sound_pcjr.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 AGI_SOUND_PCJR_H
#define AGI_SOUND_PCJR_H

#include "audio/audiostream.h"

namespace Agi {

#define CHAN_MAX 4

#define SAMPLE_RATE 22050

enum GenType {
    kGenSilence,
    kGenTone,
    kGenPeriod,
    kGenWhite
};

struct SndGenChan {
    const byte *data;
    uint16 duration;
    uint16 avail;   // turned on (1)  but when the channel's data runs out, it's set to (0)
    uint16 dissolveCount;
    byte attenuation;
    byte attenuationCopy;

    GenType genType;

    // for the sample mixer
    int freqCount;
};

struct ToneChan {
    int avail;

    int noteCount; // length of tone.. duration

    int freqCount;
    int freqCountPrev;
    int atten;  // volume

    GenType genType;
    int genTypePrev;

    int count;
    int scale;
    int sign;
    unsigned int noiseState; /* noise generator      */
    int feedback;            /* noise feedback mask */
};

class SoundGenPCJr : public SoundGen, public Audio::AudioStream {
public:
    SoundGenPCJr(AgiBase *vm, Audio::Mixer *pMixer);
    ~SoundGenPCJr() override;

    void play(int resnum) override;
    void stop() override;

    // AudioStream API
    int readBuffer(int16 *buffer, const int numSamples) override;

    bool isStereo() const override {
        return false;
    }

    bool endOfData() const override {
        return false;
    }

    int getRate() const override {
        // FIXME: Ideally, we should use _sampleRate.
        return 22050;
    }

private:
    int getNextNote(int ch);
    int getNextNote_v2(int ch);
    int getNextNote_v1(int ch);
    int volumeCalc(SndGenChan *chan);

    void writeData(uint8 val);

    int chanGen(int chan, int16 *stream, int len);

    int fillNoise(ToneChan *t, int16 *buf, int len);
    int fillSquare(ToneChan *t, int16 *buf, int len);

private:
    SndGenChan _channel[CHAN_MAX];
    ToneChan _tchannel[CHAN_MAX];
    int16 *_chanData;
    int _chanAllocated;

    int _dissolveMethod;

    uint8 *_v1data;
    uint32 _v1size;
};

} // End of namespace Agi

#endif /* AGI_SOUND_PCJR_H */