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/*=============================================================================
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) 2013 William Hart
******************************************************************************/
#include <gmp.h>
#include "flint.h"
#include "ulong_extras.h"
mp_limb_t
n_powmod_ui_preinv(mp_limb_t a, mp_limb_t exp, mp_limb_t n, mp_limb_t ninv, ulong norm)
{
mp_limb_t x;
if (n == (UWORD(1)<<norm) || (a == 0 && exp != 0)) return UWORD(0);
if (exp)
{
while ((exp & 1) == 0)
{
a = n_mulmod_preinv(a, a, n, ninv, norm);
exp >>= 1;
}
x = a;
while (exp >>= 1)
{
a = n_mulmod_preinv(a, a, n, ninv, norm);
if (exp & 1) x = n_mulmod_preinv(x, a, n, ninv, norm);
}
return x;
} else
return (UWORD(1)<<norm);
}
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