Thread: Logic for Message Timeout

How to you think clearFlag will work unless it is global?

1. It needs to be visible where needed
2. It needs to retain the value

Since, you are using it in a interrupt/timer function it likely needs to be global; but, maybe your CPU/MCU has a feature that allows some other storage class to work.

Tim S.

I would do something like this.

Create a separate source file just to handle this problem, then make the variables static.
The variables have persistent storage, but their use is limited to the few functions in the same source file.

Code:

static int clearFlag = 0;
static void *timeoutContext = 0;
static void (*handleTimeout)(void*);

void canRxInterrupt(void) {
  clearFlag = 0;
}

void timer1ms(void) {
  clearFlag++;
  if ( handleTimeout ) {
    handleTimeout(timeoutContext);
  }
}

void registerTimeoutFn( void (*fn)(void*), void *ctx) {
  timeoutContext = ctx;
  handleTimeout = fn;
}