create software for Altere PIO 's

this is my code below,

its self explanatory, i am unable to get the IOWR_ALTERA_AVALON_PIO_SET_BITS(base) to work as the output is confirming it. My PIO is set to 1

# define ALT_MODULE_CLASS_GPIO_0 altera_avalon_pio

# define GPIO_0_BIT_MODIFYING_OUTPUT_REGISTER 1

CODE:::

# include <stdio.h>

# include <unistd.h>

# include "altera_avalon_pio_regs.h"

# include "system.h"

# include <strings.h>

// Time in microseconds to wait for switch debounce

int main(void)

{

printf("Simple\n"); // print a message to show that program is running

int data1 = 0x00000309;

int val,val2;

//while(1){

IOWR_ALTERA_AVALON_PIO_DATA(GPIO_0_BASE,data1);

val = IORD_ALTERA_AVALON_PIO_DATA(GPIO_0_BASE);

printf("previous value = %x \n",val);

IOWR_ALTERA_AVALON_PIO_SET_BITS(GPIO_0_BASE+4, 0x02);

val2 =IORD_ALTERA_AVALON_PIO_DATA(GPIO_0_BASE);

printf("value after setting the bit = %x " , val2);

//}

}

-----------------OUTPUT------------------

Simple

previous value = 309

value after setting the bit = 309