reactos/lib/sdk/crt/math/i386/exp.c

   1 /* Math functions for i387.
   2    Copyright (C) 1995, 1996, 1997 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by John C. Bowman <bowman@ipp-garching.mpg.de>, 1995.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include <math.h>
  22
  23 double exp (double __x);
  24
  25 double exp (double __x)
  26 {
  27 #ifdef __GNUC__
  28   register double __value, __exponent;
  29   __asm __volatile__
  30     ("fldl2e                    # e^x = 2^(x * log2(e))\n\t"
  31      "fmul      %%st(1)         # x * log2(e)\n\t"
  32      "fst       %%st(1)\n\t"
  33      "frndint                   # int(x * log2(e))\n\t"
  34      "fxch\n\t"
  35      "fsub      %%st(1)         # fract(x * log2(e))\n\t"
  36      "f2xm1                     # 2^(fract(x * log2(e))) - 1\n\t"
  37      : "=t" (__value), "=u" (__exponent) : "0" (__x));
  38   __value += 1.0;
  39   __asm __volatile__
  40     ("fscale"
  41      : "=t" (__value) : "0" (__value), "u" (__exponent));
  42
  43   return __value;
  44 #else
  45 #error IMPLEMENT ME
  46 #endif /*__GNUC__*/
  47 }