glibc/stdlib/strtod_nan_float.h

/* Convert string for NaN payload to corresponding NaN.  For float.
   Copyright (C) 1997-2016 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	FLOAT		float
#define SET_MANTISSA(flt, mant)			\
  do						\
    {						\
      union ieee754_float u;			\
      u.f = (flt);				\
      u.ieee_nan.mantissa = (mant);		\
      if (u.ieee.mantissa != 0)			\
	(flt) = u.f;				\
    }						\
  while (0)