sysdeps/m68k/isinfl.c

   1 /* Copyright (C) 1991, 1992, 1995 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 Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 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 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <math.h>
  20 #include "ieee754.h"
  21
  22 #undef __isinfl
  23 #undef isinfl
  24
  25
  26 /* Return 0 if VALUE is finite or NaN, +1 if it
  27    is +Infinity, -1 if it is -Infinity.  */
  28 int
  29 __isinfl (long double value)
  30 {
  31   union ieee854_long_double u;
  32
  33   u.d = value;
  34
  35   /* An IEEE 854 infinity has an exponent with the
  36      maximum possible value and a zero mantissa.
  37      In Motorola's interpretation the integer bit is ignored.  */
  38   if ((u.ieee.exponent & 0x7fff) == 0x7fff &&
  39       (u.ieee.mantissa0 & 0x7fffffff) == 0 && u.ieee.mantissa1 == 0)
  40     return u.ieee.negative ? -1 : 1;
  41
  42   return 0;
  43 }
  44
  45 weak_alias (__isinfl, isinfl);