二级流水线8位加法器

module adder8_2(cout,sum,clk,cina,cinb,cin,rst_n);
 input [7:0]cina,cinb;
 input clk,cin;
 input rst_n;
 output [7:0]sum;
 output cout;
 reg cout;
 reg cout1;
 reg [3:0] sum1;
 reg [7:0]sum;
 
 always @(posedge clk or negedge rst_n) begin  //μí8???à?ó
 if(!rst_n)
   begin
     cout1=0;
     sum1=0;    
     end
 else    begin
  {cout1,sum1} = cina[3:0]+cinb[3:0]+cin;
 end
 end

 always @(posedge clk or negedge rst_n) begin  //??8???à?ó
 if(!rst_n)
   begin
     cout =0;
     sum =0;
     end
 else

 sum[3:0] = sum1;
   {cout,sum[7:4]} = cina[7:4] + cinb[7:4]+ cout1;
 //  {cout,sum[7:0]} = {{{cina[7],cina[7:4]} + {cinb[7],cinb[7:4]}+ cout1},sum1};
 end
endmodule

 

 

测试文件：

module test_adder16_2;

 // Inputs
 reg clk;
 reg [7:0] cina;
 reg [7:0] cinb;
 reg cin;
   reg rst_n;
 // Outputs
 wire cout;
 wire [7:0] sum;

 // Instantiate the Unit Under Test (UUT)
 adder8_2 uut (
  .cout(cout),
  .sum(sum),
  .clk(clk),
  .cina(cina),
  .cinb(cinb),
  .cin(cin),
  .rst_n(rst_n)
 );

 initial begin
  // Initialize Inputs
  clk = 0;
  cina = 0;
  cinb = 0;
  cin = 0;
  rst_n=1;
    #100 rst_n=0;
  // Wait 100 ns for global reset to finish
  #200;
    rst_n=1;  
  // Add stimulus here
  #100 cina = 8'b0000_0001; cinb = 8'b0000_1111; cin=1'b1;
  #200 cina = 8'b1111_0001; cinb = 8'b0000_1011; cin=1'b1;
  #200 cina = 8'b0111_0011; cinb = 8'b0100_1111; cin=1'b1;
  #200 cina = 8'b1100_1000; cinb = 8'b1000_1111; cin=1'b1;
  #200 cina = 8'b0001_1000; cinb = 8'b0100_0011; cin=1'b1;
  #200 cina = 8'b0101_1000; cinb = 8'b0000_1111; cin=1'b1;  
 end
  always #50 clk = ~clk;
     
endmodule