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_ECLIPSE_AY_MUSIC_H
#define FREESCAPE_ECLIPSE_AY_MUSIC_H

#include "audio/softsynth/ay8912.h"
#include "audio/mixer.h"
#include "freescape/music.h"

namespace Freescape {

class EclipseAYMusicPlayer : public MusicPlayer, private Audio::AY8912Stream {
public:
    EclipseAYMusicPlayer(Audio::Mixer *mixer);
    ~EclipseAYMusicPlayer() override;

    void startMusic() override;
    void stopMusic() override;
    bool isPlaying() const override;

    // AudioStream overrides
    int readBuffer(int16 *buffer, const int numSamples) override;
    bool endOfData() const override { return !_musicActive; }
    bool endOfStream() const override { return false; }

private:
    static const byte kChannelCount = 3;
    static const byte kMaxNote = 94;

    enum ADSRPhase {
        kPhaseOff,
        kPhaseAttack,
        kPhaseDecay,
        kPhaseSustain,
        kPhaseRelease
    };

    struct ChannelState {
        const byte *orderList;
        byte orderPos;

        uint16 patternDataOffset;
        uint16 patternOffset;

        byte instrumentOffset;
        byte currentNote;
        byte transpose;

        uint16 currentPeriod;

        byte durationReload;
        byte durationCounter;

        byte effectMode;
        byte effectParam;
        byte arpeggioTarget;
        byte arpeggioParam;
        byte arpeggioSequencePos;
        byte arpeggioSequence[9];
        byte arpeggioSequenceLen;

        byte noteStepCommand;
        byte stepDownCounter;

        byte vibratoPhase;
        byte vibratoCounter;

        byte delayValue;
        byte delayCounter;

        byte waveform;
        byte instrumentFlags;
        bool gateOffDisabled;

        ADSRPhase adsrPhase;
        uint16 adsrVolume; // 8.8 fixed point (0x0000 - 0x0F00)
        uint16 attackRate;
        uint16 decayRate;
        byte sustainLevel;
        uint16 releaseRate;

        void reset();
    };

    Audio::Mixer *_mixer;
    Audio::SoundHandle _handle;
    bool _musicActive;
    byte _speedDivider;
    byte _speedCounter;
    byte _mixerRegister;
    int _tickSampleCount;
    ChannelState _channels[kChannelCount];
    byte _arpeggioIntervals[8];

    void onTimer();
    void setupSong();
    void silenceAll();
    void loadNextPattern(int channel);
    void buildEffectArpeggio(int channel);
    void loadCurrentPeriod(int channel);
    void finalizeChannel(int channel);
    void processChannel(int channel, bool newBeat);
    void parseCommands(int channel);
    void applyNote(int channel, byte note);
    void applyFrameEffects(int channel);
    bool applyInstrumentVibrato(int channel);
    void applyEffectArpeggio(int channel);
    void applyTimedSlide(int channel);

    void triggerADSR(int channel, byte ad, byte sr);
    void releaseADSR(int channel);
    void updateADSR(int channel);

    byte readPatternByte(int channel);
    byte clampNote(byte note) const;
    void writeChannelPeriod(int channel, uint16 period);
};

} // namespace Freescape

#endif