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

127 lines
3.8 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) 2008, 2009 William Hart
Copyright (C) 2010 Sebastian Pancratz
******************************************************************************/
#include <stdlib.h>
#include <gmp.h>
#include "flint.h"
#include "fmpz.h"
#include "fmpz_vec.h"
#include "fmpz_poly.h"
void
_fmpz_poly_mullow(fmpz * res, const fmpz * poly1, slong len1,
const fmpz * poly2, slong len2, slong n)
{
mp_size_t limbs1, limbs2;
if (len2 < 7 || n < 7)
{
_fmpz_poly_mullow_classical(res, poly1, len1, poly2, len2, n);
return;
}
limbs1 = _fmpz_vec_max_limbs(poly1, len1);
limbs2 = _fmpz_vec_max_limbs(poly2, len2);
if (n < 16 && (limbs1 > 12 || limbs2 > 12))
{
int clear = 0, i;
fmpz *copy1, *copy2;
if (len1 >= n)
copy1 = (fmpz *) poly1;
else
{
copy1 = (fmpz *) flint_malloc(n * sizeof(fmpz));
for (i = 0; i < len1; i++)
copy1[i] = poly1[i];
flint_mpn_zero((mp_ptr) copy1 + len1, n - len1);
clear |= 1;
}
if (len2 >= n)
copy2 = (fmpz *) poly2;
else
{
copy2 = (fmpz *) flint_malloc(n * sizeof(fmpz));
for (i = 0; i < len2; i++)
copy2[i] = poly2[i];
flint_mpn_zero((mp_ptr) copy2 + len2, n - len2);
clear |= 2;
}
_fmpz_poly_mullow_karatsuba_n(res, copy1, copy2, n);
if (clear & 1)
flint_free(copy1);
if (clear & 2)
flint_free(copy2);
}
else if (limbs1 + limbs2 <= 8)
_fmpz_poly_mullow_KS(res, poly1, len1, poly2, len2, n);
else if ((limbs1+limbs2)/2048 > len1 + len2)
_fmpz_poly_mullow_KS(res, poly1, len1, poly2, len2, n);
else if ((limbs1 + limbs2)*FLINT_BITS*4 < len1 + len2)
_fmpz_poly_mullow_KS(res, poly1, len1, poly2, len2, n);
else
_fmpz_poly_mullow_SS(res, poly1, len1, poly2, len2, n);
}
void
fmpz_poly_mullow(fmpz_poly_t res,
const fmpz_poly_t poly1, const fmpz_poly_t poly2,
slong n)
{
const slong len1 = poly1->length;
const slong len2 = poly2->length;
if (len1 == 0 || len2 == 0 || n == 0)
{
fmpz_poly_zero(res);
return;
}
if (res == poly1 || res == poly2)
{
fmpz_poly_t t;
fmpz_poly_init2(t, n);
fmpz_poly_mullow(t, poly1, poly2, n);
fmpz_poly_swap(res, t);
fmpz_poly_clear(t);
return;
}
n = FLINT_MIN(n, len1 + len2 - 1);
fmpz_poly_fit_length(res, n);
if (len1 >= len2)
_fmpz_poly_mullow(res->coeffs, poly1->coeffs, len1, poly2->coeffs, len2, n);
else
_fmpz_poly_mullow(res->coeffs, poly2->coeffs, len2, poly1->coeffs, len1, n);
_fmpz_poly_set_length(res, n);
_fmpz_poly_normalise(res);
}