with System.Machine_Code; use System.Machine_Code;

package body Ada.Numerics.Aux is

   NL : constant String := ASCII.LF & ASCII.HT;

   function Exp (X : Double) return Double is
      Result : Double;
   begin
      Asm (Template =>
         "fldl2e               " & NL
       & "fmulp   %%st, %%st(1)" & NL -- X * log2 (E)
       & "fld     %%st(0)      " & NL
       & "frndint              " & NL -- Integer (X * Log2 (E))
       & "fsubr   %%st, %%st(1)" & NL -- Fraction (X * Log2 (E))
       & "fxch                 " & NL
       & "f2xm1                " & NL -- 2**(...) - 1
       & "fld1                 " & NL
       & "faddp   %%st, %%st(1)" & NL -- 2**(Fraction (X * Log2 (E)))
       & "fscale               " & NL -- E ** X
       & "fstp    %%st(1)      ",
         Outputs  => Double'Asm_Output ("=t", Result),
         Inputs   => Double'Asm_Input  ("0", X));
      return Result;
   end Exp;

   function Tanh (X : Double) return Double is
   begin

      if abs X > 23.0 then
         return Double'Copy_Sign (1.0, X);
      end if;

      return 1.0 / (1.0 + Exp (-(2.0 * X))) - 1.0 / (1.0 + Exp (2.0 * X));
   end Tanh;

end Ada.Numerics.Aux;