Need Help With Code Interpretation on a Code Dealing With Frequency

This is from a code I pulled from another form (http://forum.arduino.cc/index.php?PHPSESSID=f32jdftivuehdidac12j50uk93&topic=49133.0 it's the last code posted on the first page of the forum) and I need to annotate it and be able to explain what every thing does but this last part is really throwing me for a loop. Any help you can give would be greatly appreciated XD

ISR(TIMER1_OVF_vect)
{
    overflows += 1;
}

ISR(ANALOG_COMP_vect) // interrupt service routine that wraps a user defined function supplied by attachInterrupt
{
    tnow = TCNT1; // current time
    edges += 1;
      if (edges == 1) { // Start counting edges.
          tstart = overflows*65536 + tnow;
      }
      else if (edges == cycles + 1) { // Stop counting edges.
           tstop = overflows*65536 + tnow;
           // Turn off Timer/Counter 1 and the comparator.
           ACSR = 0; //Analog Comparator Control and Status Register set to zero
           TCCR1B = 0;
      }
}

I'm using the same code in part of my program and I was wondering the same thing. Haven't figured it out just yet but I'll keep you posted while I dig into it.

Two people with the same IP address woring on the same bit of code.
What are the chances, huh?
Must be assignment time :slight_smile: