Priority Encoder Structure

module priority (W, Y ,Z);
    input [3:0] W;
    output reg [1:0]Y;
    output reg Z;
    integer k;
    always @ (W)
        begin
        Y = 2'bx;
        Z = 0;
        for (k = 0 ; k < 4 ; k = k+1)
        if(W[k])
            begin
                Y = k;
            Z = 1;
            end
    end
endmodule