Verilog中task，fun与module的调用

本文旨在当大家写module或者task以及fun时有个模板进行借鉴，以及了解如何调用fun与task，然后就是如何写testbench文件。

一、module的调用：

//这是一个简单的3-8译码器模块
//.v文件
module digitalEncode(impo,expo);
input[2:0]impo;
output[7:0]expo;
reg[7:0]expo;
[e-mail](*)begin
	expo = 8'b0111_1111;
	case(impo)
		3'b000:expo = 8'b0111_1111;
		3'b001:expo = 8'b1011_1111;
		3'b010:expo = 8'b1101_1111;
		3'b011:expo = 8'b1110_1111;
		3'b100:expo = 8'b1111_0111;
		3'b101:expo = 8'b1111_1011;
		3'b110:expo = 8'b1111_1101;
		3'b111:expo = 8'b1111_1110;
		default:expo = 8'b1111_1111;
		endcase
end
endmodule

//testbench文件
`timescale 10ns/1ps

module digitalEncode_tb;
reg[2:0]impo;
parameter Delay = 100;
wire[7:0] expo;
digitalEncode z(impo,expo);
initial begin
	#Delay impo = 3'b000;
	#Delay impo = 3'b001;
	#Delay impo = 3'b010;
	#Delay impo = 3'b011;
	#Delay impo = 3'b100;
	#Delay impo = 3'b101;
	#Delay impo = 3'b110;
	#Delay impo = 3'b111;
	#Delay impo = 3'b111;
end
endmodule

看下仿真：

二、task的调用：

//调用了按位与的一个task
module alutask(code,a,b,c);
input [1:0] code;
input [3:0] a,b;
output [4:0] c;
reg[4:0] c;
task my_and;//任务定义，注意无端口列表
input [3:0] a,b;//名称的作用域范围为task任务内部
output [4:0] out;
integer i;
begin
	for(i = 3;i >= 0;i = i - 1)
      out[i] = a[i] & b[i];//按位与
	end
endtask
[e-mail](*)
begin
case(code)
	2'b00:my_and(a,b,c);
	2'b01:c = a|b;
	2'b10:c = a+b;
	2'b11:c = a-b;
endcase
end
endmodule

//testbench
`timescale 10ns/1ps
module alu_tb;
reg [3:0] a,b;
reg [1:0] code;
wire [4:0] c;
parameter Delay = 100;
alutask ADD(code,a,b,c);//调用被测模块
initial begin
code = 4'd0;a = 4'b0000;b = 4'b1111;
#Delay code = 4'd0; a = 4'b0111;b = 4'b1101; 
#Delay code = 4'd1; a = 4'b0001;b = 4'b0011; 
#Delay code = 4'd2; a = 4'b1001;b = 4'b0011; 
#Delay code = 4'd3; a = 4'b0011;b = 4'b0011; 
#Delay code = 4'd4; a = 4'b0111;b = 4'b1001; 
#Delay $stop;
end
initial $monitor($time,,,"code = %b a = %b b = %b c = %b",code,a,b,c);
endmodule

仿真结果：

 

三、function的调用

//module中调用fun
//fun的作用是计输入二进制数据0的个数
module count_0(a,b);
input [7:0] a;
output[2:0] b;
//wire [2:0] b;

function [2:0]Count0Fun;
input[7:0] a;
integer i;
begin
   Count0Fun = 0;
   for(i = 0;i < 8;i = i+1)begin
	   if(a[i] == 0)
			Count0Fun = Count0Fun + 1'b1;
	end
end
endfunction
assign b = Count0Fun(a);
endmodule

`timescale 10ns/1ps
module count0_tb;
reg [7:0] a;

wire [2:0] b;
parameter Delay = 10;
count_0 coun(.a(a),.b(b));
initial begin
#Delay a = 8'b00000000;
#Delay a = 8'b00000001;
#Delay a = 8'b00000011;
#Delay a = 8'b00000111;
#Delay a = 8'b00001111;
#Delay a = 8'b00011111;
#Delay a = 8'b00111111;
#Delay a = 8'b01111111;
#Delay a = 8'b11111111;
end
endmodule