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/*
Copyright (C) 2014 Fredrik Johansson
This file is part of FLINT.
FLINT 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 3 of the License, or
(at your option) any later version. See <https://www.gnu.org/licenses/>.
*/
#include "mag.h"
int
mag_cmp_2exp_si(const mag_t x, slong e)
{
int ispow2;
if (mag_is_special(x))
{
if (mag_is_zero(x))
return -1;
return 1;
}
ispow2 = (MAG_MAN(x) == MAG_ONE_HALF);
/* Fast path. */
if (!COEFF_IS_MPZ(MAG_EXP(x)))
{
if (ispow2 && (MAG_EXP(x) - 1 == e))
return 0;
else
return (MAG_EXP(x) <= e) ? -1 : 1;
}
if (ispow2)
{
fmpz_t t;
fmpz_init(t);
fmpz_one(t);
fmpz_add_si(t, t, e);
if (fmpz_equal(MAG_EXPREF(x), t))
{
fmpz_clear(t);
return 0;
}
fmpz_clear(t);
}
return (fmpz_cmp_si(MAG_EXPREF(x), e) <= 0) ? -1 : 1;
}