69. Binary Subtractor

How do you plan to solve it?

/*Write your code here*/

module sub4_2c(input [3:0]a,input [3:0]b,output [3:0] diff,output bout);


wire [4:0]diff_t;
assign diff_t = {1'b0,a} + ({1'b0,~b})+1;
assign bout = ~diff_t[4];
assign diff = diff_t[3:0];
endmodule