71. Arithmetic Logic Unit

How do you plan to solve it?

/*Write your code here*/
module alu4(
    input [3:0]a,
    input [3:0]b,
    input [2:0]op,
    output reg [3:0]y,
    output reg cf
);

always @(*)begin
    
    case(op)
    3'b000: begin
    
    {cf,y}=a+b;
   
    end
    3'b001:begin
   
    y=a+~b+1;
     cf=(a<b);
    end
    3'b010:begin
    y=a&b;
    cf=0;
    end
    3'b011:begin
    y=a|b;
    cf=0;
    end
    3'b100:begin
    y=a^b;
    cf=0;
    end
    default:begin
    y=4'b0000;
    cf=0;
    end
    endcase


    
    
end
endmodule