/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* This file is part of the LibreOffice project.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* This file incorporates work covered by the following license notice:
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed
* with this work for additional information regarding copyright
* ownership. The ASF licenses this file to you under the Apache
* License, Version 2.0 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.apache.org/licenses/LICENSE-2.0 .
*/
#include "lzwdecom.hxx"
#include <sal/log.hxx>
#include <tools/stream.hxx>
#include <algorithm>
#include <set>
LZWDecompressor::LZWDecompressor()
: pIStream(nullptr)
, nTableSize(0)
, bEOIFound(false)
, bInvert(false)
, bFirst(true)
, nOldCode(0)
, pOutBufData(nullptr)
, nOutBufDataLen(0)
, nInputBitsBuf(0)
, nInputBitsBufSize(0)
{
for (sal_uInt16 i=0; i<MAX_TABLE_SIZE; i++)
{
pTable[i].nPrevCode=0;
pTable[i].nDataCount=1;
pTable[i].nData=static_cast<sal_uInt8>(i);
}
}
LZWDecompressor::~LZWDecompressor()
{
}
void LZWDecompressor::StartDecompression(SvStream & rIStream)
{
pIStream=&rIStream;
nTableSize=258;
bEOIFound=false;
nOutBufDataLen=0;
pIStream->ReadUChar( nInputBitsBuf );
nInputBitsBufSize=8;
if ( bFirst )
{
bInvert = nInputBitsBuf == 1;
bFirst = false;
}
if ( bInvert )
nInputBitsBuf = ( ( nInputBitsBuf & 1 ) << 7 ) | ( ( nInputBitsBuf & 2 ) << 5 ) | ( ( nInputBitsBuf & 4 ) << 3 ) | ( ( nInputBitsBuf & 8 ) << 1 ) | ( ( nInputBitsBuf & 16 ) >> 1 ) | ( ( nInputBitsBuf & 32 ) >> 3 ) | ( ( nInputBitsBuf & 64 ) >> 5 ) | ( (nInputBitsBuf & 128 ) >> 7 );
}
sal_uLong LZWDecompressor::Decompress(sal_uInt8 * pTarget, sal_uLong nMaxCount)
{
sal_uLong nCount;
if (pIStream==nullptr) return 0;
nCount=0;
for (;;) {
if (pIStream->GetError()) break;
if (static_cast<sal_uLong>(nOutBufDataLen)>=nMaxCount) {
nOutBufDataLen = nOutBufDataLen - static_cast<sal_uInt16>(nMaxCount);
nCount+=nMaxCount;
while (nMaxCount>0) {
*(pTarget++)=*(pOutBufData++);
nMaxCount--;
}
break;
}
nMaxCount-=static_cast<sal_uLong>(nOutBufDataLen);
nCount+=nOutBufDataLen;
while (nOutBufDataLen>0) {
*(pTarget++)=*(pOutBufData++);
nOutBufDataLen--;
}
if (bEOIFound) break;
DecompressSome();
}
return nCount;
}
sal_uInt16 LZWDecompressor::GetNextCode()
{
sal_uInt16 nBits,nCode;
if (nTableSize<511) nBits=9;
else if (nTableSize<1023) nBits=10;
else if (nTableSize<2047) nBits=11;
else nBits=12;
nCode=0;
do {
if (nInputBitsBufSize<=nBits)
{
nCode=(nCode<<nInputBitsBufSize) | nInputBitsBuf;
nBits = nBits - nInputBitsBufSize;
pIStream->ReadUChar( nInputBitsBuf );
if ( bInvert )
nInputBitsBuf = ( ( nInputBitsBuf & 1 ) << 7 ) | ( ( nInputBitsBuf & 2 ) << 5 ) | ( ( nInputBitsBuf & 4 ) << 3 ) | ( ( nInputBitsBuf & 8 ) << 1 ) | ( ( nInputBitsBuf & 16 ) >> 1 ) | ( ( nInputBitsBuf & 32 ) >> 3 ) | ( ( nInputBitsBuf & 64 ) >> 5 ) | ( (nInputBitsBuf & 128 ) >> 7 );
nInputBitsBufSize=8;
}
else
{
nCode=(nCode<<nBits) | (nInputBitsBuf>>(nInputBitsBufSize-nBits));
nInputBitsBufSize = nInputBitsBufSize - nBits;
nInputBitsBuf&=0x00ff>>(8-nInputBitsBufSize);
nBits=0;
}
} while (nBits>0);
return nCode;
}
void LZWDecompressor::AddToTable(sal_uInt16 nPrevCode, sal_uInt16 nCodeFirstData)
{
if (nTableSize >= MAX_TABLE_SIZE)
{
//It might be possible to force emit a 256 to flush the buffer and try
//to continue later?
SAL_WARN("filter.tiff", "Too much data at scanline");
bEOIFound = true;
return;
}
unsigned char aSeenIndexes[MAX_TABLE_SIZE] = {0};
while (pTable[nCodeFirstData].nDataCount>1)
{
if (aSeenIndexes[nCodeFirstData])
{
SAL_WARN("filter.tiff", "Loop in chain");
bEOIFound = true;
return;
}
aSeenIndexes[nCodeFirstData] = 1;
nCodeFirstData=pTable[nCodeFirstData].nPrevCode;
}
pTable[nTableSize].nPrevCode=nPrevCode;
pTable[nTableSize].nDataCount=pTable[nPrevCode].nDataCount+1;
pTable[nTableSize].nData=pTable[nCodeFirstData].nData;
nTableSize++;
}
void LZWDecompressor::DecompressSome()
{
sal_uInt16 i,nCode;
nCode=GetNextCode();
if (nCode==256)
{
nTableSize=258;
nCode=GetNextCode();
if (nCode==257)
{
bEOIFound=true;
}
}
else if (nCode<nTableSize)
AddToTable(nOldCode,nCode);
else if (nCode==nTableSize)
AddToTable(nOldCode,nOldCode);
else
{
bEOIFound=true;
}
if (bEOIFound)
return;
nOldCode=nCode;
nOutBufDataLen=pTable[nCode].nDataCount;
pOutBufData=pOutBuf.data()+nOutBufDataLen;
for (i=0; i<nOutBufDataLen; i++)
{
*(--pOutBufData)=pTable[nCode].nData;
nCode=pTable[nCode].nPrevCode;
}
}
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
↑ V730 Not all members of a class are initialized inside the constructor. Consider inspecting: pOutBuf.