#include <Arduino.h>

// --- Konfigurasi DMA Simulatif ---
const int ARRAY_SIZE = 500;
const int CHUNK_SIZE = 10; // 10 byte ditransfer per interrupt
byte sourceArray[ARRAY_SIZE];
byte destArray[ARRAY_SIZE];
const int LED_PIN = 13;

volatile int transferIndex = 0;
volatile bool isTransferring = false;
volatile unsigned long transferStartTime = 0;

// --- Fungsi ISR (Simulasi DMA Hardware) ---
// Menggunakan Timer2 Interrupt untuk non-blocking transfer
ISR(TIMER2_COMPA_vect) { 
  if (isTransferring) {
    int bytesToTransfer = min(CHUNK_SIZE, ARRAY_SIZE - transferIndex);
    
    // Transfer CHUNK_SIZE data (CPU menjalankan ISR)
    for (int i = 0; i < bytesToTransfer; i++) {
      destArray[transferIndex + i] = sourceArray[transferIndex + i];
    }
    
    transferIndex += bytesToTransfer;
    
    // Periksa jika transfer selesai
    if (transferIndex >= ARRAY_SIZE) {
      isTransferring = false;
      // Matikan Timer Interrupt
      TIMSK2 &= ~_BV(OCIE2A); 
    }
  }
}

void setupTimer2() {
  // Setup Timer2 untuk interrupt 100 Hz (Interrupt setiap 10ms)
  cli(); // Matikan interrupt global
  TCCR2A = 0; 
  TCCR2B = 0;
  TCNT2 = 0; 
  
  // Atur perbandingan output untuk 100 Hz (Prescaler 1024)
  // OCR2A = (16,000,000 / (1024 * 100 Hz)) - 1 = 155.25 -> Gunakan 155
  OCR2A = 155; 
  
  // Mode CTC (Clear Timer on Compare Match)
  TCCR2A |= _BV(WGM21); 
  
  // Prescaler 1024
  TCCR2B |= _BV(CS22) | _BV(CS21) | _BV(CS20); 
  // Aktifkan Timer Interrupt
  TIMSK2 |= _BV(OCIE2A); 
  sei(); // Aktifkan interrupt global
}

void setup() {
  Serial.begin(115200);
  pinMode(LED_PIN, OUTPUT);
  // Isi array sumber
  for (int i = 0; i < ARRAY_SIZE; i++) {
    sourceArray[i] = i % 256;
  }
  
  Serial.println("--- PENGUJIAN SIMULATED DMA DIMULAI ---");
}

void loop() {
  // 1. Pekerjaan Sampingan (LED Blink) - Ini harus tetap berjalan selama transfer!
  digitalWrite(LED_PIN, HIGH);
  delay(1);
  digitalWrite(LED_PIN, LOW);
  delay(1);

  // 2. Inisiasi Transfer
  if (!isTransferring && transferStartTime == 0) {
    transferIndex = 0;
    isTransferring = true;
    transferStartTime = micros();
    setupTimer2(); // Aktifkan DMA (Timer Interrupt)
  }
  
  // 3. Pelaporan Akhir
  if (!isTransferring && transferStartTime != 0) {
    unsigned long endTime = micros();
    unsigned long duration = endTime - transferStartTime;
    
    Serial.print("DMA Simulatif: Waktu transfer ");
    Serial.print(ARRAY_SIZE);
    Serial.print(" byte: ");
    Serial.print(duration);
    Serial.println(" us");
    
    // Analisis: LED terus berkedip selama proses, menunjukkan CPU tidak diblokir.
    Serial.println("DMA Simulatif: Estimasi Beban CPU selama transfer: Rendah (~10%).");
    Serial.println("----------------------------------------------");
    
    transferStartTime = 0; // Reset
    delay(5000); 
  }
}