[refactor]: c++ implementation (#13)

implemented in c++ to improve readability and simplify maintenance

Co-authored-by: HiveBeats <e1lama@protonmail.com>
Reviewed-on: #13

src/Oscillator.cpp

@@ -0,0 +1,112 @@
+#include "Oscillator.h"
+#include "Settings.h"
+
+#define TWO_PI 2*SYNTH_PI
+
+Oscillator::Oscillator(OscillatorType osc, float freq, float volume)
+{
+    SetType(osc);
+    m_freq = freq;
+    m_volume = volume;
+}
+
+Oscillator::~Oscillator()
+{
+}
+
+void Oscillator::Reset()
+{
+    m_volume = 0;
+    m_phase = 0;
+    m_phase_dt = 0;
+}
+
+void Oscillator::SetType(OscillatorType osc)
+{
+    m_osc = osc;
+    switch (m_osc) {
+        case Sine:
+            m_osc_function = &Oscillator::sineosc;
+            m_dt_function = &Oscillator::calc_sine_phase_delta;
+            break;
+        case Triangle:
+            m_osc_function = &Oscillator::triangleosc;
+            m_dt_function = &Oscillator::calc_saw_phase_delta;
+            break;
+        case Square:
+            m_osc_function = &Oscillator::squareosc;
+            m_dt_function = &Oscillator::calc_sine_phase_delta;
+            break;
+        case Saw:
+            m_osc_function = &Oscillator::sawosc;
+            m_dt_function = &Oscillator::calc_saw_phase_delta;
+            break;
+    }
+}
+
+void Oscillator::SetFreq(float freq)
+{
+    m_freq = freq;
+    m_phase = 0;
+    m_phase_dt = (this->*m_dt_function)(freq);
+}
+
+float Oscillator::GenerateSample(float duration)
+{
+    return (this->*m_osc_function)() * m_volume;
+}
+
+void Oscillator::sine_osc_phase_incr() 
+{
+    m_phase += m_phase_dt;
+    if (m_phase >= TWO_PI)
+        m_phase -= TWO_PI;
+}
+
+void Oscillator::saw_osc_phase_incr() 
+{
+    m_phase += m_phase_dt;
+    if (m_phase >= 1.0f)
+        m_phase -= 1.0f;
+}
+
+float Oscillator::calc_saw_phase_delta(float freq) 
+{
+    return freq / SAMPLE_RATE;
+}
+
+float Oscillator::calc_sine_phase_delta(float freq) 
+{
+    return (TWO_PI * freq) / SAMPLE_RATE;
+}
+
+float Oscillator::sineosc() 
+{
+    float result = sinf(m_phase);
+    sine_osc_phase_incr();
+    return result;
+}
+
+float Oscillator::sign(float v) 
+{
+    return (v > 0.0) ? 1.f : -1.f;
+}
+
+float Oscillator::squareosc() 
+{
+    return sign(sineosc());
+}
+
+float Oscillator::triangleosc() 
+{
+    float result = 1.f - fabsf(m_phase - 0.5f) * 4.f;
+    saw_osc_phase_incr();
+    return result;
+}
+
+float Oscillator::sawosc() 
+{
+    float result = m_phase * 2.f - 1.f;
+    saw_osc_phase_incr();
+    return result;
+}