Timer

void setup()
{
    /* setup pins etc*/
while(!(PINB & 0b100));//wait for input 1


  TCCR1A = 0;// set entire TCCR1A register to 0
  TIMSK1 = _BV(TOIE1);  //enalbe interrupt
  TCCR1B = 1;// start timer 1



  while(!(PINA & 0b1000000));//wait for input 2

  cli();
  TCCR1B = 0;    //stop timer;
  temp_timer = TCNT1;  //store passed ticks


  TCCR1A = 0;        // disable timer1
  TCCR1B = 0;


  time = (0xFFFFul * (unsigned long)overflows) + (unsigned long)temp_timer;      //calculate time

    /*display speed*/
}

ISR(TIMER1_OVF_vect)
{
  overflows++;
}