/* Compute x * y + z as ternary operation.

   Copyright (C) 2010-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Jakub Jelinek <jakub@redhat.com>, 2010.

   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 <math.h>

#include <fenv.h>

#include <ieee754.h>

#include <libm-alias-double.h>

/* This implementation relies on long double being more than twice as

   precise as double and uses rounding to odd in order to avoid problems

   with double rounding.

   See a paper by Boldo and Melquiond:

   http://www.lri.fr/~melquion/doc/08-tc.pdf  */

double

__fma (double x, double y, double z)

{

  fenv_t env;

  /* Multiplication is always exact.  */

  long double temp = (long double) x * (long double) y;

  /* Ensure correct sign of an exact zero result by performing the

     addition in the original rounding mode in that case.  */

  if (temp == -z)

    return (double) temp + z;

  union ieee854_long_double u;

  feholdexcept (&env;;

  fesetround (FE_TOWARDZERO);

  /* Perform addition with round to odd.  */

  u.d = temp + (long double) z;

  if ((u.ieee.mantissa3 & 1) == 0 && u.ieee.exponent != 0x7fff)

    u.ieee.mantissa3 |= fetestexcept (FE_INEXACT) != 0;

  feupdateenv (&env;;

  /* And finally truncation with round to nearest.  */

  return (double) u.d;

}

#ifndef __fma

libm_alias_double (__fma, fma)

#endif