Problem with getting IRQ from PIO (Really simple i guess)

int context=0;
volatile int edge_capture;
int main()
{
    IOWR_ALTERA_AVALON_PIO_IRQ_MASK(PIO_0_BASE,0xF);
    alt_irq_register(PIO_0_IRQ,(void*)&edge_capture, handle_pio);
    while(5);
return 0;
}

static void handle_pio(void* context, alt_u32 id){
        IOWR_ALTERA_AVALON_PIO_IRQ_MASK(PIO_0_BASE, 0);
    /* Cast context to edge_capture's type. It is important that this be
         * declared volatile to avoid unwanted compiler optimization.
         */
        volatile int* edge_capture_ptr = (volatile int*) context;
        /* Store the value in the Button's edge capture register in *context. */
        *edge_capture_ptr = IORD_ALTERA_AVALON_PIO_EDGE_CAP(PIO_0_BASE);
        IOWR_ALTERA_AVALON_PIO_EDGE_CAP(PIO_0_BASE,0);
        IOWR_ALTERA_AVALON_PIO_IRQ_MASK(PIO_0_BASE,0xF);
}