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

--file that calculates wind direction

entity winddirection is
	generic(winddirwidth: positive := 8);
	port (clock, a,b,c,d: in std_logic;
	windfirstdir: buffer std_logic_vector(winddirwidth-1 downto 0);
	windseconddir: buffer std_logic_vector(winddirwidth-1 downto 0);
	windthirddir: buffer std_logic_vector(winddirwidth-1 downto 0));
end winddirection;

architecture behaviour of winddirection is

--constants for the outgoing letters
constant lettern: std_logic_vector(winddirwidth-1 downto 0):= "01001110";
constant lettere: std_logic_vector(winddirwidth-1 downto 0):= "01000101";
constant letters: std_logic_vector(winddirwidth-1 downto 0) := "01010011";
constant letterw: std_logic_vector(winddirwidth-1 downto 0) := "01010111";
constant letterspace: std_logic_vector(winddirwidth-1 downto 0) := "00100000";

--signals
signal qa,qb,qc,qd: std_logic;

begin

	changingstate: process(clock)

	begin

	--latch for the incoming values

		if rising_edge(clock) then


			qa <= a;
			qb <= b;
			qc <= c;
			qd <= d;
		end if;


		--for the directions 
		--for north
	end process changingstate;


	--following if statements that go through the various combinations of directions
	--the appropriate ascii directional letters are then output 

	changingsecondstate2: process(clock)
	
	begin
		
		if rising_edge(clock) then


			if (qa = '0')  and (qb ='0') and (qc = '0') and (qd ='0') then 

				--for north
						windfirstdir <= lettern;
						windseconddir <= letterspace;
						windthirddir <= letterspace;
			end if;

			if (qa = '0')  and (qb ='0') and (qc = '0') and (qd ='1') then 

				--for nne
						windfirstdir <= lettern;
						windseconddir <= lettern;
						windthirddir <= lettere;
			end if;
			
			if (qa = '0')  and (qb ='0') and (qc = '1') and (qd ='1') then 

				--for ne
						windfirstdir <= lettern;
						windseconddir <= lettere;
						windthirddir <= letterspace;
			end if;

			if (qa = '0')  and (qb ='0') and (qc = '1') and (qd ='0') then 

				--for ene
						windfirstdir <= lettere;
						windseconddir <= lettern;
						windthirddir <= lettere;
			end if;

			if (qa = '0')  and (qb ='1') and (qc = '1') and (qd ='0') then 

				--for e
						windfirstdir <= lettere;
						windseconddir <= letterspace;
						windthirddir <= letterspace;
			end if;

			if (qa = '0')  and (qb ='1') and (qc = '0') and (qd ='0') then 

				--for ese
						windfirstdir <= lettere;
						windseconddir <= letters;
						windthirddir <= lettere;
			end if;

			if (qa = '0')  and (qb ='1') and (qc = '0') and (qd ='1') then 

				--for se
						windfirstdir <= letters;
						windseconddir <= lettere;
						windthirddir <= letterspace;
			end if;

			if (qa = '0')  and (qb ='1') and (qc = '1') and (qd ='1') then 

				--for sse
						windfirstdir <= letters;
						windseconddir <= letters;
						windthirddir <= lettere;
			end if;

			if (qa = '1')  and (qb ='1') and (qc = '1') and (qd ='1') then 

				--for south
						windfirstdir <= letters;
						windseconddir <= letterspace;
						windthirddir <= letterspace;
			end if;

			if (qa = '1')  and (qb ='1') and (qc = '1') and (qd ='0') then 

				--for ssw
						windfirstdir <= letters;
						windseconddir <= letters;
						windthirddir <= letterw;
			end if;

			if (qa = '1')  and (qb ='1') and (qc = '0') and (qd ='0') then 

				--for sw
						windfirstdir <= letters;
						windseconddir <= letterw;
						windthirddir <= letterspace;
			end if;

			if (qa = '1')  and (qb ='1') and (qc = '0') and (qd ='1') then 

				--for wsw
						windfirstdir <= letterw;
						windseconddir <= letters;
						windthirddir <= letterw;
			end if;

			if (qa = '1')  and (qb ='0') and (qc = '0') and (qd ='1') then 

				--for w
						windfirstdir <= letterw;
						windseconddir <= letterspace;
						windthirddir <= letterspace;
			end if;

			if (qa = '1')  and (qb ='0') and (qc = '1') and (qd ='1') then 

				--for wnw
						windfirstdir <= letterw;
						windseconddir <= lettern;
						windthirddir <= letterw;
			end if;

			if (qa = '1')  and (qb ='0') and (qc = '1') and (qd ='0') then 

				--for nw
						windfirstdir <= lettern;
						windseconddir <= letterw;
						windthirddir <= letterspace;
			end if;

			if (qa = '1')  and (qb ='0') and (qc = '0') and (qd ='0') then 

				--for nnw
						windfirstdir <= lettern;
						windseconddir <= lettern;
						windthirddir <= letterw;
			end if;

		
		end if;

	end process changingsecondstate2;

end behaviour;		


 