testbench.v:
      ----------------------------------------------------------------------
      //
      // File header 具体参考 编码风格专题
      //
            `define MAX 20 宏定义
            `include "driver.v"
            `include "monitor.v包含有其他模块,如果在同一目录下可以不指定include
            `timescale 1n/10p指定仿真精度
            module tb; 定义模块名为tb
            reg a;
            reg b;
            reg ci
            wire sum;
            wire cout;申明线型与寄存器型
            parameter LENGTH = 20;参数化一些值

            adder adder(.a(a),
            .b(b),
            .ci(ci),
            .sum(sum),
            .cout(cout)
            );

            driver driver();
            monitor monitor();实例化DUT,以及一些驱动和监测

            `include "task.v"包含task.v文件
            initial
            begin
            add_test;

            #MAX $finish;
            endStimulus,调用了task.v里的add_test

            `undef MAX由于宏是全局的,防止有冲突发生,最后要undef

            endmodule模块结束