/* 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