R_DUART_STATUS
return read_sbdchn(sport, R_DUART_STATUS) & M_DUART_RX_RDY;
return read_sbdchn(sport, R_DUART_STATUS) & M_DUART_TX_RDY;
return read_sbdchn(sport, R_DUART_STATUS) & M_DUART_TX_EMT;
status = read_sbdchn(sport, R_DUART_STATUS);