[Ryan M.]

There is nothing actually wrong with the code you've shown so far. The most likely reason that the compiler is complaining is that before you enter the loop you set one or other of the variables to something less than 4. I didn't think that this compiler was that smart, but maybe it realized that you never alter the variables in the loop. However, if you are using interrupts, then this code should be fine. If you could post all your code, that would be extremely helpful.

It may also just be that the compiler is confused. If your code works (have you tested it?), then I'd just ignore the warning.