-- code for checking the password entered using a keypad which gives binary outputs

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

-- defining the entity

entity PASSCHECK is
port( IN1 : in std_logic_vector( 3 downto 0);
		CLK : in std_logic;
	OUT1,OUT2 : out std_logic);
end PASSCHECK;

-- IN1 is for the inputs for the password 


-- architecture of the code for checking the password

architecture behavioral of PASSCHECK is


type PASS_WORD is array ( 0  to 3 ) of integer range 0 to 12;
constant PASSWORD : PASS_WORD := (1,2,3,4);							-- the correct password with the first integer on the left most side 
signal COUNT1, COUNT2 : integer range 0 to 5;
signal temp : integer range 0 to 12;
signal MC : integer range 0 to 50000;
signal DCLK : std_logic;



--
--component NIB_TO_INT is
--port( IN1 : in std_logic_vector( 3 downto 0);
--		OUT1,OUT2 : out integer range 0 to 9);
--end component;

--OUT1<='0';
--OUT2<='0';
begin 

--COUNT1 is used to check if any botton is pressed, its value is 1 if any of the buttons is pressed.
--COUNT2 checks the number of correctly entered integers, its value changes to 5 if any of the integer entered is wrong.

	process(CLK)
	begin
		if CLK'event and CLK = '1' then
			if(MC = 500) then
				DCLK <= not DCLK;
				MC <= 0;
			else
				MC <= MC +1;
			end if;
		end if;
	end process;

	process (IN1)
	begin
	case IN1 is
	when "0000" => 
		temp <= 0;
	when "0001" => 
		temp <= 1;
	when "0010" => 
		temp <= 2;
	when "0011" => 
		temp <= 3;
	when "0100" => 
		temp <= 4;
	when "0101" => 
		temp <= 5;
	when "0110" => 
		temp <= 6;
	when "0111" => 
		temp <= 7;
	when "1000" => 
		temp <= 8;
	when "1001" => 
		temp <= 9;
	when "1010" => 
		temp <= 10;
	when "1011" => 
		temp <= 11;
	when "1100" => 
		temp <= 12;
	when others=>
		temp <=10; --since 12 refers to clear the screen	
	end case;
	end process;
	
PROCESS(temp,DCLK)
begin
	if(DCLK'event and DCLK = '0' ) then
	if(temp /= 0) then
	--	
		if(COUNT1 = 0) then
			COUNT1 <= 1;
			if(temp = 12 )then  		-- 12 is the enter key 
				if(COUNT2 = 4) then									-- if all the data is correctly entered 
					OUT1 <= '1';					--signal for correct value 
					OUT2 <= '0';
					--COUNT1 <= 0;										--initialise for the next time 
					--COUNT2 <= 0;
				else
					OUT2 <= '1';					-- if wrong data was interted then out2 becomes high
					OUT1 <= '0';
					COUNT1 <= 0;
					COUNT2 <= 0;
				end if;
			elsif(temp =10 )then		--10 is the clear button which would clear the screen/memory
				COUNT2 <= 0;
				COUNT1 <= 0;
				OUT1 <= '0';
				OUT2 <= '0';
			end if;
			if(COUNT2 < 4) then		--	checkig each data
				if(temp = PASSWORD(COUNT2)) then
					COUNT2 <= COUNT2 +1;
				else
				COUNT2 <= 5;									-- if wrong data is enterd then the vlue of count2 becomes 5 ie. wrong password 
				end if;
			end if;
			
	
			
	--
	end if;
		elsif(temp = 0) then						--either waiting for next input or just on standby
		if(COUNT1 = 1) then
			COUNT1 <= 0;														--ready to take next input
	end if;
	end if;
	end if;
end process;
end behavioral;