1 files changed, 103 insertions, 0 deletions
diff --git a/engines/zvision/utility/lzss_read_stream.cpp b/engines/zvision/utility/lzss_read_stream.cpp
new file mode 100644
index 0000000000..dc537cd8ab
--- /dev/null
+++ b/engines/zvision/utility/lzss_read_stream.cpp
@@ -0,0 +1,103 @@
+/* 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 "common/scummsys.h"
+
+#include "zvision/utility/lzss_read_stream.h"
+
+
+namespace ZVision {
+
+LzssReadStream::LzssReadStream(Common::SeekableReadStream *source)
+		: _source(source),
+		  // It's convention to set the starting cursor position to blockSize - 16
+		  _windowCursor(0x0FEE),
+		  _eosFlag(false) {
+	// Clear the window to null
+	memset(_window, 0, BLOCK_SIZE);
+}
+
+uint32 LzssReadStream::decompressBytes(byte *destination, uint32 numberOfBytes) {
+	uint32 destinationCursor = 0;
+
+	while (destinationCursor < numberOfBytes) {
+		byte flagbyte = _source->readByte();
+		if (_source->eos())
+			break;
+		uint mask = 1;
+
+		for (int i = 0; i < 8; ++i) {
+			if ((flagbyte & mask) == mask) {
+				byte data = _source->readByte();
+				if (_source->eos()) {
+					return destinationCursor;
+				}
+
+				_window[_windowCursor] = data;
+				destination[destinationCursor++] = data;
+
+				// Increment and wrap the window cursor
+				_windowCursor = (_windowCursor + 1) & 0xFFF;
+			} else {
+				byte low = _source->readByte();
+				if (_source->eos()) {
+					return destinationCursor;
+				}
+
+				byte high = _source->readByte();
+				if (_source->eos()) {
+					return destinationCursor;
+				}
+
+				uint16 length = (high & 0xF) + 2;
+				uint16 offset = low | ((high & 0xF0)<<4);
+
+				for(int j = 0; j <= length; ++j) {
+					byte temp = _window[(offset + j) & 0xFFF];
+					_window[_windowCursor] = temp;
+					destination[destinationCursor++] = temp;
+					_windowCursor = (_windowCursor + 1) & 0xFFF;
+				}
+			}
+
+			mask = mask << 1;
+		}
+	}
+
+	return destinationCursor;
+}
+
+bool LzssReadStream::eos() const {
+	return _eosFlag;
+}
+
+uint32 LzssReadStream::read(void *dataPtr, uint32 dataSize) {
+	uint32 bytesRead = decompressBytes(static_cast<byte *>(dataPtr), dataSize);
+	if (bytesRead < dataSize) {
+		// Flag that we're at EOS
+		_eosFlag = true;
+	}
+
+	return dataSize;
+}
+
+} // End of namespace ZVision