Library ieee;
use ieee.std_logic_1164.all;

entity sequenzerkennung is
    port(
        --low active Reset
        reset, x, clk :     in  std_logic;
        y :                     out     std_logic;
        leds :              out     std_logic_vector(8 downto 0)
    );
end sequenzerkennung;

architecture bhv of sequenzerkennung is
    type states is (A, B, C, D, E, F, G, H, I);

    --Signals für Neue States (Übergang)
    signal state, new_state : states;
    signal s_x, s_y             : std_logic;
    signal s_leds               : std_logic_vector(8 downto 0);

    begin
        process(reset, clk)
        begin
            if (reset = '0') then
                state <= A;
                leds    <= "000000001";
                y       <= '0';
            elsif (rising_edge(clk)) then
                state <= new_state;
                leds    <= s_leds;
                y       <= s_y;
                s_x     <= x;
            end if;
        end process;

        process (state, s_x)
        begin
            s_y <= '0';
            case state is
                when A =>
                    if (s_x = '0') then
                        new_state   <= B;
                        s_leds      <= "000000010";
                    else
                        new_state   <= F;
                        s_leds      <= "000100000";
                    end if;
                when B =>
                    if (s_x = '0') then
                        new_state   <= C;
                        s_leds      <= "000000100";
                    else
                        new_state   <= F;
                        s_leds      <= "000100000";
                    end if;
                when C =>
                    if (s_x = '0') then
                        new_state   <= D;
                        s_leds      <= "000001000";
                    else
                        new_state   <= F;
                        s_leds      <= "000100000";
                    end if;
                when D =>
                    if (s_x = '0') then
                        new_state   <= E;
                        s_leds      <= "000010000";
                        s_y         <= '1';
                    else
                        new_state <= F;
                        s_leds      <= "000100000";
                    end if;
                when E =>
                    if (s_x = '0') then
                        new_state   <= E;
                        s_leds      <= "000010000";
                    else
                        new_state   <= F;
                        s_leds      <= "000100000";
                    end if;
                when F =>
                    if (s_x = '0') then
                        new_state   <= B;
                        s_leds      <= "000000010";
                    else
                        new_state   <= G;
                        s_leds      <= "001000000";
                    end if;
                when G =>
                    if (s_x = '0') then
                        new_state   <= B;
                        s_leds      <= "000000010";
                    else
                        new_state   <= H;
                        s_leds      <= "010000000";
                        s_y             <= '1';
                    end if;
                when H =>
                    if (s_x = '0') then
                        new_state   <= B;
                        s_leds      <= "000000010";
                    else
                        new_state   <= I;
                        s_leds      <= "100000000";
                        s_y             <= '1';
                    end if;
                when I =>
                    if (s_x = '0') then
                        new_state   <= B;
                        s_leds      <= "000000010";
                    else
                        new_state   <= I;
                        s_leds      <= "100000000";
                        s_y             <= '1';
                    end if;
            end case;
        end process;
end bhv;