----------------------------------------------------------
-- keyEncode
-- Author   : Gautam Karnik
-- Date     : March 30, 2001
-- Filename : keyEncode.vhd
-- Architecture : Behavioral
-- Description  : This entity takes in the row and column
--                value of the key that has been pressed
--                and encodes the data for either user 1 
--                or user 2.  Each user can have data 
--                values from 0 to 7.
----------------------------------------------------------
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 keyEncode is
      	port ( resetn   : in std_logic;
			   clock    : in std_logic;
			   row      : in std_logic_vector ( 3 downto 0 );
			   col      : in std_logic_vector ( 3 downto 0 );
			   usr1_data  : out std_logic_vector ( 2 downto 0);
			   usr2_data  : out std_logic_vector ( 2 downto 0)
      	     );
end entity keyEncode;

architecture behavioral of keyEncode is 

type KEY_TYPE is ( keyNone, key0, key1, key2, key3, key4, key5, key6, key7, key8,
			 key9, key10, key11, key12, key13, key14, key15 );
signal key        : KEY_TYPE;
begin

translate : process ( clock, resetn )

begin
	 wait until rising_edge ( clock );
     if (resetn = '0') then
		key <= keyNone;

     else
		-- Button numbers for the keypad
		-- 0  1  2  3
		-- 4  5  6  7 
		-- 8  9  10 11
		-- 12 13 14 15
		CASE col IS
			WHEN "0001" =>
			  CASE row is
				WHEN "1110" => key <= key0;
				WHEN "1101" => key <= key4;
				WHEN "1011" => key <= key8;
				WHEN "0111" => key <= key12;
				WHEN OTHERS => key <= keyNone;
			  END CASE;	
			WHEN "0010" =>
			  CASE row is
				WHEN "1110" => key <= key1;
				WHEN "1101" => key <= key5;
				WHEN "1011" => key <= key9;
				WHEN "0111" => key <= key13;
				WHEN OTHERS => key <= keyNone;
			  END CASE;	
			WHEN "0100" =>
			  CASE row is
				WHEN "1110" => key <= key2;
				WHEN "1101" => key <= key6;
				WHEN "1011" => key <= key10;
				WHEN "0111" => key <= key14;
				WHEN OTHERS => key <= keyNone;
			  END CASE;	
			WHEN "1000" =>
			  CASE row is
				WHEN "1110" => key <= key3;
				WHEN "1101" => key <= key7;
				WHEN "1011" => key <= key11;
				WHEN "0111" => key <= key15;
				WHEN OTHERS => key <= keyNone;
			  END CASE;	
			WHEN OTHERS =>
			  key <= keyNone;
			END CASE;
	end if;
end process translate;

	with key select
		usr1_data <= "000" when key0,
				     "001" when key1,
					 "010" when key2,
					 "011" when key3,
					 "100" when key4,
					 "101" when key5,
					 "110" when key6,
					 "111" when key7,
					 "000" when others;

	with key select
		usr2_data <= "000" when key8,
				     "001" when key9,
					 "010" when key10,
					 "011" when key11,
					 "100" when key12,
					 "101" when key13,
					 "110" when key14,
					 "111" when key15,
					 "000" when others;
				 

end behavioral;