glibc/sysdeps/ieee754/dbl-64/s_fpclassify.c

/* Return classification value corresponding to argument.
   Copyright (C) 1997-2022 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
   <https://www.gnu.org/licenses/>.  */

#include <math.h>

#include <math_private.h>


int
__fpclassify (double x)
{
  uint32_t hx, lx;
  int retval = FP_NORMAL;

  EXTRACT_WORDS (hx, lx, x);
  lx |= hx & 0xfffff;
  hx &= 0x7ff00000;
  if ((hx | lx) == 0)
    retval = FP_ZERO;
  else if (hx == 0)
    retval = FP_SUBNORMAL;
  else if (hx == 0x7ff00000)
    retval = lx != 0 ? FP_NAN : FP_INFINITE;

  return retval;
}
libm_hidden_def (__fpclassify)