44. Bus Error Checker

module error_checker_xz (
    input [7:0] bus,
    output all_known,
    output has_unknown,
    output [7:0] bus_if_known
);
    wire has_xz = (^bus) === 1'bx;

    assign all_known = ~has_xz;
    assign has_unknown = has_xz;
    assign bus_if_known = all_known ? bus : 8'd0;
endmodule