			{	// xtra bits

			TInt xtra=(code>>2)-1;

			code-=xtra<<2;

			code<<=xtra;

			code|=iBits->ReadL(xtra);

			}

		if (val<KDeflateDistCodeBase-TEncoding::ELiterals)

			{	// length code... get the code

			iLen=code+KDeflateMinLength;

			tree=iEncoding->iDistance;

			continue;			// read the huffman code

			}

		// distance code

		iRptr=out-(code+1);

		if (iRptr+KDeflateMaxDistance<end)

			iRptr+=KDeflateMaxDistance;

		}

useHistory:

		TInt tfr=Min(end-out,iLen);

		iLen-=tfr;

		const TUint8* from=iRptr;

		do

			{

			*out++=*from++;

			if (from==end)

				from-=KDeflateMaxDistance;

			} while (--tfr!=0);

		iRptr=from;

		tree=iEncoding->iLitLen;

		};

	return out-iOut;

	}