diff -r 000000000000 -r e4d67989cc36 lowlevellibsandfws/apputils/src/BADICTIONARYCOMPRESSION.CPP --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/lowlevellibsandfws/apputils/src/BADICTIONARYCOMPRESSION.CPP Tue Feb 02 02:01:42 2010 +0200 @@ -0,0 +1,172 @@ +// Copyright (c) 2001-2009 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: +// + +#include +#include +#include "BADICTIONARYCOMPRESSION.H" + +RDictionaryCompressionBitStream::RDictionaryCompressionBitStream() : + iNumberOfBitsUsedForDictionaryTokens(0), + iOffsetToFirstBit(-1), + iOffsetToCurrentBit(-1), + iOffsetOnePastLastBit(-1), + iOwnsBitBuffer(EFalse), + iBuffer(NULL), + iAssertObj() + { + } + +void RDictionaryCompressionBitStream::OpenL( + TInt aNumberOfBitsUsedForDictionaryTokens, + TInt aOffsetToFirstBit, + TInt aOffsetOnePastLastBit, + TBool aTransferringOwnershipOfBuffer, + TUint8* aBuffer, + const TBaAssert& aAssertObj) + { + iNumberOfBitsUsedForDictionaryTokens = aNumberOfBitsUsedForDictionaryTokens; + iOffsetToFirstBit = aOffsetToFirstBit; + iOffsetToCurrentBit = aOffsetToFirstBit; + iOffsetOnePastLastBit = aOffsetOnePastLastBit; + iOwnsBitBuffer = aTransferringOwnershipOfBuffer; + iBuffer = aBuffer; + iAssertObj = aAssertObj; + + iAssertObj.AssertDebL(aBuffer!=NULL,EBafPanicNullPointer); + iAssertObj.AssertDebL(aOffsetToFirstBit>=0,EBafPanicNegativeOffsetToFirstBit1); + iAssertObj.AssertDebL(aOffsetToFirstBit<=aOffsetOnePastLastBit,EBafPanicNegativeLengthOfBitBuffer); + } + +void RDictionaryCompressionBitStream::Close() + { + if (iOwnsBitBuffer) + { + iOwnsBitBuffer=EFalse; + delete [] iBuffer; + } + iBuffer=NULL; + } + +TBool RDictionaryCompressionBitStream::EndOfStreamL() const + { + __ASSERT_DEBUG(iBuffer!=NULL,Panic(EBafPanicNotConstructed1)); + iAssertObj.AssertDebL(iOffsetToFirstBit>=0,EBafPanicNegativeOffsetToFirstBit2); + iAssertObj.AssertDebL(iOffsetToCurrentBit>=iOffsetToFirstBit,EBafPanicBadCurrentBitPosition1); + iAssertObj.AssertDebL(iOffsetToCurrentBit<=iOffsetOnePastLastBit,EBafPanicBadCurrentBitPosition2); + return iOffsetToCurrentBit>=iOffsetOnePastLastBit; + } + +TInt RDictionaryCompressionBitStream::IndexOfDictionaryEntryL() + { + // 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 + __ASSERT_DEBUG(iBuffer!=NULL,Panic(EBafPanicNotConstructed2)); + iAssertObj.AssertDebL(!EndOfStreamL(),EBafPanicEndOfStream1); + if (!CurrentBitIsOn()) + { + ++iOffsetToCurrentBit; + return ReadIntegerL(iNumberOfBitsUsedForDictionaryTokens); + } + return KErrNotFound; + } + +void RDictionaryCompressionBitStream::ReadL(TDes8& aBufferToAppendTo,TBool aCalypsoFileFormat) + { + // can only be called if IndexOfDictionaryEntry returned a negative value + __ASSERT_DEBUG(iBuffer!=NULL,Panic(EBafPanicNotConstructed3)); + iAssertObj.AssertDebL(!EndOfStreamL(),EBafPanicEndOfStream2); + TInt numberOfConsecutivePrefixBits=0; + TInt i; + for (i=0; i<4; ++i) + { + const TBool currentBitIsOn=CurrentBitIsOn(); + ++iOffsetToCurrentBit; // increment this regardless whether the current bit is on + if (!currentBitIsOn) + { + break; + } + ++numberOfConsecutivePrefixBits; + } + iAssertObj.AssertDebL(numberOfConsecutivePrefixBits>0,EBafPanicBadNumberOfConsecutivePrefixBits1); + iAssertObj.AssertDebL(numberOfConsecutivePrefixBits<=4,EBafPanicBadNumberOfConsecutivePrefixBits2); + TInt numberOfBytesToRead; + if (numberOfConsecutivePrefixBits==3) + { + numberOfBytesToRead=3+ReadIntegerL(3); + } + else if (numberOfConsecutivePrefixBits==4) + { + numberOfBytesToRead=ReadIntegerL(8); + if (!aCalypsoFileFormat) + { + numberOfBytesToRead+=3+(1<<3); + } + } + else + { + numberOfBytesToRead=numberOfConsecutivePrefixBits; + } + const TInt numberOfBitsOffByteBoundary=iOffsetToCurrentBit%8; + const TUint8* currentByte=iBuffer+(iOffsetToCurrentBit/8); + iAssertObj.AssertDebL( + (numberOfBytesToRead + aBufferToAppendTo.Length()) <= aBufferToAppendTo.MaxLength(), + EBafPanicBufLength); + for (i=0; i=0,EBafPanicBadNumberOfBitsOffByteBoundary1); + if (numberOfBitsOffByteBoundary>0) + { + byte>>=numberOfBitsOffByteBoundary; + byte|=(*(currentByte+1)<<(8-numberOfBitsOffByteBoundary)); + byte&=0xff; + } + aBufferToAppendTo.Append(byte); + } + iOffsetToCurrentBit+=numberOfBytesToRead*8; + iAssertObj.AssertDebL(numberOfBitsOffByteBoundary==iOffsetToCurrentBit%8,EBafPanicBadNumberOfBitsOffByteBoundary2); + } + +TBool RDictionaryCompressionBitStream::CurrentBitIsOn() const + { + // does not increment the current bit-position + __ASSERT_DEBUG(iBuffer!=NULL,Panic(EBafPanicNotConstructed4)); + return iBuffer[iOffsetToCurrentBit/8]&(1<<(iOffsetToCurrentBit%8)); + } + +TUint RDictionaryCompressionBitStream::ReadIntegerL(TInt aNumberOfBits) + { + // increments the current bit-position + __ASSERT_DEBUG(iBuffer!=NULL,Panic(EBafPanicNotConstructed5)); + TInt integer=0; + TInt numberOfBitsLeftToRead=aNumberOfBits; + FOREVER + { + const TInt offsetToFirstBitToReadInCurrentByte=iOffsetToCurrentBit%8; + const TInt offsetOnePastLastBitToReadInCurrentByte=Min(8,offsetToFirstBitToReadInCurrentByte+numberOfBitsLeftToRead); + const TInt numberOfBitsReadFromCurrentByte=offsetOnePastLastBitToReadInCurrentByte-offsetToFirstBitToReadInCurrentByte; + iAssertObj.AssertDebL(numberOfBitsReadFromCurrentByte>0,EBafPanicBadNumberOfBitsReadFromCurrentByte); + const TUint bitsReadFromCurrentByte=((iBuffer[iOffsetToCurrentBit/8]>>offsetToFirstBitToReadInCurrentByte)&((1<=0,EBafPanicBadNumberOfBitsLeftToRead); + if (numberOfBitsLeftToRead<=0) + { + break; + } + } + return integer; + } +