---選擇站點，算出票價（既2元，4 元）


選擇票數，算出所需要的錢（票數分1張，兩張，三張，四張）
投幣，每次計算投的錢數，或紙幣，1，2，5，10元；
比較需要的錢和投的錢
如果無余額，做出票工作
如果有余額，做出票工作，轉入找零
找零狀態
可以取消，返回選擇站點狀態


library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;

entity ticketsell is
port (clk       :in std_logic;
      coin5j  :in std_logic_vector(3 downto 0);
   coin1  :in std_logic_vector(3 downto 0);
   paper1  :in std_logic_vector(3 downto 0);
   paper2  :in std_logic_vector(3 downto 0);
   paper5  :in std_logic_vector(3 downto 0);
   paper10 :in std_logic_vector(3 downto 0);
      station   :in std_logic_vector(1 downto 0);
      number    :in std_logic_vector(1 downto 0);
      reset     :in std_logic;
      ticketout :out std_logic_vector(3 downto 0);
      zhaoling  :out std_logic_vector(15 downto 0));
    
      end ticketsell;
 architecture behave of ticketsell is 

        type state_type is(s0,s1,s2); 
        signal state: state_type;
        signal money:std_logic_vector(15 downto 0);
          begin
            process(clk,reset)
                begin
                if reset='1' then
               state<=s0;
                elsif clk'event and clk='1' then
                  case state is 

                  when s0=>
                    case station is
                    when "01"=>
                    money<="0010";
                    state<=s1;
                    when "10"=>
                     money<="0100";
                     state<=s1;
                     when others=>null;
                     end case;

                  when s1=>
                   if money="0010" then
                    case number is
                    when "01"=>
                     money<="0010";
                    when "10"=>
                     money<="0100";
                    when "11"=>
                     money<="0110";
                      end case;
                       state<=s2;
                else  money="0100" then
                   case number is
                    when "01"=>
                     money<="0100";
                    when "10"=>
                     money<="1000";
                    when "11"=>
                     money<="1100";
                      end case;
                       state<=s2;
                      end if;
          
                  when s2=>
                     if (coin5j*0.5+coin+paper1+2*paper2+5*paper5+10*paper10)>=money then
                       ticketout<=number;
                       zhaoling<=coin5j*0.5+coin+paper1+2*paper2+5*paper5+10*paper10-money;
                    else  state<=s1;
                          ticketout<="0";
                          zhaoling<="0"
                      end if;
                      end case;
                      end if;
                      end process;
                      end behave;