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.

[Mark Rages]

It's not generic in that way, because "interrupt_setting_mask" is only 32 bits, "IRQ_ENABLED << irq" is only 32 bits, and so on.

[Vidar Berg]

@Mark, think you're right, not sure if there is a good reason for disabling the interrupts in this way. I've reported this internally, and will update this thread when I hear back from the team.

[Susheel Nuguru]

This is a bug, as it wont work on nRF52 as IRQ numbers extend until bit 38.(so I will add this into list of bugs in SDK11), also it is slow (not wrong but slow) to do it like this in a loop.

[Clem Taylor]

I always just did: NVIC->ICER[0] = NVIC->ISER[0]; // Interrupt Clear Enable Register