//******************////copyright 2007, DTK//all right reserved////project name: : test6//filename    : file_function//author      : wangyang//data        : 2007/8/2//version     : 1.0////module name : module_function//abstract     : use function design ...////modification history//---------------------------------//&Log&//******************module tryfunction(Clk,N,Result,Reset);  input[3:0] N;  input Reset;  input Clk;  output[31:0] Result;  reg[31:0] Result;  always @(posedge Clk)    //clk??????????   begin 		 if(!Reset)            //reset??????    			Result<=0;      	else        		begin          		Result <= N * Factorial(N)/((N*2)+1);        		end   end    function [31:0] Factorial;      //?????    input  [3:0]  Operand;    reg    [3:0]  Index;    begin      Factorial = Operand ? 1 : 0;      for(Index = 2; Index <= Operand; Index = Index + 1)        Factorial = Index * Factorial;    end  endfunction  endmodule//????????//`include "./tryfunction.v"`timescale 1ns/100ps`define clk_cycle 50module tryfuct_test;reg[3:0] N,I;reg Reset,Clk;wire[31:0] Result;initial  begin    N=0;    Reset=1;    Clk=0;    #100 Reset=0;    #100 Reset=1;    for(I=0;I<=15;I=I+1)      begin        #200 N=I;      end    #100 $stop;  endalways #`clk_cycle Clk=~Clk;  tryfunction tryfunct(.Clk(Clk),.N(N),.Result(Result),.Reset(Reset));endmodule