（1）异步FIFO的配置过程：
ps：异步fifo相比较同步fifo少一个实际深度
（2）异步FIFO的调用:
module dcfifo
(input wr_clk ,input rd_clk ,input [7:0] data_in ,input wr_en ,input rd_en ,output [15:0] data_out ,output full ,output empty ,output [6:0] rd_data_count ,output [7:0] wr_data_count
);dcfifo_8x256_to_16x128 dcfifo_8x256_to_16x128_inst (.wr_clk (wr_clk ), // input wire wr_clk.rd_clk (rd_clk ), // input wire rd_clk.din (data_in ), // input wire [7 : 0] din.wr_en (wr_en ), // input wire wr_en.rd_en (rd_en ), // input wire rd_en.dout (data_out ), // output wire [15 : 0] dout.full (full ), // output wire full.empty (empty ), // output wire empty.rd_data_count (rd_data_count ), // output wire [6 : 0] rd_data_count.wr_data_count (wr_data_count ) // output wire [7 : 0] wr_data_count
);endmodule
（3）异步FIFP仿真文件代码：
`timescale 1ns / 1psmodule dcfifo_tb;reg wr_clk ;
reg rd_clk ;
reg [7:0] data_in ;
reg wr_en ;
reg rd_en ;
reg reset_n ;
reg [1:0] cnt ;
reg full_reg0 ;
reg full_reg1 ;wire [15:0] data_out ;
wire full ;
wire empty ;
wire [6:0] rd_data_count ;
wire [7:0] wr_data_count ;//50MHz读时钟initial wr_clk = 1'd1;always #10 wr_clk = ~wr_clk;//25MHz写时钟 initial rd_clk = 1'd1;always #20 rd_clk = ~rd_clk;//复位信号initial begin reset_n <= 1'd0;#15;reset_n <= 1'd1;#100_000;$stop;end//cnt信号 always@(posedge wr_clk or negedge reset_n)if(!reset_n)cnt <= 2'd0;else if(cnt == 2'd3)cnt <= 2'd0;else cnt <= cnt + 2'd1;//wr_en信号always@(posedge wr_clk or negedge reset_n)if(!reset_n)wr_en <= 1'd0;else if((cnt == 2'd3) && (rd_en == 1'd0))wr_en <= 1'd1;else wr_en <= 1'd0;//data_in信号always@(posedge wr_clk or negedge reset_n)if(!reset_n)data_in <= 8'd0;else if((data_in == 8'd255) && (wr_en == 1'd1))data_in <= 8'd0;else if(wr_en == 1'd1)data_in <= data_in + 8'd1;else data_in <= data_in;//full_reg0、full_reg1信号设计always@(posedge rd_clk or negedge reset_n)if(!reset_n)beginfull_reg0 <= 1'd0;full_reg1 <= 1'd0; endelse beginfull_reg0 <= full;full_reg1 <= full_reg0;end//rd_en信号always@(posedge rd_clk or negedge reset_n)if(!reset_n)rd_en <= 1'd0;else if(full_reg1 && (wr_en == 1'd0))rd_en <= 1'd1;else if(empty)rd_en <= 1'd0;else rd_en <= rd_en;dcfifo dcfifo_inst
(.wr_clk (wr_clk ),.rd_clk (rd_clk ),.data_in (data_in ),.wr_en (wr_en ),.rd_en (rd_en ),.data_out (data_out ),.full (full ),.empty (empty ),.rd_data_count (rd_data_count),.wr_data_count (wr_data_count)
);endmodule
（4）仿真波形：
