Trying to set flags in simulink

To make sure that the data is not corrupted when the ISR writes to IaTimeHigh or IaTimeLow in the middle of the division, I need to set some flags both in the ISR and in the divide function. That is easy in the ISR function but not so easy in the divide function.

I think that I need to use an atomic subsystem for the divide function. I will first try to set flags using the "to memory" block twice in the atomic subsystem. The place on the page may define the order of execution.

That method did not seem to work reliably.

Another option I have tried was to pass the variables through an atomic subsystem that set a flag. That did not seem to work but I think that I need to get the system working in a very simple sense first. Even if my data is sometimes corrupted by the isr, there should be still an answer most of the time.

here is the isr function that I tried to use with flags

/***********************
* CUSTOM ISR FUNCTIONS *


***********************/
interrupt void xint1_isr(void)
{
IntCount.XINT1++;

// save time 2 from last time as time 0
Ia.Time0 = Ia.Time2;



// read in the times from the register
// always reads in the oldest value then clears that value EVG p3-6


Ia.Time1 = EvaRegs.CAP1FIFO;


Ia.Time2 = EvaRegs.CAP1FIFO;

// calculate the high and low times
if (afm4_B.IaCalcBusy == 0)
{
afm4_B.IaTimeHigh = Ia.Time1 - Ia.Time0;


afm4_B.IaTimeLow = Ia.Time2 - Ia.Time1;
afm4_B.IaUpdated = 1;
}
else
{
afm4_B.IaTimeHighAlt = Ia.Time1 - Ia.Time0;


afm4_B.IaTimeLowAlt = Ia.Time2 - Ia.Time1;
}

// Acknowledge interrupt to receive more interrupts from PIE group 1


PieCtrlRegs.PIEACK.all = PIEACK_GROUP1;
}