GCD FINDER VHDL CODE

HEY GUYS I HAD DEVELOPED VHDL CODE TO FIND GCD YOU CAN GO THROUGH IT


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


entity gcd is
port(   X:    in unsigned(3 downto 0);
        Y:    in unsigned(3 downto 0);
        o:  out unsigned(3 downto 0)
);
end gcd;

architecture gcd of gcd is
begin
    process(X,Y)
variable tmp_X, tmp_Y: unsigned(3 downto 0);
    begin
tmp_X := X;
tmp_Y := Y;

for i in 0 to 15 loop
   if (tmp_X/=tmp_Y) then
if (tmp_X < tmp_Y) then
               tmp_Y := tmp_Y - tmp_X;
else
   tmp_X := tmp_X - tmp_Y;
                    exit loop;
end if;
   else
o<= tmp_X;
   end if;
end loop;

    end process;
end gcd;