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-- this entity is the output buffer that stores characters 
-- to be output to the LEDS
-- the array is indexed by a multiplier from 
-- the count given by the input generation block (time or temp)

-- INPUTS: index from input geneator block and character code from LUT
-- OUTPUTS: a sequence of LED commands (on/off) for the mux in the output block

-- GENERICS: width how many columns of LEDs in a display block 
-- ( num of "pixels" in display area not the whole circle)
-- char_width : how many LED columns are in one char, plus one space after the char
-- height: how mnay LEDs tall a character is.
 
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;

entity outputbuffer is 
	generic (
		width 	   : positive := 20;
		char_width : positive := 4;
		height	   : positive := 5; 
		ctrl_width : positive := 3 );
	port (
		clock 		  : in std_logic;
		index 		  : in std_logic_vector (ctrl_width-1 downto 0);
		char_bitmap   : in std_logic_vector (((char_width-1)*height)-1 downto 0);
		LED_0_pattern : out std_logic_vector (width-1 downto 0);
		LED_1_pattern : out std_logic_vector (width-1 downto 0);
		LED_2_pattern : out std_logic_vector (width-1 downto 0);
		LED_3_pattern : out std_logic_vector (width-1 downto 0);
		LED_4_pattern : out std_logic_vector (width-1 downto 0) );
end entity outputbuffer;

architecture behavioural of outputbuffer is
signal n : integer;
signal char0, char1, char2, char3, char4  : std_logic_vector( height*char_width-1 downto 0 );
begin

	latch_LUT_data : process( clock )
	variable i : integer range (width/char_width)-1 downto 0;
	begin
		
				if rising_edge( clock ) then
			if index = "000" then 
				char0(((char_width-1)*height)-1 downto 0) <= char_bitmap;
				char0( ((char_width)*height)-1 downto ((char_width-1)*height)) <= "00000";
			elsif index = "001" then
				char1(((char_width-1)*height)-1 downto 0) <= char_bitmap;
				char1( ((char_width)*height)-1 downto ((char_width-1)*height)) <= "00000";
			elsif index = "010" then
				char2(((char_width-1)*height)-1 downto 0) <= char_bitmap;
				char2( ((char_width)*height)-1 downto ((char_width-1)*height)) <= "00000";
			elsif index = "011" then
				char3(((char_width-1)*height)-1 downto 0) <= char_bitmap;
				char3( ((char_width)*height)-1 downto ((char_width-1)*height)) <= "00000";
			elsif index = "100" then
				char4(((char_width-1)*height)-1 downto 0) <= char_bitmap;
				char4( ((char_width)*height)-1 downto ((char_width-1)*height)) <= "00000";
			end if;
		end if;

	end process latch_LUT_data;

	assign_outputs: for n in 0 to char_width-1 generate
		LED_0_pattern(n) <= char0(n*height);
		LED_1_pattern(n) <= char0(n*height+ 1);
		LED_2_pattern(n) <= char0(n*height+ 2);
		LED_3_pattern(n) <= char0(n*height+ 3);
		LED_4_pattern(n) <= char0(n*height+ 4);

		LED_0_pattern(n+char_width) <= char1(n*height);
		LED_1_pattern(n+char_width) <= char1(n*height+ 1);
		LED_2_pattern(n+char_width) <= char1(n*height+ 2);
		LED_3_pattern(n+char_width) <= char1(n*height+ 3);
		LED_4_pattern(n+char_width) <= char1(n*height+ 4);

		LED_0_pattern(n+(char_width)*2) <= char2(n*height);
		LED_1_pattern(n+(char_width)*2) <= char2(n*height+ 1);
		LED_2_pattern(n+(char_width)*2) <= char2(n*height+ 2);
		LED_3_pattern(n+(char_width)*2) <= char2(n*height+ 3);
		LED_4_pattern(n+(char_width)*2) <= char2(n*height+ 4);
	
		LED_0_pattern(n+(char_width)*3) <= char3(n*height);
		LED_1_pattern(n+(char_width)*3) <= char3(n*height+ 1);
		LED_2_pattern(n+(char_width)*3) <= char3(n*height+ 2);
		LED_3_pattern(n+(char_width)*3) <= char3(n*height+ 3);
		LED_4_pattern(n+(char_width)*3) <= char3(n*height+ 4);

		LED_0_pattern(n+(char_width)*4) <= char4(n*height);
		LED_1_pattern(n+(char_width)*4) <= char4(n*height+ 1);
		LED_2_pattern(n+(char_width)*4) <= char4(n*height+ 2);
		LED_3_pattern(n+(char_width)*4) <= char4(n*height+ 3);
		LED_4_pattern(n+(char_width)*4) <= char4(n*height+ 4);
	end generate assign_outputs;
	
	--LED_0_pattern <= "00110011001100110011";
	--LED_1_pattern <= "00110011001100110011";
	--LED_2_pattern <= "00110011001100110011";
	--LED_3_pattern <= "00110011001100110011";
	--LED_4_pattern <= "00110011001100110011";
	
end behavioural;