interrupts_disable() implementation question

[Mark Rages]

The function interrupts_disable() is defined in components/libraries/bootloader_dfu/dfu_app_handler.c and examples/dfu/experimental_ant_bootloader/bootloader.c like so:

/**@brief Function for disabling all interrupts before jumping from bootloader to application.
 */
static void interrupts_disable(void)
{
    uint32_t interrupt_setting_mask;
    uint32_t irq;

    // Fetch the current interrupt settings.
    interrupt_setting_mask = NVIC->ISER[0];

    // Loop from interrupt 0 for disabling of all interrupts.
    for (irq = 0; irq < MAX_NUMBER_INTERRUPTS; irq++)
    {
        if (interrupt_setting_mask & (IRQ_ENABLED << irq))
        {
            // The interrupt was enabled, hence disable it.
            NVIC_DisableIRQ((IRQn_Type)irq);
        }
    }
}

Is there a reason that it is defined this way? It is convoluted and buggy for nRF52 (I2S_IRQn isn't cleared, for example). Instead of the simpler:

static void interrupts_disable(void)
{
    NVIC->ICER[0] = 0xffffffff;
#ifdef NRF52
    NVIC->ICER[1] = 0xffffffff;
#endif
}

I am looking for ways to save space in the bootloader.

edit: fixed bug from comments

[RK]

yes you could replace that with the one write to NVIC->ICER[]. The function is probably written that way to be generic, some Cortex (including some shipped by Nordic) have more than 32 interrupts and so just re-defining MAX_NUMBER_INTERRUPTS and looping is going to work on them all.