--==================================================================================
--
-- timer = 100.000.000)  ->  1/1     second
-- timer =  50.000.000)  ->  1/2     second = 500 mili second
-- timer =  25.000.000)  ->  1/4     second = 250 mili second
-- timer =  10.000.000)  ->  1/10    second = 100 mili second
-- timer =     100.000)  ->  1/1000  second =   1 mili second
-- timer =      50.000)  ->  1/2000  second = 0.5 mili second = 500 micro second

--===================================================================================

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.NUMERIC_STD.ALL;

entity Stop_Watch is
	Port ( 	clk         			: IN  STD_LOGIC ;   -- 100 MHz
				OPERATION				: IN	STD_LOGIC ;
				RESET						: IN  STD_LOGIC ;
				Period_Info				: IN	STD_LOGIC_VECTOR(3 DOWNTO 0) ;
				SW_Period_Over_Flag 	: OUT STD_LOGIC ;
				Period					: OUT INTEGER range 0 to 5*10E+3);
end Stop_Watch;

architecture Behavioral of Stop_Watch is

signal s_clk      			  : STD_LOGIC ;
signal s_OPERATION			  : STD_LOGIC ;
signal s_RESET      			  : STD_LOGIC ;
signal s_SW_Period_Over_Flag : STD_LOGIC ;
signal s_Period_Info			  : STD_LOGIC_VECTOR(3 DOWNTO 0) ;
signal i_Period				  : INTEGER range 0 to 5*10E+3 := 0;

begin
	
	s_clk 			<= clk ;
	s_OPERATION		<= OPERATION ;
	s_RESET 			<= RESET ;
	s_Period_Info	<=	Period_Info	;
	
	i_Period <=	1		when s_period_info = "0001" else	
					5 		when s_period_info = "0010" else	
					10		when s_period_info = "0011" else	
					30		when s_period_info = "0100" else 	
					60		when s_period_info = "0101" else 	
					300	when s_period_info = "0110" else 	
					600	when s_period_info = "0111" else 	
					1800	when s_period_info = "1000" else 	
					3600	when s_period_info = "1001" else 	
					1 ;
					 
					 
	process(s_clk, s_OPERATION, s_RESET, i_Period )
	variable v_timer 				: integer range 0 to 5*100E+6 := 0;
	variable v_timer_seconds 	: integer range 0 to 5*10E+3 := 0;
	begin
		if ( rising_edge( s_clk ) ) then
			if (s_OPERATION = '1') then
				if ( s_RESET = '1' ) then
					v_timer := 0 ;
				else
				
					if ( v_timer =  5 ) then
						v_timer := 0;
						if ( v_timer_seconds = i_Period) then
							v_timer_seconds := 0 ;
							s_SW_Period_Over_Flag <= '1';
						else
							v_timer_seconds	:= v_timer_seconds + 1 ;
							s_SW_Period_Over_Flag <= '0';
						end if;						
					else						
						s_SW_Period_Over_Flag <= '0';
						v_timer := v_timer + 1 ;
					end if ;
					
				end if ;
			else
				v_timer := 0 ;
			end if ;			
		end if ;
	end process ;

	SW_Period_Over_Flag <= s_SW_Period_Over_Flag ;
	Period <= i_Period ;
	
end Behavioral;