为什么我在合成时没有看到输出？

我一直致力于实际完成的实验室任务，但遇到的问题是我在合成时没有看到输出 . 我有7块，单独测试时会显示正确的输出 . 在使用顶级模块和测试平台文件时，我怎么会得到任何输出？下面是我的顶级模块，其次是我的测试台，因为我怀疑问题可能存在 . 我看了一遍，无法确定我可能做错的事情 . 任何帮助，将不胜感激 .

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

entity top_module is port(
    x,y : in std_logic_vector(7 downto 0);
    opcode : in std_logic_vector(2 downto 0);
    z : out std_logic_vector(7 downto 0)
    );
end top_module;

architecture behavior of top_module is

signal bwAnd, bwOr, bwXor, add, subtract, bwComplement, mux_in1, mux_in2, mux_in3, mux_in4, mux_in5, mux_in6 : std_logic_vector(7 downto 0);


component BW_And is port(
    x,y : in std_logic_vector(7 downto 0);
    z1 : out std_logic_vector(7 downto 0)
    );
end component;

component BW_Rr is port(
    x,y : in std_logic_vector(7 downto 0);
    z2 : out std_logic_vector(7 downto 0)
    );
end component;

component BW_Xor is port(
    x,y : in std_logic_vector(7 downto 0);
    z3 : out std_logic_vector(7 downto 0)
    );
end component;

component full_adder_8 is port(
    x,y : in std_logic_vector(7 downto 0);
    cin : in std_logic_vector(7 downto 0) := "00000000";
    sum, cout: out std_logic_vector(7 downto 0)
    );
end component;

component full_subtractor_8 is port(
    x,y : in std_logic_vector(7 downto 0);
    cin : in std_logic_vector(7 downto 0) := "11111111";
difference, cout: out std_logic_vector(7 downto 0)
    );
end component;

component Complement is port(
    x : in std_logic_vector(7 downto 0);
    z4 : out std_logic_vector(7 downto 0)
    );
end component;

component mux is port(
    z1,z2,z3,sum,difference,z4 : in std_logic_vector(7 downto 0);
    opcode : in std_logic_vector(2 downto 0);
    mux_out : out std_logic_vector(7 downto 0)
    );
end component;

begin

--instantiating components and mapping ports

c0: BW_And port map(x => x, y => y, z1 => bwAnd);

c1: BW_Or port map(x => x, y => y, z2 => bwOr);

c2: BW_Xor port map(x => x, y => y, z3 => bwXor);

c3: full_adder_8 port map(x => x, y => y, sum => add);

c4: full_subtractor_8 port map(x => x, y => y, difference => subtract);

c5: Complement port map(x => x, z4 => bwComplement);

c6: mux port map(z1 => mux_in1, z2 => mux_in2, z3 => mux_in3, sum => mux_in4, difference => mux_in5, z4 =>mux_in6, opcode => opcode, mux_out => z);

end behavior;

试验台：

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

entity Lab4 is
end Lab4;

architecture behavior of Lab4 is

component top_module is port(
    x,y : in std_logic_vector(7 downto 0);
    opcode : in std_logic_vector(2 downto 0);
    z : out std_logic_vector(7 downto 0)
    );
end component;

signal test_x : std_logic_vector(7 downto 0);
signal test_y : std_logic_vector(7 downto 0);
signal test_opcode : std_logic_vector(2 downto 0) := "000";
signal test_z : std_logic_vector(7 downto 0);

begin

    uut: top_module port map (x => test_x, y => test_y, opcode => test_opcode, z => test_z);

sim_proc : process
begin

    test_x <= "00010100"; test_y <= "11001111"; test_opcode <= "000";
    wait for 100 ns;
    test_x <= "00010100"; test_y <= "11001111"; test_opcode <= "001";
    wait for 100 ns;
    test_x <= "00010100"; test_y <= "11001111"; test_opcode <= "010";
    wait for 100 ns;
    test_x <= "00010100"; test_y <= "11001111"; test_opcode <= "011";
    wait for 100 ns;
    test_x <= "00010100"; test_y <= "11001111"; test_opcode <= "100";
    wait for 100 ns;
    test_x <= "00010100"; test_y <= "11001111"; test_opcode <= "101";

end process;
end behavior;

每个组件的实体：

entity BW_And is port(
    x,y : in std_logic_vector(7 downto 0);
    z1 : out std_logic_vector(7 downto 0)
    );
end BW_And;

entity BW_Or is port(
    x,y : in std_logic_vector(7 downto 0);
    z2 : out std_logic_vector(7 downto 0)
    );
end BW_Or;

entity BW_Xor is port(
    x,y : in std_logic_vector(7 downto 0);
    z3 : out std_logic_vector(7 downto 0)
    );
end BW_Xor;

entity full_adder_8 is port(
    x,y : in std_logic_vector(7 downto 0);
    cin : in std_logic_vector(7 downto 0) := "00000000";
    sum, cout: out std_logic_vector(7 downto 0)
    );
end full_adder_8;

entity full_subtractor_8 is port(
    x,y : in std_logic_vector(7 downto 0);
    cin : in std_logic_vector(7 downto 0) := "11111111";
    difference, cout: out std_logic_vector(7 downto 0)
    );
end full_subtractor_8;

entity Complement is port(
    x : in std_logic_vector(7 downto 0);
    z4 : out std_logic_vector(7 downto 0)
    );
end Complement;

entity mux is port(
    z1,z2,z3,sum,difference,z4 : in std_logic_vector(7 downto 0);
    opcode : in std_logic_vector(2 downto 0);
    mux_out : out std_logic_vector(7 downto 0)
    );
end mux;