library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
use IEEE.NUMERIC_STD.ALL;

---- Uncomment the following library declaration if instantiating
---- any Xilinx primitives in this code.
--library UNISIM;
--use UNISIM.VComponents.all;

entity CordicRtl is
    Port ( x   : in real; --in  signed(15 downto 0);
           clk  : in real; --in  std_ulogic;
           arcsin : out real--out  signed(15 downto 0));
     ); 
end CordicRtl;

architecture Behavioral of CordicRtl is

function ArcTan(x: natural) return real is --Tan^-1(2^-i), dove i va da 0 a 6
variable risultato : real;
begin
 case x is
   when 0 => risultato := 45.00;--10#45#;--2#0000000000101101#;--45;
   when 1 => risultato := 26.56;--10#26#;--2#0000000000011010#;--26,56505118;
   when 2 => risultato := 14.03;--10#14#;--2#0000000000001110#;--14,03624347;
   when 3 => risultato := 7.12;--10#7#;--2#0000000000000111#;--7,125016349;
   when 4 => risultato := 3.57;--10#3#;--2#0000000000000011#;--3,576364375;
   when 5 => risultato := 1.78;--10#1#;--2#0000000000000001#;--1,789910608;
   when 6 => risultato := 0.89;--10#0#;--2#0000000000000000#;--0,89517371;
   when others => risultato := 0.0;--10#0#;--2#0000000000000000#;--0;
  end case;
  return risultato;
 end function ArcTan;
 
begin

main: process(x,clk) is

constant An: real := 1.647;
--variable X, Y, Z, c : real;
type XYVector is array(15 downto 0) of real;--signed(15 downto 0);
variable X,Y,Z,c : XYVector;

begin

--case clk is
 --when 0 => 
--if clk = 0 then
 --c := x * An;
 --X := 1.0;
 --Y := 0.0;

--end if;

--else if (clk := 1) Z := 0.0;
--converti x in real
c(0) := 0.0; --x*An
X(0) := 1.0;
Y(0) := 0.0;
Z(0) := 0.0;
 
for i in 6 downto 0 loop
--variable x :natural;
case x is
 when 1 =>--x := 
  c(i+1) := x * An;
  X(i+1) := X(i) - SHL(Y(i), "10"); --shift
  Y(i+1) := Y(i) + SHL(X(i), "10");
  Z(i+1) := Z(i) - SHL(ArcTan(x), "10");
 when 2 =>
  c(i+1) := x * An;
  X(i+1) := X(i) - SHL(Y(i), "10"); --shift
  Y(i+1) := Y(i) + SHL(X(i), "10");
  Z(i+1) := Z(i) - SHL(ArcTan(x), "10");
 when 3 =>
  c(i+1) := x * An;
  X(i+1) := X(i) - SHL(Y(i), "10"); --shift
  Y(i+1) := Y(i) + SHL(X(i), "10");
  Z(i+1) := Z(i) - SHL(ArcTan(x), "10");
 when 4 =>
  c(i+1) := x * An;
  X(i+1) := X(i) - SHL(Y(i), "10"); --shift
  Y(i+1) := Y(i) + SHL(X(i), "10");
  Z(i+1) := Z(i) - SHL(ArcTan(x), "10");
 when 5 =>
  c(i+1) := x * An;
  X(i+1) := X(i) - SHL(Y(i), "10"); --shift
  Y(i+1) := Y(i) + SHL(X(i), "10");
  Z(i+1) := Z(i) - SHL(ArcTan(x), "10");
end case;
end loop;
--case ruota of
 --when x := 0 => --caso base
  --c := x * An;
  --X := 1.0;
  --Y := 0.0;
 --when x := 1 =>
  --c := x * An;
  --X := X 
end Behavioral;