sysdeps/m68k/s_isinfl.c

   1 /* Copyright (C) 1991, 1992, 1995, 1997, 2002 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 #include "ieee754.h"
  21
  22 /* Return 0 if VALUE is finite or NaN, +1 if it
  23    is +Infinity, -1 if it is -Infinity.  */
  24 int
  25 __isinfl (long double value)
  26 {
  27   union ieee854_long_double u;
  28
  29   u.d = value;
  30
  31   /* An IEEE 854 infinity has an exponent with the
  32      maximum possible value and a zero mantissa.
  33      In Motorola's interpretation the integer bit is ignored.  */
  34   if ((u.ieee.exponent & 0x7fff) == 0x7fff &&
  35       (u.ieee.mantissa0 & 0x7fffffff) == 0 && u.ieee.mantissa1 == 0)
  36     return u.ieee.negative ? -1 : 1;
  37
  38   return 0;
  39 }
  40
  41 hidden_def (__isinfl)
  42 weak_alias (__isinfl, isinfl);