/* Return positive difference between arguments.  i386 version.

   Copyright (C) 1997-2018 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/>.  */

#include <errno.h>

#include <fpu_control.h>

#include <math.h>

#include <math-narrow-eval.h>

#include <math_private.h>

#include <libm-alias-double.h>

double

__fdim (double x, double y)

{

  if (islessequal (x, y))

    return 0.0;

  /* To avoid double rounding, set double precision for the

     subtraction.  math_narrow_eval is still needed to eliminate

     excess range in the case of overflow.  If the result of the

     subtraction is in the subnormal range for double, it is exact, so

     no issues of double rounding for subnormals arise.  */

  fpu_control_t cw, cw_double;

  _FPU_GETCW (cw);

  cw_double = (cw & ~_FPU_EXTENDED) | _FPU_DOUBLE;

  _FPU_SETCW (cw_double);

  double r = math_narrow_eval (x - y);

  _FPU_SETCW (cw);

  if (isinf (r) && !isinf (x) && !isinf (y))

    __set_errno (ERANGE);

  return r;

}

libm_alias_double (__fdim, fdim)