1 // Copyright (c) 2005-2009 Nokia Corporation and/or its subsidiary(-ies).

     2 // All rights reserved.

     3 // This component and the accompanying materials are made available

     4 // under the terms of "Eclipse Public License v1.0"

     5 // which accompanies this distribution, and is available

     6 // at the URL "http://www.eclipse.org/legal/epl-v10.html".

     7 //

     8 // Initial Contributors:

     9 // Nokia Corporation - initial contribution.

    10 //

    11 // Contributors:

    12 //

    13 // Description:

    14 //

    15 

    16 #ifndef BYTE_PAIR_H

    17 #define BYTE_PAIR_H

    18 

    19 #ifdef __VC32__

    20 #ifdef __MSVCDOTNET__

    21 #include <strstream>

    22 #include <iomanip>

    23 #else //!__MSVCDOTNET__

    24 #include <strstrea.h>

    25 #include <iomanip.h>

    26 #endif //__MSVCDOTNET__

    27 #else // !__VC32__

    28 #ifdef __TOOLS2__ 

    29 #include <sstream>

    30 #include <iomanip>

    31 using namespace std;

    32 #else

    33 #include <strstream.h>

    34 #include <iomanip.h>

    35 #endif

    36 #endif // __VC32__

    37 

    38 

    39 

    40 #include <e32cmn.h>

    41 const TInt MaxBlockSize = 0x1000;

    42 class CBytePair {

    43     private:

    44         TBool iFastCompress;

    45         TUint16 PairCount[0x10000];

    46         TUint16 PairBuffer[MaxBlockSize*2];

    47         TInt PairsFound;

    48 

    49         TUint16 GlobalPairs[0x10000];

    50         TUint16 GlobalTokenCounts[0x100];

    51 

    52         TUint16 ByteCount[0x100+4];

    53 

    54         void CountBytes(TUint8* data, TInt size) {

    55             memset(ByteCount,0,sizeof(ByteCount));

    56             TUint8* dataEnd = data+size;

    57             while(data<dataEnd)

    58                 ++ByteCount[*data++];

    59         }

    60         inline void ByteUsed(TInt b) {

    61             ByteCount[b] = 0xffff;

    62         }

    63         int TieBreak(int b1,int b2) {

    64             return -ByteCount[b1]-ByteCount[b2];

    65         }

    66 

    67         void InitPairCount(TUint8* data, TInt size, TInt minFrequency, TInt marker);

    68         TInt MostCommonPair(TInt& pair);

    69         TInt LeastCommonByte(TInt& byte);

    70     public:

    71         CBytePair(TBool fastCompress) {

    72             iFastCompress = fastCompress;

    73             memset(GlobalPairs,0,sizeof(GlobalPairs));

    74             memset(GlobalTokenCounts,0,sizeof(GlobalTokenCounts));

    75         }

    76         TInt Compress(TUint8* dst, TUint8* src, TInt size);

    77         TInt Decompress(TUint8* dst, TInt dstSize, TUint8* src, TInt srcSize, TUint8*& srcNext);

    78 };

    79 TInt BytePairCompress(TUint8* dst, TUint8* src, TInt size, CBytePair *aBPE);

    80 

    81 #endif

    82