help with multiplier

architecture Behavioral of new_twin1 is

type arr is array (3 downto 0) of std_logic_vector(3 downto 0);

type arr2 is array(4 downto 0) of std_logic_vector(7 downto 0);

signal and_1:arr:=("0000","0000","0000","0000");

signal t6:arr2:=("00000000","00000000","00000000","00000000","00000000");

signal temp:std_logic_vector(3 downto 0);

signal sum:std_logic_vector(7 downto 0):="00000000";

begin

process(clk)

variable z,t,k:integer;

variable t2:std_logic_vector(3 downto 0):="0000";

variable t7:std_logic_vector(7 downto 0);--:="00000000";

begin

for i in 0 to 3 loop

t6(i)(7 downto 0)<=("00000000");

end loop;

for i in 0 to 3 loop

 for j in 0 to 3 loop

  and_1(i)(j)<=(x(i) and y(j));

 end loop;

end loop;

t6(3)<=  "0000" & and_1(0);

k:=0; 

for i in 2 downto 0 loop

 t6(i)<=t2( i downto 0) & and_1(k+1) & t2(k downto 0);

 k:=k+1;

end loop;

for i in 0 to 3 loop

 t6(4)<=t6(4)+t6(i);

end loop

----just tried this alternative which too dint work---

--  t6(4)<=t6(0);

--  t6(4)<=t6(4)+t6(1);

--  t6(4)<=t6(4)+t6(2);

--  t6(4)<=t6(4)+t6(3);

end process;

end Behavioral;