/*
  Praktikum: Simulasi Register & Flag - Versi Interaktif
  Dosen: Muhammad Ikhwan Fathulloh

  Tujuan:
    - Memahami fungsi register umum (R0–R31)
    - Melihat status bit flag (C, Z, N, V, S) secara visual
    - Menampilkan flag aktif secara bergantian berdasarkan kondisi tertentu
*/

#define LED_C 2
#define LED_Z 3
#define LED_N 4
#define LED_V 5
#define LED_S 6

byte R0, R1, R2;
bool C, Z, N, V, S;

int mode = 0;  // 0 = Simulasi acak, 1 = Demo flag bergantian
unsigned long lastChange = 0;

void setup() {
  Serial.begin(9600);
  pinMode(LED_C, OUTPUT);
  pinMode(LED_Z, OUTPUT);
  pinMode(LED_N, OUTPUT);
  pinMode(LED_V, OUTPUT);
  pinMode(LED_S, OUTPUT);

  Serial.println("=== Simulasi Register dan Flag ===");
  Serial.println("Menyalakan semua LED (tes rangkaian)...");
  testAllLED();
  Serial.println("Masuk ke mode simulasi...");
}

void loop() {
  if (mode == 0) {
    // Mode Simulasi Acak
    simulateRandomOperation();
  } else {
    // Mode Demo Flag Bergantian
    demoFlagSequence();
  }

  // Ubah mode setiap 20 detik
  if (millis() - lastChange > 20000) {
    mode = 1 - mode;
    lastChange = millis();
    Serial.println(mode == 0 ? "\nKembali ke mode Simulasi Acak\n" : "\nMasuk ke mode Demo Flag Bergantian\n");
  }
  delay(1500);
}

void testAllLED() {
  digitalWrite(LED_C, HIGH);
  digitalWrite(LED_Z, HIGH);
  digitalWrite(LED_N, HIGH);
  digitalWrite(LED_V, HIGH);
  digitalWrite(LED_S, HIGH);
  delay(2000);
  digitalWrite(LED_C, LOW);
  digitalWrite(LED_Z, LOW);
  digitalWrite(LED_N, LOW);
  digitalWrite(LED_V, LOW);
  digitalWrite(LED_S, LOW);
}

void simulateRandomOperation() {
  R0 = random(0, 200);
  R1 = random(0, 200);
  int sum = R0 + R1;
  R2 = sum & 0xFF;

  // Flag logic
  C = (sum > 255);
  Z = (R2 == 0);
  N = (R2 & 0x80);
  V = ((R0 & 0x80) == (R1 & 0x80)) && ((R0 & 0x80) != (R2 & 0x80));
  S = N ^ V;

  printFlags();
  updateLEDs();
}

void demoFlagSequence() {
  static int step = 0;
  step = (step + 1) % 5;

  // Matikan semua LED dulu
  digitalWrite(LED_C, LOW);
  digitalWrite(LED_Z, LOW);
  digitalWrite(LED_N, LOW);
  digitalWrite(LED_V, LOW);
  digitalWrite(LED_S, LOW);

  switch (step) {
    case 0:
      Serial.println("🟢 Demo Carry (C=1): Overflow 8-bit");
      C = 1; Z = N = V = S = 0;
      break;
    case 1:
      Serial.println("🟢 Demo Zero (Z=1): Hasil 0");
      Z = 1; C = N = V = S = 0;
      break;
    case 2:
      Serial.println("🟢 Demo Negative (N=1): Bit ke-7 aktif");
      N = 1; C = Z = V = S = 0;
      break;
    case 3:
      Serial.println("🟢 Demo Overflow (V=1): Overflow signed");
      V = 1; C = Z = N = S = 0;
      break;
    case 4:
      Serial.println("🟢 Demo Sign (S=1): Kombinasi N dan V");
      S = 1; C = Z = N = V = 0;
      break;
  }
  updateLEDs();
}

void updateLEDs() {
  digitalWrite(LED_C, C);
  digitalWrite(LED_Z, Z);
  digitalWrite(LED_N, N);
  digitalWrite(LED_V, V);
  digitalWrite(LED_S, S);
}

void printFlags() {
  Serial.println("----------------------");
  Serial.print("R0: "); Serial.println(R0);
  Serial.print("R1: "); Serial.println(R1);
  Serial.print("R2: "); Serial.println(R2);
  Serial.print("Flags -> ");
  Serial.print("C: "); Serial.print(C);
  Serial.print(" | Z: "); Serial.print(Z);
  Serial.print(" | N: "); Serial.print(N);
  Serial.print(" | V: "); Serial.print(V);
  Serial.print(" | S: "); Serial.println(S);
}