ay.music.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 FREESCAPE_CASTLE_AY_MUSIC_H
#define FREESCAPE_CASTLE_AY_MUSIC_H
 
#include "audio/mixer.h"
#include "audio/softsynth/ay8912.h"
#include "freescape/music.h"
 
namespace Freescape {
 
class CastleAYMusicPlayer : public MusicPlayer, private Audio::AY8912Stream {
public:
    CastleAYMusicPlayer(Audio::Mixer *mixer);
    ~CastleAYMusicPlayer() override;
 
    void startMusic() override;
    void stopMusic() override;
    bool isPlaying() const override;
 
    int readBuffer(int16 *buffer, const int numSamples) override;
    bool endOfData() const override { return !_musicActive; }
    bool endOfStream() const override { return false; }
 
private:
    enum {
        kChannelCount = 3,
        kMaxNote = 94
    };
 
    enum ADSRPhase {
        kPhaseOff,
        kPhaseAttack,
        kPhaseDecay,
        kPhaseSustain,
        kPhaseRelease
    };
 
    struct ChannelState {
        const byte *orderList;
        uint16 orderPosition;
        byte patternIndex;
        uint16 patternDataOffset;
        uint16 patternOffset;
        uint16 delay;
        byte instrument;
        int8 transpose;
        byte currentNote;
        uint16 baseSIDFrequency;
        uint16 basePeriod;
        uint16 currentPeriod;
        uint16 adsrVolume;
        uint16 attackRate;
        uint16 decayRate;
        byte sustainLevel;
        uint16 releaseRate;
        int16 sidFrequencyOffset;
        byte vibratoStep;
        bool vibratoReverse;
        bool toneEnabled;
        bool noiseEnabled;
        bool active;
        ADSRPhase adsrPhase;
 
        void reset(const byte *channelOrderList);
    };
 
    Audio::Mixer *_mixer;
    Audio::SoundHandle _handle;
    bool _musicActive;
    byte _mixerRegister;
    int _tickSampleCount;
    uint32 _tick;
    ChannelState _channels[kChannelCount];
 
    void onTimer();
    void setupSong();
    void silenceAll();
    void loadNextPattern(int channel);
    byte readPatternByte(int channel);
    void parseCommands(int channel);
    void noteOn(int channel, byte note);
    void noteOff(int channel);
    void writeChannelPeriod(int channel, uint16 period);
    void noteToPeriod(int note, uint16 &period) const;
    void applyFrameEffects(int channel);
    void triggerADSR(int channel, byte attackDecay, byte sustainRelease);
    void releaseADSR(int channel);
    void updateADSR(int channel);
    void setChannelOutput(int channel, bool toneEnabled, bool noiseEnabled);
    void writeNoisePeriod(uint16 period);
    byte sidControlForInstrument(byte instrument) const;
    byte instrumentVolumeScale(byte instrument) const;
};
 
} // namespace Freescape
 
#endif