51. Opcode Decoder

How do you plan to solve it?

module alu_decoder (
    input  [1:0] opcode,
    output reg [3:0] alu_op
);
    always @* begin
        case (opcode)
            // Write solution here
            0: alu_op=4'b0001;
            1: alu_op=4'b0010;
            2: alu_op=4'b0100;
            3: alu_op=4'b1000;
            default: alu_op=4'b0000;
        endcase
    end
endmodule