wip: oscillator class

inc/Note.h

@@ -0,0 +1,8 @@
+#pragma once
+
+#include <string>
+
+struct Note {
+    std::string& name;
+    int length;
+}

inc/Oscillator.h

@@ -0,0 +1,38 @@
+#pragma once
+#include<vector>
+#include "OscillatorType.h"
+
+typedef float (Oscillator::*OscFunction)(void);
+typedef float (Oscillator::*DtFunction)(float);
+
+class Oscillator
+{
+    private:
+        OscillatorType m_osc;
+        float m_freq;
+        float m_volume;
+        float m_phase;
+        float m_phase_dt;
+        OscFunction m_osc_function;
+        DtFunction m_dt_function;
+        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 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);
+        void Reset();
+        float GenerateSample(float duration);
+};

inc/OscillatorType.h

@@ -0,0 +1,7 @@
+#pragma once
+typedef enum {
+    Sine,
+    Triangle,
+    Saw,
+    Square
+} OscillatorType;

inc/Settings.h

@@ -0,0 +1,16 @@
+#pragma once
+
+#define SAMPLE_RATE 48000.f
+#define BPM 120.f
+#define BEAT_DURATION 60.f/BPM
+#define PITCH_STANDARD 440.f
+#define VOLUME 0.5f
+#define ATTACK_MS 100.f
+#define STREAM_BUFFER_SIZE 4096
+
+#define SYNTH_PI 3.1415926535f
+#define SYNTH_VOLUME 0.5f
+
+#define WINDOW_WIDTH 640
+#define WINDOW_HEIGHT 480
+#define OSCILLATOR_PANEL_WIDTH 200

src/Oscillator.cpp

@@ -0,0 +1,103 @@
+#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 = &sineosc;
+            m_dt_function = &calc_sine_phase_delta;
+            break;
+        case Triangle:
+            m_osc_function = &triangleosc;
+            m_dt_function = &calc_saw_phase_delta;
+            break;
+        case Square:
+            m_osc_function = &squareosc;
+            m_dt_function = &calc_sine_phase_delta;
+            break;
+        case Saw:
+            m_osc_function = &sawosc;
+            m_dt_function = &calc_saw_phase_delta;
+            break;
+    }
+}
+
+void Oscillator::SetFreq(float freq)
+{
+    m_freq = freq;
+    m_phase = 0;
+    m_phase_dt = m_dt_function(freq);
+}
+
+float Oscillator::GenerateSample(float duration)
+{
+    return 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;
+}