function wps_pin_checksum(pin)
{
        var accum = 0;
        while (pin) {
                accum += 3 * (pin % 10);
                pin /= 10;
                pin = Math.floor(pin);
                accum += pin % 10;
                pin /= 10;
                pin = Math.floor(pin);
        }
        return (10 - accum % 10) % 10;
}