1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/os/ossrv/lowlevellibsandfws/apputils/src/BADICTIONARYCOMPRESSION.CPP Fri Jun 15 03:10:57 2012 +0200
1.3 @@ -0,0 +1,172 @@
1.4 +// Copyright (c) 2001-2009 Nokia Corporation and/or its subsidiary(-ies).
1.5 +// All rights reserved.
1.6 +// This component and the accompanying materials are made available
1.7 +// under the terms of "Eclipse Public License v1.0"
1.8 +// which accompanies this distribution, and is available
1.9 +// at the URL "http://www.eclipse.org/legal/epl-v10.html".
1.10 +//
1.11 +// Initial Contributors:
1.12 +// Nokia Corporation - initial contribution.
1.13 +//
1.14 +// Contributors:
1.15 +//
1.16 +// Description:
1.17 +//
1.18 +
1.19 +#include <e32std.h>
1.20 +#include <baflpan.h>
1.21 +#include "BADICTIONARYCOMPRESSION.H"
1.22 +
1.23 +RDictionaryCompressionBitStream::RDictionaryCompressionBitStream() :
1.24 + iNumberOfBitsUsedForDictionaryTokens(0),
1.25 + iOffsetToFirstBit(-1),
1.26 + iOffsetToCurrentBit(-1),
1.27 + iOffsetOnePastLastBit(-1),
1.28 + iOwnsBitBuffer(EFalse),
1.29 + iBuffer(NULL),
1.30 + iAssertObj()
1.31 + {
1.32 + }
1.33 +
1.34 +void RDictionaryCompressionBitStream::OpenL(
1.35 + TInt aNumberOfBitsUsedForDictionaryTokens,
1.36 + TInt aOffsetToFirstBit,
1.37 + TInt aOffsetOnePastLastBit,
1.38 + TBool aTransferringOwnershipOfBuffer,
1.39 + TUint8* aBuffer,
1.40 + const TBaAssert& aAssertObj)
1.41 + {
1.42 + iNumberOfBitsUsedForDictionaryTokens = aNumberOfBitsUsedForDictionaryTokens;
1.43 + iOffsetToFirstBit = aOffsetToFirstBit;
1.44 + iOffsetToCurrentBit = aOffsetToFirstBit;
1.45 + iOffsetOnePastLastBit = aOffsetOnePastLastBit;
1.46 + iOwnsBitBuffer = aTransferringOwnershipOfBuffer;
1.47 + iBuffer = aBuffer;
1.48 + iAssertObj = aAssertObj;
1.49 +
1.50 + iAssertObj.AssertDebL(aBuffer!=NULL,EBafPanicNullPointer);
1.51 + iAssertObj.AssertDebL(aOffsetToFirstBit>=0,EBafPanicNegativeOffsetToFirstBit1);
1.52 + iAssertObj.AssertDebL(aOffsetToFirstBit<=aOffsetOnePastLastBit,EBafPanicNegativeLengthOfBitBuffer);
1.53 + }
1.54 +
1.55 +void RDictionaryCompressionBitStream::Close()
1.56 + {
1.57 + if (iOwnsBitBuffer)
1.58 + {
1.59 + iOwnsBitBuffer=EFalse;
1.60 + delete [] iBuffer;
1.61 + }
1.62 + iBuffer=NULL;
1.63 + }
1.64 +
1.65 +TBool RDictionaryCompressionBitStream::EndOfStreamL() const
1.66 + {
1.67 + __ASSERT_DEBUG(iBuffer!=NULL,Panic(EBafPanicNotConstructed1));
1.68 + iAssertObj.AssertDebL(iOffsetToFirstBit>=0,EBafPanicNegativeOffsetToFirstBit2);
1.69 + iAssertObj.AssertDebL(iOffsetToCurrentBit>=iOffsetToFirstBit,EBafPanicBadCurrentBitPosition1);
1.70 + iAssertObj.AssertDebL(iOffsetToCurrentBit<=iOffsetOnePastLastBit,EBafPanicBadCurrentBitPosition2);
1.71 + return iOffsetToCurrentBit>=iOffsetOnePastLastBit;
1.72 + }
1.73 +
1.74 +TInt RDictionaryCompressionBitStream::IndexOfDictionaryEntryL()
1.75 + {
1.76 + // 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
1.77 + __ASSERT_DEBUG(iBuffer!=NULL,Panic(EBafPanicNotConstructed2));
1.78 + iAssertObj.AssertDebL(!EndOfStreamL(),EBafPanicEndOfStream1);
1.79 + if (!CurrentBitIsOn())
1.80 + {
1.81 + ++iOffsetToCurrentBit;
1.82 + return ReadIntegerL(iNumberOfBitsUsedForDictionaryTokens);
1.83 + }
1.84 + return KErrNotFound;
1.85 + }
1.86 +
1.87 +void RDictionaryCompressionBitStream::ReadL(TDes8& aBufferToAppendTo,TBool aCalypsoFileFormat)
1.88 + {
1.89 + // can only be called if IndexOfDictionaryEntry returned a negative value
1.90 + __ASSERT_DEBUG(iBuffer!=NULL,Panic(EBafPanicNotConstructed3));
1.91 + iAssertObj.AssertDebL(!EndOfStreamL(),EBafPanicEndOfStream2);
1.92 + TInt numberOfConsecutivePrefixBits=0;
1.93 + TInt i;
1.94 + for (i=0; i<4; ++i)
1.95 + {
1.96 + const TBool currentBitIsOn=CurrentBitIsOn();
1.97 + ++iOffsetToCurrentBit; // increment this regardless whether the current bit is on
1.98 + if (!currentBitIsOn)
1.99 + {
1.100 + break;
1.101 + }
1.102 + ++numberOfConsecutivePrefixBits;
1.103 + }
1.104 + iAssertObj.AssertDebL(numberOfConsecutivePrefixBits>0,EBafPanicBadNumberOfConsecutivePrefixBits1);
1.105 + iAssertObj.AssertDebL(numberOfConsecutivePrefixBits<=4,EBafPanicBadNumberOfConsecutivePrefixBits2);
1.106 + TInt numberOfBytesToRead;
1.107 + if (numberOfConsecutivePrefixBits==3)
1.108 + {
1.109 + numberOfBytesToRead=3+ReadIntegerL(3);
1.110 + }
1.111 + else if (numberOfConsecutivePrefixBits==4)
1.112 + {
1.113 + numberOfBytesToRead=ReadIntegerL(8);
1.114 + if (!aCalypsoFileFormat)
1.115 + {
1.116 + numberOfBytesToRead+=3+(1<<3);
1.117 + }
1.118 + }
1.119 + else
1.120 + {
1.121 + numberOfBytesToRead=numberOfConsecutivePrefixBits;
1.122 + }
1.123 + const TInt numberOfBitsOffByteBoundary=iOffsetToCurrentBit%8;
1.124 + const TUint8* currentByte=iBuffer+(iOffsetToCurrentBit/8);
1.125 + iAssertObj.AssertDebL(
1.126 + (numberOfBytesToRead + aBufferToAppendTo.Length()) <= aBufferToAppendTo.MaxLength(),
1.127 + EBafPanicBufLength);
1.128 + for (i=0; i<numberOfBytesToRead; ++i, ++currentByte)
1.129 + {
1.130 + TUint byte=*currentByte;
1.131 + iAssertObj.AssertDebL(numberOfBitsOffByteBoundary>=0,EBafPanicBadNumberOfBitsOffByteBoundary1);
1.132 + if (numberOfBitsOffByteBoundary>0)
1.133 + {
1.134 + byte>>=numberOfBitsOffByteBoundary;
1.135 + byte|=(*(currentByte+1)<<(8-numberOfBitsOffByteBoundary));
1.136 + byte&=0xff;
1.137 + }
1.138 + aBufferToAppendTo.Append(byte);
1.139 + }
1.140 + iOffsetToCurrentBit+=numberOfBytesToRead*8;
1.141 + iAssertObj.AssertDebL(numberOfBitsOffByteBoundary==iOffsetToCurrentBit%8,EBafPanicBadNumberOfBitsOffByteBoundary2);
1.142 + }
1.143 +
1.144 +TBool RDictionaryCompressionBitStream::CurrentBitIsOn() const
1.145 + {
1.146 + // does not increment the current bit-position
1.147 + __ASSERT_DEBUG(iBuffer!=NULL,Panic(EBafPanicNotConstructed4));
1.148 + return iBuffer[iOffsetToCurrentBit/8]&(1<<(iOffsetToCurrentBit%8));
1.149 + }
1.150 +
1.151 +TUint RDictionaryCompressionBitStream::ReadIntegerL(TInt aNumberOfBits)
1.152 + {
1.153 + // increments the current bit-position
1.154 + __ASSERT_DEBUG(iBuffer!=NULL,Panic(EBafPanicNotConstructed5));
1.155 + TInt integer=0;
1.156 + TInt numberOfBitsLeftToRead=aNumberOfBits;
1.157 + FOREVER
1.158 + {
1.159 + const TInt offsetToFirstBitToReadInCurrentByte=iOffsetToCurrentBit%8;
1.160 + const TInt offsetOnePastLastBitToReadInCurrentByte=Min(8,offsetToFirstBitToReadInCurrentByte+numberOfBitsLeftToRead);
1.161 + const TInt numberOfBitsReadFromCurrentByte=offsetOnePastLastBitToReadInCurrentByte-offsetToFirstBitToReadInCurrentByte;
1.162 + iAssertObj.AssertDebL(numberOfBitsReadFromCurrentByte>0,EBafPanicBadNumberOfBitsReadFromCurrentByte);
1.163 + const TUint bitsReadFromCurrentByte=((iBuffer[iOffsetToCurrentBit/8]>>offsetToFirstBitToReadInCurrentByte)&((1<<numberOfBitsReadFromCurrentByte)-1));
1.164 + integer|=(bitsReadFromCurrentByte<<(aNumberOfBits-numberOfBitsLeftToRead));
1.165 + iOffsetToCurrentBit+=numberOfBitsReadFromCurrentByte;
1.166 + numberOfBitsLeftToRead-=numberOfBitsReadFromCurrentByte;
1.167 + iAssertObj.AssertDebL(numberOfBitsLeftToRead>=0,EBafPanicBadNumberOfBitsLeftToRead);
1.168 + if (numberOfBitsLeftToRead<=0)
1.169 + {
1.170 + break;
1.171 + }
1.172 + }
1.173 + return integer;
1.174 + }
1.175 +