module alu (input [31:0] input_a, input_b,
            input [3:0] op_code,
            output reg [31:0] out);
    
    always@ (*) begin
        case (op_code)
            4'b0000 : out <= input_a + input_b;
            4'b0001 : out <= input_a - input_b;
            4'b0010 : out <= input_a << input_b;
            4'b0011 : out <= (input_a < input_b) ? 1 : 0;
            4'b0100 : out <= input_a ^ input_b;
            4'b0101 : out <= input_a >> input_b;
            4'b0111 : out <= input_a >>> input_b;
            4'b1000 : out <= input_a | input_b;
            4'b1001 : out <= input_a & input_b;
            default : out <= 32'b0;
        endcase
    end

endmodule