(void) lpc_usart.iir_fcr;
while (lpc_usart.lsr & (1 << LPC_USART_LSR_RDR)) {
char c = lpc_usart.rbr_thr;
if (!ao_fifo_full(ao_usart_rx_fifo))
ao_fifo_insert(ao_usart_rx_fifo, c);
(void) lpc_usart.iir_fcr;
while (lpc_usart.lsr & (1 << LPC_USART_LSR_RDR)) {
char c = lpc_usart.rbr_thr;
if (!ao_fifo_full(ao_usart_rx_fifo))
ao_fifo_insert(ao_usart_rx_fifo, c);