sysdeps/m68k/fpu/s_frexpl.c

   1 /* Copyright (C) 2003 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <math.h>
  20
  21 long double
  22 __frexpl (long double value, int *expptr)
  23 {
  24   long double mantissa, exponent;
  25   int iexponent;
  26   unsigned long fpsr;
  27
  28   __asm ("ftst%.x %1\n"
  29          "fmove%.l %/fpsr, %0"
  30          : "=dm" (fpsr) : "f" (value));
  31   if (fpsr & (7 << 24))
  32     {
  33       /* Not finite or zero.  */
  34       *expptr = 0;
  35       return value;
  36     }
  37   __asm ("fgetexp%.x %1, %0" : "=f" (exponent) : "f" (value));
  38   iexponent = (int) exponent + 1;
  39   *expptr = iexponent;
  40   /* Unnormalized numbers must be handled specially, otherwise fscale
  41      results in overflow.  */
  42   if (iexponent <= -16384)
  43     {
  44       value *= 0x1p16383L;
  45       iexponent += 16383;
  46     }
  47   else if (iexponent >= 16384)
  48     {
  49       value *= 0x1p-16383L;
  50       iexponent -= 16383;
  51     }
  52
  53   __asm ("fscale%.l %2, %0"
  54          : "=f" (mantissa)
  55          : "0" (value), "dmi" (-iexponent));
  56   return mantissa;
  57 }
  58
  59 weak_alias (__frexpl, frexpl)