78 lines
1.9 KiB
C
78 lines
1.9 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_remove(mp_limb_t * n, mp_limb_t p)
|
||
|
|
{
|
||
|
|
int exp, i;
|
||
|
|
mp_limb_t powp[6];
|
||
|
|
mp_limb_t quot, rem;
|
||
|
|
|
||
|
|
if (p == 2)
|
||
|
|
{
|
||
|
|
count_trailing_zeros(exp, *n);
|
||
|
|
if (exp)
|
||
|
|
(*n) >>= exp;
|
||
|
|
|
||
|
|
return exp;
|
||
|
|
}
|
||
|
|
|
||
|
|
powp[0] = p;
|
||
|
|
|
||
|
|
for (i = 0; ; i++)
|
||
|
|
{
|
||
|
|
if ((*n) < powp[i])
|
||
|
|
break;
|
||
|
|
quot = (*n) / powp[i];
|
||
|
|
rem = (*n) - quot * powp[i];
|
||
|
|
if (rem != UWORD(0))
|
||
|
|
break;
|
||
|
|
powp[i + 1] = powp[i] * powp[i];
|
||
|
|
(*n) = quot;
|
||
|
|
}
|
||
|
|
|
||
|
|
exp = (1 << i) - 1;
|
||
|
|
|
||
|
|
while (i > 0)
|
||
|
|
{
|
||
|
|
i--;
|
||
|
|
if ((*n) < powp[i])
|
||
|
|
continue;
|
||
|
|
quot = (*n) / powp[i];
|
||
|
|
rem = (*n) - quot * powp[i];
|
||
|
|
if (rem == UWORD(0))
|
||
|
|
{
|
||
|
|
exp += (UWORD(1) << i);
|
||
|
|
(*n) = quot;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return exp;
|
||
|
|
}
|