1 /*

     2 * Copyright (c) 1998-2009 Nokia Corporation and/or its subsidiary(-ies).

     3 * All rights reserved.

     4 * This component and the accompanying materials are made available

     5 * under the terms of the License "Eclipse Public License v1.0"

     6 * which accompanies this distribution, and is available

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

     8 *

     9 * Initial Contributors:

    10 * Nokia Corporation - initial contribution.

    11 *

    12 * Contributors:

    13 *

    14 * Description: 

    15 * e32tools\petran\Szip\inflate.cpp

    16 *

    17 */

    18 

    19 

    20 #include "deflate.h"

    21 #include "panic.h"

    22 #include "h_utl.h"

    23 

    24 // Class RInflater

    25 //

    26 // The inflation algorithm, complete with huffman decoding

    27 

    28 inline CInflater::CInflater(TBitInput& aInput)

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

    30 	{}

    31 

    32 void CInflater::ConstructL()

    33 	{

    34 	iEncoding=new TEncoding;

    35 	if(iEncoding==NULL)

    36 		Panic(EHuffmanOutOfMemory);

    37 	InitL();

    38 	iLen=0;

    39 	iOut=new TUint8[KDeflateMaxDistance];

    40 	if(iOut==NULL)

    41 		Panic(EHuffmanOutOfMemory);

    42 

    43 	iAvail=iLimit=iOut;

    44 	}

    45 

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

    47 	{

    48 	CInflater* self=new CInflater(aInput);

    49 	if(self==NULL)

    50 		Panic(EHuffmanOutOfMemory);

    51 	self->ConstructL();

    52 	return self;

    53 	}

    54 

    55 CInflater::~CInflater()

    56 	{

    57 	delete iEncoding;

    58 	delete [] iOut;

    59 	}

    60 

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

    62 	{

    63 	TInt tfr=0;

    64 	for (;;)

    65 		{

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

    67 		if (len && aBuffer)

    68 			{

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

    70 			aBuffer+=len;

    71 			}

    72 		aLength-=len;

    73 		iAvail+=len;

    74 		tfr+=len;

    75 		if (aLength==0)

    76 			return tfr;

    77 		len=InflateL();

    78 		if (len==0)

    79 			return tfr;

    80 		iAvail=iOut;

    81 		iLimit=iAvail+len;

    82 		}

    83 	}

    84 

    85 TInt CInflater::SkipL(TInt aLength)

    86 	{

    87 	return ReadL(0,aLength);

    88 	}

    89 

    90 void CInflater::InitL()

    91 	{

    92 // read the encoding

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

    94 // validate the encoding

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

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

    97 		Panic(EHuffmanCorruptFile);

    98 // convert the length tables into huffman decoding trees

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

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

   101 	}

   102 

   103 TInt CInflater::InflateL()

   104 //

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

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

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

   108 //

   109 	{

   110 // empty the history buffer into the output

   111 	TUint8* out=iOut;

   112 	TUint8* const end=out+KDeflateMaxDistance;

   113 	const TUint32* tree=iEncoding->iLitLen;

   114 	if (iLen<0)	// EOF

   115 		return 0;

   116 	if (iLen>0)

   117 		goto useHistory;

   118 //

   119 	while (out<end)

   120 		{

   121 		// get a huffman code

   122 		{

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

   124 		if (val<0)

   125 			{

   126 			*out++=TUint8(val);

   127 			continue;			// another literal/length combo

   128 			}

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

   130 			{	// eos marker. we're done

   131 			iLen=-1;

   132 			break;

   133 			}

   134 		// get the extra bits for the code

   135 		TInt code=val&0xff;

   136 		if (code>=8)

   137 			{	// xtra bits

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

   139 			code-=xtra<<2;

   140 			code<<=xtra;

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

   142 			}

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

   144 			{	// length code... get the code

   145 			iLen=code+KDeflateMinLength;

   146 			tree=iEncoding->iDistance;

   147 			continue;			// read the huffman code

   148 			}

   149 		// distance code

   150 		iRptr=out-(code+1);

   151 		if (iRptr+KDeflateMaxDistance<end)

   152 			iRptr+=KDeflateMaxDistance;

   153 		}

   154 useHistory:

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

   156 		iLen-=tfr;

   157 		const TUint8* from=iRptr;

   158 		do

   159 			{

   160 			*out++=*from++;

   161 			if (from==end)

   162 				from-=KDeflateMaxDistance;

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

   164 		iRptr=from;

   165 		tree=iEncoding->iLitLen;

   166 		};

   167 	return out-iOut;

   168 	}

   169 

   170 

   171