1.7 求两个数的差值

`timescale 1ns/1ns
module data_minus(
  input clk,
  input rst_n,
  input [7:0]a,
  input [7:0]b,
  output reg [8:0]c
);
//**************code********************//
  always @(posedge clk or negedge rst_n) begin
    if(!rst_n) begin
      c <= 9'b0;
    end
    else begin
      if(a > b) begin
        c <= a - b;
      end
      else begin
        c <= b - a;
      end
    end
  end
//**************code********************//
endmodule