delta.pl

$prevbit = 0;
$n=0;
for (qx!cat ddtaa.asc!) {
  chomp($a = $_);
  if ($n >= 2300) {
    if (($n - 2300) % 80 == 0) {
      $bit = ($a > 0) ? 1 : 0;
      print (($bit != $prevbit) ? "1" : "0");
      $prevbit = $bit;
    }
  }
  $n ++;
}