glibc/sysdeps/ieee754/ldbl-128ibm/math-nan-payload-ldouble.h

/* NaN payload handling or ldbl-128ibm.
   Copyright (C) 1997-2019 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 Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#define SET_NAN_PAYLOAD(flt, mant)				\
  do								\
    {								\
      union ibm_extended_long_double u;				\
      u.ld = (flt);						\
      u.d[0].ieee_nan.mantissa0 = (mant) >> 32;			\
      u.d[0].ieee_nan.mantissa1 = (mant);			\
      if ((u.d[0].ieee.mantissa0 | u.d[0].ieee.mantissa1) != 0)	\
	(flt) = u.ld;						\
    }								\
  while (0)