library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.std_logic_unsigned.all;
entity registers_min_max is
port( din   : in std_logic_vector(3 downto 0);
      reset : in std_logic;
      clk   : in std_logic;
      sel   : in std_logic_vector(1 downto 0);
      max_out : out std_logic_vector(3 downto 0);
      min_out : out std_logic_vector(3 downto 0);
      reg_out : out std_logic_vector(3 downto 0));
end registers_min_max ;

architecture arch_minmax of registers_min_max is

  type reg_array is array (0 to 3) of std_logic_vector (3 downto 0);
  signal reg : reg_array;
  signal max : std_logic_vector (3 downto 0);
  signal min : std_logic_vector (3 downto 0);
  signal max_reg,min_reg : std_logic_vector (3 downto 0);
  begin
  process(clk,reset)

    begin
      if (reset = '1') then

          for i in 0 to 3 loop
            reg(i) <= "1000";
          end loop;



    elsif (clk'event and clk='1') then
      for i in 0 to 3 loop

        if(i > 0) then
            reg(i) <= reg(i-1);
      elsif (i = 0) then
            reg(i) <= din;

          end if;
        end loop;
    end if;
  end process;

  process (reg)

      variable small :std_logic_vector (3 downto 0);
      variable big : std_logic_vector (3 downto 0);
      begin

        big := "0000";
        small := "1111";

        for i in 0 to 3 loop
          if (reg(i) > big) then
            big := reg(i);


        end if;
      end loop;

      for i in 0 to 3 loop

        if (reg(i) < small) then
          small := reg(i);

        end if;
      end loop;
      max <= big;
      min <=small;


    end process;

    process(clk,reset)
      begin

        if (reset = '1') then
          max_reg <= (others =>'0');
          min_reg <= (others =>'1');

        elsif (clk'event and clk='1') then
          max_reg <= max;
          min_reg <= min;

        end if;
      end process;
      max_out <= not max_reg;
      min_out <= not min_reg;

      process(reg,sel)
        begin
          reg_out <= not reg(conv_integer(sel));
        end process;
      end arch_minmax;