Dealing with micros rollover in an ISR

have implemented algorithm correctly:

void  dostartdisplay()
{
    uint32_t luntimeelapsed = micros(), lunperiod = 0, lunmask = 0;
   
    lunperiod = luntimeelapsed - lintlasttimeelasped;
    lunmask = lunperiod >> 31;
    lunperiod = (lunmask ^ lunperiod) - lunmask;
   
    lintlasttimeelasped = luntimeelapsed;
    luntimeslice = lunperiod / (60 * 6);
    luncount = 0;
//    timer1.attachinterrupt(dodisplay, luntimeslice);
//    dodisplay();
}

i trying rid of if statement had consume more cpu cycles.

why not reduce isr to

code: [select]

void  dostartdisplay() {
    luntimeelapsed = micros();
}

and rest of calculation outside isr

your names not chosen relate to.

...r

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