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author | Paul Gilbert | 2015-03-15 16:52:55 -0400 |
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committer | Willem Jan Palenstijn | 2015-05-07 22:49:22 +0200 |
commit | 87a9ba5f2f5b9c3cde675c238ce718147417df03 (patch) | |
tree | 53d88c7f5f573b7cc0ebc474e0fda3319765cfb7 /engines/sherlock/decompress.cpp | |
parent | 6d8134f7518a2c368a55cfc49ba0a625a9744645 (diff) | |
download | scummvm-rg350-87a9ba5f2f5b9c3cde675c238ce718147417df03.tar.gz scummvm-rg350-87a9ba5f2f5b9c3cde675c238ce718147417df03.tar.bz2 scummvm-rg350-87a9ba5f2f5b9c3cde675c238ce718147417df03.zip |
SHERLOCK: Initial commit
Diffstat (limited to 'engines/sherlock/decompress.cpp')
-rw-r--r-- | engines/sherlock/decompress.cpp | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/engines/sherlock/decompress.cpp b/engines/sherlock/decompress.cpp new file mode 100644 index 0000000000..61110be840 --- /dev/null +++ b/engines/sherlock/decompress.cpp @@ -0,0 +1,82 @@ +/* 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 |