diff options
Diffstat (limited to 'mpc/src/uceil_log2.c')
-rw-r--r-- | mpc/src/uceil_log2.c | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/mpc/src/uceil_log2.c b/mpc/src/uceil_log2.c new file mode 100644 index 0000000000..df946128d8 --- /dev/null +++ b/mpc/src/uceil_log2.c @@ -0,0 +1,33 @@ +/* mpc_ceil_log2 - returns ceil(log(d)/log(2)) + +Copyright (C) 2004, 2009, 2010 INRIA + +This file is part of GNU MPC. + +GNU MPC 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 3 of the License, or (at your +option) any later version. + +GNU MPC 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 this program. If not, see http://www.gnu.org/licenses/ . +*/ + +#include "mpc-impl.h" + +/* returns ceil(log(d)/log(2)) if d > 0 */ +/* Don't use count_leading_zeros since it is in longlong.h */ +mpfr_prec_t +mpc_ceil_log2 (mpfr_prec_t d) +{ + mpfr_prec_t exp; + + for (exp = 0; d > 1; d = (d + 1) / 2) + exp++; + return exp; +} |