/*=============================================================================

    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
    Copyright (C) 2013 Mike Hansen

******************************************************************************/


#ifdef T

#include "templates.h"

void
_TEMPLATE(T, poly_mulmod_preinv) (
    TEMPLATE(T, struct) * res,
    const TEMPLATE(T, struct) * poly1, slong len1,
    const TEMPLATE(T, struct) * poly2, slong len2,
    const TEMPLATE(T, struct) * f, slong lenf,
    const TEMPLATE(T, struct) * finv, slong lenfinv,
    const TEMPLATE(T, ctx_t) ctx)
{
    TEMPLATE(T, struct) * T, *Q;
    slong lenT, lenQ;

    lenT = len1 + len2 - 1;
    lenQ = lenT - lenf + 1;

    T = _TEMPLATE(T, vec_init) (lenT + lenQ, ctx);
    Q = T + lenT;

    if (len1 >= len2)
        _TEMPLATE(T, poly_mul) (T, poly1, len1, poly2, len2, ctx);
    else
        _TEMPLATE(T, poly_mul) (T, poly2, len2, poly1, len1, ctx);

    _TEMPLATE(T, poly_divrem_newton_n_preinv) (Q, res, T, lenT, f, lenf,
                                               finv, lenfinv, ctx);
    _TEMPLATE(T, vec_clear) (T, lenT + lenQ, ctx);
}

void
TEMPLATE(T, poly_mulmod_preinv) (TEMPLATE(T, poly_t) res,
                                 const TEMPLATE(T, poly_t) poly1,
                                 const TEMPLATE(T, poly_t) poly2,
                                 const TEMPLATE(T, poly_t) f,
                                 const TEMPLATE(T, poly_t) finv,
                                 const TEMPLATE(T, ctx_t) ctx)
{
    slong len1, len2, lenf;
    TEMPLATE(T, struct) * fcoeffs;

    lenf = f->length;
    len1 = poly1->length;
    len2 = poly2->length;

    if (lenf == 0)
    {
        TEMPLATE_PRINTF("Exception (%s_poly_mulmod). Divide by zero.\n", T);
        abort();
    }

    if (lenf == 1 || len1 == 0 || len2 == 0)
    {
        TEMPLATE(T, poly_zero) (res, ctx);
        return;
    }

    if (len1 + len2 - lenf > 0)
    {
        if (f == res)
        {
            fcoeffs = _TEMPLATE(T, vec_init) (lenf, ctx);
            _TEMPLATE(T, vec_set) (fcoeffs, f->coeffs, lenf, ctx);
        }
        else
            fcoeffs = f->coeffs;

        TEMPLATE(T, poly_fit_length) (res, lenf - 1, ctx);
        _TEMPLATE(T, poly_mulmod_preinv) (res->coeffs, poly1->coeffs, len1,
                                          poly2->coeffs, len2,
                                          fcoeffs, lenf, finv->coeffs,
                                          finv->length, ctx);
        if (f == res)
            _TEMPLATE(T, vec_clear) (fcoeffs, lenf, ctx);

        res->length = lenf - 1;
        _TEMPLATE(T, poly_normalise) (res, ctx);
    }
    else
    {
        TEMPLATE(T, poly_mul) (res, poly1, poly2, ctx);
    }
}


#endif