library IEEE;
use IEEE.std_logic_1164.all;

entity control is
    port (
        clk: in STD_LOGIC;                       -- clk input (16 KHz)
        rst: in STD_LOGIC;                       -- reset input
        Addrclk: out STD_LOGIC;                  -- output to clock the address counter
        data: in STD_LOGIC_VECTOR (7 downto 0);  -- input from the data lines of the RAM
        LLed: out STD_LOGIC_VECTOR (7 downto 0); -- output for the Left LED
        RLed: out STD_LOGIC_VECTOR (7 downto 0); -- output for the Right LED
        ALSel: out std_logic                     -- Address/LED Selection (0=Addr,1=LED)
    );
end control;

architecture control_arch of control is

constant CNTMAX: integer := 8000;        -- LED/Address cycle length.
                                         -- Larger = slower system (letters stay on LED longer)

signal L: std_logic_vector(7 downto 0);  -- Left LED internal buffer
signal R: std_logic_vector(7 downto 0);  -- Right LED internal buffer
signal cnt: integer range 0 to CNTMAX;   -- clock divider counter

begin

LLED <= L;    -- output to left LED
RLED <= R;    -- output to right LED
  
  
  -- clock divider
  process(clk, rst)
  begin
    if rst = '1' then                   -- reset counter on reset
      cnt <= 0;
    elsif clk'event and clk = '1' then  -- clock divider counter
      cnt <= cnt + 1;
    end if;
  end process;
  
  
  -- output control
  process(cnt, rst, data, L, R)
  begin
    if rst = '1' then  -- clear LED buffers on reset

    -- <<RESET SIGNAL ASSIGNMENTS HERE>> --

    else
      case cnt is  -- There are 4 stages in the RAM/LED cycle.
                   -- Fill in each stage with the correct signal assignments.
                   -- Things that need to be accomplished (not necessarily in this order):
                   --   Set the RAM address as output
                   --   Increment the RAM address counter (raise addrclk)
                   --   Read the new character from the RAM output
                   --   In connection to reading the new char, shift the current char from right to left LED
                   --   set output to CHARs for the LEDs for the rest of the time
                   -- Remember that this module is where the LED contents are buffered, so
                   -- you need to do the shifting from the right to the left somewhere
                   -- in this cycle.  Also remember that all the statements (including signal
                   -- assignments) are executed concurrently, not sequentially.  Hint: This is why we
                   -- need 3 and not 2 steps.
                   
        -- step 1
        when 1 =>

        -- step 2
        when 2 =>  

        -- step 3
        when 3 =>  

        -- default values for output for the rest of the time
        when others =>

        
      end case;
    end if;
  end process;
  
end control_arch;