char btn_prev = 0;
char x=1;

void setup() {
  char *inp = (char*)0x106;
  Serial.begin(115200);
  init_port();
  init_timer();
  
  while(1){
    if(*inp && x){
      Serial.println("hello");
    }
    delay1();
  }

}

void init_port(){
  volatile char *ddr1 = (char*)0x30;
  *ddr1 = 0x03;

  volatile char *ddr2 = (char*)0x107;
  *ddr2 = 0x00;
}

void init_timer(){
  volatile char *TCCR1_A = (char*)0x80;
  volatile char *TCCR1_B = (char*)0x81;
  volatile short *TCNT_1  = (short*)0x84;
  volatile short *OCR1_A  = (short*)0x88;
  volatile char *TIMSK_1 = (char*)0x6F;

  *TCCR1_A = 0x00;
  *TCCR1_B = 0x0C;
  *TCNT_1 = 0;
  *OCR1_A = 62500;
  *TIMSK_1 = 0x03;
}

ISR (TIMER1_COMPA_vect){
  volatile char *btn_inp = (char*)0x106;
  volatile char *out = (char*)0x31;
  if(*btn_inp!=0){
    x=0;
    *out = 0x01;
    for(volatile long i=0;i<200000;i++);
    *out = 0x00; 
  }
  if(*btn_inp==0){
    x=0;
  }
  btn_prev = *btn_inp;
}

// void init_timer_2(){
//   volatile char *TCCR3_A = (char*)0x90;
//   volatile char *TCCR3_B = (char*)0x91;
//   volatile short *TCNT_3  = (short*)0x94;
//   volatile short *OCR3_A  = (short*)0x98;
//   volatile char *TIMSK_3 = (char*)0x71;

//   *TCCR3_A = 0x00;
//   *TCCR3_B = 0x0C;
//   *TCNT_3 = 0;
//   *OCR3_A = 3500;
//   *TIMSK_3 = 0x03;
// }

// void ext_timer(){
//   volatile char *EICR_A = (char*)0x69;
//   volatile char *EI_MSK = (char*)0x3D;

//   *EICR_A = 0x0F;
//   *EI_MSK = 0x03;
// }

// ISR (INT0_vect){
//   volatile char *out = (char*)0x31;
//   *out = 0x01;
//   for(volatile long i=0;i<100000;i++);
//   *out = 0x00;
// }

// ISR (INT1_vect){
//   volatile char *out = (char*)0x10B;
//   *out = 0x01;
//   for(volatile long i=0;i<100000;i++);
//   *out = 0x00;
// }

void delay1(){
  volatile long i;
  for(i=0;i<50000;i++);
}


void loop() {
  // put your main code here, to run repeatedly:

}