###### tags: `hdl` `test` `thu`

# HDL-TEST20221230

## EX01
### 15 ns:
- $A \rightarrow 0$
- $B \rightarrow 0$
### 25 ns:
- $C \rightarrow 0$

## EX02
### Module

module counter (output reg [2:0] cnt, input clk, clear);

	always @ (posedge clk) begin
		if (!clear)
			cnt <= 0;
		else
			case (cnt)
				0: cnt <= 1;
				1: cnt <= 3;
				3: cnt <= 7;
				7: cnt <= 6;
				6: cnt <= 4;
				4: cnt <= 0;
			endcase
	end
endmodule

### Testbench

module test1_tb;
	wire [2:0] cnt;
	reg clk, clear;
	
	counter circuit (cnt, clk, clear);

	// output
	initial begin
		clk = 0; clear = 0;

		#10 clear = 1;


		#80 $finish;
	end
	always #5 clk = ~clk;
	initial begin
		$display ("\t\tTIME\tclear\t|\tcnt");
		$display ("\t\t------------------------------------------------------------");
		$monitor ("%t\t%b\t|\t%d", $time, clear, cnt);
	end

endmodule


## EX03

### Task + Testbench

module test1_tb;
	reg [9:0] sum;
	reg [4:0] num;
	// for task
	reg [9:0] tmp;
	reg [4:0] counter;
	

	// output
	initial begin
		num = 12;
	factorSum (sum, num);
		#80 $finish;
	end
	initial begin
		$display ("\t\tTIME\tnum\t|\tsum");
		$display ("\t\t------------------------------------------------------------");
		$monitor ("%t\t%d\t|\t%d", $time, num, sum);
	end

	task factorSum (output [9:0] sum, input [4:0] num); begin
		tmp = 0; counter = 1;
	
		if (num != 0) begin
			while (counter <= num) begin 
				if (num % counter == 0)
					tmp += counter;
				counter++;
			end
		end
		sum = tmp;
	end endtask
endmodule


#### $28 = 1 + 2 + 3 + 4 + 6 + 12$

## EX04
### Function + Testbench

module test1_tb;
	reg [8:0] sum;
	reg [3:0] num;

	// output
	initial begin
		$display ("\t\tTIME\tnum\t|\tsum");
		$display ("\t\t------------------------------------------------------------");
		$monitor ("%t\t%d\t|\t%d", $time, num, sum);
		num = 0;
		while (num < 12) begin
			#1 num += 1;
			sum = Fib(num);
		end
		#20 $finish;
	end
	initial begin
	end

	function automatic integer Fib (input [3:0] terms); begin
		if (terms == 0 || terms == 1)
			Fib = 1;
		else
			Fib = Fib (terms - 1) + Fib (terms - 2);
	end endfunction
endmodule