glibc/sysdeps/m68k/s_isinfl.c

/* Copyright (C) 1991, 1992, 1995, 1997 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <math.h>
#include "ieee754.h"

#undef __isinfl
#undef isinfl


/* Return 0 if VALUE is finite or NaN, +1 if it
   is +Infinity, -1 if it is -Infinity.  */
int
__isinfl (long double value)
{
  union ieee854_long_double u;

  u.d = value;

  /* An IEEE 854 infinity has an exponent with the
     maximum possible value and a zero mantissa.
     In Motorola's interpretation the integer bit is ignored.  */
  if ((u.ieee.exponent & 0x7fff) == 0x7fff &&
      (u.ieee.mantissa0 & 0x7fffffff) == 0 && u.ieee.mantissa1 == 0)
    return u.ieee.negative ? -1 : 1;

  return 0;
}

weak_alias (__isinfl, isinfl);