SR_FE
sr &= SR_PE | SR_FE | SR_OVR | SR_BRK;
else if (sr & SR_FE)
else if (sr & SR_FE)
port->read_status_mask |= SR_PE | SR_FE;
port->ignore_status_mask |= SR_PE | SR_OVR | SR_FE | SR_BRK;