Yes, it is: it calculates the quotient and remainder in one operation.
Aside from that, the same behaviour can be achieved with /+% (and a decent optimizer will optimize them into a single div anyway).
In order to sum it up: if you care about squeezing out last bits of performance, this may be your function of choice, especially if the optimizer on your platform is not so advanced. This is often the case for embedded platforms. Otherwise, use whatever way you find more readable.
