实验要求

该项目主要实现一个深度为8、位宽为8bit的同步FIFO存储单元。模块功能应包括读控制、写控制、同时读写控制、FIFO满状态、FIFO空状态等逻辑部分。
该项目由一个功能模块和一个testbench组成。其中功能模块的端口信号如下表所示。


提示：
（1）设定一个写地址waddr[2:0]，每来一个写使能wr，则写地址加一；
（2）设定一个读地址raddr[2:0]，每来一个读使能rd，则读地址加一；
（3）若同时读写，则读写地址不变，只是将输入数据din直接赋值给dout;
（4）FIFO中数据的个数cout=waddr-raddr;
（5）状态指示：

• 当cout=8时，FIFO满（full=1）;
• 当cout=6时，FIFO快满了（almost_full=1）;
• 当cout=4时，FIFO半满（半空）（half=1）;
• 当cout=2时，FIFO快空了（almost_empty=1）;
• 当cout=0时，FIFO空（empty=1）;

sfifo

module sfifo(
	clk,
	rst_n,
	data_in,
	wr,
	rd,
	full,
	empty,
	data_out,
	sfifo_cnt,
	half,
	almost_empty,
	almost_full);

	input clk;
	input rst_n;
	input [7:0] data_in;
	input wr;
	input rd;
	output full;
	output empty;
	output almost_full;
	output almost_empty;
	output half;
	output [7:0] data_out;
	output [3:0] sfifo_cnt;

	wire clk;
	wire rst_n;
	wire [7:0] data_in;
	wire wr;
	wire rd;
	wire full;
	wire empty;
	wire almost_full;
	wire almost_empty;
	wire half;
	reg [7:0] data_out;
	reg [3:0] sfifo_cnt;

	`define DEL 1 // Clock-to-output delay
	
	reg [7:0] sfifo_ram[0:7];  // sfifo_ram initialized
	reg [2:0] rd_ptr;  // Read pointer
	reg [2:0] wr_ptr;  // Write pointer 
	
	assign empty = ( sfifo_cnt == 0 ) ? 1 : 0;  //Empty signal
	assign full  = ( sfifo_cnt == 8 ) ? 1 : 0;  //Full signal
	assign almost_full  = ( sfifo_cnt == 6 ) ? 1 : 0; //Almost Full signal
	assign almost_empty  = ( sfifo_cnt == 2 ) ? 1 : 0;//Almost Empty signal
	assign half  = ( sfifo_cnt == 4 ) ? 1 : 0;//HALF signal
	
	// sfifo_cnt changed
	// 当读有效, cnt--
	// 当写有效, cnt++
	always @( posedge clk or negedge rst_n) begin
	  if( ~rst_n ) begin
	    sfifo_cnt <= #`DEL 4'h0;
	  end
	  else if( rd && ~wr ) begin
	    sfifo_cnt <= #`DEL sfifo_cnt - 1;
	  end
	  else if( ~rd && wr ) begin
	    sfifo_cnt <= #`DEL sfifo_cnt + 1;
	  end
	  else begin 
	    sfifo_cnt <= sfifo_cnt;
	  end
	end      
	

	always @( posedge clk or negedge rst_n) begin
	  if( ~rst_n ) begin
	    rd_ptr <= #`DEL 3'h0;
	  end
	  else if( rd ) begin
	    if( rd_ptr == 3'h7 ) begin
	      rd_ptr <= #`DEL 3'h0;
	    end
	    else begin
	      rd_ptr <= #`DEL rd_ptr +1;
	    end
	  end
	  else begin
	    rd_ptr <= rd_ptr;
	  end
	end    
	
 
	always @( posedge clk or negedge rst_n) begin
	  if( ~rst_n ) begin
	    wr_ptr <= #`DEL 3'h0;
	  end
	  else if( wr ) begin
	    if( wr_ptr == 3'h7 ) begin
	      wr_ptr <= #`DEL 3'h0;
	    end
	    else begin
	      wr_ptr <= #`DEL wr_ptr +1;
	    end
	  end
	  else begin
	    wr_ptr <= wr_ptr;
	  end
	end 
	

	always @( posedge clk or negedge rst_n) begin
	  if( ~rst_n ) begin
	    data_out <= #`DEL 8'h0;
	  end
	  else if( wr ) begin
	    sfifo_ram[wr_ptr] <= #`DEL data_in;
	  end
	  else if( rd ) begin 
	    data_out <= #`DEL sfifo_ram[rd_ptr];
	  end
	end      
	
	
endmodule   

sfifo_test

module sfifo_test();

	reg clk;
	reg rst_n;
	reg [7:0] data_in;
	reg wr;
	reg rd;
	wire full;
	wire empty;
	wire almost_full;
	wire almost_empty;
	wire half;
	wire [7:0] data_out;
	wire [3:0] sfifo_cnt;

	initial begin
	  rst_n=1;
	  clk=0;
	  wr=0;
	  rd=0;
	  data_in=0;
	  #1 rst_n=0;
	  #5 rst_n=1;
	  #3 wr=1;
	  #5 rd=1;
	  #5 rd=0;
	  #5 wr=0;
	  #5 wr=1;
	  #10 rd=1;
	  #10 rd=0;
	  
	end
	always begin
	  #5 clk=~clk;
	end
	always @(posedge clk or negedge rst_n) begin
	  if (~rst_n) begin
	    data_in<=0;
	    wr<=0;
	    rd<=0;
	  end
	  else begin
	    data_in<=$random;
	  end
	end
	
	initial begin
		$dumpfile ("F:/Robei/practice/prac_07_sfifo/sfifo_test.vcd");
		$dumpvars;
		
		#5000;
		$stop;
	end
	//---Module instantiation---
	sfifo sfifo1(
		.clk(clk),
		.rst_n(rst_n),
		.data_in(data_in),
		.wr(wr),
		.rd(rd),
		.full(full),
		.empty(empty),
		.almost_full(almost_full),
		.almost_empty(almost_empty),
		.half(half),
		.data_out(data_out),
		.sfifo_cnt(sfifo_cnt)
		);

	

endmodule    

实验结果

整体波形

读

写

同时读写