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engines/mediastation/datafile.h

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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/>.
+ *
+ */
+
+#ifndef MEDIASTATION_DATAFILE_H
+#define MEDIASTATION_DATAFILE_H
+
+#include "common/file.h"
+#include "common/stream.h"
+#include "common/path.h"
+#include "common/rect.h"
+#include "common/str.h"
+
+namespace MediaStation {
+
+// The version number of this engine,
+// in the form 4.0r8 (major . minor r revision).
+struct VersionInfo {
+	uint16 major = 0;
+	uint16 minor = 0;
+	uint16 patch = 0;
+};
+
+typedef Common::Array<Common::Point> Polygon;
+
+// A Media Station datafile consists of one or more RIFF-style "subfiles". Aside
+// from some oddness at the start of the subfile, each subfile is basically
+// standard sequence of chunks inside a LIST chunk, like you'd see in any RIFF
+// file. These chunks have special IDs:
+//  - igod: Indicates a chunk that contains metadata about actor(s) in metadata sections.
+//  - a000, where 000 is a string that represents a 3-digit hexadecimal number.
+//          Indicates a chunk that contains actor data (sounds and bitmaps).
+
+enum DatumType {
+	kDatumTypeEmpty = 0x00,
+	kDatumTypeUint8 = 0x02,
+	kDatumTypeUint16 = 0x03,
+	kDatumTypeUint32 = 0x04,
+	kDatumTypeInt8 = 0x05,
+	kDatumTypeInt16 = 0x06,
+	kDatumTypeInt32 = 0x07,
+	kDatumTypeFloat = 0x08,
+	kDatumTypeDouble = 0x09,
+	kDatumTypeFilename = 0x0a,
+	kDatumTypeRect = 0x0d,
+	kDatumTypePoint = 0x0e,
+	kDatumTypeGraphicSize = 0x0f,
+	kDatumTypeGraphicUnit = 0x10,
+	kDatumTypeTime = 0x11,
+	kDatumTypeString = 0x12,
+	kDatumTypeVersion = 0x13,
+	kDatumTypeChannelIdent = 0x1b,
+	kDatumTypePolygon = 0x1d,
+};
+
+class ParameterReadStream : public Common::SeekableReadStream {
+public:
+	// Data files are internally little-endian, even on game versions targeting
+	// big-endian systems. The original engine has code for swapping byte order
+	// at runtime when needed. All of these internally assume the data files are
+	// stored little-endian on disk.
+	byte readTypedByte();
+	uint16 readTypedUint16();
+	uint32 readTypedUint32();
+	int8 readTypedSByte();
+	int16 readTypedSint16();
+	int32 readTypedSint32();
+	float readTypedFloat();
+	double readTypedDouble();
+	Common::String readTypedFilename();
+	Common::Rect readTypedRect();
+	Common::Point readTypedPoint();
+	Common::Point readTypedGraphicSize();
+	int16 readTypedGraphicUnit();
+	double readTypedTime();
+	Common::String readTypedString();
+	VersionInfo readTypedVersion();
+	uint32 readTypedChannelIdent();
+	Polygon readTypedPolygon();
+
+private:
+	void readAndVerifyType(DatumType type);
+};
+
+class Chunk : public ParameterReadStream {
+public:
+	Chunk() = default;
+	Chunk(Common::SeekableReadStream *stream);
+
+	uint32 bytesRemaining();
+
+	uint32 _id = 0;
+	uint32 _length = 0;
+
+	// ReadStream implementation
+	virtual bool eos() const { return _parentStream->eos(); };
+	virtual bool err() const { return _parentStream->err(); };
+	virtual void clearErr() { _parentStream->clearErr(); };
+	virtual uint32 read(void *dataPtr, uint32 dataSize);
+	virtual int64 pos() const { return _parentStream->pos(); };
+	virtual int64 size() const { return _parentStream->size(); };
+	virtual bool skip(uint32 offset) { return seek(offset, SEEK_CUR); };
+	virtual bool seek(int64 offset, int whence = SEEK_SET);
+
+private:
+	Common::SeekableReadStream *_parentStream = nullptr;
+	uint32 _dataStartOffset = 0;
+	uint32 _dataEndOffset = 0;
+};
+
+class Subfile {
+public:
+	Subfile() = default;
+	Subfile(Common::SeekableReadStream *stream);
+
+	Chunk nextChunk();
+	bool atEnd();
+
+	Chunk _currentChunk;
+	uint32 _rate;
+
+private:
+	Common::SeekableReadStream *_stream = nullptr;
+	Chunk _rootChunk;
+};
+
+// The stream loading class hierarchy presented below is a bit complex for reading directly
+// from streams, like we can do on modern computers, without needing to worry about
+// buffering from CD-ROM. But we are staying close to the original logic and class
+// hierarchy where possible, so some of that original architecture is reflected here.
+typedef uint32 ChannelIdent;
+
+class CdRomStream : public Common::File {
+public:
+	CdRomStream() {};
+	void openStream(uint streamId);
+	void closeStream() { close(); }
+
+	Subfile getNextSubfile();
+
+private:
+	uint _fileId = 0;
+};
+
+class ChannelClient {
+public:
+	virtual ~ChannelClient() {};
+
+	void setChannelIdent(ChannelIdent channelIdent) { _channelIdent = channelIdent; }
+	ChannelIdent channelIdent() const { return _channelIdent; }
+
+	virtual void readChunk(Chunk &chunk) {};
+
+	void registerWithStreamManager();
+	void unregisterWithStreamManager();
+
+protected:
+	ChannelIdent _channelIdent = 0;
+};
+
+class StreamFeed {
+public:
+	StreamFeed(uint streamId) : _id(streamId) {};
+	virtual ~StreamFeed() {};
+
+	virtual void openFeed(uint streamId, uint startOffset) = 0;
+
+	// The original also has forceCloseFeed, which doesn't do some other cleanup
+	// that the regular closeFeed does. However, since we are not doing caching and
+	// some other functionality in the original, we don't need this.
+	virtual void closeFeed() = 0;
+	virtual void stopFeed() = 0;
+	virtual void readData() = 0;
+
+	uint _id = 0;
+
+protected:
+	CdRomStream *_stream = nullptr;
+};
+
+class ImtStreamFeed : public StreamFeed {
+public:
+	ImtStreamFeed(uint streamId);
+	~ImtStreamFeed();
+
+	virtual void openFeed(uint streamId, uint startOffset) override;
+	virtual void closeFeed() override;
+	// This implementation is currently empty because all this has to do with read timing.
+	virtual void stopFeed() override {};
+	virtual void readData() override;
+};
+
+class StreamFeedManager {
+public:
+	~StreamFeedManager();
+
+	void registerChannelClient(ChannelClient *client);
+	void unregisterChannelClient(ChannelClient *client);
+	ChannelClient *channelClientForChannel(uint clientId) { return _channelClients.getValOrDefault(clientId); }
+
+	ImtStreamFeed *openStreamFeed(uint streamId, uint offsetInStream = 0, uint maxBytesToRead = 0);
+	void closeStreamFeed(StreamFeed *streamFeed);
+
+private:
+	Common::HashMap<uint, StreamFeed *> _streamFeeds;
+	Common::HashMap<ChannelIdent, ChannelClient *> _channelClients;
+};
+
+} // End of namespace MediaStation
+
+#endif