tonesynth.h

/*
    Minimal Synthesizer for Qt applications
    Copyright (C) 2022-2023 Pedro Lopez-Cabanillas <plcl@users.sf.net>

    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 library 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 TONESYNTH_H
#define TONESYNTH_H

#include <QIODevice>
#include <QObject>
#include <QString>
#include <QMap>
#include <QAudioFormat>

class ToneSynthesizer : public QIODevice
{
    Q_OBJECT

public:
    enum class EnvelopeState : int {
        silentState,
        attackState,
        sustainState,
        releaseState
    };
    Q_ENUM(EnvelopeState)

    ToneSynthesizer(const QAudioFormat &format);
    qint64 readData(char *data, qint64 maxlen) override;
    qint64 writeData(const char *data, qint64 len) override;
	qint64 size() const override;
	qint64 bytesAvailable() const override;

    void setOctave(int newOctave);
    qint64 lastBufferSize() const;
    void resetLastBufferSize();

public slots:
    void start();
    void stop();
    void noteOn(const QString& note);
    void noteOff();

private:
    QAudioFormat m_format;
    int m_octave; /* octave 3 */
    /* Equal temperament scale */
    const QMap<QString, qreal> m_freq{
        {"C'",	261.626},
        {"B",	246.942},
        {"A#",	233.082},
        {"A",	220.000},
        {"G#",	207.652},
        {"G",	195.998},
        {"F#",	184.997},
        {"F",	174.614},
        {"E",	164.814},
        {"D#",	155.563},
        {"D",	146.832},
        {"C#",	138.591},
        {"C",	130.813}
    };
    qreal m_angleDelta;
    qreal m_currentAngle;
    qint64 m_lastBufferSize;
    // Envelope generation
    EnvelopeState m_envelState;
    qreal m_envelVolume;
    qreal m_envelDelta;
    quint64 m_envelCount;
    quint64 m_attackTime;
    quint64 m_releaseTime;
};

#endif // TONESYNTH_H