ALL_INTS
bus_space_write_1(iot, ioh, INT_MASK_REG, ALL_INTS);
bus_space_write_1(iot, ioh, STATUS_REG, ALL_INTS);
bus_space_write_1(iot, ioh, INT_MASK_REG, ALL_INTS);
ALL_INTS & ~(RX_BIT | TX_BIT));
bus_space_write_1(iot, ioh, STATUS_REG, ALL_INTS); /* clear ints */
if (status & ALL_INTS) {