// Copyright (c) 2005-2009 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:

// e32\kernel\byte_pair.cpp

// 

//

#include <e32cia.h>

#include "u32std.h"

TInt BytePairDecompress(TUint8* dst, TInt dstSize, TUint8* src, TInt srcSize, TUint8*& srcNext)

	{

	TUint8* dstStart = dst;

	TUint8* dstEnd = dst+dstSize;

	TUint8* srcEnd = src+srcSize;

	TUint32 LUT[0x100/2];

	TUint8* LUT0 = (TUint8*)LUT;

	TUint8* LUT1 = LUT0+0x100;

	TUint8 stack[0x100];

	TUint8* stackStart = stack+sizeof(stack);

	TUint8* sp = stackStart;

	TUint32 marker = ~0u;

	TInt numTokens;

	TUint32 p1;

	TUint32 p2;

	TUint32* l = (TUint32*)LUT;

	TUint32 b = 0x03020100;

	TUint32 step = 0x04040404;

	do

		{

		*l++ = b;

		b += step;

		}

	while(b>step);

	if(src>=srcEnd)

		goto error;

	numTokens = *src++;

	if(numTokens)

		{

		if(src>=srcEnd)

			goto error;

		marker = *src++;

		LUT0[marker] = (TUint8)~marker;

		if(numTokens<32)

			{

			TUint8* tokenEnd = src+3*numTokens;

			if(tokenEnd>srcEnd)

				goto error;

			do

				{

				TInt b = *src++;

				TInt p1 = *src++;

				TInt p2 = *src++;

				LUT0[b] = (TUint8)p1;

				LUT1[b] = (TUint8)p2;

				}

			while(src<tokenEnd);

			}

		else

			{

			TUint8* bitMask = src;

			src += 32;

			if(src>srcEnd)

				goto error;

			TInt b=0;

			do

				{

				TUint8 mask = bitMask[b>>3];

				if(mask&(1<<(b&7)))

					{

					if(src>=srcEnd)

						goto error;

					TInt p1 = *src++;

					if(src>=srcEnd)

						goto error;

					TInt p2 = *src++;

					LUT0[b] = (TUint8)p1;

					LUT1[b] = (TUint8)p2;		

					--numTokens;

					}

				++b;

				}

			while(b<0x100);

			if(numTokens)

				goto error;

			}

		}

	if(src>=srcEnd)

		goto error;

	b = *src++;

	if(dst>=dstEnd)

		goto error;

	p1 = LUT0[b];

	if(p1!=b)

		goto not_single;

next:

	if(src>=srcEnd)

		goto done_s;

	b = *src++;

	*dst++ = (TUint8)p1;

	if(dst>=dstEnd)

		goto done_d;

	p1 = LUT0[b];

	if(p1==b)

		goto next;

not_single:

	if(b==marker)

		goto do_marker;

do_pair:

	p2 = LUT1[b];

	b = p1;

	p1 = LUT0[b];

	if(sp<=stack)

		goto error;

	*--sp = (TUint8)p2;

recurse:

	if(b!=p1)

		goto do_pair;

	if(sp==stackStart)

		goto next;

	b = *sp++;

	*dst++ = (TUint8)p1;

	if(dst>=dstEnd)

		goto error;

	p1 = LUT0[b];

	goto recurse;

do_marker:

	if(src>=srcEnd)

		goto error;

	p1 = *src++;

	goto next;

error:

	srcNext = 0;

	return KErrCorrupt;

done_s:

	*dst++ = (TUint8)p1;

	srcNext = src;

	return dst-dstStart;

done_d:

	--src;

	srcNext = src;

	return dst-dstStart;

	}