-- LED TEST for HDL Bread Board (XC95108 PC84 -7 / 10MHz)

library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.std_logic_unsigned.all;

entity LED is
   port (
	RESET: in std_logic;
	START: in std_logic; -- not used now...(use RESET instead)	
	ENABLE: in std_logic; -- :=STOP
	LEDS: out std_logic_vector (7 downto 0) ;
	CLK: in std_logic
	) ;

--   !! CAUTION !!  You need assignment signals to pins into  " Edit Constraints " in EXPRESS 
--   RESET  : signal is  "P2"; (Push = 0)

--   START : signal is  "P4"; (Push = 0)
     -- "P3" Other side of START button (usualy = 0, Push = 1)
--   STOP : signal is  "P7"; (= ENABLE, Push = 0)
     -- "P6" Other side of STOP button (usualy = 0, Push = 1) 
--   LEDS  : Output signal is  "P43,P44,P45,P46,P47,P48,P50,P51";
--   CLK : Input signal is  "P9";)
         
end LED;

architecture LED_ARCH of LED is

signal OSCOUT, C2CLK, CLOCK : std_logic; -- OSCOUT,C2CLK are not used now.
signal COUNT : std_logic_vector (23 downto 0);
-- signal COUNT : std_logic_vector (3 downto 0);
signal FIBOUT, PREV_FIB, FIBADD : std_logic_vector (7 downto 0);
  
begin

-- Syetm Clock = 10MHZ, divide by (2**24) = > Clock Frequency 1 Hz 
 process ( CLK ) 
 begin
       if CLK = '1' and CLK'event then
               if COUNT > "111111111111111111111111" then
               -- if COUNT > "1111" then
            	COUNT <= "000000000000000000000000";
            	-- COUNT <= "0000";
               else
            	COUNT <= COUNT + '1';
               end if;
               CLOCK <= COUNT(23);
               -- CLOCK <= COUNT(3);
       end if;
 end process;

  process
  begin
  	-- Write your own Code !
  	
	if  RESET   = '0'  then
	    FIBOUT <= "00000001";
	    PREV_FIB <= "00000000";
	  end if ;
	  wait until CLOCK'event and CLOCK = '0' and ENABLE = '1' ;
	    PREV_FIB <= FIBOUT;
	    case (FIBOUT="00000000") and (PREV_FIB="00000000") is
	      when true =>   FIBOUT <= "00000001";
	      when others => FIBOUT <= FIBADD;
	    end case;
  end process ;
  
-- incliment  FIBOUT
FIBADD <= FIBOUT +  PREV_FIB; 

-- Assign to output port and Display to LEDs
LEDS <=  FIBOUT xor "00000001" ;

end  LED_ARCH ;