public static function fromTimeOfDay(array $tod)
    {
        $str = $tod['sec'] . str_pad($tod['usec'], 6, '0', STR_PAD_LEFT);
        $m = new self();
        $m->int = (int)$str;
        $m->sec = (int)substr($str, 0, 10);
        $m->usec = (int)substr($str, -6);
        return $m;
    }