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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $URL: https://scummvm-startrek.googlecode.com/svn/trunk/lzss.cpp $
* $Id: lzss.cpp 18 2010-12-17 01:22:54Z clone2727 $
*
*/
#include "common/textconsole.h"
#include "common/memstream.h"
#include "common/util.h"
#include "startrek/lzss.h"
namespace StarTrek {
Common::SeekableReadStream *decodeLZSS(Common::SeekableReadStream *indata, uint32 uncompressedSize) {
uint32 N = 0x1000; /* History buffer size */
byte *histbuff = new byte[N]; /* History buffer */
memset(histbuff, 0, N);
uint32 outstreampos = 0;
uint32 bufpos = 0;
byte *outLzssBufData = (byte *)malloc(uncompressedSize);
for (;;) {
byte flagbyte = indata->readByte();
if (indata->eos())
break;
for (byte i = 0; i < 8; i++) {
if ((flagbyte & (1 << i)) == 0) {
uint32 offsetlen = indata->readUint16LE();
if (indata->eos())
break;
uint32 length = (offsetlen & 0xF) + 3;
uint32 offset = (bufpos - (offsetlen >> 4)) & (N - 1);
for (uint32 j = 0; j < length; j++) {
byte tempa = histbuff[(offset + j) & (N - 1)];
outLzssBufData[outstreampos++] = tempa;
histbuff[bufpos] = tempa;
bufpos = (bufpos + 1) & (N - 1);
}
} else {
byte tempa = indata->readByte();
if (indata->eos())
break;
outLzssBufData[outstreampos++] = tempa;
histbuff[bufpos] = tempa;
bufpos = (bufpos + 1) & (N - 1);
}
}
}
delete[] histbuff;
if (outstreampos != uncompressedSize)
error("Size mismatch in LZSS decompression; expected %d bytes, got %d bytes", uncompressedSize, outstreampos);
return new Common::MemoryReadStream(outLzssBufData, uncompressedSize, DisposeAfterUse::YES);
}
} // End of namespace StarTrek
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