vhdl语言的八路抢答器

以下是一个简单的八路抢答器的 VHDL 代码实现，可以参考：

entity quizmaster is
    port(clk : in std_logic;
         reset : in std_logic;
         question : in std_logic_vector(7 downto 0);
         q_valid : in std_logic;
         buzzer : in std_logic_vector(7 downto 0);
         answer : out std_logic_vector(2 downto 0);
         a_valid : out std_logic);
end quizmaster;

architecture Behavioral of quizmaster is
    signal q_counter : integer range 0 to 7 := 0;
    signal reset_flag : std_logic := '0';
    signal question_flag : std_logic := '0';
    signal buzzer_flag : std_logic_vector(7 downto 0) := (others => '0');
    signal buzzer_winner : integer range 0 to 7 := -1;
    signal buzzer_pressed : std_logic_vector(7 downto 0) := (others => '0');
    signal answer_flag : std_logic := '0';
    signal answer_value : integer range 0 to 7 := -1;
begin
    process(clk, reset)
    begin
        if reset = '1' then
            q_counter <= 0;
            reset_flag <= '1';
            question_flag <= '0';
            buzzer_flag <= (others => '0');
            buzzer_winner <= -1;
            buzzer_pressed <= (others => '0');
            answer_flag <= '0';
            answer_value <= -1;
        elsif rising_edge(clk) then
            reset_flag <= '0';
            if q_valid = '1' and question_flag = '0' then
                question_flag <= '1';
                q_counter <= 0;
            end if;
            if question_flag = '1' then
                if q_counter = 7 then
                    question_flag <= '0';
                    buzzer_flag <= (others => '1');
                else
                    q_counter <= q_counter + 1;
                end if;
            end if;
            for i in 0 to 7 loop
                if buzzer(i) = '1' and buzzer_flag(i) = '1' and buzzer_pressed(i) = '0' then
                    buzzer_winner <= i;
                    buzzer_pressed(i) <= '1';
                    buzzer_flag(i) <= '0';
                end if;
            end loop;
            if buzzer_winner /= -1 and answer_flag = '0' then
                answer_flag <= '1';
                answer_value <= buzzer_winner;
            end if;
            if a_valid = '1' and answer_flag = '1' then
                answer_flag <= '0';
                buzzer_winner <= -1;
                buzzer_pressed <= (others => '0');
                answer_value <= -1;
            end if;
        end if;
    end process;

    answer <= std_logic_vector(to_unsigned(answer_value, 3));
    a_valid <= answer_flag;
end Behavioral;

本代码实现了一个基本的八路抢答器，它包括一个计数器，用于控制问答环节的进行；一个状态机，用于控制整个抢答的流程；一个标志位，用于表示当前是否有人按下了按钮；一个数组，用于记录每个参赛者是否按下了按钮；以及一个标志位和一个变量，用于记录当前获胜者和回答正确的参赛者。