PDResonant.h

/*
 * PDResonant.h
 *
 * This file is part of Mozzi.
 *
 * Copyright 2013-2024 Tim Barrass and the Mozzi Team
 *
 * Mozzi is licensed under the GNU Lesser General Public Licence (LGPL) Version 2.1 or later.
 *
 */
 
#include <mozzi_midi.h>
#include <ADSR.h>
#include <Oscil.h>
#include <Phasor.h>
// wavetable for oscillator:
#include <tables/sin2048_int8.h>
 
class PDResonant
{
 
public:
 
    PDResonant():
            PDM_SCALE(0.05)
    {
        aOsc.setTable(SIN2048_DATA);
        aAmpEnv.setADLevels(255, 255);
        aAmpEnv.setTimes(50, 300, 60000, 1000);
        kResonantFreqEnv.setADLevels(255,100);
    }
 
    void noteOn(byte channel, byte pitch, byte velocity)
    {
        kResonantFreqEnv.noteOn();
        aAmpEnv.noteOn();
        freq = mtof(pitch);
        aBaseCounter.setFreq(freq); // gets modulated in updateControl()
        aResonanceFreqCounter.setFreq(freq);
    }
 
 
    void noteOff(byte channel, byte pitch, byte velocity)
    {
        aAmpEnv.noteOff();
        kResonantFreqEnv.noteOff();
    }
 
 
    void setPDEnv(int attack, int decay)
    {
        // sustain and release timesare hardcoded here but don't need to be
        kResonantFreqEnv.setTimes(attack, decay, 60000, 1000);
        kResonantFreqEnv.update();
 
        float resonance_freq = freq + ((float)freq * ((float)kResonantFreqEnv.next()*PDM_SCALE));
        aResonanceFreqCounter.setFreq(resonance_freq);
    }
 
 
    void update()
    {
        aAmpEnv.update();
        kResonantFreqEnv.update();
        // change freq of resonant freq counter, following the envelope
        float resonance_freq = freq + ((float)freq * ((float)kResonantFreqEnv.next()*PDM_SCALE));
        aResonanceFreqCounter.setFreq(resonance_freq);
    }
 
    int next()
    {
        static byte previous_base_counter;
        byte base_counter = aBaseCounter.next()>>24;
 
        // reset resonance counter (wiki b.)
        if (base_counter<previous_base_counter) aResonanceFreqCounter.set(0);
        previous_base_counter= base_counter;
 
        // index (phase) needs to end up as 11bit to match 2048 wavetable size
        unsigned int index = aResonanceFreqCounter.next()>>21; // 11 bits fits 2048 cell sin table
 
        // amp ramp smooths the jump when aResonanceFreqCounter is reset (wiki d.)
        byte amp_ramp = 255-base_counter;
 
        // wiki e., with amp envelope added
        return ((long)aAmpEnv.next() * amp_ramp * aOsc.atIndex(index))>>16;
 
        // return ((index>>3)*amp_ramp)>>8; // this also sounds good - squelchy sawtooth
    }
 
 
private:
    const float PDM_SCALE;
    byte amp;
    int freq;
 
    Phasor <MOZZI_AUDIO_RATE> aBaseCounter;
    Phasor <MOZZI_AUDIO_RATE> aResonanceFreqCounter;
 
    Oscil <SIN2048_NUM_CELLS, MOZZI_AUDIO_RATE> aOsc;
    ADSR <MOZZI_CONTROL_RATE, MOZZI_AUDIO_RATE> aAmpEnv;
    ADSR <MOZZI_CONTROL_RATE, MOZZI_CONTROL_RATE> kResonantFreqEnv;
 
};