A generic mux

// modified from Anas Salah Eddin's lecture
module mux #(parameter m = 2, w = 2) (
    input [m-1:0][w-1:0] x,
    input [$clog2(m)-1:0] s,
    output reg [w-1:0] y
    );

    integer k;

    always @(w, s)
    begin
        y = 'bx;
        for (k = 0; k < m; k = k + 1)
            if (s == k) y = x[k];
    end
endmodule