使用子模块实现三输入数的大小比较

https://www.nowcoder.com/practice/bfc9e2f37fe84c678f6fd04dbce0ad27?tpId=301&tqId=5000623&ru=%2Fpractice%2Fbfc9e2f37fe84c678f6fd04dbce0ad27&qru=%2Fta%2Fverilog-start%2Fquestion-ranking&sourceUrl=%2Fexam%2Foj%3Fpage%3D1%26tab%3DVerilog%25E7%25AF%2587%26topicId%3D301

`timescale 1ns/1ns
module main_mod(
	input clk,
	input rst_n,
	input [7:0]a,
	input [7:0]b,
	input [7:0]c,
	
	output [7:0]d
);

wire [7:0] m,n;
sub_mod mod_ab(
	.clk(clk),
	.rst_n(rst_n),
	.data_a(a),
	.data_b(b),
	.data_c(m)
);

sub_mod mod_am(
	.clk(clk),
	.rst_n(rst_n),
	.data_a(a),
	.data_b(c),
	.data_c(n)
);

sub_mod mod_mn(
	.clk(clk),
	.rst_n(rst_n),
	.data_a(m),
	.data_b(n),
	.data_c(d)
);

endmodule


module sub_mod(
	input clk,
	input rst_n,
	input [7:0] data_a,
	input [7:0] data_b,
	output reg [7:0] data_c 
);

always @(posedge clk or negedge rst_n)
	if(!rst_n)
		data_c <= 0;
	else if(data_a > data_b)
		data_c <= data_b;
	else
		data_c <= data_a;
	
endmodule

module compare_tb;
  reg rst_n = 0;
  reg clk = 0;
  reg [7:0] a = 0;
  reg [7:0] b = 0;
  reg [7:0] c = 0;

  initial begin
    rst_n = 0; #100;
    rst_n = 1; #300;
    a = 8'd3; #0;
    b = 8'd5; #0;
    c = 8'd7; #0;
    #10000;
    $finish;
  end

  always begin #5 clk = !clk; end
  main_mod compare_test(
    .clk(clk),
    .rst_n(rst_n),
    .a(a),
    .b(b),
    .c(c)
  );

  initial
  begin
    $dumpfile("compare_test.vcd");
    $dumpvars(0, compare_test);
  end
endmodule