FIFO:How to slow down the clock Frequency from 50 Mhz

init_input_fifo();
	IOWR(ENABLE_PIO_BASE, 0, 0x1);
    printf("STATUS = %d\n", altera_avalon_fifo_read_status(FIFO_0_IN_CSR_BASE,    altera_avalon_fifo_status_all));
	level=altera_avalon_fifo_read_level(FIFO_0_IN_CSR_BASE);
	printf("\nLevel=%u\n",level);
	if(level !=0)
	{
	for(i=0;i<=500;i++)
	 {
    	        //result[i]=IORD_ALTERA_AVALON_FIFO_DATA(FIFO_0_OUT_BASE);
    	        data[i]=altera_avalon_fifo_read_fifo(FIFO_0_OUT_BASE, FIFO_0_IN_CSR_BASE);
    	    	printf("data=%lu\t",data[i]);
       }
	}
 
	printf("\n Full=%d\n", altera_avalon_fifo_read_almostfull(FIFO_0_IN_CSR_BASE));
	printf("Empty=%d\n",altera_avalon_fifo_read_almostempty(FIFO_0_IN_CSR_BASE));
}

Now my code is right.