利用VHDL实现以下功能：1、能显示十字路口东西、南北两个方向的红灯、黄灯、绿灯的指示状态，用两组发光二极管表示两个方向的红灯、黄灯、绿灯。2、实现正常的倒计时功能。用两组数码管作为LED作为东西、南北方向的时间显示，时间为红灯45秒、绿灯40秒、黄灯5秒。3、实现特殊状态的功能。按下按键1后能实现：（1）计时器停止计数并保持在原来的状态。（2）东西、南北路口均显示红灯状态。（3）特殊状态解除后能继续计数。4、能实现总体清零功能

好的，这是一个复杂的功能，需要用到VHDL语言进行设计和实现。根据您的要求，我可以给您提供一份代码框架供您参考：

entity Traffic_Light is
    Port (
        clk : in std_logic;             --时钟信号
        reset : in std_logic;           --复位信号
        btn1 : in std_logic;            --按键1
        north_south_LED : out std_logic_vector(2 downto 0); --南北方向的LED指示灯
        east_west_LED : out std_logic_vector(2 downto 0);  --东西方向的LED指示灯
        north_south_time : out std_logic_vector(5 downto 0); --南北方向的倒计时时间
        east_west_time : out std_logic_vector(5 downto 0)   --东西方向的倒计时时间
    );
end Traffic_Light;

architecture Behavioral of Traffic_Light is

    signal count : integer range 0 to 90 := 0;  --计数器，用于控制红绿灯时间
    signal NS_state : std_logic_vector(2 downto 0) := "000"; --南北方向灯的状态
    signal EW_state : std_logic_vector(2 downto 0) := "000"; --东西方向灯的状态
    signal NS_time_left : integer range 0 to 45 := 45;  --南北方向倒计时剩余时间
    signal EW_time_left : integer range 0 to 40 := 40;  --东西方向倒计时剩余时间
    signal NS_time_stop : boolean := false;  --南北方向计时器停止计数标志
    signal EW_time_stop : boolean := false;  --东西方向计时器停止计数标志
    signal special_state : boolean := false; --特殊状态标志
    signal NS_LED_output : std_logic_vector(6 downto 0) := "0000000"; --南北方向LED输出
    signal EW_LED_output : std_logic_vector(6 downto 0) := "0000000"; --东西方向LED输出

begin

    process(clk, reset, btn1)
    begin
        if reset = '1' then          --复位信号
            count <= 0;
            NS_state <= "000";
            EW_state <= "000";
            north_south_LED <= NS_state;
            east_west_LED <= EW_state;
            NS_time_left <= 45;
            EW_time_left <= 40;
            NS_time_stop <= false;
            EW_time_stop <= false;
            special_state <= false;
            NS_LED_output <= "0000000";
            EW_LED_output <= "0000000";
            north_south_time <= (others => '0');
            east_west_time <= (others => '0');
        elsif rising_edge(clk) then  --时钟上升沿
            if not special_state then   --正常状态
                if count = 0 then        --绿灯
                    NS_state <= "001";
                    EW_state <= "010";
                    north_south_LED <= NS_state;
                    east_west_LED <= EW_state;
                    north_south_time <= std_logic_vector(to_unsigned(NS_time_left, 6));
                    east_west_time <= std_logic_vector(to_unsigned(EW_time_left, 6));
                elsif count < 45 then    --黄灯
                    NS_state <= "010";
                    EW_state <= "010";
                    north_south_LED <= NS_state;
                    east_west_LED <= EW_state;
                    north_south_time <= std_logic_vector(to_unsigned(NS_time_left, 6));
                    east_west_time <= std_logic_vector(to_unsigned(EW_time_left, 6));
                elsif count < 50 then    --红灯
                    NS_state <= "100";
                    EW_state <= "001";
                    north_south_LED <= NS_state;
                    east_west_LED <= EW_state;
                    north_south_time <= std_logic_vector(to_unsigned(NS_time_left, 6));
                    east_west_time <= std_logic_vector(to_unsigned(EW_time_left, 6));
                else
                    count <= -1;
                    NS_time_left <= NS_time_left - 1 when not NS_time_stop else NS_time_left;
                    EW_time_left <= EW_time_left - 1 when not EW_time_stop else EW_time_left;
                    north_south_time <= std_logic_vector(to_unsigned(NS_time_left, 6));
                    east_west_time <= std_logic_vector(to_unsigned(EW_time_left, 6));
                    if NS_time_left = 0 then
                        NS_time_left <= 45;
                        NS_state <= "000";
                        EW_state <= "010";
                    elsif EW_time_left = 0 then
                        EW_time_left <= 40;
                        NS_state <= "001";
                        EW_state <= "000";
                    end if;
                end if;
                count <= count + 1;
            else    --特殊状态
                NS_state <= "100";
                EW_state <= "100";
                north_south_LED <= NS_state;
                east_west_LED <= EW_state;
                north_south_time <= std_logic_vector(to_unsigned(NS_time_left, 6));
                east_west_time <= std_logic_vector(to_unsigned(EW_time_left, 6));
                if btn1 = '1' then   --按键1按下
                    NS_time_stop <= true;
                    EW_time_stop <= true;
                    NS_time_left <= NS_time_left;
                    EW_time_left <= EW_time_left;
                else   --按键1释放
                    NS_time_stop <= false;
                    EW_time_stop <= false;
                end if;
            end if;
        end if;
        
        --总体清零功能
        if btn1 = '1' then
            count <= 0;
            NS_state <= "000";
            EW_state <= "000";
            north_south_LED <= NS_state;
            east_west_LED <= EW_state;
            NS_time_left <= 45;
            EW_time_left <= 40;
            NS_time_stop <= false;
            EW_time_stop <= false;
            special_state <= false;
            NS_LED_output <= "0000000";
            EW_LED_output <= "0000000";
            north_south_time <= (others => '0');
            east_west_time <= (others => '0');
        end if;
        
        --LED输出控制
        case NS_state is
            when "000" =>
                NS_LED_output <= "0001000";  --南北方向红灯
            when "001" =>
                NS_LED_output <= "0000100";  --南北方向绿灯
            when "010" =>
                NS_LED_output <= "0000010";  --南北方向黄灯
            when others =>
                NS_LED_output <= "0000000";
        end case;
        
        case EW_state is
            when "000" =>
                EW_LED_output <= "0001000";  --东西方向红灯
            when "001" =>
                EW_LED_output <= "0000100";  --东西方向绿灯
            when "010" =>
                EW_LED_output <= "0000010";  --东西方向黄灯
            when others =>
                EW_LED_output <= "0000000";
        end case;
        
        north_south_LED(2 downto 0) <= NS_LED_output(2 downto 0);
        east_west_LED(2 downto 0) <= EW_LED_output(2 downto 0);
        
    end process;

end Behavioral;

上面的代码框架实现了您所需的功能，您可以根据实际需要进行修改和完善。需要注意的是，这只是一个简单的代码框架，还需要进行仿真和调试才能保证正确性。