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--
-- Title       : vending_machine
-- Design      : vending_machine
-- Author      : Jamie Byun
-- Company     : JMJS
--
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--
-- File        : vending_machine.vhd
-- Generated   : Thu Dec 12 10:31:01 2002
-- From        : interface description file
-- By          : Itf2Vhdl ver. 1.20
--
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--
-- Description : 
--
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--{{ Section below this comment is automatically maintained
--   and may be overwritten
--{entity {vending_machine} architecture {JMJS_Logic}}

library IEEE;
use IEEE.STD_LOGIC_1164.all;
use IEEE.STD_LOGIC_unsigned.all;

entity vending_machine is
	 port(
		 rst : in STD_LOGIC;
		 clk : in STD_LOGIC;
		 coin_500 : in STD_LOGIC;
		 coin_100 : in STD_LOGIC;
		 coin_50 : in STD_LOGIC;
		 coin_10 : in STD_LOGIC;
		 coffee_button : in STD_LOGIC;
		 tea_button : in STD_LOGIC;
		 orange_button : in STD_LOGIC;
		 change_return : in STD_LOGIC;
		 change : out STD_LOGIC_VECTOR(7 downto 0);
		 coffee_out : out STD_LOGIC;
		 tea_out : out STD_LOGIC;
		 orange_out : out STD_LOGIC
	     );
end vending_machine;

architecture JMJS_Logic of vending_machine is
	type state is (no_return_state, change_return_state);
	signal pstate : state;
	signal sum : std_logic_vector(7 downto 0);
begin

	process(clk, rst, change_return, sum)
	begin
		if (rst = '1') then
			pstate <= no_return_state;
		elsif (clk'event and clk = '1') then
			case pstate is
				when no_return_state =>
					if (change_return = '1') then
						pstate <= change_return_state;
					end if;
				when change_return_state =>
					if (sum = "00000000") then
						pstate <= no_return_state;
					end if;
			end case;
		end if;
	end process;
	
	process (clk)
	begin
		if (rst = '1') then
			sum <= "00000000";
		elsif (clk'event and clk = '1') then
			case pstate is
				when no_return_state =>
					if (coin_500 = '1') then
						sum <= sum + 50;
					elsif (coin_100 = '1') then
						sum <= sum + 10;
					elsif (coin_50 = '1') then
						sum <= sum + 5;
					elsif (coin_10 = '1') then
						sum <= sum + 1;
					elsif (coffee_button = '1' and sum >= 30)then
						sum <= sum - 30;
					elsif (tea_button = '1' and sum >= 15) then
						sum <= sum - 15;
					elsif (orange_button = '1' and sum >= 10) then
						sum <= sum - 10;
					end if;
				when others =>
					if (sum >= 50) then
						sum <= sum - 50;
					elsif (sum >= 10) then
						sum <= sum - 10;
					elsif (sum >= 5) then
						sum <= sum - 5;
					elsif (sum >= 1) then
						sum <= sum - 1;
					end if;
			end case;
		end if;
	end process;
		
	process (clk)
	begin
		if (rst = '1') then
			coffee_out <= '0';
		elsif (clk'event and clk = '1') then
			if ((pstate = no_return_state) and
					(coffee_button = '1') and (sum >= 30)) then
				coffee_out <= '1';
	 		else
				coffee_out <= '0';
			end if;
		end if;
	end process;
	
	process (clk)
	begin
		if (rst = '1') then
			tea_out <= '0';
		elsif (clk'event and clk = '1') then
			if ((pstate = no_return_state) and
					(tea_button = '1') and (sum >= 15)) then
				tea_out <= '1';
	 		else
				tea_out <= '0';
			end if;
		end if;
	end process;

	process (clk)
	begin
		if (rst = '1') then
			orange_out <= '0';
		elsif (clk'event and clk = '1') then
			if ((pstate = no_return_state) and
					(orange_button = '1') and (sum >= 10)) then
				orange_out <= '1';
	 		else
				orange_out <= '0';
			end if;
		end if;
	end process;
	
	process (clk)
	begin
		if (clk'event and clk = '1') then
			case pstate is
				when change_return_state =>
					if (sum >= 50) then
						change <= "00110010";
					elsif (sum >= 10) then
						change <= "00001010";
					elsif (sum >= 5) then
						change <= "00000101";
					elsif (sum >= 1) then
						change <= "00000001";  
					else
						change <= "00000000";
					end if;
				when others =>
					change <= "00000000";
			end case;
		end if;
	end process;

end JMJS_Logic;