1/* mpfr_min_prec -- minimal size in bits to hold the mantissa
2
3Copyright 2009, 2010, 2011, 2012, 2013 Free Software Foundation, Inc.
4Contributed by the AriC and Caramel projects, INRIA.
5
6This file is part of the GNU MPFR Library.
7
8The GNU MPFR Library is free software; you can redistribute it and/or modify
9it under the terms of the GNU Lesser General Public License as published by
10the Free Software Foundation; either version 3 of the License, or (at your
11option) any later version.
12
13The GNU MPFR Library is distributed in the hope that it will be useful, but
14WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
16License for more details.
17
18You should have received a copy of the GNU Lesser General Public License
19along with the GNU MPFR Library; see the file COPYING.LESSER.  If not, see
20http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
2151 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
22
23#include "mpfr-impl.h"
24
25mpfr_prec_t
26mpfr_min_prec (mpfr_srcptr x)
27{
28  if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (x)))
29    return 0;
30
31  /* from a suggestion by Andreas Enge (2010-11-18) */
32  return MPFR_LIMB_SIZE (x) * GMP_NUMB_BITS - mpn_scan1 (MPFR_MANT (x), 0);
33}
34