volatile int edge_capture_mpvs_ctrl;
static void init_brightness_irq(){
    /* Recast the edge_capture pointer to match the
    alt_irq_register() function prototype. */
    void* edge_capture_ptr = (void*) &edge_capture_mpvs_ctrl;
    /* Enable all 4 button interrupts. */
    IOWR_ALTERA_AVALON_PIO_IRQ_MASK(LB_MPVS_IRQ_BRIGHTNESS_BASE, 0xf);
    /* Reset the edge capture register. */
    IOWR_ALTERA_AVALON_PIO_EDGE_CAP(LB_MPVS_IRQ_BRIGHTNESS_BASE, 0x0);
    /* Register the ISR. */
    #ifdef ALT_ENHANCED_INTERRUPT_API_PRESENT
    alt_ic_isr_register(
                                LB_MPVS_IRQ_BRIGHTNESS_IRQ_INTERRUPT_CONTROLLER_ID,
                                LB_MPVS_IRQ_BRIGHTNESS_IRQ,
                                brightness_irq,
                                edge_capture_ptr,
                                0x0
                            );
    #else
    alt_irq_register(
                            LB_MPVS_IRQ_BRIGHTNESS_IRQ,
                            edge_capture_ptr,
                            brightness_irq
                        );
    #endif
}

static void  brightness_irq(void* context) {
    volatile int* edge_capture_ptr = (volatile int*) context;
    /*
    * Read the edge capture register on the button PIO.
    * Store value.
    */
    *edge_capture_ptr =IORD_ALTERA_AVALON_PIO_EDGE_CAP(LB_MPVS_IRQ_BRIGHTNESS_BASE);
    /* Write to the edge capture register to reset it. */
    IOWR_ALTERA_AVALON_PIO_EDGE_CAP(LB_MPVS_IRQ_BRIGHTNESS_BASE, 0);
    /* Read the PIO to delay ISR exit. This is done to prevent a
    spurious interrupt in systems with high processor -> pio
    latency and fast interrupts. */
    IORD_ALTERA_AVALON_PIO_EDGE_CAP(LB_MPVS_IRQ_BRIGHTNESS_BASE);
    //реагирование на прерывание

}