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

implemented in c++ to improve readability and simplify maintenance

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

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(const char* root_note, char* target_note) {
+        const 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()
+{
+}