arb/mag/cmp_2exp_si.c
2015-11-05 18:06:54 +00:00

71 lines
1.8 KiB
C

/*=============================================================================
This file is part of ARB.
ARB 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.
ARB 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 ARB; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
=============================================================================*/
/******************************************************************************
Copyright (C) 2014 Fredrik Johansson
******************************************************************************/
#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;
}