--------------------------------------------------------------------------------
-- SpecialScreenPrinter.vhd
-- prints dynamic text based on the current state and the contents of RAM or 
-- variable registers.
--
-- 156 (13%) logic cells, complex, 8.1
-- 171 (14%) logic cells, 77.5ns, 12.90MHz, simple, 7.21
-- 172 (14%) logic cells, 65.2ns, 15.33MHz, simple, 8.1
-- 160 (13%) logic cells, 82.5ns, 12.12MHz (simple, 7.21)
-- 169 (14%) logic cells, (simple, 7.21, new handshaking)
-- 
--------------------------------------------------------------------------------
 
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;
 
library work;
use work.Constants_Package.all;
use work.Time_Package.all;
use work.Control_Package.all;
use work.BCD_Package.all;
 

entity SpecialScreenPrinter is
    port(
      clock: in std_logic;
      start: in std_logic;
  
      ready: in std_logic;
      done: out std_logic;
      --busy: out std_logic;

      digit: out std_logic_vector(BCD_WIDTH-1 downto 0);
      LCDinstruction: out std_logic_vector(LCD_INSTRUCTION_WIDTH-1 downto 0);
  
      currentState: in std_logic_vector(STATE_WIDTH-1 downto 0);
  
      currentYear: in std_logic_vector(YEAR_WIDTH-1 downto 0);
      currentMonth: in std_logic_vector(MONTH_WIDTH-1 downto 0);
      currentDay: in std_logic_vector(DAY_WIDTH-1 downto 0);
      currentHour: in std_logic_vector(HOUR_WIDTH-1 downto 0);
      currentMinute: in std_logic_vector(MINUTE_WIDTH-1 downto 0);
      currentSecond: in std_logic_vector(SECOND_WIDTH-1 downto 0);
      currentWeekday: in std_logic_vector(WEEKDAY_WIDTH-1 downto 0);
  
      eventHour: std_logic_vector(HOUR_WIDTH-1 downto 0);
      eventMinute: std_logic_vector(MINUTE_WIDTH-1 downto 0);
      eventWeekday: std_logic_vector(WEEKDAY_WIDTH-1 downto 0)
    );
end SpecialScreenPrinter;


architecture printer of SpecialScreenPrinter is

  constant NORMAL_SCREEN_WIDTH: positive := 4;
  constant EDIT_SCREEN_WIDTH: positive := 4;

  -- n = normal state
  -- w = edit weekly event state
  -- yr: year, mo: month, da: day, hr: hour, mi: minute, se: second, wk: weekday
  -- b# = blank position
  -- c = colon

  constant nyr3: std_logic_vector(NORMAL_SCREEN_WIDTH-1 downto 0) := "0000";
  constant nyr2: std_logic_vector(NORMAL_SCREEN_WIDTH-1 downto 0) := "0001";
  constant nyr1: std_logic_vector(NORMAL_SCREEN_WIDTH-1 downto 0) := "0010";
  constant nyr0: std_logic_vector(NORMAL_SCREEN_WIDTH-1 downto 0) := "0011";
  constant nmo1: std_logic_vector(NORMAL_SCREEN_WIDTH-1 downto 0) := "0100";
  constant nmo0: std_logic_vector(NORMAL_SCREEN_WIDTH-1 downto 0) := "0101";
  constant nda1: std_logic_vector(NORMAL_SCREEN_WIDTH-1 downto 0) := "0110";
  constant nda0: std_logic_vector(NORMAL_SCREEN_WIDTH-1 downto 0) := "0111";
  constant nhr1: std_logic_vector(NORMAL_SCREEN_WIDTH-1 downto 0) := "1000";
  constant nhr0: std_logic_vector(NORMAL_SCREEN_WIDTH-1 downto 0) := "1001";
  constant nmi1: std_logic_vector(NORMAL_SCREEN_WIDTH-1 downto 0) := "1010";
  constant nmi0: std_logic_vector(NORMAL_SCREEN_WIDTH-1 downto 0) := "1011";
  constant nse1: std_logic_vector(NORMAL_SCREEN_WIDTH-1 downto 0) := "1100";
  constant nse0: std_logic_vector(NORMAL_SCREEN_WIDTH-1 downto 0) := "1101";
  constant nwk0: std_logic_vector(NORMAL_SCREEN_WIDTH-1 downto 0) := "1110";
  constant nb2f: std_logic_vector(NORMAL_SCREEN_WIDTH-1 downto 0) := "1111";

  constant whr1: std_logic_vector(EDIT_SCREEN_WIDTH-1 downto 0) := "0000";
  constant whr0: std_logic_vector(EDIT_SCREEN_WIDTH-1 downto 0) := "0001";
  constant wmi1: std_logic_vector(EDIT_SCREEN_WIDTH-1 downto 0) := "0010";
  constant wmi0: std_logic_vector(EDIT_SCREEN_WIDTH-1 downto 0) := "0011";
  constant wwk0: std_logic_vector(EDIT_SCREEN_WIDTH-1 downto 0) := "0100";
  constant wb25: std_logic_vector(EDIT_SCREEN_WIDTH-1 downto 0) := "0101";

  signal StatusPrintNormalState:
    std_logic_vector(NORMAL_SCREEN_WIDTH-1 downto 0);
  signal StatusPrintEditWeeklyState:
    std_logic_vector(EDIT_SCREEN_WIDTH-1 downto 0);

  signal active: std_logic;
  signal backing_up: std_logic;
  signal instruction_sent: std_logic;

begin

  --busy <= active;

  specialPrinter: process(clock) is

  begin
   if rising_edge(clock) then
    if start = '1' then
      active <= '1';
      done <= '0';
      backing_up <= '0';
      StatusPrintNormalState <= nyr3;
      StatusPrintEditWeeklyState <= whr1;
      --LCDinstruction <= GOTO_LINE2;
      LCDinstruction <= NO_ACTION;
      instruction_sent <= '0';

    elsif active = '1' and ready = '1' then
     if instruction_sent = '0' then

      instruction_sent <= '1';

      case currentState is
        ------------------------------------------------------------------------
        when NORMAL_STATE | ALARM_STATE =>
          case StatusPrintNormalState is
            when nyr3 =>
              digit <= currentYear(4*BCD_WIDTH-1 downto 3*BCD_WIDTH);
            when nyr2 =>
              digit <= currentYear(3*BCD_WIDTH-1 downto 2*BCD_WIDTH);
            when nyr1 =>
              digit <= currentYear(2*BCD_WIDTH-1 downto 1*BCD_WIDTH);
            when nyr0 =>
              digit <= currentYear(1*BCD_WIDTH-1 downto 0*BCD_WIDTH);
            when nmo1 =>
              digit <= currentMonth(2*BCD_WIDTH-1 downto 1*BCD_WIDTH);
            when nmo0 =>
              digit <= currentMonth(1*BCD_WIDTH-1 downto 0*BCD_WIDTH);
            when nda1 =>
              digit <= currentDay(2*BCD_WIDTH-1 downto 1*BCD_WIDTH);
            when nda0 =>
              digit <= currentDay(1*BCD_WIDTH-1 downto 0*BCD_WIDTH);
            when nhr1 =>
              digit <= currentHour(2*BCD_WIDTH-1 downto 1*BCD_WIDTH);
            when nhr0 =>
              digit <= currentHour(1*BCD_WIDTH-1 downto 0*BCD_WIDTH);
            when nmi1 =>
              digit <= currentMinute(2*BCD_WIDTH-1 downto 1*BCD_WIDTH);
            when nmi0 =>
              digit <= currentMinute(1*BCD_WIDTH-1 downto 0*BCD_WIDTH);
            when nse1 =>
              digit <= currentSecond(2*BCD_WIDTH-1 downto 1*BCD_WIDTH);
            when nse0 =>
              digit <= currentSecond(1*BCD_WIDTH-1 downto 0*BCD_WIDTH);
            when nwk0 =>
              digit <= currentWeekday(1*BCD_WIDTH-1 downto 0*BCD_WIDTH);
            when others =>
              -- do nothing
          end case;

          case StatusPrintNormalState is
            when nyr3 | nyr2 | nyr1 | nyr0 | nmo1 | nmo0 | nda1 | nda0 |
                 nhr1 | nhr0 | nmi1 | nmi0 | nse1 | nse0 | nwk0 =>
--              if backing_up = '0' then
                LCDinstruction <= PRINT_CHAR;
                StatusPrintNormalState <= StatusPrintNormalState + '1';
--              else

--                if StatusPrintNormalState = nyr3 and backing_up = '1' then
--                  -- last state; deactivate myself
--                  active <= '0';
--                  done <= '1';
--                  backing_up <= '0';
--                  LCDinstruction <= NO_ACTION;
--                else
--                  LCDinstruction <= BACKUP_CURSOR;
--                  StatusPrintNormalState <= StatusPrintNormalState - '1';
--                end if;
--              end if;

            when nb2f =>
              -- last state; deactivate myself
              active <= '0';
              done <= '1';
              backing_up <= '0';
              LCDinstruction <= NO_ACTION;

--              backing_up <= '1';
--              LCDinstruction <= BACKUP_CURSOR;
--              StatusPrintNormalState <= StatusPrintNormalState - '1';

            when others =>
              LCDinstruction <= NO_ACTION;

          end case;
 
        ------------------------------------------------------------------------
        when EDIT_WEEKLY_EVENT_STATE =>
          if backing_up = '0' then
            case StatusPrintEditWeeklyState is
              when whr1 =>
                digit <= eventHour(2*BCD_WIDTH-1 downto 1*BCD_WIDTH);
              when whr0 =>
                digit <= eventHour(1*BCD_WIDTH-1 downto 0*BCD_WIDTH);
              when wmi1 =>
                digit <= eventMinute(2*BCD_WIDTH-1 downto 1*BCD_WIDTH);
              when wmi0 =>
                digit <= eventMinute(1*BCD_WIDTH-1 downto 0*BCD_WIDTH);
              when wwk0 =>
                digit <= eventWeekday(1*BCD_WIDTH-1 downto 0*BCD_WIDTH);
              when others =>
                -- do nothing
            end case;

            case StatusPrintEditWeeklyState is
              when  whr1 | whr0 | wmi1 | wmi0 | wwk0  =>
                LCDinstruction <= PRINT_CHAR;
                StatusPrintEditWeeklyState <= StatusPrintEditWeeklyState + '1';

              when wb25 =>
                backing_up <= '1';
                LCDinstruction <= BACKUP_CURSOR;
                StatusPrintEditWeeklyState <= StatusPrintEditWeeklyState - '1';  

              when others =>  
                LCDinstruction <= NO_ACTION;

            end case;
          else  -- backing_up = '1'
            if StatusPrintEditWeeklyState = whr1 and backing_up = '1' then
              -- last state; deactivate myself
              active <= '0';
              done <= '1';
              backing_up <= '0';
              LCDinstruction <= NO_ACTION;
            else
              LCDinstruction <= BACKUP_CURSOR;
              StatusPrintEditWeeklyState <= StatusPrintEditWeeklyState - '1';
            end if;
          end if;

        ------------------------------------------------------------------------
        when others => -- state that doesn't need any dynamic text printed
          LCDinstruction <= NO_ACTION;
          active <= '0';
          done <= '1';

      end case; -- currentState
     else -- instruction_sent = '1'
       -- wait for ready to drop to 0
     end if;
    elsif active = '1' and ready = '0' then
    -- I'm assuming that if it's active for the first time, the LCDready
    -- is guaranteed to be 1.
      LCDinstruction <= NO_ACTION;
      instruction_sent <= '0';
      done <= '0';

    else -- not start, not (active and ready), not (active and !ready)
      LCDinstruction <= NO_ACTION;
      done <= '0';

      -- Added this line so MAX+plus II will quit bugging me about
      -- a flipflop stuck at gnd. I know it and I mean it, darnit!
      -- Don't worry, this line is harmless.
      --if currentState = INITIAL_STATE then
      --  LCDinstruction <= ADVANCE_CURSOR;
      --end if;

    end if;
      
   end if; -- rising edge

  end process specialPrinter;

end printer;