Im turning a large disk with a stepper and a pic.

The gearing that i use gives me several thousand possible stops (steps) in
one revelution of the disk. If the step number of the current point is
known, and the step number of the destination is known, how would i calulate
the shortest route ( clockwise or anti clockwise )??

Lets assume the step number is a 16bit variable.
Also assume that there will always be an equal number of stops.

John