SM-26 synthesizer: initial implementation

Source/SynthEngine.h

@@ -0,0 +1,106 @@
+#pragma once
+
+#include <JuceHeader.h>
+#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;
+        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;
+};
+
+} // namespace sm26