sysdeps/ieee754/ldbl-96/s_issignalingl.c

   1 /* Test for signaling NaN.
   2    Copyright (C) 2013-2023 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <math.h>
  20 #include <math_private.h>
  21 #include <nan-high-order-bit.h>
  22 #include <nan-pseudo-number.h>
  23
  24 int
  25 __issignalingl (long double x)
  26 {
  27   uint32_t exi, hxi, lxi;
  28   GET_LDOUBLE_WORDS (exi, hxi, lxi, x);
  29
  30   /* By default we do not recognize a pseudo NaN as sNaN.  However on 80387 and
  31      later all pseudo numbers including pseudo NaNs result in a signal and are
  32      hence recognized as signaling.  */
  33   int ret = is_pseudo_signaling (exi, hxi);
  34
  35 #if HIGH_ORDER_BIT_IS_SET_FOR_SNAN
  36 # error not implemented
  37 #else
  38   /* To keep the following comparison simple, toggle the quiet/signaling bit,
  39      so that it is set for sNaNs.  This is inverse to IEEE 754-2008 (as well as
  40      common practice for IEEE 754-1985).  */
  41   hxi ^= 0x40000000;
  42   /* If lxi != 0, then set any suitable bit of the significand in hxi.  */
  43   hxi |= (lxi | -lxi) >> 31;
  44   /* We have to compare for greater (instead of greater or equal), because x's
  45      significand being all-zero designates infinity not NaN.  */
  46   return ret || (((exi & 0x7fff) == 0x7fff) && (hxi > 0xc0000000));
  47 #endif
  48 }
  49 libm_hidden_def (__issignalingl)