----------------------------------------------------------
-- keyValidator
-- Author   : Gautam Karnik
-- Date     : March 30, 2001
-- Filename : keyValidator.vhd
-- Architecture : Behavioral
-- Description  : This entity determines when we have
--                valid keypad data.  This occurs when:
--                   the key is pressed and 
--                   the channel is ready and
--                   either user 1 or user 2 is online.
----------------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all; 
use ieee.std_logic_unsigned.all; 
library work;
use work.CDMA_pkg.all;

entity keyValidator is
	port ( 
		resetn, clock   : in std_logic;
		channel_status : in std_logic;
		usr1_online, usr2_online : in std_logic;
		keyPressed   : in std_logic;
		keyValid     : out std_logic
	);
end entity keyValidator;

architecture behavioral of keyValidator is 

	signal high : std_logic;
	signal keyPressed_delay1, keyPressed_delay2, key : std_logic;

begin

	high <= '1';

delay1 : dff_en
	port map (
		resetn 	=> resetn, 
		clock 	=> clock,
		enable 	=> high,
		d 		=> keyPressed,
		q 		=> keyPressed_delay1
	);

delay2 : dff_en
	port map (
		resetn 	=> resetn, 
		clock 	=> clock,
		enable 	=> high,
		d 		=> keyPressed_delay1,
		q 		=> keyPressed_delay2
	);

delays : process (resetn, keyPressed, keyPressed_delay2) is
	begin
		if resetn = '0' then
			key <= '0';
		elsif keyPressed = '1' then
			key <= '1';
		elsif keyPressed_delay2 = '1' then
			key <= '0';
		else
			key <= key;
		end if;
	end process delays;

	keyValid <= (key and channel_status) and 
					(usr1_online or usr2_online);	

end behavioral;