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

97 lines
3.0 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) 2010 William Hart
******************************************************************************/
#include <stdlib.h>
#include <gmp.h>
#include "flint.h"
#include "nmod_vec.h"
#include "nmod_poly.h"
void _nmod_poly_mulhigh(mp_ptr res, mp_srcptr poly1, slong len1,
mp_srcptr poly2, slong len2, slong n, nmod_t mod)
{
slong bits, bits2;
if (len1 + len2 <= 6)
{
_nmod_poly_mulhigh_classical(res, poly1, len1, poly2, len2, n, mod);
return;
}
bits = FLINT_BITS - (slong) mod.norm;
bits2 = FLINT_BIT_COUNT(len1);
if (2 * bits + bits2 <= FLINT_BITS && len1 + len2 < 16)
_nmod_poly_mulhigh_classical(res, poly1, len1, poly2, len2, n, mod);
else
_nmod_poly_mul_KS(res, poly1, len1, poly2, len2, 0, mod);
}
void nmod_poly_mulhigh(nmod_poly_t res,
const nmod_poly_t poly1, const nmod_poly_t poly2, slong start)
{
slong len1, len2, len_out;
len1 = poly1->length;
len2 = poly2->length;
len_out = len1 + len2 - 1;
if (len1 == 0 || len2 == 0 || start >= len_out)
{
nmod_poly_zero(res);
return;
}
if (res == poly1 || res == poly2)
{
nmod_poly_t temp;
nmod_poly_init2(temp, poly1->mod.n, len_out);
if (len1 >= len2)
_nmod_poly_mulhigh(temp->coeffs, poly1->coeffs, len1,
poly2->coeffs, len2, start, poly1->mod);
else
_nmod_poly_mulhigh(temp->coeffs, poly2->coeffs, len2,
poly1->coeffs, len1, start, poly1->mod);
nmod_poly_swap(temp, res);
nmod_poly_clear(temp);
} else
{
nmod_poly_fit_length(res, len_out);
if (len1 >= len2)
_nmod_poly_mulhigh(res->coeffs, poly1->coeffs, len1,
poly2->coeffs, len2, start, poly1->mod);
else
_nmod_poly_mulhigh(res->coeffs, poly2->coeffs, len2,
poly1->coeffs, len1, start, poly1->mod);
}
res->length = len_out;
_nmod_poly_normalise(res);
}