1  /* Return 1 if argument is a NaN, else 0.
       2     Copyright (C) 2007-2023 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  /* Ugly kludge to avoid declarations.  */
      20  #define __isnanf	not___isnanf
      21  #define isnanf		not_isnanf
      22  #define __GI___isnanf	not__GI___isnanf
      23  
      24  #include <math.h>
      25  #include <math_private.h>
      26  #include <math_ldbl_opt.h>
      27  
      28  #undef __isnanf
      29  #undef isnanf
      30  #undef __GI___isnanf
      31  
      32  int
      33  __isnan (double x)
      34  {
      35    uint64_t ix;
      36    EXTRACT_WORDS64 (ix, x);
      37    return ix * 2 > 0xffe0000000000000ul;
      38  }
      39  
      40  hidden_def (__isnan)
      41  weak_alias (__isnan, isnan)
      42  
      43  /* It turns out that the 'double' version will also always work for
      44     single-precision.  */
      45  strong_alias (__isnan, __isnanf)
      46  weak_alias (__isnan, isnanf)
      47  
      48  /* ??? GCC 4.8 fails to look through chains of aliases with asm names
      49     attached.  Work around this for now.  */
      50  hidden_ver (__isnan, __isnanf)
      51  
      52  #ifdef NO_LONG_DOUBLE
      53  strong_alias (__isnan, __isnanl)
      54  weak_alias (__isnan, isnanl)
      55  #endif
      56  #if LONG_DOUBLE_COMPAT(libc, GLIBC_2_0)
      57  compat_symbol (libc, __isnan, __isnanl, GLIBC_2_0);
      58  compat_symbol (libc, isnan, isnanl, GLIBC_2_0);
      59  #endif