-- keypush.vhd
-- Christopher Kowalski
-- EE 552
--
-- This code will output the value of a key on a keyboard after the key has been released.

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;

package key_pack is

component key is
	port(keyboard,
		reset,
		keyclock	: in std_logic;
		scancode 	: out std_logic_vector(7 downto 0);
		gotcode		: out std_logic);
end component key;

end package key_pack;






library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;
library work;
use work.key_pack.all;


entity keypush is
	port(keyboard,
		clock,
		reset,
		keyread,
		keyclock	: in std_logic;
		key_out	 	: out std_logic_vector(7 downto 0);
		gotkey		: out std_logic);
end keypush;

architecture structural of keypush is

	-- declare internal signals
signal key_command	: std_logic_vector(7 downto 0);
signal key_done		: std_logic;

		
begin


	keyreader:	component key
		port map(keyboard	=> keyboard,
				reset		=> reset,
				keyclock	=> keyclock,
				scancode 	=> key_command,
				gotcode		=> key_done);

	getkey	: process (clock) is

	--process variable
	variable step:natural range 0 to 3;

	begin
		if rising_edge(clock) then
		if reset = '1' then
			key_out <= (others => '0');
			gotkey <= '0';
			step:= 0;
		elsif (key_done = '1') and (key_command = "11110000") then  --F0 is sent from the keyboard
			step:= 1;
		elsif (step = 1) and (key_done = '0') then	-- wait until an other key is pressed
			step:= 2;
		elsif (step = 2) and (key_done = '1') then	-- when the key has been read in register it.
			key_out <= key_command;
			gotkey <= '1';
			step:= 3;
		elsif (step = 3) and (keyread = '1') then	-- a handshaking signal.  When your system has
													-- read the key assert a signal high to tell
													-- this code that you have read the key.
			key_out <= (others => '0');				-- clear the key value, you don't have to do this
			gotkey <= '0';							-- low this signal until a new key is detected
			step:= 0;
		end if;
		end if;

	end process getkey;

-- NOTE: the key must be read by your system before the next key is released other wise the next
-- key will be ignored.

end structural;