vcs+Makefile实现简单的testbench

网络上找的文章，实现了一遍。

步骤如下：

1. 创建verilog代码，包括8位加法器代码和testbench代码。

adder8.v

module adder8 (
input clk,
input [7:0] a_i,
input [7:0] b_i,
output reg [8:0] c_o
);
always @ (posedge clk) begin
c_o <= a_i + b_i;
end
endmodule

adder8_tb.v

// TB_SEED is random seed
`ifndef TB_SEED
`define TB_SEED 0
`endif
module adder8_tb();
wire [8:0] result;
reg [7:0] input_0;
reg [7:0] input_1;
reg clk;
// clk2 is delay of clk, is used to verify result
wire #5 clk2;
assign clk2 = clk;
initial begin
$fsdbDumpfile("adder8.fsdb");
$fsdbDumpvars();
$display("TB_SEED is %d", `TB_SEED);
clk = 0;
input_0 = 8'd0;
input_1 = 8'd0;
#10000
$display("All test PASS!");
$finish;
end
// system clk is 50MHz
always begin
#10 clk = ~clk;
end
//generate random input
always @ (negedge clk) begin
input_0 = $random() % 256;
input_1 = $random() % 256;
end
//get verified output
always @ (posedge clk2) begin
if ((input_0 + input_1) != result) begin
$display("Test failed for %x + %x = %x", input_0, input_1, result);
$finish;
end else begin
$display("%x + %x = %x", input_0, input_1, result);end
end
//instantiate adder8
adder8 dut(
.clk(clk),
.a_i(input_0),
.b_i(input_1),
.c_o(result)
);
endmodule

2.编写Makefile文件，

VCS= vcs -sverilog -timescale=1ns/1ns +vpi -l build.log -debug_access+all
SIMV = ./simv -l simv.log
ifndef TB_SEED
	TB_SEED = 1024
endif
all: comp run
comp:
	$(VCS) +define+TB_SEED=$(TB_SEED) +incdir+. \
	adder8.v \
	adder8_tb.v
run:
	$(SIMV) +fsdbfile+top.fsdb
dbg:
	verdi -f file.f -ssf top.fsdb &
clean:
	rm -rf core csrc simv* vc_hdrs.h ucli.key urg* *.log *.fsdb novas.* verdiLog

注意：Makefile里面的空格排版位tab键。

file.f里面内容为：

adder8_tb.v
adder8.v

编译项目： Make

清除项目: Make clean

查看波形：Make dbg

编译日志文件为：build .log

仿真日志文件为：simv.log

仿真结果为：