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      1 /* mpfr_set_prec -- reset the precision of a floating-point number
      2 
      3 Copyright 1999, 2001-2002, 2004, 2006-2023 Free Software Foundation, Inc.
      4 Contributed by the AriC and Caramba projects, INRIA.
      5 
      6 This file is part of the GNU MPFR Library.
      7 
      8 The GNU MPFR Library is free software; you can redistribute it and/or modify
      9 it under the terms of the GNU Lesser General Public License as published by
     10 the Free Software Foundation; either version 3 of the License, or (at your
     11 option) any later version.
     12 
     13 The GNU MPFR Library is distributed in the hope that it will be useful, but
     14 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
     15 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
     16 License for more details.
     17 
     18 You should have received a copy of the GNU Lesser General Public License
     19 along with the GNU MPFR Library; see the file COPYING.LESSER.  If not, see
     20 https://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
     21 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
     22 
     23 #include "mpfr-impl.h"
     24 
     25 MPFR_HOT_FUNCTION_ATTR void
     26 mpfr_set_prec (mpfr_ptr x, mpfr_prec_t p)
     27 {
     28   mp_size_t xsize, xoldsize;
     29 
     30   MPFR_LOG_MSG (("prec=%Pd\n", p));
     31 
     32   /* first, check if p is correct */
     33   MPFR_ASSERTN (MPFR_PREC_COND (p));
     34 
     35   /* Calculate the new number of limbs */
     36   xsize = MPFR_PREC2LIMBS (p);
     37 
     38   /* Realloc only if the new size is greater than the old */
     39   xoldsize = MPFR_GET_ALLOC_SIZE (x);
     40   if (xsize > xoldsize)
     41     {
     42       mpfr_size_limb_t *tmp;
     43 
     44       tmp = (mpfr_size_limb_t *) mpfr_reallocate_func
     45         (MPFR_GET_REAL_PTR(x),
     46          MPFR_MALLOC_SIZE(xoldsize),
     47          MPFR_MALLOC_SIZE(xsize));
     48       MPFR_SET_MANT_PTR(x, tmp);
     49       MPFR_SET_ALLOC_SIZE(x, xsize);
     50     }
     51   MPFR_PREC (x) = p;
     52   MPFR_SET_NAN (x); /* initializes to NaN */
     53 }
     54 
     55 #undef mpfr_get_prec
     56 mpfr_prec_t
     57 mpfr_get_prec (mpfr_srcptr x)
     58 {
     59   return MPFR_PREC(x);
     60 }
     61