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

Copyright 1993-1995, 2000, 2001 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 either:

  * 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.

or

  * the GNU General Public License as published by the Free Software

    Foundation; either version 2 of the License, or (at your option) any

    later version.

or both in parallel, as here.

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 General Public License

for more details.

You should have received copies of the GNU General Public License and the

GNU Lesser General Public License along with the GNU MP Library.  If not,

see https://www.gnu.org/licenses/.  */

#include "gmp.h"

#include "gmp-impl.h"

/* A full new_prec+1 limbs are always retained, even though just new_prec

   would satisfy the requested precision.  If size==new_prec+1 then

   certainly new_prec+1 should be kept since no copying is needed in that

   case.  If just new_prec was kept for size>new_prec+1 it'd be a bit

   inconsistent.  */

void

mpf_set_prec (mpf_ptr x, mp_bitcnt_t new_prec_in_bits)

{

  mp_size_t  old_prec, new_prec, new_prec_plus1;

  mp_size_t  size, sign;

  mp_ptr     xp;

  new_prec = __GMPF_BITS_TO_PREC (new_prec_in_bits);

  old_prec = PREC(x);

  /* do nothing if already the right precision */

  if (new_prec == old_prec)

    return;

  PREC(x) = new_prec;

  new_prec_plus1 = new_prec + 1;

  /* retain most significant limbs */

  sign = SIZ(x);

  size = ABS (sign);

  xp = PTR(x);

  if (size > new_prec_plus1)

    {

      SIZ(x) = (sign >= 0 ? new_prec_plus1 : -new_prec_plus1);

      MPN_COPY_INCR (xp, xp + size - new_prec_plus1, new_prec_plus1);

    }

  PTR(x) = __GMP_REALLOCATE_FUNC_LIMBS (xp, old_prec+1, new_prec_plus1);

}