1/* mpc_ceil_log2 - returns ceil(log(d)/log(2))
2
3Copyright (C) 2004, 2009, 2010 INRIA
4
5This file is part of GNU MPC.
6
7GNU MPC is free software; you can redistribute it and/or modify it under
8the terms of the GNU Lesser General Public License as published by the
9Free Software Foundation; either version 3 of the License, or (at your
10option) any later version.
11
12GNU MPC is distributed in the hope that it will be useful, but WITHOUT ANY
13WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
14FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
15more details.
16
17You should have received a copy of the GNU Lesser General Public License
18along with this program. If not, see http://www.gnu.org/licenses/ .
19*/
20
21#include "mpc-impl.h"
22
23/* returns ceil(log(d)/log(2)) if d > 0 */
24/* Don't use count_leading_zeros since it is in longlong.h */
25mpfr_prec_t
26mpc_ceil_log2 (mpfr_prec_t d)
27{
28  mpfr_prec_t exp;
29
30  for (exp = 0; d > 1; d = (d + 1) / 2)
31    exp++;
32  return exp;
33}
34