牛客--VL29--信号发生器

`timescale 1ns/1ns
module signal_generator(
	input clk,
	input rst_n,
	input [1:0] wave_choise,
	output reg [4:0]wave
	);

	reg [4:0] cnt;
	reg flag;

	always@(posedge clk or negedge rst_n) begin
		if(!rst_n)
			cnt <= 0;
		else if(wave_choise == 0) begin
			cnt <= (cnt == 19) ? 0 : cnt + 1;
		end
		else
			cnt <= 0;

	end

	always@(posedge clk or negedge rst_n) begin
		if(!rst_n)
			flag <= 0;
		else if(wave_choise == 2) begin
			if(wave == 1)
				flag <= 1;
			else if(wave == 19)
				flag <= 0;
			else
				flag <= flag;
		end
		else
			flag <= 0;
	end


	always@(posedge clk or negedge rst_n) begin
		if(!rst_n)
			wave <= 0;
		else
			case(wave_choise)
				0:
					begin
						if(cnt == 9)
							wave <= 20;
						else if(cnt == 19)
							wave <= 0;
						else
							wave <= wave;

					end
				
				1:
					begin
						wave <= (wave == 20) ? 0 : wave + 1;
					end
				
				2:
					begin
						wave <= (flag == 0) ? wave -1 : wave + 1;
					end
				default:
					wave <= 0;


			endcase
	end

  
endmodule