ADL: Add support for Serenia data blocks

2 files changed, 92 insertions, 10 deletions

diff --git a/engines/adl/disk.cpp b/engines/adl/disk.cpp
index b2746bcee7..5ee9b268ae 100644
--- a/engines/adl/disk.cpp
+++ b/engines/adl/disk.cpp
@@ -30,6 +30,59 @@
 
 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;
+
+	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);
+}
+
 const uint trackLen = 256 * 26;
 
 static bool detectDOS33_NIB(Common::SeekableReadStream &f) {
@@ -309,6 +362,7 @@ bool DiskImage::open(const Common::String &filename) {
 		_tracks = 40;
 		_sectorsPerTrack = 8;
 		_bytesPerSector = 512;
+		_firstSector = 1;
 		_stream = f;
 	}
 
@@ -335,8 +389,10 @@ Common::SeekableReadStream *DiskImage::createReadStream(uint track, uint sector,
 	if (sectorLimit == 0)
 		sectorLimit = _sectorsPerTrack;
 
-	if (sector >= sectorLimit)
-		error("Sector %i is out of bounds for %i-sector reading", sector, sectorLimit);
+	if (sector < _firstSector || sector >= sectorLimit + _firstSector)
+		error("Sector %u is out of bounds for %u-sector %u-based reading", sector, sectorLimit, _firstSector);
+
+	sector -= _firstSector;
 
 	while (dataOffset < bytesToRead) {
 		uint bytesRemInTrack = (sectorLimit - 1 - sector) * _bytesPerSector + _bytesPerSector - offset;
diff --git a/engines/adl/disk.h b/engines/adl/disk.h
index a13c2eeb47..97b66a9a9e 100644
--- a/engines/adl/disk.h
+++ b/engines/adl/disk.h
@@ -62,7 +62,7 @@ protected:
 				_filename(filename),
 				_offset(offset) { }
 
-		Common::SeekableReadStream *createReadStream() const {
+		Common::SeekableReadStream *createReadStream() const override {
 			return _files->createReadStream(_filename, _offset);
 		}
 
@@ -80,7 +80,8 @@ public:
 			_tracks(0),
 			_sectorsPerTrack(0),
 			_bytesPerSector(0),
-			_sectorLimit(0) { }
+			_sectorLimit(0),
+			_firstSector(0) { }
 
 	~DiskImage() {
 		delete _stream;
@@ -105,7 +106,7 @@ protected:
 				_sectorLimit(sectorLimit),
 				_disk(disk) { }
 
-		Common::SeekableReadStream *createReadStream() const {
+		Common::SeekableReadStream *createReadStream() const override {
 			return _disk->createReadStream(_track, _sector, _offset, _size, _sectorLimit);
 		}
 
@@ -116,15 +117,15 @@ protected:
 	};
 
 	Common::SeekableReadStream *_stream;
-	uint _tracks, _sectorsPerTrack, _bytesPerSector;
+	uint _tracks, _sectorsPerTrack, _bytesPerSector, _firstSector;
 	uint _sectorLimit;
 };
 
 // Data in plain files
 class Files_Plain : public Files {
 public:
-	const DataBlockPtr getDataBlock(const Common::String &filename, uint offset = 0) const;
-	Common::SeekableReadStream *createReadStream(const Common::String &filename, uint offset = 0) const;
+	const DataBlockPtr getDataBlock(const Common::String &filename, uint offset = 0) const override;
+	Common::SeekableReadStream *createReadStream(const Common::String &filename, uint offset = 0) const override;
 };
 
 // Data in files contained in Apple DOS 3.3 disk image
@@ -134,8 +135,8 @@ public:
 	~Files_AppleDOS();
 
 	bool open(const Common::String &filename, uint trackVTOC = 17);
-	const DataBlockPtr getDataBlock(const Common::String &filename, uint offset = 0) const;
-	Common::SeekableReadStream *createReadStream(const Common::String &filename, uint offset = 0) const;
+	const DataBlockPtr getDataBlock(const Common::String &filename, uint offset = 0) const override;
+	Common::SeekableReadStream *createReadStream(const Common::String &filename, uint offset = 0) const override;
 
 private:
 	enum FileType {
@@ -169,6 +170,31 @@ private:
 	Common::HashMap<Common::String, TOCEntry> _toc;
 };
 
+// On the Apple II, sector headers contain a disk volume number. This number
+// is used by ADL multi-disk games. The PC port has the disk volume number
+// as the first data byte of every sector that contains game data. We need
+// to skip this number as we read in the data. Additionally, the data is now
+// prefixed with an uint16 containing the data size.
+class DataBlock_PC : public DataBlock {
+public:
+	DataBlock_PC(DiskImage *disk, byte track, byte sector, uint16 offset = 0) :
+			_disk(disk),
+			_track(track),
+			_sector(sector),	
+			_offset(offset) { }
+
+	virtual ~DataBlock_PC() { }
+
+	Common::SeekableReadStream *createReadStream() const override;
+
+private:
+	void read(Common::SeekableReadStream &stream, byte *const dataPtr, const uint32 size) const;
+
+	DiskImage *_disk;
+	byte _track, _sector;
+	uint16 _offset;
+};
+
 } // End of namespace Adl
 
 #endif