-- test 2, ISE 14.7 
---A.Kurka, 13.05.21, 
--afkt mit neue Formel, mit 10 clk und 5 componenten
--    P(X) = P0 + X*(P1 + X*P2), ausgewertet von innen nach außen
--		Q(X) = Q0 + X*(Q1 + X*Q2), ausgewertet von innen nach außen
--		a(X) = P(X) / Q(X)
--========================================================== 
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

--X"3f7ffffd",--P0	+0.99999984852024669 	index 0
--X"be8c8cb6",--P1	-0.27451104135987186
--X"00000000",--P2   +0.0							index 2
--X"00000000" 						
----------------------------------
--X"3f800000",--Q0	+1.0 							index 0
--X"beb73881",--Q1	-0.35785296234245088
--X"3c36a182",--Q2  +0.011146905255803363 	indesx 2
--X"00000000"

entity afkt is
	generic(	P0:std_logic_vector(31 downto 0):=X"00000000";
				P1:std_logic_vector(31 downto 0):=X"00000000";
				P2:std_logic_vector(31 downto 0):=X"00000000";
				Q0:std_logic_vector(31 downto 0):=X"00000000";
				Q1:std_logic_vector(31 downto 0):=X"00000000";
				Q2:std_logic_vector(31 downto 0):=X"00000000"
				);		
	port(	nrst	: in std_logic;
			clk		: in std_logic;
			ceafkt	: in std_logic; -- startimpuls afkt
			Xinp	: in std_logic_vector(31 downto 0); -- Input in [0, 0.5] in FP-Format
			aout	: OUT std_logic_vector(31 downto 0) -- Output in [1, 1.047197+] in FP-Format, 1.047197=2*asin(0.5)
			);
end afkt;

architecture Behavioral of afkt is
----------------------------------------------------
COMPONENT mulFP IS
	port (
	a: IN std_logic_VECTOR(31 downto 0);
	b: IN std_logic_VECTOR(31 downto 0);
	clk: IN std_logic;
	ce: IN std_logic;
	result: OUT std_logic_VECTOR(31 downto 0));
END COMPONENT;
---------------------------------------------
COMPONENT addFP IS
	port (
	a: IN std_logic_VECTOR(31 downto 0);
	b: IN std_logic_VECTOR(31 downto 0);
	clk: IN std_logic;
	ce: IN std_logic;
	result: OUT std_logic_VECTOR(31 downto 0));
END COMPONENT;
------------------------------------------------------------
COMPONENT divFP IS
	port (
	a: IN std_logic_VECTOR(31 downto 0);
	b: IN std_logic_VECTOR(31 downto 0);
	clk: IN std_logic;
	ce: IN std_logic;
	result: OUT std_logic_VECTOR(31 downto 0)
	);
END COMPONENT;
-----------------------------------------------------
TYPE T_PQTab IS ARRAY(0 TO 3) OF std_logic_vector(31 DOWNTO 0); -- Koeff Tabelle für Polynom mit Grad <= 3.
--==========================================================================
CONSTANT Cnan : std_logic_vector(31 DOWNTO 0) := X"FFC00000"; -- silent NaN (Not-a-Number) in FP IEEE single (32bit)
CONSTANT C0	:std_logic_vector(31 DOWNTO 0) := X"FFC00000";--Null im FP Format
------------------------------------------------------------------------
-- Koeffizienten-Tabellen für P / Q, MiniMax Approximation, X in [0, 1/2].
-- a(x) = p(x) / q(x) = asin(sqrt(x/2)) / sqrt(x/2)
-- p(x) = 2.2395545700203E+01 + x * (-9.2247557732604 + x * 4.9573581589364E-01)
-- q(x) = 2.2395545641439E+01 + x * (-1.1091046068928E+01 + x)
-- |rel. Fehler| < 1.63e-9 (5e-7 mit IEEE single).
--
--CONSTANT PTab : T_PQTab :=
--(
--	X"41b32a14", -- P0	+2.2395545700203E+01
--	X"c113989a", -- P1	-9.2247557732604
--	X"3efdd116", -- P2	+4.9573581589364E-01
--	X"00000000"  -- unused
--);
--CONSTANT QTab : T_PQTab :=
--(
--	X"41b32a14", -- Q0	+2.2395545641439E+01
--	X"c13174ed", -- Q1	-1.1091046068928E+01
--	X"3f800000", -- Q2	+1.0
--	X"00000000"  -- unused
--);
-- koeffizienten Tabellen für P , MinMax Approximation
CONSTANT PTab :T_PQTab:= -- alle werte in FP
(
P0,------------------X"3f7ffffd",--P0	+0.99999984852024669 	index 0
P1,-------------------X"be8c8cb6",--P1	-0.27451104135987186
P2,--------------------X"00000000",--P2   +0.0							index 2
X"00000000" 						
);
--------------------------------
CONSTANT QTab :T_PQTab:= -- alle werte in FP
(
Q0,--------------X"3f800000",--Q0	+1.0 							index 0
Q1,----------X"beb73881",--Q1	-0.35785296234245088
Q2,-----------X"3c36a182",--Q2  +0.011146905255803363 	indesx 2
X"00000000"
);  
--==================== Signale für afkt ==================================
SIGNAL stateafkt	:integer range 0 to 7:= 0;
--SIGNAL ceafkt 	:std_logic:='0';-- Startimpuls afkt, extern
SIGNAL ce1			:std_logic:='0';-- Start Pmul = Xinp*Pinp;   Qmul = Xinp*Qinp
SIGNAL ce2			:std_logic:='0';-- Start Padd = Pmul+PKoeff; Qadd = Qmul+QKoeff
SIGNAL ce3			:std_logic:='0';-- Start aout = Pplus/Qplus
SIGNAL ce4			:std_logic:='0';-- Start aout = Padd/Qadd
SIGNAL RDYdiv		:std_logic:='0';-- Div Result Ready 
SIGNAL Pinp			:std_logic_vector(31 DOWNTO 0):=X"00000000";-- 2. Input cPmul
SIGNAL Qinp			:std_logic_vector(31 DOWNTO 0):=X"00000000";-- 2. input cQmul

SIGNAL Pmul			:std_logic_vector(31 DOWNTO 0):=X"00000000";-- Resultat cPmul
SIGNAL Qmul			:std_logic_vector(31 DOWNTO 0):=X"00000000";-- Resultat cQmul
SIGNAL Pplus		:std_logic_vector(31 DOWNTO 0):=X"00000000";-- Resultat cPmul
SIGNAL Qplus		:std_logic_vector(31 DOWNTO 0):=X"00000000";-- Resultat cQmul
SIGNAL Pa			:std_logic_vector(31 DOWNTO 0):=X"00000000";-- Resultat cPadd
SIGNAL Qa			:std_logic_vector(31 DOWNTO 0):=X"00000000";-- Resultat cPadd
SIGNAL Padd			:std_logic_vector(31 DOWNTO 0):=X"00000000";-- Resultat cPadd, Ergebnis Auswertung P()
SIGNAL Qadd			:std_logic_vector(31 DOWNTO 0):=X"00000000";-- Resultat cQadd, Ergebnis Auswertung Q()
SIGNAL PKoeff		:std_logic_vector(31 DOWNTO 0):=X"00000000";-- Koeff von P()
SIGNAL QKoeff		:std_logic_vector(31 DOWNTO 0):=X"00000000";-- Koeff von Q()
--================================================================
begin
--=========== a(x) ==============================================
-- a(X) = (P0 + P1*X + P2*X^2) / (Q0 + Q1*X + Q2*X^2)
-- Berechnungsformel:
--		P(X) = P0 + X*(P1 + X*P2), ausgewertet von innen nach außen
--		Q(X) = Q0 + X*(Q1 + X*Q2), ausgewertet von innen nach außen
--		a(X) = P(X) / Q(X)

--************************************************************************ 
pafkt:PROCESS(clk) -- Process für a(Xinp), vorläufig 8(?) clk.

-- als Index in PTab und QTab.
VARIABLE TabIdx : INTEGER RANGE 0 TO 3 := 0;
VARIABLE count :INTEGER RANGE 0 TO 7:= 0;
BEGIN
	IF rising_edge(clk) THEN	
		IF nrst = '0' THEN 
			TabIdx := 0; -- Init Inx Pointer
			PKoeff <= C0; 
			QKoeff <= C0; 
			Pinp   <= C0;
			Qinp   <= C0; 
			ce1 <= '0';
			ce2 <= '0';
			ce4 <= '0';
			stateafkt <= 0;
		ELSE
			CASE stateafkt IS
			WHEN 0 => -- Start afkt
				IF ceafkt = '1' THEN
					TabIdx := 2; -- Init Index in Tabellen (1 = max. Polynomgrad - 1)--****************.
					Pinp <= PTab(2); -- Init Pinp = PTab(2), (2 = max. Polynomgrad)
					Qinp <= QTab(2); -- Init Qinp = QTab(2), (2 = max. Polynomgrad)
					ce1 <= '1';--starten mul
					ce2 <= '0';
					ce3 <= '0';
					ce4 <= '0';
					stateafkt <= 1;-- Dann Auswertung gestartet
				ELSE
					Padd <= X"00000000";
					Qadd <= X"00000000";
					stateafkt <= 0;
				END IF;
				---------------------------------
			WHEN 1 => -- ausführen  mul : Xinp * Ptab(2),Xinp * Qtab(2),   
					ce1 <= '0'; -- reset
					
					-- Pmul,Qmul sind bereit
						-- Decrement Tab-Index
					TabIdx := TabIdx - 1;
					PKoeff <= PTab(TabIdx);
					QKoeff <= QTab(TabIdx);
					stateafkt <= 2;
			WHEN 2 =>
					Pplus <= Pmul;
					Qplus <= Qmul;
					ce2 <= '1';
					stateafkt <= 3;
			When 3 =>
					ce2 <= '0';
					stateafkt <= 4;
			When 4 =>
					Padd <= Pa;
					Qadd <= Qa;
					IF TabIdx = 0 THEN
						Pplus <= X"00000000";
						Qplus <= X"00000000";
						ce3 <= '1';-- start div
						count := 1;
						stateafkt <= 5; -- und div
					ELSE
						Pinp <= Pa;
						Qinp <= Qa;
						ce1 <= '1';	-- start für Pmul,Qmul		
						stateafkt <= 1; -- und wiederholen
					END IF;
			WHEN 5 =>  -- div fertig
				IF count > 0 THEN
					count := count - 1;
					ce3 <= '0';
					stateafkt <= 5;
				ELSE
						stateafkt <= 0;--un warten auf neustart
				END IF;
			WHEN OTHERS =>
					stateafkt <= 0;
			END CASE; -- stateafkt
		END IF; -- nrst
	END IF; --clk
END PROCESS; --end pafkt

--=========Components Implementation====================================
-- ce1
cPmul:		mulFP port map(a=>Xinp, b=>Pinp, clk=>clk, ce=>ce1, result=>Pmul);
cQmul:		mulFP port map(a=>Xinp, b=>Qinp, clk=>clk, ce=>ce1, result=>Qmul);
-- ce2
cPadd: 		addFP port map(a=>Pplus, b=>PKoeff, clk=>clk, ce=>ce2, result=>Pa);--
cQadd: 		addFP port map(a=>Qplus, b=>QKoeff, clk=>clk, ce=>ce2, result=>Qa);--
-- ce3
cPQdiv:		divFP port map(a=>Padd, b=>Qadd,clk=>clk, ce=>ce3,result=>aout);

--===============================================================================00
end Behavioral;