feat(filter): Add modulation support and LFO integration

core/Oscillator.hpp

@@ -0,0 +1,39 @@
+#ifndef OSCILLATOR_HPP_INCLUDED
+#define OSCILLATOR_HPP_INCLUDED
+
+#include <cstdint>
+
+#ifndef M_PI
+#define M_PI 3.14159265358979323846
+#endif
+
+class Oscillator {
+  enum WaveShape { kWaveShapeSine, kWaveShapeTriangle, kWaveShapeSquare };
+
+public:
+  Oscillator(float initFreq);
+  void process(float *out, uint32_t frames);
+
+  void setFrequency(float newFreq);
+  float getFrequency() const;
+
+  void setGain(float newGain);
+  float getGain() const;
+
+  void setSampleRate(float newSampleRate);
+  float getSampleRate() const;
+
+  void setWaveShape(WaveShape shape);
+  WaveShape getWaveShape() const;
+
+private:
+  float freq_;
+  float gain_;
+  WaveShape waveShape_;
+  float sampleRate_;
+  float phase_;
+  float inc_;
+  void recalc_();
+};
+
+#endif // OSCILLATOR_HPP_INCLUDED