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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.
*
*/
#include "sherlock/decompress.h"
namespace Sherlock {
/**
* Decompresses an LZW compressed resource. If no outSize is specified, it will
* decompress the entire resource. If, however, an explicit size is specified,
* it will decompress only up to that many bytes from the stream starting at
* whatever position it was previously.
*/
Common::SeekableReadStream *decompressLZ(Common::SeekableReadStream &source, int32 outSize) {
if (outSize == -1) {
source.seek(5);
outSize = source.readSint32LE();
}
byte lzWindow[4096];
uint16 lzWindowPos;
uint16 cmd;
byte *outBuffer = new byte[outSize];
byte *outBufferEnd = outBuffer + outSize;
Common::MemoryReadStream *outS = new Common::MemoryReadStream(outBuffer, outSize, DisposeAfterUse::YES);
memset(lzWindow, 0xFF, 0xFEE);
lzWindowPos = 0xFEE;
cmd = 0;
while (1) {
cmd >>= 1;
if (!(cmd & 0x100)) {
cmd = source.readByte() | 0xFF00;
}
if (cmd & 1) {
byte literal = source.readByte();
*outBuffer++ = literal;
lzWindow[lzWindowPos] = literal;
lzWindowPos = (lzWindowPos + 1) & 0x0FFF;
} else {
int copyPos, copyLen;
copyPos = source.readByte();
copyLen = source.readByte();
copyPos = copyPos | ((copyLen & 0xF0) << 4);
copyLen = (copyLen & 0x0F) + 3;
while (copyLen--) {
byte literal = lzWindow[copyPos];
copyPos = (copyPos + 1) & 0x0FFF;
*outBuffer++ = literal;
lzWindow[lzWindowPos] = literal;
lzWindowPos = (lzWindowPos + 1) & 0x0FFF;
}
}
if (outBuffer >= outBufferEnd)
break;
}
return outS;
}
} // namespace Sherlock
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