I am looking at a C++ class which has the following lines:

```
while( x > y );
return x - y;

```

`x` and `y` are member variables of type `volatile int`. I do not understand this construct. 

I found the code stub here: <https://gist.github.com/r-lyeh/cc50bbed16759a99a226>. I guess it is not guaranteed to be correct or even work.