pqc/external/flint-2.4.3/ulong_extras/remove2_precomp.c
2014-05-24 23:16:06 +02:00

58 lines
1.6 KiB
C

/*=============================================================================
This file is part of FLINT.
FLINT is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
FLINT 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with FLINT; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
=============================================================================*/
/******************************************************************************
Copyright (C) 2009 William Hart
******************************************************************************/
#include <gmp.h>
#include "flint.h"
#include "ulong_extras.h"
int
n_remove2_precomp(mp_limb_t * n, mp_limb_t p, double ppre)
{
int exp = 0;
mp_limb_t quot, rem = UWORD(0);
if (p == 2)
{
count_trailing_zeros(exp, *n);
if (exp)
(*n) >>= exp;
return exp;
}
do
{
if ((*n) < p)
break;
rem = n_divrem2_precomp(&quot, *n, p, ppre);
if (rem)
break;
exp++;
(*n) = quot;
} while (1);
return exp;
}