sm-26/Source/SynthEngine.h

#pragma once

#include <JuceHeader.h>
#include <array>
#include "SynthParams.h"
#include "Presets.h"

namespace sm26 {

class SynthEngine
{
public:
    static constexpr int kNumVoices = 12;

    SynthEngine();

    void prepare (double sampleRate, int maxBlockSize);
    void reset();

    void loadPreset (const Preset& p);
    int  presetIndex() const { return currentPresetIndex; }
    void setPresetIndex (int i);

    void setParam (int id, float n01);
    float getParam (int id) const;

    struct KnobView {
        const char* name;
        int param;
        float value01;
        float lo;
        float hi;
    };
    KnobView knobView (int knob) const;

    float knobValue (int knob) const;

    void process (AudioBuffer<float>& buffer, MidiBuffer& midi, int n,
                  double bpm, bool transportPlaying);

    int  notesPlaying() const { return activeNotes; }
    float lastBpm() const { return lastBpmValue; }
    bool transport() const { return wasPlaying; }
    int  delayTimeSamples() const { return lastDelaySamples; }

    const char* waveNameFor (int index) const;

private:
    struct Voice {
        bool   active = false;
        int    note = 60;
        double velocity = 0.8;
        double ph1 = 0.0, ph2 = 0.0;
        double inc1 = 0.0, inc2 = 0.0, glidedInc1 = 0.0;
        double env = 0.0;
        int    envState = 0;
        int    age = 0;
        int    fadeLen = 32;
        double ic1eq = 0.0, ic2eq = 0.0;
    };

    void noteOn (int note, float vel);
    void noteOff (int note);
    void allNotesOff();
    Voice* findFreeOrSteal();
    void resetVoice (Voice& v, int note, float vel);
    float oscWave (int wave, double phase);
    float computeSingleSample (Voice& v, float& outL, float& outR,
                               double fad, double frel, double fsus, double fcut,
                               double fq, double drive, double glideCoef, double bpm);
    double cutoffFor (const Voice& v, double baseCutoff, double envAmt, double env);

    double sampleRate = 48000.0;
    int maxBlock = 512;

    float params[kNumParams];
    int knobParams[kNumKnobs];
    const char* knobNames[kNumKnobs];
    float knobLows[kNumKnobs];
    float knobHighs[kNumKnobs];

    Voice voices[kNumVoices];
    int activeNotes = 0;

    struct DelayLine
    {
        std::vector<std::vector<float>> buf;
        std::vector<int> writePos;
        int maxLen = 1;
        void prepare (double sr)
        {
            maxLen = (int) (sr * 18.0) + 4;
            buf.assign (2, std::vector<float> (maxLen, 0.0f));
            writePos.assign (2, 0);
        }
        void clear() { for (auto& c : buf) std::fill (c.begin(), c.end(), 0.0f); }
    };

    DelayLine delay;
    double lastDelaySamples = 0.0;
    double lastBpmValue = 120.0;
    bool wasPlaying = false;

    int currentPresetIndex = 0;
    mutable juce::SpinLock paramLock;

    std::array<float, kNumParams> smooth;
    float smCoef = 1.0f;
    float ftA = 1.0f, ftB = 0.0f, ftC = 0.0f;
};

} // namespace sm26