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

104 lines
3.1 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
******************************************************************************/
#define ulong ulongxx /* interferes with system includes */
#include <stdlib.h>
#include <stdio.h>
#undef ulong
#define ulong mp_limb_t
#include <gmp.h>
#include "flint.h"
#include "ulong_extras.h"
static int is_prime(mp_limb_t n, int proved)
{
return proved ? n_is_prime(n) : n_is_probabprime(n);
}
void n_factor(n_factor_t * factors, mp_limb_t n, int proved)
{
ulong factor_arr[FLINT_MAX_FACTORS_IN_LIMB];
ulong exp_arr[FLINT_MAX_FACTORS_IN_LIMB];
ulong factors_left;
ulong exp;
mp_limb_t cofactor, factor, cutoff;
cofactor = n_factor_trial(factors, n, FLINT_FACTOR_TRIAL_PRIMES);
if (cofactor == UWORD(1)) return;
if (is_prime(cofactor, proved))
{
n_factor_insert(factors, cofactor, UWORD(1));
return;
}
factor_arr[0] = cofactor;
factors_left = 1;
exp_arr[0] = 1;
cutoff = FLINT_FACTOR_TRIAL_CUTOFF;
while (factors_left > 0)
{
factor = factor_arr[factors_left - 1];
if (factor >= cutoff)
{
if ((cofactor = n_factor_power235(&exp, factor)))
{
exp_arr[factors_left - 1] *= exp;
factor_arr[factors_left - 1] = factor = cofactor;
}
if ((factor >= cutoff) && !is_prime(factor, proved))
{
if ((
#if FLINT64
(factor < FLINT_FACTOR_ONE_LINE_MAX) &&
#endif
(cofactor = n_factor_one_line(factor, FLINT_FACTOR_ONE_LINE_ITERS)))
|| (cofactor = n_factor_SQUFOF(factor, FLINT_FACTOR_SQUFOF_ITERS)))
{
exp_arr[factors_left] = exp_arr[factors_left - 1];
factor_arr[factors_left] = cofactor;
factor_arr[factors_left - 1] /= cofactor;
factors_left++;
} else
{
flint_printf("Exception (n_factor). Failed to factor %wd.\n", n);
abort();
}
} else
{
n_factor_insert(factors, factor, exp_arr[factors_left - 1]);
factors_left--;
}
} else
{
n_factor_insert(factors, factor, exp_arr[factors_left - 1]);
factors_left--;
}
}
}