OXYGEN_MPU401
if (oxygen_read8(chip, OXYGEN_MPU401 + 1) & MPU401_TX_FULL)
oxygen_write8(chip, OXYGEN_MPU401 + port, data);
return !(oxygen_read8(chip, OXYGEN_MPU401 + 1) & MPU401_RX_EMPTY);
oxygen_read8(chip, OXYGEN_MPU401);
u8 data = oxygen_read8(chip, OXYGEN_MPU401);
chip->addr + OXYGEN_MPU401,