TCH
bus_space_write_1(iot, ioh, TCH, n >> 16);
bus_space_write_1(iot, ioh, TCH, n >> 16);
amount = ((bus_space_read_1(iot, ioh, TCH) << 16) |
bus_space_write_1(iot, ioh, TCH, n >> 16);
bus_space_read_1(iot, ioh, TCH),
bus_space_write_1(iot, ioh, TCH, 0);
bus_space_write_1(iot, ioh, TCH, 2);
bus_space_write_1(iot, ioh, TCH, 0);