datafile.h

/* 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;
};
 
// 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();
 
private:
    void readAndVerifyType(DatumType type);
};
 
class Chunk : public ParameterReadStream {
public:
    Chunk() = default;
    Chunk(Common::SeekableReadStream *stream);
 
    uint32 bytesRemaining();
    uint32 startPos() const { return _dataStartOffset; }
 
    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