module error_checker_xz(
input [7:0] bus,
output all_known,
output has_unknown,
output [7:0] bus_if_known
);
// Reduction XOR becomes 'x' if any bit is x or z
assign has_unknown = (^bus === 1'bx);
assign all_known = ~has_unknown;
assign bus_if_known = all_known ? bus : 8'h00;
endmodule