1 // Copyright (c) 1998-2009 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 // e32tools\petran\Szip\inflate.cpp

    15 // 

    16 //

    17 

    18 #include "deflate.h"

    19 #include "panic.h"

    20 #include "h_utl.h"

    21 

    22 // Class RInflater

    23 //

    24 // The inflation algorithm, complete with huffman decoding

    25 

    26 inline CInflater::CInflater(TBitInput& aInput)

    27 	:iBits(&aInput),iEncoding(0),iOut(0)

    28 	{}

    29 

    30 void CInflater::ConstructL()

    31 	{

    32 	iEncoding=new TEncoding;

    33 	if(iEncoding==NULL)

    34 		Panic(EHuffmanOutOfMemory);

    35 	InitL();

    36 	iLen=0;

    37 	iOut=new TUint8[KDeflateMaxDistance];

    38 	if(iOut==NULL)

    39 		Panic(EHuffmanOutOfMemory);

    40 

    41 	iAvail=iLimit=iOut;

    42 	}

    43 

    44 CInflater* CInflater::NewLC(TBitInput& aInput)

    45 	{

    46 	CInflater* self=new CInflater(aInput);

    47 	if(self==NULL)

    48 		Panic(EHuffmanOutOfMemory);

    49 	self->ConstructL();

    50 	return self;

    51 	}

    52 

    53 CInflater::~CInflater()

    54 	{

    55 	delete iEncoding;

    56 	delete [] iOut;

    57 	}

    58 

    59 TInt CInflater::ReadL(TUint8* aBuffer,TInt aLength)

    60 	{

    61 	TInt tfr=0;

    62 	for (;;)

    63 		{

    64 		TInt len=Min(aLength,iLimit-iAvail);

    65 		if (len && aBuffer)

    66 			{

    67 			HMem::Copy(aBuffer,iAvail,len);

    68 			aBuffer+=len;

    69 			}

    70 		aLength-=len;

    71 		iAvail+=len;

    72 		tfr+=len;

    73 		if (aLength==0)

    74 			return tfr;

    75 		len=InflateL();

    76 		if (len==0)

    77 			return tfr;

    78 		iAvail=iOut;

    79 		iLimit=iAvail+len;

    80 		}

    81 	}

    82 

    83 TInt CInflater::SkipL(TInt aLength)

    84 	{

    85 	return ReadL(0,aLength);

    86 	}

    87 

    88 void CInflater::InitL()

    89 	{

    90 // read the encoding

    91 	Huffman::InternalizeL(*iBits,iEncoding->iLitLen,KDeflationCodes);

    92 // validate the encoding

    93 	if (!Huffman::IsValid(iEncoding->iLitLen,TEncoding::ELitLens) ||

    94 		!Huffman::IsValid(iEncoding->iDistance,TEncoding::EDistances))

    95 		Panic(EHuffmanCorruptFile);

    96 // convert the length tables into huffman decoding trees

    97 	Huffman::Decoding(iEncoding->iLitLen,TEncoding::ELitLens,iEncoding->iLitLen);

    98 	Huffman::Decoding(iEncoding->iDistance,TEncoding::EDistances,iEncoding->iDistance,KDeflateDistCodeBase);

    99 	}

   100 

   101 TInt CInflater::InflateL()

   102 //

   103 // consume all data lag in the history buffer, then decode to fill up the output buffer

   104 // return the number of available bytes in the output buffer. This is only ever less than

   105 // the buffer size if the end of stream marker has been read

   106 //

   107 	{

   108 // empty the history buffer into the output

   109 	TUint8* out=iOut;

   110 	TUint8* const end=out+KDeflateMaxDistance;

   111 	const TUint32* tree=iEncoding->iLitLen;

   112 	if (iLen<0)	// EOF

   113 		return 0;

   114 	if (iLen>0)

   115 		goto useHistory;

   116 //

   117 	while (out<end)

   118 		{

   119 		// get a huffman code

   120 		{

   121 		TInt val=iBits->HuffmanL(tree)-TEncoding::ELiterals;

   122 		if (val<0)

   123 			{

   124 			*out++=TUint8(val);

   125 			continue;			// another literal/length combo

   126 			}

   127 		if (val==TEncoding::EEos-TEncoding::ELiterals)

   128 			{	// eos marker. we're done

   129 			iLen=-1;

   130 			break;

   131 			}

   132 		// get the extra bits for the code

   133 		TInt code=val&0xff;

   134 		if (code>=8)

   135 			{	// xtra bits

   136 			TInt xtra=(code>>2)-1;

   137 			code-=xtra<<2;

   138 			code<<=xtra;

   139 			code|=iBits->ReadL(xtra);

   140 			}

   141 		if (val<KDeflateDistCodeBase-TEncoding::ELiterals)

   142 			{	// length code... get the code

   143 			iLen=code+KDeflateMinLength;

   144 			tree=iEncoding->iDistance;

   145 			continue;			// read the huffman code

   146 			}

   147 		// distance code

   148 		iRptr=out-(code+1);

   149 		if (iRptr+KDeflateMaxDistance<end)

   150 			iRptr+=KDeflateMaxDistance;

   151 		}

   152 useHistory:

   153 		TInt tfr=Min(end-out,iLen);

   154 		iLen-=tfr;

   155 		const TUint8* from=iRptr;

   156 		do

   157 			{

   158 			*out++=*from++;

   159 			if (from==end)

   160 				from-=KDeflateMaxDistance;

   161 			} while (--tfr!=0);

   162 		iRptr=from;

   163 		tree=iEncoding->iLitLen;

   164 		};

   165 	return out-iOut;

   166 	}

   167 

   168 

   169