comcn_read_reg
while (!ISSET(stat = comcn_read_reg(com_lsr), LSR_RXRDY))
c = comcn_read_reg(com_data);
stat = comcn_read_reg(com_iir);
while (!ISSET(comcn_read_reg(com_lsr), LSR_TXRDY) && --timo)
while (!ISSET(comcn_read_reg(com_lsr), LSR_TXRDY) && --timo)
uint8_t comcn_read_reg(bus_size_t);