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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) 2009 William Hart
******************************************************************************/
#include <gmp.h>
#include "flint.h"
#include "ulong_extras.h"
mp_limb_t
n_mod2_precomp(mp_limb_t a, mp_limb_t n, double npre)
{
mp_limb_t quot;
slong rem;
if (a < n)
return a;
if ((mp_limb_signed_t) n < WORD(0))
return a - n;
if (n == 1)
{
quot = a;
rem = 0;
} else
{
quot = (mp_limb_t) ((double) a * npre);
rem = a - quot * n;
}
if (rem < (mp_limb_signed_t) (-n))
quot -= (mp_limb_t) ((double) (-rem) * npre);
else if (rem >= (slong) n)
quot += (mp_limb_t) ((double) rem * npre);
else if (rem < WORD(0))
return rem + n;
else
return rem;
rem = a - quot * n;
if (rem >= (slong) n)
return rem - n;
else if (rem < WORD(0))
return rem + n;
else
return rem;
}
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