Toggling switch button to start and pause using logic '0' or '1'

PORT

(

clOCK : IN STD_LOGIC;

ce : IN STD_LOGIC;

rst : IN STD_LOGIC;

d1: BUFFER STD_LOGIC_VECTOR (3 DOWNTO 0);

clk_2: OUT STD_LOGIC

);

-- {{ALTERA_IO_END}} DO NOT REMOVE THIS LINE!

END mod_mod;

-- Architecture Body

ARCHITECTURE mod_mod_architecture OF mod_mod IS

SIGNAL M: STD_LOGIC;

BEGIN

PROCESS (clock,rst,M)

BEGIN

IF (rst = '0') THEN

d1 <= "0000";

ELSIF (clOCK 'EVENT AND clOCK='1') THEN

IF (ce = '0') THEN

d1<= "0000" ;

ELSE

d1<= d1 + '1';

M<= '0';

END IF;

IF d1= "1001" THEN

d1<= "0000";

M<= '1';

END IF;

END IF;

clk_2<=M;

END PROCESS;

end mod_mod;

I want ce to perform the function of start and stop.I want it to be like if i press ce switch it should change the logic from 1 to 0 to purse and for the next state to start after pressing same ce switch.