44. Bus Error Checker

How do you plan to solve it?

 module error_checker_xz(
    input [7:0] bus,
    output all_known,
    output has_unknown,
    output [7:0] bus_if_known
 );

 wire any_xz = (^(bus ^ bus)) === 1'bx;

 assign has_unknown = any_xz;
 assign all_known = ~any_xz ;
 assign bus_if_known = {8{all_known}} & bus;


 endmodule