Arduino Dual Buzzer Melody Code

// ------ pins ------
#define BUZZER1_PIN 8
#define BUZZER2_PIN 9

// ------ include note frequencies ------
#define NOTE_B0 31
#define NOTE_C1 33
#define NOTE_CS1 35
#define NOTE_D1 37
#define NOTE_DS1 39
#define NOTE_E1 41
#define NOTE_F1 44
#define NOTE_FS1 46
#define NOTE_G1 49
#define NOTE_GS1 52
#define NOTE_A1 55
#define NOTE_AS1 58
#define NOTE_B1 62
#define NOTE_C2 65
#define NOTE_CS2 69
#define NOTE_D2 73
#define NOTE_DS2 78
#define NOTE_E2 82
#define NOTE_F2 87
#define NOTE_FS2 93
#define NOTE_G2 98
#define NOTE_GS2 104
#define NOTE_A2 110
#define NOTE_AS2 117
#define NOTE_B2 123
#define NOTE_C3 131
#define NOTE_CS3 139
#define NOTE_D3 147
#define NOTE_DS3 156
#define NOTE_E3 165
#define NOTE_F3 175
#define NOTE_FS3 185
#define NOTE_G3 196
#define NOTE_GS3 208
#define NOTE_A3 220
#define NOTE_AS3 233
#define NOTE_B3 247
#define NOTE_C4 262
#define NOTE_CS4 277
#define NOTE_D4 294
#define NOTE_DS4 311
#define NOTE_E4 330
#define NOTE_F4 349
#define NOTE_FS4 370
#define NOTE_G4 392
#define NOTE_GS4 415
#define NOTE_A4 440
#define NOTE_AS4 466
#define NOTE_B4 494
#define NOTE_C5 523
#define NOTE_CS5 554
#define NOTE_D5 587
#define NOTE_DS5 622
#define NOTE_E5 659
#define NOTE_F5 698
#define NOTE_FS5 740
#define NOTE_G5 784
#define NOTE_GS5 831
#define NOTE_A5 880
#define NOTE_AS5 932
#define NOTE_B5 988
#define NOTE_C6 1047
#define NOTE_CS6 1109
#define NOTE_D6 1175
#define NOTE_DS6 1245
#define NOTE_E6 1319
#define NOTE_F6 1397
#define NOTE_FS6 1480
#define NOTE_G6 1568
#define NOTE_GS6 1661
#define NOTE_A6 1760
#define NOTE_AS6 1865
#define NOTE_B6 1976
#define NOTE_C7 2093
#define NOTE_CS7 2217
#define NOTE_D7 2349
#define NOTE_DS7 2489
#define NOTE_E7 2637
#define NOTE_F7 2794
#define NOTE_FS7 2960
#define NOTE_G7 3136
#define NOTE_GS7 3322
#define NOTE_A7 3520
#define NOTE_AS7 3729
#define NOTE_B7 3951
#define NOTE_C8 4186
#define NOTE_REST 0

// ------ note struct ------
struct Note {
  int frequency;
  int duration;
};

// ------ buzzer melodies ------ (IMPORTANT)
Note melody1[] = {
  
};
Note melody2[] = {
  
};

int length1 = sizeof(melody1) / sizeof(Note);
int length2 = sizeof(melody2) / sizeof(Note);

// ------ buzzer state ------
int currentNote1 = 0;
int currentNote2 = 0;

unsigned long noteStartTime1 = 0;
unsigned long noteStartTime2 = 0;

bool buzzerState1 = false;
bool buzzerState2 = false;

unsigned long toggleTime1 = 0;
unsigned long toggleTime2 = 0;

unsigned long halfPeriod1 = 0;
unsigned long halfPeriod2 = 0;

void setup() {
  pinMode(BUZZER1_PIN, OUTPUT);
  pinMode(BUZZER2_PIN, OUTPUT);
}

void loop() {
  unsigned long now = millis();

  // Buzzer 1
  if (currentNote1 < length1) {
    Note n1 = melody1[currentNote1];
    if (now - noteStartTime1 >= n1.duration) {
      currentNote1++;
      noteStartTime1 = now;
      if (currentNote1 < length1 && melody1[currentNote1].frequency > 0) {
        halfPeriod1 = 500000L / melody1[currentNote1].frequency;
        toggleTime1 = micros();
      } else {
        digitalWrite(BUZZER1_PIN, LOW);
      }
    } else if (n1.frequency > 0 && (micros() - toggleTime1 >= halfPeriod1)) {
      buzzerState1 = !buzzerState1;
      digitalWrite(BUZZER1_PIN, buzzerState1);
      toggleTime1 = micros();
    }
  }

  // Buzzer 2
  if (currentNote2 < length2) {
    Note n2 = melody2[currentNote2];
    if (now - noteStartTime2 >= n2.duration) {
      currentNote2++;
      noteStartTime2 = now;
      if (currentNote2 < length2 && melody2[currentNote2].frequency > 0) {
        halfPeriod2 = 500000L / melody2[currentNote2].frequency;
        toggleTime2 = micros();
      } else {
        digitalWrite(BUZZER2_PIN, LOW);
      }
    } else if (n2.frequency > 0 && (micros() - toggleTime2 >= halfPeriod2)) {
      buzzerState2 = !buzzerState2;
      digitalWrite(BUZZER2_PIN, buzzerState2);
      toggleTime2 = micros();
    }
  }
}