[feat]: Oscillator fine-tune (#22)

closes #19

Reviewed-on: #22

inc/Oscillator.h

@@ -5,31 +5,41 @@
 class Oscillator {
   private:
     OscillatorType m_osc;
-    float m_freq;
+    float m_fine;
+    float m_key;
     float m_volume;
     float m_phase;
-    float m_phase_dt;
     float (Oscillator::*m_osc_function)(void);
+    void SineOscPhaseIncr();
+    void SawOscPhaseIncr();
+    float CalcSawPhaseDelta(float freq);
+    float CalcSinePhaseDelta(float freq);
+    float SawOsc();
+    float TriangleOsc();
+    float SquareOsc();
+    float Sign(float v);
+    float SineOsc();
+
+  protected:
+    float m_phase_dt;
     float (Oscillator::*m_dt_function)(float freq);
-    void sine_osc_phase_incr();
-    void saw_osc_phase_incr();
-    float calc_saw_phase_delta(float freq);
-    float calc_sine_phase_delta(float freq);
-    float sawosc();
-    float triangleosc();
-    float squareosc();
-    float sign(float v);
-    float sineosc();
 
   public:
-    Oscillator(OscillatorType osc, float freq, float volume);
+    Oscillator(OscillatorType osc, float fine, float volume);
     ~Oscillator();
     OscillatorType GetType() { return m_osc; }
     void SetType(OscillatorType osc);
     float GetVolume() { return m_volume; }
     void SetVolume(float volume) { m_volume = volume; }
-    float GetFreq() { return m_freq; }
-    void SetFreq(float freq);
+    float GetKey() { return m_key; }
+    void SetKey(float key);
+    float GetFine() { return m_fine; }
+    void SetFine(float fine) {
+        if (fine != m_fine) {
+            assert(fine >= -2.f && fine <= 2.f);
+            m_fine = fine;
+        }
+    }
     void Reset();
     float Process();
 };