// Copyright (c) 2006-2013 INRIA Nancy-Grand Est (France). All rights reserved.
//
// This file is part of CGAL (www.cgal.org)
//
// $URL: https://github.com/CGAL/cgal/blob/v5.6.1/Algebraic_kernel_d/include/CGAL/RS/exact_signat_1.h $
// $Id: exact_signat_1.h 52164b1 2019-10-19T15:34:59+02:00 Sébastien Loriot
// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
//
// Author: Luis Peñaranda <luis.penaranda@gmx.com>

#ifndef CGAL_RS_EXACT_SIGNAT_1_H
#define CGAL_RS_EXACT_SIGNAT_1_H

#include <CGAL/Polynomial_traits_d.h>
#include "dyadic.h"

namespace CGAL{
namespace RS_AK1{

template <class Polynomial_,class Bound_>
struct ExactSignat_1{
        typedef Polynomial_                                     Polynomial;
        typedef Bound_                                          Bound;
        typedef CGAL::Polynomial_traits_d<Polynomial>           PT;
        typedef typename PT::Degree                             Degree;
        Polynomial pol;
        ExactSignat_1(const Polynomial &p):pol(p){};
        CGAL::Sign operator()(const Bound&)const;
}; // struct ExactSignat_1

template <>
inline CGAL::Sign
ExactSignat_1<Polynomial<Gmpz>,Gmpfr>::operator()(const Gmpfr &x)const{
        int d=Degree()(pol);
        if(d==0)
                return pol[0].sign();
        // Construct a Gmpfr containing exactly the leading coefficient.
        Gmpfr h(pol[d],pol[d].bit_size());
        CGAL_assertion(h==pol[d]);
        // Horner's evaluation.
        for(int i=1;i<d;++i){
                CGALRS_dyadic_mul(h.fr(),h.fr(),x.fr());
                CGALRS_dyadic_add_z(h.fr(),h.fr(),pol[d-i].mpz());
        }
        // TODO: We can avoid doing the last addition.
        return h.sign();
}

} // namespace RS_AK1
} // namespace CGAL

#endif // CGAL_RS_EXACT_SIGNAT_1_H

