s_fpclassify.c

来自「glibc2.5版源代码」· C语言 代码 · 共 45 行

/* Return classification value corresponding to argument.
   Copyright (C) 1997, 2002 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <[e-mail]>, 1997.

   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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <math.h>

#include "math_private.h"


int
__fpclassify (double x)
{
  u_int32_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)