-----------------------------------------------------------------
-- scancode_to_vector.vhd
-- Christopher Kowalski
--
-- Scan Code converter from a recieved Scan code value to an encoded 
-- bit Vector.
--
-- Following the code is a table containing the Scan Code conversion.
--

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;

entity scancode_to_vector is
	port(scancode	: in std_logic_vector(7 downto 0);
		reset,
		clock,
		transfer	: in std_logic;
		done 		: out std_logic;
		vector 		: out std_logic_vector(3 downto 0));
end scancode_to_vector;

architecture behavioural of scancode_to_vector is

	-- declare internal signals
		
begin

		
	convert : process (clock) is

	-- process variable
	variable count:natural range 0 to 2;
	
	begin
		if rising_edge(clock) then
		if reset = '1' then
			vector <= (others => '0');
			count := 0;
			done <= '0';
		elsif transfer = '1' then  -- a load signal
			if count = 2 then 	-- this gives the circuit time to have the
				done <= '1';	-- correct value at it's output

			else
			case scancode is
				
			when "01110111" =>			-- x77 NumLock
				vector <= "0000";

			when "01101100" =>			-- x6C 7
				vector <= "0001";

			when "01110101" =>			-- x75 8
				vector <= "0010";

			when "01111101" =>			-- x7D 9
				vector <= "0011";

			when "01101011" =>			-- x6B 4
				vector <= "0100";

			when "01110011" =>			-- x73 5
				vector <= "0101";

			when "01110100" =>			-- x74 6
				vector <= "0110";

			when "01101001" =>			-- x69 1
				vector <= "0111";

			when "01110010" =>			-- x72 2
				vector <= "1000";

			when "01111010" =>			-- x7A 3
				vector <= "1001";

			when "01110000" =>			-- x70 0
				vector <= "1010";

			when "01110001" =>			-- x71 .
				vector <= "1011";

			when "01111001" =>			-- x79 +
				vector <= "1100";

			when others =>
				vector <= "1111";

			end case;
			count:= (count +1);
			end if;

		elsif transfer = '0' then
			done <= '0';
			count := 0;

		end if;		
		end if;

	end process convert;
end behavioural;


--------------------------------------------------------------------------
-- |Scan	|	Scan in HEX		|	Binary Value	|	Encoded Vector	|
-- |--------|-------------------|-------------------|-------------------|
-- | Numlock|	77				|	0111 0111		|	0000			|
-- | 7		|	6C				|	0110 1100		|	0001			|
-- | 8		|	75				|	0111 0101		|	0010			|
-- | 9		|	7D				|	0111 1101		|	0011			|
-- | 4		|	6B				|	0110 1011		|	0100			|
-- | 5		|	73				|	0111 0011		|	0101			|
-- | 6		|	74				|	0111 0100		|	0110			|
-- | 1		|	69				|	0110 1001		|	0111			|
-- | 2		|	72				|	0111 0010		|	1000			|
-- | 3		|	7A				|	0111 1010		|	1001			|
-- | 0		|	70				|	0111 0000		|	1010			|
-- | .		|	71				|	0111 0001		|	1011			|
-- | +		|	79				|	0111 1001		|	1100			|
-- | ERROR	|	FF				|	1111 1111		|	1111			|
--------------------------------------------------------------------------
--