Nios II UART Troubles

OK, I am porting some code from Nios 1 to Nios 2 and I am stuck on the UART code. Here is the original code:

char poll_uart_rx( void )
{
    int i;
    i = nr_uart_rxchar( na_uart_0 );
    if( i == -1 )
  return( 0 );
    else
  return( (char) i );
}

The new Nios 2 documentation says to use getchar() or getc(). These both seem to be blocking reads. I need a non-blocking read. Looking through "altera_avalon_uart.c" I found that 'alt_avalon_uart_read' supports non-blocking reads, but what newlib call do I make to get a non-blocking read? Thanks