Small changes. I implemented the permutation generator in systemverilog and made a testbench for it (looks for frozen random values, zero random values (breaks xorshift), and for invalid permutation states (multiple entries point to the same thing)). I used the xorshift32 algorithm because of how cheap it is on hardware. I would have used xorshift16, but the larger state prevents exhaustion of search space. Pictured is incremental changes in simulation.