niceSOFT/mpfr | Gitverse

src/set_prec.c
58 строк2 KB
Vincent Lefèvre
03 янв 2018, 13:53
03 янв 2018, 13:532fce388
/* mpfr_set_prec -- reset the precision of a floating-point number

Copyright 1999, 2001-2002, 2004, 2006-2018 Free Software Foundation, Inc.
Contributed by the AriC and Caramba projects, INRIA.

This file is part of the GNU MPFR Library.

The GNU 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 3 of the License, or (at your
option) any later version.

The GNU 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 GNU MPFR Library; see the file COPYING.LESSER.  If not, see
http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */

#include "mpfr-impl.h"

MPFR_HOT_FUNCTION_ATTR void
mpfr_set_prec (mpfr_ptr x, mpfr_prec_t p)
{
  mp_size_t xsize, xoldsize;

  /* first, check if p is correct */
  MPFR_ASSERTN (MPFR_PREC_COND (p));

  /* Calculate the new number of limbs */
  xsize = MPFR_PREC2LIMBS (p);

  /* Realloc only if the new size is greater than the old */
  xoldsize = MPFR_GET_ALLOC_SIZE (x);
  if (xsize > xoldsize)
    {
      mpfr_size_limb_t *tmp;

      tmp = (mpfr_size_limb_t *) mpfr_reallocate_func
        (MPFR_GET_REAL_PTR(x),
         MPFR_MALLOC_SIZE(xoldsize),
         MPFR_MALLOC_SIZE(xsize));
      MPFR_SET_MANT_PTR(x, tmp);
      MPFR_SET_ALLOC_SIZE(x, xsize);
    }
  MPFR_PREC (x) = p;
  MPFR_SET_NAN (x); /* initializes to NaN */
}

#undef mpfr_get_prec
mpfr_prec_t
mpfr_get_prec (mpfr_srcptr x)
{
  return MPFR_PREC(x);
}