In a very simple task containing an infinite loop and running on os_itv_wait() I would like to measure how long the code takes to run using os_time_get(). For example if os_itv_wait() lets my code run every 5 ticks and the difference between os_time_get() called at the top and bottom of my code is 2 ticks I know that I have time to spare. If the code takes 8 ticks I have a problem.
In my case I am running my code every 1 tick and can accept that occasionally the code runs in over 1 tick but I don't want it to take 2 ticks. Ideally therefore I'd like a sub-tick resolution timer but I haven't got that (without running a hardware timer which is a future possibility).
So for this test I'm looking to see if a whole tick has expired by the time I reach the end of the code - but this relies on the os_itv_wait() being synchronous and changing at the same time as the os_time_get() result and I don't know if they are.
For example, if os_itv_wait() allows my code to run but os_time_get() value changes 100us later I am likely to see a change between the top and bottom of my code times on every run.
I suspect that it is all driven from the same counter. A change in that counter value is synchronous with os_itv_wait() allowing my code to run and os_time_get() returning the new value.