sl@0: // Copyright (c) 2001-2009 Nokia Corporation and/or its subsidiary(-ies).
sl@0: // All rights reserved.
sl@0: // This component and the accompanying materials are made available
sl@0: // under the terms of "Eclipse Public License v1.0"
sl@0: // which accompanies this distribution, and is available
sl@0: // at the URL "http://www.eclipse.org/legal/epl-v10.html".
sl@0: //
sl@0: // Initial Contributors:
sl@0: // Nokia Corporation - initial contribution.
sl@0: //
sl@0: // Contributors:
sl@0: //
sl@0: // Description:
sl@0: //
sl@0: 
sl@0: #include <e32std.h>
sl@0: #include <baflpan.h>
sl@0: #include "BADICTIONARYCOMPRESSION.H"
sl@0: 
sl@0: RDictionaryCompressionBitStream::RDictionaryCompressionBitStream() :
sl@0: 	iNumberOfBitsUsedForDictionaryTokens(0),
sl@0: 	iOffsetToFirstBit(-1),
sl@0: 	iOffsetToCurrentBit(-1),
sl@0: 	iOffsetOnePastLastBit(-1),
sl@0: 	iOwnsBitBuffer(EFalse),
sl@0: 	iBuffer(NULL),
sl@0: 	iAssertObj()
sl@0: 	{
sl@0: 	}
sl@0: 
sl@0: void RDictionaryCompressionBitStream::OpenL(
sl@0: 				TInt aNumberOfBitsUsedForDictionaryTokens,
sl@0: 				TInt aOffsetToFirstBit,
sl@0: 				TInt aOffsetOnePastLastBit,
sl@0: 				TBool aTransferringOwnershipOfBuffer,
sl@0: 				TUint8* aBuffer,
sl@0: 				const TBaAssert& aAssertObj)
sl@0: 	{
sl@0: 	iNumberOfBitsUsedForDictionaryTokens = aNumberOfBitsUsedForDictionaryTokens;
sl@0: 	iOffsetToFirstBit = aOffsetToFirstBit;
sl@0: 	iOffsetToCurrentBit = aOffsetToFirstBit;
sl@0: 	iOffsetOnePastLastBit = aOffsetOnePastLastBit;
sl@0: 	iOwnsBitBuffer = aTransferringOwnershipOfBuffer;
sl@0: 	iBuffer = aBuffer;
sl@0: 	iAssertObj = aAssertObj;
sl@0: 
sl@0: 	iAssertObj.AssertDebL(aBuffer!=NULL,EBafPanicNullPointer);
sl@0: 	iAssertObj.AssertDebL(aOffsetToFirstBit>=0,EBafPanicNegativeOffsetToFirstBit1);
sl@0: 	iAssertObj.AssertDebL(aOffsetToFirstBit<=aOffsetOnePastLastBit,EBafPanicNegativeLengthOfBitBuffer);
sl@0: 	}
sl@0: 
sl@0: void RDictionaryCompressionBitStream::Close()
sl@0: 	{
sl@0: 	if (iOwnsBitBuffer)
sl@0: 		{
sl@0: 		iOwnsBitBuffer=EFalse;
sl@0: 		delete [] iBuffer;
sl@0: 		}
sl@0: 	iBuffer=NULL;
sl@0: 	}
sl@0: 
sl@0: TBool RDictionaryCompressionBitStream::EndOfStreamL() const
sl@0: 	{
sl@0: 	__ASSERT_DEBUG(iBuffer!=NULL,Panic(EBafPanicNotConstructed1));
sl@0: 	iAssertObj.AssertDebL(iOffsetToFirstBit>=0,EBafPanicNegativeOffsetToFirstBit2);
sl@0: 	iAssertObj.AssertDebL(iOffsetToCurrentBit>=iOffsetToFirstBit,EBafPanicBadCurrentBitPosition1);
sl@0: 	iAssertObj.AssertDebL(iOffsetToCurrentBit<=iOffsetOnePastLastBit,EBafPanicBadCurrentBitPosition2);
sl@0: 	return iOffsetToCurrentBit>=iOffsetOnePastLastBit;
sl@0: 	}
sl@0: 
sl@0: TInt RDictionaryCompressionBitStream::IndexOfDictionaryEntryL()
sl@0: 	{
sl@0: 	// increments the current bit-position if it returns a value >=0; returns KErrNotFound if the next thing in the stream is plain data rather than the index of a dictionary entry
sl@0: 	__ASSERT_DEBUG(iBuffer!=NULL,Panic(EBafPanicNotConstructed2));
sl@0: 	iAssertObj.AssertDebL(!EndOfStreamL(),EBafPanicEndOfStream1);
sl@0: 	if (!CurrentBitIsOn())
sl@0: 		{
sl@0: 		++iOffsetToCurrentBit;
sl@0: 		return ReadIntegerL(iNumberOfBitsUsedForDictionaryTokens);
sl@0: 		}
sl@0: 	return KErrNotFound;
sl@0: 	}
sl@0: 
sl@0: void RDictionaryCompressionBitStream::ReadL(TDes8& aBufferToAppendTo,TBool aCalypsoFileFormat)
sl@0: 	{
sl@0: 	// can only be called if IndexOfDictionaryEntry returned a negative value
sl@0: 	__ASSERT_DEBUG(iBuffer!=NULL,Panic(EBafPanicNotConstructed3));
sl@0: 	iAssertObj.AssertDebL(!EndOfStreamL(),EBafPanicEndOfStream2);
sl@0: 	TInt numberOfConsecutivePrefixBits=0;
sl@0: 	TInt i;
sl@0: 	for (i=0; i<4; ++i)
sl@0: 		{
sl@0: 		const TBool currentBitIsOn=CurrentBitIsOn();
sl@0: 		++iOffsetToCurrentBit; // increment this regardless whether the current bit is on
sl@0: 		if (!currentBitIsOn)
sl@0: 			{
sl@0: 			break;
sl@0: 			}
sl@0: 		++numberOfConsecutivePrefixBits;
sl@0: 		}
sl@0: 	iAssertObj.AssertDebL(numberOfConsecutivePrefixBits>0,EBafPanicBadNumberOfConsecutivePrefixBits1);
sl@0: 	iAssertObj.AssertDebL(numberOfConsecutivePrefixBits<=4,EBafPanicBadNumberOfConsecutivePrefixBits2);
sl@0: 	TInt numberOfBytesToRead;
sl@0: 	if (numberOfConsecutivePrefixBits==3)
sl@0: 		{
sl@0: 		numberOfBytesToRead=3+ReadIntegerL(3);
sl@0: 		}
sl@0: 	else if (numberOfConsecutivePrefixBits==4)
sl@0: 		{
sl@0: 		numberOfBytesToRead=ReadIntegerL(8);
sl@0: 		if (!aCalypsoFileFormat)
sl@0: 			{
sl@0: 			numberOfBytesToRead+=3+(1<<3);
sl@0: 			}
sl@0: 		}
sl@0: 	else
sl@0: 		{
sl@0: 		numberOfBytesToRead=numberOfConsecutivePrefixBits;
sl@0: 		}
sl@0: 	const TInt numberOfBitsOffByteBoundary=iOffsetToCurrentBit%8;
sl@0: 	const TUint8* currentByte=iBuffer+(iOffsetToCurrentBit/8);
sl@0: 	iAssertObj.AssertDebL(
sl@0: 		(numberOfBytesToRead + aBufferToAppendTo.Length()) <= aBufferToAppendTo.MaxLength(),
sl@0: 		EBafPanicBufLength);
sl@0: 	for (i=0; i<numberOfBytesToRead; ++i, ++currentByte)
sl@0: 		{
sl@0: 		TUint byte=*currentByte;
sl@0: 		iAssertObj.AssertDebL(numberOfBitsOffByteBoundary>=0,EBafPanicBadNumberOfBitsOffByteBoundary1);
sl@0: 		if (numberOfBitsOffByteBoundary>0)
sl@0: 			{
sl@0: 			byte>>=numberOfBitsOffByteBoundary;
sl@0: 			byte|=(*(currentByte+1)<<(8-numberOfBitsOffByteBoundary));
sl@0: 			byte&=0xff;
sl@0: 			}
sl@0: 		aBufferToAppendTo.Append(byte);
sl@0: 		}
sl@0: 	iOffsetToCurrentBit+=numberOfBytesToRead*8;
sl@0: 	iAssertObj.AssertDebL(numberOfBitsOffByteBoundary==iOffsetToCurrentBit%8,EBafPanicBadNumberOfBitsOffByteBoundary2);
sl@0: 	}
sl@0: 
sl@0: TBool RDictionaryCompressionBitStream::CurrentBitIsOn() const
sl@0: 	{
sl@0: 	// does not increment the current bit-position
sl@0: 	__ASSERT_DEBUG(iBuffer!=NULL,Panic(EBafPanicNotConstructed4));
sl@0: 	return iBuffer[iOffsetToCurrentBit/8]&(1<<(iOffsetToCurrentBit%8));
sl@0: 	}
sl@0: 
sl@0: TUint RDictionaryCompressionBitStream::ReadIntegerL(TInt aNumberOfBits)
sl@0: 	{
sl@0: 	// increments the current bit-position
sl@0: 	__ASSERT_DEBUG(iBuffer!=NULL,Panic(EBafPanicNotConstructed5));
sl@0: 	TInt integer=0;
sl@0: 	TInt numberOfBitsLeftToRead=aNumberOfBits;
sl@0: 	FOREVER
sl@0: 		{
sl@0: 		const TInt offsetToFirstBitToReadInCurrentByte=iOffsetToCurrentBit%8;
sl@0: 		const TInt offsetOnePastLastBitToReadInCurrentByte=Min(8,offsetToFirstBitToReadInCurrentByte+numberOfBitsLeftToRead);
sl@0: 		const TInt numberOfBitsReadFromCurrentByte=offsetOnePastLastBitToReadInCurrentByte-offsetToFirstBitToReadInCurrentByte;
sl@0: 		iAssertObj.AssertDebL(numberOfBitsReadFromCurrentByte>0,EBafPanicBadNumberOfBitsReadFromCurrentByte);
sl@0: 		const TUint bitsReadFromCurrentByte=((iBuffer[iOffsetToCurrentBit/8]>>offsetToFirstBitToReadInCurrentByte)&((1<<numberOfBitsReadFromCurrentByte)-1));
sl@0: 		integer|=(bitsReadFromCurrentByte<<(aNumberOfBits-numberOfBitsLeftToRead));
sl@0: 		iOffsetToCurrentBit+=numberOfBitsReadFromCurrentByte;
sl@0: 		numberOfBitsLeftToRead-=numberOfBitsReadFromCurrentByte;
sl@0: 		iAssertObj.AssertDebL(numberOfBitsLeftToRead>=0,EBafPanicBadNumberOfBitsLeftToRead);
sl@0: 		if (numberOfBitsLeftToRead<=0)
sl@0: 			{
sl@0: 			break;
sl@0: 			}
sl@0: 		}
sl@0: 	return integer;
sl@0: 	}
sl@0: