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)