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

142 lines
4.1 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) 2008, 2009 William Hart
Copyright (C) 2010, 2012 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_mul_KS(fmpz * res, const fmpz * poly1, slong len1,
const fmpz * poly2, slong len2)
{
const slong in1_len = len1, in2_len = len2;
int neg1, neg2;
slong limbs1, limbs2, loglen;
slong bits1, bits2, bits;
mp_limb_t *arr1, *arr2, *arr3;
slong sign = 0;
FMPZ_VEC_NORM(poly1, len1);
FMPZ_VEC_NORM(poly2, len2);
if (!len1 | !len2)
{
if (in1_len + in2_len - 1 > 0)
_fmpz_vec_zero(res, in1_len + in2_len - 1);
return;
}
neg1 = (fmpz_sgn(poly1 + len1 - 1) > 0) ? 0 : -1;
neg2 = (fmpz_sgn(poly2 + len2 - 1) > 0) ? 0 : -1;
bits1 = _fmpz_vec_max_bits(poly1, len1);
if (bits1 < 0)
{
sign = 1;
bits1 = -bits1;
}
if (poly1 != poly2)
{
bits2 = _fmpz_vec_max_bits(poly2, len2);
if (bits2 < 0)
{
sign = 1;
bits2 = -bits2;
}
}
else
bits2 = bits1;
loglen = FLINT_BIT_COUNT(FLINT_MIN(len1, len2));
bits = bits1 + bits2 + loglen + sign;
limbs1 = (bits * len1 - 1) / FLINT_BITS + 1;
limbs2 = (bits * len2 - 1) / FLINT_BITS + 1;
if (poly1 == poly2)
{
arr1 = (mp_limb_t *) flint_calloc(limbs1, sizeof(mp_limb_t));
arr2 = arr1;
_fmpz_poly_bit_pack(arr1, poly1, len1, bits, neg1);
}
else
{
arr1 = (mp_limb_t *) flint_calloc(limbs1 + limbs2, sizeof(mp_limb_t));
arr2 = arr1 + limbs1;
_fmpz_poly_bit_pack(arr1, poly1, len1, bits, neg1);
_fmpz_poly_bit_pack(arr2, poly2, len2, bits, neg2);
}
arr3 = (mp_limb_t *) flint_malloc((limbs1 + limbs2) * sizeof(mp_limb_t));
if (limbs1 == limbs2)
mpn_mul_n(arr3, arr1, arr2, limbs1);
else if (limbs1 > limbs2)
mpn_mul(arr3, arr1, limbs1, arr2, limbs2);
else
mpn_mul(arr3, arr2, limbs2, arr1, limbs1);
if (sign)
_fmpz_poly_bit_unpack(res, len1 + len2 - 1, arr3, bits, neg1 ^ neg2);
else
_fmpz_poly_bit_unpack_unsigned(res, len1 + len2 - 1, arr3, bits);
if ((len1 < in1_len) | (len2 < in2_len))
_fmpz_vec_zero(res + (len1 + len2 - 1), (in1_len - len1) + (in2_len - len2));
flint_free(arr1);
flint_free(arr3);
}
void
fmpz_poly_mul_KS(fmpz_poly_t res,
const fmpz_poly_t poly1, const fmpz_poly_t poly2)
{
const slong len1 = poly1->length;
const slong len2 = poly2->length;
const slong rlen = len1 + len2 - 1;
if (len1 == 0 || len2 == 0)
{
fmpz_poly_zero(res);
}
else
{
fmpz_poly_fit_length(res, rlen);
if (len1 >= len2)
_fmpz_poly_mul_KS(res->coeffs, poly1->coeffs, len1,
poly2->coeffs, len2);
else
_fmpz_poly_mul_KS(res->coeffs, poly2->coeffs, len2,
poly1->coeffs, len1);
_fmpz_poly_set_length(res, rlen);
}
}