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/*=============================================================================
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) 2011 Fredrik Johansson
Copyright (C) 2012 Lina Kulakova
Copyright (C) 2013 Martin Lee
******************************************************************************/
#undef ulong
#define ulong ulongxx/* interferes with system includes */
#include <stdlib.h>
#undef ulong
#include <gmp.h>
#define ulong mp_limb_t
#include "flint.h"
#include "fmpz_vec.h"
#include "fmpz_mod_poly.h"
void _fmpz_mod_poly_mulmod_preinv(fmpz * res, const fmpz * poly1, slong len1,
const fmpz * poly2, slong len2, const fmpz * f, slong lenf,
const fmpz* finv, slong lenfinv, const fmpz_t p)
{
fmpz * T, * Q;
slong lenT, lenQ;
lenT = len1 + len2 - 1;
lenQ = lenT - lenf + 1;
T = _fmpz_vec_init(lenT + lenQ);
Q = T + lenT;
if (len1 >= len2)
_fmpz_mod_poly_mul(T, poly1, len1, poly2, len2, p);
else
_fmpz_mod_poly_mul(T, poly2, len2, poly1, len1, p);
_fmpz_mod_poly_divrem_newton_n_preinv(Q, res, T, lenT, f, lenf,
finv, lenfinv, p);
_fmpz_vec_clear(T, lenT + lenQ);
}
void
fmpz_mod_poly_mulmod_preinv(fmpz_mod_poly_t res, const fmpz_mod_poly_t poly1,
const fmpz_mod_poly_t poly2, const fmpz_mod_poly_t f,
const fmpz_mod_poly_t finv)
{
slong len1, len2, lenf;
fmpz * fcoeffs;
lenf = f->length;
len1 = poly1->length;
len2 = poly2->length;
if (lenf == 0)
{
flint_printf("Exception (fmpz_mod_poly_mulmod_preinv). Divide by zero\n");
abort();
}
if (lenf <= len1 || lenf <= len2)
{
flint_printf("Exception (fmpz_mod_poly_mulmod_preinv). Input larger than modulus.\n");
abort();
}
if (lenf == 1 || len1 == 0 || len2 == 0)
{
fmpz_mod_poly_zero(res);
return;
}
if (len1 + len2 - lenf > 0)
{
if (f == res)
{
fcoeffs = _fmpz_vec_init(lenf);
_fmpz_vec_set(fcoeffs, f->coeffs, lenf);
}
else
fcoeffs = f->coeffs;
fmpz_mod_poly_fit_length(res, len1 + len2 - 1);
_fmpz_mod_poly_mulmod_preinv(res->coeffs, poly1->coeffs, len1,
poly2->coeffs, len2, fcoeffs, lenf,
finv->coeffs, finv->length, &res->p);
if (f == res)
_fmpz_vec_clear(fcoeffs, lenf);
_fmpz_mod_poly_set_length(res, lenf - 1);
_fmpz_mod_poly_normalise(res);
}
else
{
fmpz_mod_poly_mul(res, poly1, poly2);
}
}
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