/* mpf_set_prec(x) -- Change the precision of x.

Copyright (C) 1993, 1994, 1995, 2000 Free Software Foundation, Inc.

This file is part of the GNU MP Library.

The GNU MP 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 MP 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 MP Library; see the file COPYING.LIB.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */

#include "gmp.h"
#include "gmp-impl.h"

void
#if __STDC__
mpf_set_prec (mpf_ptr x, unsigned long int prec_in_bits)
#else
mpf_set_prec (x, prec_in_bits)
     mpf_ptr x;
     unsigned long int prec_in_bits;
#endif
{
  mp_size_t prec;
  mp_size_t size = ABS (x->_mp_size);

  prec = (MAX (53, prec_in_bits) + 2 * BITS_PER_MP_LIMB - 1)/BITS_PER_MP_LIMB;

  /* We want the most significant limbs, so move the limbs down if we are
     about to truncate the value.  */
  if (size > prec + 1)
    {
      mp_size_t offset = size - (prec + 1);
      mp_ptr xp = x->_mp_d;

      MPN_COPY_INCR (xp, xp + offset, prec + 1);
    }

  x->_mp_d = (mp_ptr) (*_mp_reallocate_func)
    (x->_mp_d,
     (x->_mp_prec + 1) * BYTES_PER_MP_LIMB, (prec + 1) * BYTES_PER_MP_LIMB);
  x->_mp_prec = prec;

  /* If the precision decreased, truncate the number.  */
  if (size > prec + 1)
    x->_mp_size = x->_mp_size >= 0 ? (prec + 1) : -(prec + 1);
}