pqc/external/flint-2.4.3/fmpz_poly/sqrlow.c

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2014-05-18 22:03:37 +00:00
/*=============================================================================
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, 2011 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_sqrlow(fmpz * res, const fmpz * poly, slong len, slong n)
{
mp_size_t limbs;
if (n < 7)
{
_fmpz_poly_sqrlow_classical(res, poly, len, n);
return;
}
limbs = _fmpz_vec_max_limbs(poly, len);
if (n < 16 && limbs > 12)
{
int i;
fmpz *copy;
copy = flint_malloc(n * sizeof(fmpz));
for (i = 0; i < len; i++)
copy[i] = poly[i];
flint_mpn_zero((mp_ptr) copy + len, n - len);
_fmpz_poly_sqrlow_karatsuba_n(res, copy, n);
flint_free(copy);
}
else if (limbs <= 4)
_fmpz_poly_sqrlow_KS(res, poly, len, n);
else if (limbs/2048 > len)
_fmpz_poly_sqrlow_KS(res, poly, len, n);
else if (limbs*FLINT_BITS*4 < len)
_fmpz_poly_sqrlow_KS(res, poly, len, n);
else
_fmpz_poly_mullow_SS(res, poly, len, poly, len, n);
}
void fmpz_poly_sqrlow(fmpz_poly_t res, const fmpz_poly_t poly, slong n)
{
const slong len = poly->length;
if (len == 0 || n == 0)
{
fmpz_poly_zero(res);
return;
}
if (res == poly)
{
fmpz_poly_t t;
fmpz_poly_init2(t, n);
fmpz_poly_sqrlow(t, poly, n);
fmpz_poly_swap(res, t);
fmpz_poly_clear(t);
return;
}
n = FLINT_MIN(2 * len - 1, n);
fmpz_poly_fit_length(res, n);
_fmpz_poly_sqrlow(res->coeffs, poly->coeffs, len, n);
_fmpz_poly_set_length(res, n);
_fmpz_poly_normalise(res);
}