wip: synth class

inc/KeyBoard.h

@@ -0,0 +1,80 @@
+#pragma once
+#include "Settings.h"
+#include <cmath>
+#include <cstring>
+#include <cstdlib>
+#include <string>
+
+class KeyBoard
+{
+private:
+    /* data */
+    static int get_semitone_shift_internal(char* root_note, char* target_note) {
+        char* pitch_classes[12] =
+            { "C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "B" };
+
+        // Extract the note number and pitch class for the root note
+        int root_note_num = (int)root_note[strlen(root_note) - 1] - '0';
+
+        char* root_pitch_class_str = (char*)malloc((strlen(root_note) - 1) * sizeof(char));
+        strncpy(root_pitch_class_str, root_note, strlen(root_note) - 1);
+
+        int root_pitch_class = -1;
+
+        for (int i = 0; i < 12; i++) {
+            if (strcmp(pitch_classes[i], root_pitch_class_str) == 0) {
+                root_pitch_class = i;
+                break;
+            }
+        }
+
+        free(root_pitch_class_str);
+
+        // Extract the note number and pitch class for the target note
+        int target_note_num = (int)target_note[strlen(target_note) - 1] - '0';
+
+        char* target_pitch_class_str =
+            (char*)malloc((strlen(target_note) - 1) * sizeof(char));
+        strncpy(target_pitch_class_str, target_note, strlen(target_note) - 1);
+
+        int target_pitch_class = -1;
+
+        for (int i = 0; i < 12; i++) {
+            if (strcmp(pitch_classes[i], target_pitch_class_str) == 0) {
+                target_pitch_class = i;
+                break;
+            }
+        }
+
+        free(target_pitch_class_str);
+
+        // Calculate the semitone shift using the formula
+        return (target_note_num - root_note_num) * 12 +
+            (target_pitch_class - root_pitch_class);
+    }
+public:
+    KeyBoard(/* args */);
+    ~KeyBoard(); 
+
+    static float GetHzBySemitone(int semitone) {
+        return PITCH_STANDARD * powf(powf(2.f, (1.f / 12.f)), semitone);
+    }
+
+    static int GetSemitoneShift(const std::string& target_note) {
+        char* target_note_cstr = new char[target_note.length() + 1];
+        strcpy(target_note_cstr, target_note.c_str());
+        
+        int result = get_semitone_shift_internal("A4", target_note_cstr);
+        
+        delete target_note_cstr;
+        return result;
+    }
+};
+
+KeyBoard::KeyBoard(/* args */)
+{
+}
+
+KeyBoard::~KeyBoard()
+{
+}

inc/Note.h

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

inc/Oscillator.h

@@ -0,0 +1,39 @@
+#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

inc/Synth.h

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <vector>
+#include "Oscillator.h"
+#include "Note.h"
+
+class Synth
+{
+private:
+    std::vector<Oscillator&> m_oscillators;
+    //OscillatorUI* ui_oscillators;
+    Note m_current_note;
+    std::vector<float> m_out_signal;
+    std::vector<float> & sum_oscillators(float duration);
+    std::vector<float> & note(int semitone, float beats);
+    
+public:
+    Synth(/* args */);
+    ~Synth();
+    std::vector<float> & GetNoteSound(Note input)
+};
+
+Synth::Synth(/* args */)
+{
+    m_oscillators.push_back(new Oscillator(OscillatorType.Sine, 440.f, VOLUME));
+}
+
+Synth::~Synth()
+{
+}

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 = &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;
+}

src/Synth.cpp

@@ -0,0 +1,45 @@
+#include "Synth.h"
+#include "Settings.h"
+#include "KeyBoard.h"
+#include "OscillatorType.h"
+#include "Note.h"
+
+std::vector<float> & Synth::sum_oscillators(float duration)
+{
+    size_t sample_count = (size_t)(duration * SAMPLE_RATE);
+
+    std::vector<float> output;// = new std::vector<float>();
+    output.reserve(sample_count);
+
+    for (size_t i = 0; i < sample_count; i++) 
+    {
+        float sample = 0.0f;
+        for (Oscillator& osc : m_oscillators)
+        {
+            sample += osc.GenerateSample(duration);
+        }
+
+        output.push_back(sample);
+    }
+
+    return output;
+}
+
+std::vector<float> & Synth::note(int semitone, float beats) 
+{
+    float hz = KeyBoard::GetHzBySemitone(semitone);
+    float duration = beats * BEAT_DURATION;
+    
+    // will change after oscillator starts to be more autonomous
+    for (size_t i = 0; i < m_oscillators.size(); i++) {
+        m_oscillators[i].SetFreq(hz);
+    }
+
+    return sum_oscillators(duration);
+}
+
+std::vector<float> & Synth::GetNoteSound(Note input) {
+    float length = 1.f / input.length;
+    int semitone_shift = KeyBoard::GetSemitoneShift(input.name);
+    return note(semitone_shift, length);
+}