Some issues about functional simulation

i still don't catch it.

it is a example of a polyphase filter.when i simulate using q ii,simply functional simulation,the signals are not reset to '0'.

PACKAGE n_bits_int IS

SUBTYPE BITS8 IS INTEGER RANGE -128 TO 127;

SUBTYPE BITS9 IS INTEGER RANGE -2**8 TO 2**8 - 1;

SUBTYPE BITS17 IS INTEGER RANGE -2**16 TO 2**16 - 1;

TYPE ARRAY_BITS17_4 IS ARRAY (0 TO 3) of BITS17;

END n_bits_int;

LIBRARY work;

USE work.n_bits_int.ALL;

LIBRARY ieee;

USE ieee.std_logic_1164.ALL;

USE ieee.std_logic_arith.ALL;

USE ieee.std_logic_signed.ALL;

ENTITY db4poly IS

PORT (clk : IN STD_LOGIC;

x_in : IN BITS8;

y_out : OUT BITS9);

END db4poly;

ARCHITECTURE flex OF db4poly IS

TYPE STATE_TYPE IS(even,odd);

SIGNAL state : STATE_TYPE;

SIGNAL x_odd,x_even,x_wait : BITS8;

SIGNAL clk_div2 : STD_LOGIC;

SIGNAL r : ARRAY_BITS17_4; --Arrays for multiplier and trap;

SIGNAL x33,x99,x107,y : BITS17;

BEGIN

Mutiplex:PROCESS --->Split into even and odd

BEGIN --samples at clk rate

WAIT UNTIL clk ='1';

CASE state IS

WHEN even =>

x_even <= x_in;

x_odd <= x_wait;

clk_div2 <= '1';

state <= odd;

WHEN odd =>

x_wait <= x_in;

clk_div2 <= '0';

state <= even;

END CASE;

END PROCESS Mutiplex;

AddPolyphase:PROCESS(clk_div2,x_odd,x_even,x33,x99,x107)

VARIABLE m : ARRAY_BITS17_4;

BEGIN

--compute auxiliary multiplication of the filter

x33 <= x_odd * 32 + x_odd;

x99 <= x33 *2 + x33;

x107 <= x99 + 8 * x_odd;

--compute all coefficients for the transposed filter

m(0) := 4 * 32 * x_even - x_even;

m(1) := 2 * x107;

m(2) := 8 * (8 * x_even - x_even) + x_even;

m(3) := x33;

----> compute the filters and infer registers

IF clk_div2'EVENT and (clk_div2 = '0') THEN

--compute filter G0

r(0) <= r(2) + m(0);

r(2) <= m(2);

--compute filter G1

r(1) <= -r(3) + m(1);

r(3) <= m(3);

--add the polyphase components

y <= r(0) + r(1);

END IF;

END PROCESS Addpolyphase;

y_out <= y / 256; --connect to output

END flex;