how to set i/O

i have set one i/o pin to bidirectional(tri-state) I/O port,and finished the hardware compile.

but in the nios II IDE ,how to set the bidirectional(tri-state) I/O port to out por

!

the following is my code (the name of pio is ADATA)

int main()

{//dir=0;

//IOWR_ALTERA_AVALON_PIO_DATA(LEVELCONTROL_BASE,1);

IOWR_ALTERA_AVALON_PIO_DIRECTION(ADATA_BASE,0XFFFF);

//alt_irq_register(TIMER_0_IRQ,0, handle_Timer0_interrupts);

//IOWR_ALTERA_AVALON_TIMER_PERIODL(TIMER_0_BASE, 0X1F40);

//IOWR_ALTERA_AVALON_TIMER_CONTROL(TIMER_0_BASE, 7);

IOWR_ALTERA_AVALON_PIO_DATA(ADATA_BASE, 0XFFFF);

while (1) {;}

}!

but when i test the value of the pio ,there is no value(even i set IOWR_ALTERA_AVALON_PIO_DATA(ADATA_BASE, 0)

why ??

thanks! http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/sad.gif