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library IEEE; 
use IEEE.std_logic_1164.all; 
use IEEE.std_logic_arith.all; 
use IEEE.std_logic_unsigned.all; 
entity count_down is 
    port(reset: in std_logic; 
         clk:in std_logic; 
         ena_1Hz:in std_logic; 
         recount:in std_logic; 
         load: in std_logic_vector(7 downto 0); 
         seg7:out std_logic_vector(15 downto 0); 
         next_state: out std_logic); 
end;    
architecture BEHAVIOR of count_down is      
signal cnt_ff:std_logic_vector(7 downto 0);  
begin 
   count:process(clk,reset) 
   begin 
       if (reset='1') then 
          cnt_ff<="00000000"; 
          seg7<="0000000000000000"; 
       elsif (clk'event and clk='1') then 
          if ena_1Hz='1' then 
             if (recount='1') then 
                cnt_ff<=load-1; 
             else 
                cnt_ff<=cnt_ff-1;   
             end if; 
          end if;           
          case conv_integer(cnt_ff) is 
               when 0=>seg7(15 downto 0)<="0011111100111111"; 
               when 1=>seg7(15 downto 0)<="0011111100000110"; 
               when 2=>seg7(15 downto 0)<="0011111101011011"; 
               when 3=>seg7(15 downto 0)<="0011111101001111"; 
               when 4=>seg7(15 downto 0)<="0011111101100110"; 
               when 5=>seg7(15 downto 0)<="0011111101101101"; 
               when 6=>seg7(15 downto 0)<="0011111101111101"; 
               when 7=>seg7(15 downto 0)<="0011111100000111"; 
               when 8=>seg7(15 downto 0)<="0011111101111111"; 
               when 9=>seg7(15 downto 0)<="0011111101111011"; 
               when 10=>seg7(15 downto 0)<="0000011000111111"; 
               when 11=>seg7(15 downto 0)<="0000011000000110"; 
               when 12=>seg7(15 downto 0)<="0000011001011011"; 
               when 13=>seg7(15 downto 0)<="0000011001001111"; 
               when 14=>seg7(15 downto 0)<="0000011001100110"; 
               when 15=>seg7(15 downto 0)<="0000011001101101"; 
               when 16=>seg7(15 downto 0)<="0000011001111101"; 
               when 17=>seg7(15 downto 0)<="0000011000000111"; 
               when 18=>seg7(15 downto 0)<="0000011001111111"; 
               when 19=>seg7(15 downto 0)<="0000011001111011"; 
               when 20=>seg7(15 downto 0)<="0101101100111111"; 
               when 21=>seg7(15 downto 0)<="0101101100000110"; 
               when 22=>seg7(15 downto 0)<="0101101101011011"; 
               when 23=>seg7(15 downto 0)<="0101101101001111"; 
               when 24=>seg7(15 downto 0)<="0101101101100110"; 
               when 25=>seg7(15 downto 0)<="0101101101101101"; 
               when 26=>seg7(15 downto 0)<="0101101101111101"; 
               when 27=>seg7(15 downto 0)<="0101101100000111"; 
               when 28=>seg7(15 downto 0)<="0101101101111111"; 
               when 29=>seg7(15 downto 0)<="0101101101111011";                
               when others=>seg7(15 downto 0)<="0011111100111111"; 
          end case; 
       end if; 
   end process;  
 
   next_state <= '1' when cnt_ff=1 else 
                 '0'; 
 
end BEHAVIOR;