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-- Company:
-- Engineer:
--
-- Create Date:    08:41:32 11/10/2010
-- Design Name:
-- Module Name:    tiktok - Behavioral
-- Project Name:
-- Target Devices:
-- Tool versions:
-- Description:
--
-- Dependencies:
--
-- Revision:
-- Revision 0.01 - File Created
-- Additional Comments:
--
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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 counter is
    Port ( led   : inout std_logic_vector (7 downto 0);
           clk   : in std_logic;
              reset : in std_logic;
              up    : in std_logic;
              down  : in std_logic
              );
end counter;

architecture Behavioral of counter is
    signal clkdiv : std_logic;
    signal shift : std_logic;
begin

    div: process(clk)
        variable q1 : std_logic_vector(22 downto 0);
    begin
        if clk = '1' and clk'event then
            q1 := q1 + '1';
            if q1(22) = '1' then
                q1 := (others => '0');
                clkdiv <= not clkdiv;
            end if;
        end if;
    end process div;

    P1: process(clkdiv, reset, up, down)
    begin
        if reset = '1' then
            led <= (others => '0');
        elsif clkdiv'event and clkdiv = '1' then
            if (up xor down) = '1' then
                if up = '1' then
                    led <= led + '1';
                else
                    led <= led - '1';
                end if;
            end if;
        end if;
    end process P1;
end Behavioral;