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Diffstat (limited to '')
| -rw-r--r-- | vcl/source/filter/igif/decode.cxx | 214 |
1 files changed, 214 insertions, 0 deletions
diff --git a/vcl/source/filter/igif/decode.cxx b/vcl/source/filter/igif/decode.cxx new file mode 100644 index 000000000..b062593a9 --- /dev/null +++ b/vcl/source/filter/igif/decode.cxx @@ -0,0 +1,214 @@ +/* -*- 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 "decode.hxx" + +#include <cstdlib> +#include <cstring> + +struct GIFLZWTableEntry +{ + GIFLZWTableEntry* pPrev; + GIFLZWTableEntry* pFirst; + sal_uInt8 nData; +}; + +GIFLZWDecompressor::GIFLZWDecompressor(sal_uInt8 cDataSize) + : pTable(new GIFLZWTableEntry[4098]) + , pOutBufData(pOutBuf.data() + 4096) + , pBlockBuf(nullptr) + , nInputBitsBuf(0) + , bEOIFound(false) + , nDataSize(cDataSize) + , nBlockBufSize(0) + , nBlockBufPos(0) + , nClearCode(1 << nDataSize) + , nEOICode(nClearCode + 1) + , nTableSize(nEOICode + 1) + , nCodeSize(nDataSize + 1) + , nOldCode(0xffff) + , nOutBufDataLen(0) + , nInputBitsBufSize(0) +{ + for (sal_uInt16 i = 0; i < nTableSize; ++i) + { + pTable[i].pPrev = nullptr; + pTable[i].pFirst = &pTable[i]; + pTable[i].nData = static_cast<sal_uInt8>(i); + } + + memset(pTable.get() + nTableSize, 0, sizeof(GIFLZWTableEntry) * (4098 - nTableSize)); +} + +GIFLZWDecompressor::~GIFLZWDecompressor() +{ +} + +Scanline GIFLZWDecompressor::DecompressBlock( sal_uInt8* pSrc, sal_uInt8 cBufSize, + sal_uLong& rCount, bool& rEOI ) +{ + sal_uLong nTargetSize = 4096; + sal_uLong nCount = 0; + sal_uInt8* pTarget = static_cast<sal_uInt8*>(std::malloc( nTargetSize )); + sal_uInt8* pTmpTarget = pTarget; + + nBlockBufSize = cBufSize; + nBlockBufPos = 0; + pBlockBuf = pSrc; + + while (pTarget && ProcessOneCode()) + { + nCount += nOutBufDataLen; + + if( nCount > nTargetSize ) + { + sal_uLong nNewSize = nTargetSize << 1; + sal_uLong nOffset = pTmpTarget - pTarget; + if (auto p = static_cast<sal_uInt8*>(std::realloc(pTarget, nNewSize))) + pTarget = p; + else + { + free(pTarget); + pTarget = nullptr; + break; + } + + nTargetSize = nNewSize; + pTmpTarget = pTarget + nOffset; + } + + memcpy( pTmpTarget, pOutBufData, nOutBufDataLen ); + pTmpTarget += nOutBufDataLen; + pOutBufData += nOutBufDataLen; + nOutBufDataLen = 0; + + if ( bEOIFound ) + break; + } + + rCount = nCount; + rEOI = bEOIFound; + + return pTarget; +} + +bool GIFLZWDecompressor::AddToTable( sal_uInt16 nPrevCode, sal_uInt16 nCodeFirstData ) +{ + if( nTableSize < 4096 ) + { + GIFLZWTableEntry* pE = pTable.get() + nTableSize; + pE->pPrev = pTable.get() + nPrevCode; + pE->pFirst = pE->pPrev->pFirst; + GIFLZWTableEntry *pEntry = pTable[nCodeFirstData].pFirst; + if (!pEntry) + return false; + pE->nData = pEntry->nData; + nTableSize++; + + if ( ( nTableSize == static_cast<sal_uInt16>(1 << nCodeSize) ) && ( nTableSize < 4096 ) ) + nCodeSize++; + } + return true; +} + +bool GIFLZWDecompressor::ProcessOneCode() +{ + bool bRet = false; + bool bEndOfBlock = false; + + while( nInputBitsBufSize < nCodeSize ) + { + if( nBlockBufPos >= nBlockBufSize ) + { + bEndOfBlock = true; + break; + } + + nInputBitsBuf |= static_cast<sal_uLong>(pBlockBuf[ nBlockBufPos++ ]) << nInputBitsBufSize; + nInputBitsBufSize += 8; + } + + if ( !bEndOfBlock ) + { + // fetch code from input buffer + sal_uInt16 nCode = sal::static_int_cast< sal_uInt16 >( + static_cast<sal_uInt16>(nInputBitsBuf) & ( ~( 0xffff << nCodeSize ) )); + nInputBitsBuf >>= nCodeSize; + nInputBitsBufSize = nInputBitsBufSize - nCodeSize; + + if ( nCode < nClearCode ) + { + bool bOk = true; + if ( nOldCode != 0xffff ) + bOk = AddToTable(nOldCode, nCode); + if (!bOk) + return false; + } + else if ( ( nCode > nEOICode ) && ( nCode <= nTableSize ) ) + { + if ( nOldCode != 0xffff ) + { + bool bOk; + if ( nCode == nTableSize ) + bOk = AddToTable( nOldCode, nOldCode ); + else + bOk = AddToTable( nOldCode, nCode ); + if (!bOk) + return false; + } + } + else + { + if ( nCode == nClearCode ) + { + nTableSize = nEOICode + 1; + nCodeSize = nDataSize + 1; + nOldCode = 0xffff; + nOutBufDataLen = 0; + } + else + bEOIFound = true; + + return true; + } + + nOldCode = nCode; + + if (nCode >= 4096) + return false; + + // write character(/-sequence) of code nCode in the output buffer: + GIFLZWTableEntry* pE = pTable.get() + nCode; + do + { + if (pOutBufData == pOutBuf.data()) //can't go back past start + return false; + nOutBufDataLen++; + *(--pOutBufData) = pE->nData; + pE = pE->pPrev; + } + while( pE ); + + bRet = true; + } + + return bRet; +} + +/* vim:set shiftwidth=4 softtabstop=4 expandtab: */ |