protected function _get_mod_time($dir)
{
// filemtime() may return false, but raises an error for non-existing files
$date = file_exists($dir) ? getdate(filemtime($dir)) : getdate($this->now);
return array('file_mtime' => ($date['hours'] << 11) + ($date['minutes'] << 5) + $date['seconds'] / 2, 'file_mdate' => ($date['year'] - 1980 << 9) + ($date['mon'] << 5) + $date['mday']);
}