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engines/adl/disk.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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "common/stream.h"
+#include "common/substream.h"
+#include "common/memstream.h"
+
+#include "common/formats/disk_image.h"
+
+#include "adl/disk.h"
+
+namespace Adl {
+
+void DataBlock_PC::read(Common::SeekableReadStream &stream, byte *const dataPtr, const uint32 size) const {
+	uint32 ofs = 0;
+
+	while (ofs < size) {
+		const uint bps = _disk->getBytesPerSector();
+		uint bytesToRead = bps - ((_offset + stream.pos()) % bps);
+
+		if (bytesToRead == bps) {
+			stream.readByte(); // Skip volume byte
+			--bytesToRead;
+		}
+
+		if (bytesToRead > size - ofs)
+			bytesToRead = size - ofs;
+
+		if (stream.read(dataPtr + ofs, bytesToRead) < bytesToRead)
+			error("Failed to read data block");
+
+		ofs += bytesToRead;
+	}
+}
+
+Common::SeekableReadStream *DataBlock_PC::createReadStream() const {
+	const uint bps = _disk->getBytesPerSector();
+	uint sectors = 0;
+
+	// Every data sector starts with a volume byte that we need to skip,
+	// so we need to take that into account during our computations here
+	if (_offset == bps - 1)
+		sectors = 1;
+
+	Common::StreamPtr diskStream(_disk->createReadStream(_track, _sector, _offset, sectors));
+
+	byte sizeBuf[2];
+	read(*diskStream, sizeBuf, 2);
+
+	uint16 blockSize = READ_LE_UINT16(sizeBuf);
+	sectors = 0;
+
+	const uint16 remSize = _disk->getBytesPerSector() - MAX<uint>(_offset, 1);
+
+	if (blockSize + 2 > remSize)
+		sectors = (blockSize + 2 - remSize - 1) / (_disk->getBytesPerSector() - 1) + 1;
+
+	diskStream.reset(_disk->createReadStream(_track, _sector, _offset, sectors));
+	read(*diskStream, sizeBuf, 2);
+
+	byte *buf = static_cast<byte *>(malloc(blockSize));
+	read(*diskStream, buf, blockSize);
+
+	return new Common::MemoryReadStream(buf, blockSize, DisposeAfterUse::YES);
+}
+
+} // End of namespace Common