Listing 4

extern volatile uint32_t UART_TXBUF;
extern volatile uint8_t  UART_TXCTL;
UART_TXBUF = 10;
UART_TXCTL = 3;

// compile this with:
//   gcc listing4.c
//       -gUART_UART_TXBUF=0xfffe0004 
//       -gUART_TXCTL=0xfffe0001