--------------------------------------------------------
-- LCD decoder
-- EE 552 Project
-- Audio Processing Unit
-- February, 2003
--
-- FILE NAME: lcd_decoder.vhd
--
-- DESCRIPTION: This module recieves the message code
--	and sends the appropriate ASCII characters to 
--	the driver.  
--------------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;
library work;
use work.interface.all;

entity lcd_decoder is
	generic(datawidth: positive := 8);
	port(	clock:			in std_logic;					-- slow clock.
		reset:			in std_logic;					-- system reset.
		message_code:		in std_logic_vector(datawidth-1 downto 0);	-- message to be displayed.
		char_out:		out std_logic_vector(datawidth-1 downto 0);	-- character signal to driver.
		char_sent:		out std_logic;					-- indicate character sent.
		dvr_ready:		in std_logic;					-- detect if the driver is ready for next character.
		char_recvd:		in std_logic					-- detect if the driver has recieved and printed last character.
		);
end lcd_decoder;

architecture Output of lcd_decoder is

	type state_type is (CLEAR, HOME, NOP, WELCOME, START, FINISH);
	type char_type is (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, 
			U, V, W, X, Y, Z, carrage_return, r_arrow, space, NIL);
	signal state, next_state, last_state : state_type;
	signal char : char_type;

	signal home_once, char_print: std_logic;
	signal count : std_logic_vector(5 downto 0);

begin
		
process(clock, state, reset, dvr_ready, char_recvd, next_state, last_state, char)

begin
		if reset = '0' then
			state <= CLEAR;
			char_sent <= '0';
		elsif rising_edge(clock) then	
				case message_code(7 downto 0) is
			
				when "00000000" =>
					next_state <= WELCOME;

				when "00000001" =>
					next_state <= START;

				when "00000010" =>
					next_state <= FINISH;

				when others =>
					next_state <= NOP;
				end case;
		 
	case state is
	when CLEAR =>
		home_once <= '0';
		count <= "000000";
		char_print <= '0';
		if dvr_ready ='1' then
			char_sent <= '1';
			char_out <= "00000001";
			state <= clear;
		elsif char_recvd = '1' then
			char_sent <= '0';
			state <= next_state;
		else
			state <= clear;
		end if;



	when HOME =>
		char_print <='0';
		if next_state /= last_state then
			state<= CLEAR;
		elsif dvr_ready ='1' then
			if home_once = '0' then
				home_once <= '1';
				char_sent <= '1';
				char_out <= "00000011";
				state <= HOME;
			else
				state <= HOME;
			end if;
		elsif char_recvd = '1' then
			char_sent <= '0';	
			state <= HOME;	
		else
			state <= HOME;
		end if;


	when NOP =>
		state<= last_state;


	when WELCOME =>  	
	last_state <= WELCOME;		--prints "WELCOME"		
					--	 "APU ->"
	case count is			
		when "000000" =>
			char <= W;
			char_print <='1';
		when "000001" =>
			char <= E;
			char_print <='1';
		when "000010" =>
			char <= L;
			char_print <='1';
		when "000011" =>
			char <= C;
			char_print <='1';
		when "000100" =>
			char <= O;
			char_print <='1';
		when "000101" =>
			char <= M;
			char_print <='1';
		when "000110" =>
			char <= E;
			char_print <='1';
		when "000111" =>
			char <= carrage_return;
			char_print <='1';
		when "001000" =>
			char <= A;
			char_print <='1';
		when "001001" =>
			char <= P;
			char_print <='1';
		when "001010" =>
			char <= U;
			char_print <='1';
		when "001011" =>
			char <= space;
			char_print <='1';
		when "001100" =>
			char <= r_arrow;
			char_print <='1';
		when others =>
			state<= HOME;
			char_print <='0';
		end case;


			
	when START =>			-- prints "BEGIN"
	last_state <= START;	

	case count is			
		when "000000" =>
			char <= B;
			char_print <='1';
		when "000001" =>
			char <= E;
			char_print <='1';
		when "000010" =>
			char <= G;
			char_print <='1';
		when "000011" =>
			char <= I;
			char_print <='1';
		when "000100" =>
			char <= N;
			char_print <='1';
		when others =>
			state<= HOME;
			char_print <='0';
		end case;


	when FINISH =>			-- prints "END"
	last_state <= FINISH;	

	case count is			
		when "000000" =>
			char <= E;
			char_print <='1';
		when "000001" =>
			char <= N;
			char_print <='1';
		when "000010" =>
			char <= D;
			char_print <='1';
		when others =>
			state<= HOME;
			char_print <='0';
		end case;
	end case;

	if char_print ='1' then
		case char is

			when A =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01000001";
				end if;	

			when B =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01000010";
				end if;

			when C =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01000011";
				end if;
	
			when D =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01000100";
				end if;	

			when E =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01000101";
				end if;	

			when F =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01000110";
 				end if;

			when G =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01000111";
				end if;	

			when H =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01001000";
				end if;

			when I =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01001001";
				end if;	

			when J =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01001010";
				end if;

			when K =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01001011";
				end if;

			when L =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01001100";
				end if;
	
			when M =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01001101";
				end if;	

			when N =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01001110";
				end if;

			when O =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01001111";
				end if;

			when P =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01010000";
				end if;

			when Q =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01010001";
				end if;

			when R =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01010010";
				end if;

			when S =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01010011";
				end if;

			when T =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01010100";
				end if;

			when U =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01010101";
				end if;

			when V =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01010110";
				end if;

			when W =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01010111";
				end if;

			when X =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01011000";
				end if;

			when Y =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01011001";
				end if;

			when Z =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01011010";
				end if;

			when carrage_return =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "00000010";
				end if;

			when r_arrow =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "01111110";
				end if;

			when space =>
				if char_recvd = '1' then
					count <= count+"000001";
					char_sent <= '0';
				elsif dvr_ready ='1' then
					char_sent <= '1';
					char_out <= "00100000";
				end if;

			when NIL =>
				char_out <= "00000000";
				char_sent <='0';
			end case;
		end if;
	end if;
end process;

end Output;