mirror of
https://github.com/libretro/scummvm.git
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81 lines
2.4 KiB
C++
81 lines
2.4 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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*/
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#include "sherlock/decompress.h"
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namespace Sherlock {
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/**
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* Decompresses an LZW compressed resource. If no outSize is specified, it will
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* decompress the entire resource. If, however, an explicit size is specified,
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* it will decompress only up to that many bytes from the stream starting at
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* whatever position it was previously.
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*/
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Common::SeekableReadStream *decompressLZ(Common::SeekableReadStream &source, int32 outSize) {
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if (outSize == -1) {
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source.seek(5);
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outSize = source.readSint32LE();
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}
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byte lzWindow[4096];
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uint16 lzWindowPos;
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uint16 cmd;
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byte *outBuffer = new byte[outSize];
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byte *outBufferEnd = outBuffer + outSize;
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Common::MemoryReadStream *outS = new Common::MemoryReadStream(outBuffer, outSize, DisposeAfterUse::YES);
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memset(lzWindow, 0xFF, 0xFEE);
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lzWindowPos = 0xFEE;
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cmd = 0;
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do {
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cmd >>= 1;
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if (!(cmd & 0x100))
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cmd = source.readByte() | 0xFF00;
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if (cmd & 1) {
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byte literal = source.readByte();
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*outBuffer++ = literal;
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lzWindow[lzWindowPos] = literal;
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lzWindowPos = (lzWindowPos + 1) & 0x0FFF;
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} else {
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int copyPos, copyLen;
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copyPos = source.readByte();
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copyLen = source.readByte();
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copyPos = copyPos | ((copyLen & 0xF0) << 4);
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copyLen = (copyLen & 0x0F) + 3;
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while (copyLen--) {
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byte literal = lzWindow[copyPos];
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copyPos = (copyPos + 1) & 0x0FFF;
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*outBuffer++ = literal;
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lzWindow[lzWindowPos] = literal;
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lzWindowPos = (lzWindowPos + 1) & 0x0FFF;
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}
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}
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} while (outBuffer < outBufferEnd);
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return outS;
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}
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} // namespace Sherlock
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