/* mpfr_add_si -- add a floating-point number with a machine integer
   mpfr_sub_si -- sub  a floating-point number with a machine integer
   mpfr_si_sub -- sub  a machine number with a floating-point number

Copyright 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
Contributed by the Arenaire and Cacao projects, INRIA.

This file is part of the MPFR Library.

The MPFR 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 MPFR 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 MPFR Library; see the file COPYING.LIB.  If not, write to
the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
MA 02110-1301, USA. */

#include "mpfr-impl.h"

int
mpfr_add_si (mpfr_ptr y, mpfr_srcptr x, long int u, mp_rnd_t rnd_mode)
{
  if (u >= 0)
    return mpfr_add_ui (y, x, u, rnd_mode);
  else
    return mpfr_sub_ui (y, x, -u, rnd_mode);
}

int
mpfr_sub_si (mpfr_ptr y, mpfr_srcptr x, long int u, mp_rnd_t rnd_mode)
{
  if (u >= 0)
    return mpfr_sub_ui (y, x, u, rnd_mode);
  else
    return mpfr_add_ui (y, x, -u, rnd_mode);
}

int
mpfr_si_sub (mpfr_ptr y, long int u, mpfr_srcptr x, mp_rnd_t rnd_mode)
{
  if (u >= 0)
    return mpfr_ui_sub (y, u, x, rnd_mode);
  else
    {
    int res = -mpfr_add_ui (y, x, -u, MPFR_INVERT_RND (rnd_mode));
    MPFR_CHANGE_SIGN (y);
    return res;
    }
}