title: Difference between timer values not as expected
body: <p>I'm sorry if this is a basic question.
  I am working on an embedded project. Somewhere in the project in some driver files there is a function named _time returnTime() that is said to return a mcu time with a 10 microseconds resolution. I guess it reads the registers for a timer module of the mcu and returns them and this timer has a 10 microseconds resolution.</p>
  
  <p>I also have a user defined function. I want to test how much it takes to execute this function.
  So I have decided to use function returnTime for this by calling it before the first and after the last instructions of my function.</p>
  
  <p>In the function that I want to test how long it takes to execute I do something like this:</p>
  
  <pre><code>myFunction()   
  {
      time1 = returnTime();
        ...
      time2 = returnTime();
      time_elapsed = time2 - time1;
   }
  </code></pre>
  
  <p>When I do this function time_elapsed is a value of 5 and sometimes 4. Is that possible. Since the <code>returnTime()</code> function returns a time with 10 microsecond resolution shouldn't time_elapsed also be a value which is a multiple of 10?(like 0, 10, 20,...etc)</p>