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

109 lines
2.9 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) 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_KS(fmpz * res, const fmpz * poly, slong len, slong n)
{
int neg;
slong bits, limbs, loglen, sign = 0;
mp_limb_t *arr_in, *arr_out;
FMPZ_VEC_NORM(poly, len);
if (len == 0)
{
_fmpz_vec_zero(res, n);
return;
}
neg = (fmpz_sgn(poly + len - 1) > 0) ? 0 : -1;
if (n > 2 * len - 1)
{
_fmpz_vec_zero(res + 2 * len - 1, n - (2 * len - 1));
n = 2 * len - 1;
}
bits = _fmpz_vec_max_bits(poly, len);
if (bits < 0)
{
sign = 1;
bits = - bits;
}
loglen = FLINT_BIT_COUNT(len);
bits = 2 * bits + loglen + sign;
limbs = (bits * len - 1) / FLINT_BITS + 1;
arr_in = flint_calloc(limbs, sizeof(mp_limb_t));
arr_out = flint_malloc((2 * limbs) * sizeof(mp_limb_t));
_fmpz_poly_bit_pack(arr_in, poly, len, bits, neg);
mpn_sqr(arr_out, arr_in, limbs);
if (sign)
_fmpz_poly_bit_unpack(res, n, arr_out, bits, 0);
else
_fmpz_poly_bit_unpack_unsigned(res, n, arr_out, bits);
flint_free(arr_in);
flint_free(arr_out);
}
void fmpz_poly_sqrlow_KS(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_KS(t, poly, n);
fmpz_poly_swap(res, t);
fmpz_poly_clear(t);
return;
}
fmpz_poly_fit_length(res, n);
_fmpz_poly_sqrlow_KS(res->coeffs, poly->coeffs, len, n);
_fmpz_poly_set_length(res, n);
_fmpz_poly_normalise(res);
}