Countingsort algorithm implementation

Recently I created the following GitHub repository:

It contains a Rust implementation of the fast countingsort sorting algorithm (it can by 5 times as fast as quicksort for sorting 250 numbers, and it has a linear complexity).
I am still working on it, but any advice is welcome.

I completed the algorithm, with some documentation and testing, not really structured. For performance reasons, I used the unsafe ptr::copy_nonoverlapping function.