arb/arf/cmpabs_2exp_si.c

/*
    Copyright (C) 2014 Fredrik Johansson

    This file is part of Arb.

    Arb is free software: you can redistribute it and/or modify it under
    the terms of the GNU Lesser General Public License (LGPL) as published
    by the Free Software Foundation; either version 2.1 of the License, or
    (at your option) any later version.  See <http://www.gnu.org/licenses/>.
*/

#include "arf.h"

int
arf_cmpabs_2exp_si(const arf_t x, slong e)
{
    if (arf_is_special(x))
    {
        if (arf_is_zero(x)) return -1;
        if (arf_is_inf(x)) return 1;
        return 0;
    }

    /* Fast path. */
    if (!COEFF_IS_MPZ(ARF_EXP(x)))
    {
        if (ARF_IS_POW2(x) && (ARF_EXP(x) - 1 == e))
            return 0;
        else
            return (ARF_EXP(x) <= e) ? -1 : 1;
    }

    if (ARF_IS_POW2(x))
    {
        fmpz_t t;
        fmpz_init(t);

        fmpz_one(t);
        fmpz_add_si(t, t, e);

        if (fmpz_equal(ARF_EXPREF(x), t))
        {
            fmpz_clear(t);
            return 0;
        }

        fmpz_clear(t);
    }

    return (fmpz_cmp_si(ARF_EXPREF(x), e) <= 0) ? -1 : 1;
}