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/* __gmpfr_int_ceil_log2 -- Integer ceil of log2(x)
Copyright 2004, 2005 Free Software Foundation, Inc.
This file is part of the MPFR Library.
The MPFR Library 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 2.1 of the License, or (at your
option) any later version.
The MPFR 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 Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the MPFR Library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 51 Franklin Place, Fifth Floor, Boston,
MA 02110-1301, USA. */
#define MPFR_NEED_LONGLONG_H /* for count_leading_zeros */
#include "mpfr-impl.h"
int
__gmpfr_int_ceil_log2 (unsigned long n)
{
if (n == 1)
return 0;
else
{
int b;
mp_limb_t limb = n - 1;
MPFR_ASSERTN (limb == n - 1);
count_leading_zeros (b, limb);
return BITS_PER_MP_LIMB - b;
}
}
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