library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use work.math_pkg.all;

package gen_pkg is
	subtype alu_ops is std_logic_vector(2 downto 0);
	constant ALU_NOP : alu_ops := "000";
	constant ALU_SUB : alu_ops := "001";
	constant ALU_ADD : alu_ops := "010";
	constant ALU_MUL : alu_ops := "011";
	constant ALU_DIV : alu_ops := "100";
	constant ALU_DONE : alu_ops := "101";

	constant CBITS : integer := 32;
	subtype csigned is signed((CBITS-1) downto 0);
	subtype divinteger is unsigned(4 downto 0);
	-- integer ist 32bit (31bit + sign)
	subtype cinteger is integer;


	constant HSPALTE_MAX : integer := 71;
	subtype hspalte is std_logic_vector(6 downto 0);

	constant HZEILE_MAX : integer := 100;
	subtype hzeile is std_logic_vector(6 downto 0);

	-- 50 zeilen * 71 zeichen * 2 (berechnung + ergebnis) = 7100 bytes
	constant H_RAM_SIZE : integer := HZEILE_MAX * HSPALTE_MAX;
	constant H_RAM_WIDTH : integer := log2c(H_RAM_SIZE);

	subtype hbyte is std_logic_vector(7 downto 0);
	subtype hstring is string(1 to HSPALTE_MAX+1);
	subtype hstr_int is integer range 0 to HSPALTE_MAX+1;

	procedure icwait(signal clk_i : IN std_logic; cycles: natural);

	function ascii2sc (x : hbyte) return hbyte;
	function valid_char (x : hbyte) return boolean;
	function zeile2char(i : std_logic_vector; stelle : natural) return hbyte;

	-- http://www.marjorie.de/ps2/scancode-set2.htm
	constant SC_KP_0 : hbyte := x"70";
	constant SC_KP_1 : hbyte := x"69";
	constant SC_KP_2 : hbyte := x"72";
	constant SC_KP_3 : hbyte := x"7a";
	constant SC_KP_4 : hbyte := x"6b";
	constant SC_KP_5 : hbyte := x"73";
	constant SC_KP_6 : hbyte := x"74";
	constant SC_KP_7 : hbyte := x"6c";
	constant SC_KP_8 : hbyte := x"75";
	constant SC_KP_9 : hbyte := x"7d";

	constant SC_0 : hbyte := x"45";
	constant SC_1 : hbyte := x"16";
	constant SC_2 : hbyte := x"1e";
	constant SC_3 : hbyte := x"26";
	constant SC_4 : hbyte := x"25";
	constant SC_5 : hbyte := x"2e";
	constant SC_6 : hbyte := x"36";
	constant SC_7 : hbyte := x"3d";
	constant SC_8 : hbyte := x"3e";
	constant SC_9 : hbyte := x"46";

	constant SC_KP_PLUS : hbyte := x"79";
	constant SC_KP_MINUS : hbyte := x"7b";
	constant SC_KP_MUL : hbyte := x"7c";
	constant SC_KP_DIV : hbyte := x"4a"; -- inkl. 0xe0!

	-- fuer deutsches layout, alle anderen zeichen sind unguenstig belegt
	constant SC_PLUS : hbyte := x"5b";

	constant SC_ENTER : hbyte := x"5a";
	constant SC_BKSP : hbyte := x"66";
	constant SC_SPACE : hbyte := x"29";
end package gen_pkg;

package body gen_pkg is
	procedure icwait(signal clk_i : IN std_logic; cycles: Natural) is
	begin
		for i in 1 to cycles loop
			wait until clk_i= '0' and clk_i'event;
		end loop;
	end;

	function ascii2sc (x : hbyte) return hbyte is
		variable y : hbyte;
	begin
		case x is
			when x"30" => y := SC_KP_0;
			when x"31" => y := SC_KP_1;
			when x"32" => y := SC_KP_2;
			when x"33" => y := SC_KP_3;
			when x"34" => y := SC_KP_4;
			when x"35" => y := SC_KP_5;
			when x"36" => y := SC_KP_6;
			when x"37" => y := SC_KP_7;
			when x"38" => y := SC_KP_8;
			when x"39" => y := SC_KP_9;
			when x"2b" => y := SC_KP_PLUS;
			when x"2d" => y := SC_KP_MINUS;
			when x"2a" => y := SC_KP_MUL;
			when x"2f" => y := SC_KP_DIV;
			when x"20" => y := SC_SPACE;
			when x"1c" => y := SC_ENTER;
			when x"0e" => y := SC_BKSP;
			when others => y := x"41";
		end case;
		return y;
	end function;

	function valid_char (x : hbyte) return boolean is
		variable y : boolean;
	begin
		case x is
			when SC_KP_0 | SC_KP_1 | SC_KP_2 | SC_KP_3 |
				SC_KP_4 | SC_KP_5 | SC_KP_6 | SC_KP_7 |
				SC_KP_8 | SC_KP_9 | SC_KP_PLUS |
				SC_KP_MINUS | SC_KP_MUL |
				SC_KP_DIV | SC_SPACE |
				SC_BKSP | SC_ENTER =>
					y := true;
			when others => y := false;
		end case;
		return y;
	end function;

	function zeile2char(i : std_logic_vector; stelle : natural) return hbyte is
		subtype zeilnum is string(1 to 2);
		type zeilnum_arr is array (natural range 0 to 49) of zeilnum;
		constant zn : zeilnum_arr := (
			0 => "00", 1 => "01", 2 => "02", 3 => "03", 4 => "04",
			5 => "05", 6 => "06", 7 => "07", 8 => "08", 9 => "09",
			10 => "10", 11 => "11", 12 => "12", 13 => "13", 14 => "14",
			15 => "15", 16 => "16", 17 => "17", 18 => "18", 19 => "19",
			20 => "20", 21 => "21", 22 => "22", 23 => "23", 24 => "24",
			25 => "25", 26 => "26", 27 => "27", 28 => "28", 29 => "29",
			30 => "30", 31 => "31", 32 => "32", 33 => "33", 34 => "34",
			35 => "35", 36 => "36", 37 => "37", 38 => "38", 39 => "39",
			40 => "40", 41 => "41", 42 => "42", 43 => "43", 44 => "44",
			45 => "45", 46 => "46", 47 => "47", 48 => "48", 49 => "49",
			others => "xy");
		variable t : signed(hzeile'length downto 0);
	begin
		t := signed('0' & i);
		t := t / 2;
		return hbyte(to_unsigned(character'pos(zn(to_integer(t))(stelle)),8));
	end;
end package body gen_pkg;