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authorPaul Gilbert2015-03-15 16:52:55 -0400
committerWillem Jan Palenstijn2015-05-07 22:49:22 +0200
commit87a9ba5f2f5b9c3cde675c238ce718147417df03 (patch)
tree53d88c7f5f573b7cc0ebc474e0fda3319765cfb7 /engines/sherlock/decompress.cpp
parent6d8134f7518a2c368a55cfc49ba0a625a9744645 (diff)
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SHERLOCK: Initial commit
Diffstat (limited to 'engines/sherlock/decompress.cpp')
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diff --git a/engines/sherlock/decompress.cpp b/engines/sherlock/decompress.cpp
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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