date_counter.vhd

采用VHDL语言编写的万年历程序

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
entity date_counter is
--iday_cntl表示日期的各位，iday_cnth表示日期的十位,其他依此类推
    Port ( reset:        in std_logic;
	        --start:        in std_logic;
	        clk_day :      in std_logic;
	        iday_cntl  :   in std_logic_vector(3 downto 0);
	        iday_cnth  :   in std_logic_vector(3 downto 0);
			  imonth_cntl  : in std_logic_vector(3 downto 0);
			  imonth_cnth :  in std_logic_vector(3 downto 0);
			  iyear_cntl  :  in std_logic_vector(3 downto 0);
			  iyear_cntml :  in std_logic_vector(3 downto 0);
			  iyear_cntmh  : in std_logic_vector(3 downto 0);
			  iyear_cnth :   in std_logic_vector(3 downto 0);
			  oday_cntl  :   out std_logic_vector(3 downto 0);
	        oday_cnth  :   out std_logic_vector(3 downto 0);
			  omonth_cntl  : out std_logic_vector(3 downto 0);
			  omonth_cnth :  out std_logic_vector(3 downto 0);
			  oyear_cntl  :  out std_logic_vector(3 downto 0);
			  oyear_cntml :  out std_logic_vector(3 downto 0);
			  oyear_cntmh  : out std_logic_vector(3 downto 0);
			  oyear_cnth :   out std_logic_vector(3 downto 0));
-----------------------------------------------------------------------------
	 function leap_identify(year:integer)return boolean is
	 begin                     --判断是否是闰年的函数
	   if (year rem 4)=0 then  --虽然，1900和2100年不是闰年(1900和2100可以被4整除)，
		                        --但是实际运用一般不大可能超出这个范围(1901-2099),
		   return true;         --即使超出这两年，也可以通过再预置解决；
		else 
		   return false;
	   end if;
	 end leap_identify;
end date_counter;
-------------------------------------------------------------------------------
architecture Behavioral of date_counter is

begin
   process(clk_day,reset,iday_cntl,iday_cnth,imonth_cntl,imonth_cnth,iyear_cntl,iyear_cntml,iyear_cntmh,iyear_cnth)
	     type mon is array(11 downto 0)of std_logic_vector(7 downto 0);
        constant leapyear : mon := ("00110001","00110000","00110001","00110000","00110001","00110001","00110000","00110001","00110000","00110001","00101000","00110001");
        constant n_leapyear : mon := ("00110001","00110000","00110001","00110000","00110001","00110001","00110000","00110001","00110000","00110001","00101001","00110001");
	     variable temp:mon;
		  variable day_cntl:std_logic_vector(3 downto 0);
		  variable day_cnth:std_logic_vector(3 downto 0);
		  variable month_cntl:std_logic_vector(3 downto 0);
		  variable month_cnth:std_logic_vector(3 downto 0);
		  variable year_cntl:std_logic_vector(3 downto 0);
		  variable year_cntml:std_logic_vector(3 downto 0);
		  variable year_cntmh:std_logic_vector(3 downto 0);
		  variable year_cnth:std_logic_vector(3 downto 0);
		  variable temp1:std_logic_vector(7 downto 0);
	  begin
	      if reset='0'then
			  --enable='0'表示将预置日期代入
			   day_cntl:=iday_cntl ;
				day_cnth:=iday_cnth;
				month_cnth:=imonth_cnth;
				month_cntl:=imonth_cntl ;
				year_cntl:=iyear_cntl ;
			   year_cntml:=iyear_cntml;
			   year_cntmh:=iyear_cntmh;
 		      year_cnth:=iyear_cnth;
			  --初始化
 				oday_cntl<=day_cntl;oday_cnth<=day_cnth;
				omonth_cntl<=month_cntl;omonth_cnth<=month_cnth;
				oyear_cntl<=year_cntl;oyear_cntml<=year_cntml;oyear_cntmh<=year_cntmh;oyear_cnth<=year_cnth;
         elsif rising_edge(clk_day)then
			   --if start='0'then
--------------------------------------------
              --判断是否是闰年(只须判断年的十位个位即可)
		        if leap_identify(conv_integer(year_cntl)+conv_integer(year_cnth)*10) then
		           temp:=leapyear ;--是闰年
		        else 
		           temp:=n_leapyear;--不是闰年
		        end if;
--------------------------------------------
			      temp1:=day_cnth&day_cntl;
			     if temp1=temp(conv_integer(month_cntl)+conv_integer(month_cnth)*10-1) then
			        --判断这一年的这个月是否结束
----------------------------------------------------------------
			        day_cntl:="0000";day_cnth:="0000";
				     --从1号开始计日
			        if month_cnth="0001"and month_cntl="0010" then
		           --到了12月;    
				        month_cntl:="0000";month_cnth:="0000";
				     --从一月开始计
----------------------------------------------------------------
					     year_cntl:=year_cntl+1;
					     --年加一
					     if year_cntl="1010"then
					        year_cntl:="0000";
					        year_cntml:=year_cntml+1;
					     end if;
					     if year_cntml="1010"then
					        year_cntml:="0000";
					        year_cntmh:=year_cntmh+1;
					     end if;
					     if year_cntmh="1010"then
					        year_cntmh:="0000";
					        year_cnth:=year_cnth+1;
					     end if;
				     end if;
----------------------------------------------------------------
                 month_cntl:=month_cntl+1;
				     --月加一
				     if month_cntl="1010"then
				        month_cntl:="0000";
				        month_cnth:=month_cnth+1;
				     end if;
----------------------------------------------------------------
			      end if;
               day_cntl:=day_cntl+1;
				    --日期加一
			      if day_cntl="1010"then
				      day_cntl:="0000";
					   day_cnth:=day_cnth+1; 
				   end if;
--------------------------------------------
			      oday_cntl<=day_cntl;
				   oday_cnth<=day_cnth;
				   omonth_cnth<=month_cnth;
				   omonth_cntl<=month_cntl ;
				   oyear_cntl<=year_cntl ;
			      oyear_cntml<=year_cntml;
			      oyear_cntmh<=year_cntmh;
 		         oyear_cnth<=year_cnth; 
		     --end if;	
		  end if;   		     
	  end process;
end Behavioral;