RR_RXRDY
if ((rr & RR_RXRDY) != 0) {
} while (((rr = getsiocsr(sio)) & RR_RXRDY) != 0);
if ((rr & RR_RXRDY) != 0) {
} while (((rr = getsiocsr(sio)) & RR_RXRDY) != 0);
while ((getsiocsr(sio) & RR_RXRDY) == 0)