pqc/external/flint-2.4.3/fmpz/divexact_si.c
2014-05-24 23:16:06 +02:00

65 lines
2.0 KiB
C

/*=============================================================================
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
Copyright (C) 2010 Sebastian Pancratz
******************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <gmp.h>
#include "flint.h"
#include "ulong_extras.h"
#include "fmpz.h"
void fmpz_divexact_si(fmpz_t f, const fmpz_t g, slong h)
{
fmpz c1 = *g;
if (h == 0)
{
flint_printf("Exception (fmpz_divexact_si). Division by zero.\n");
abort();
}
if (!COEFF_IS_MPZ(c1)) /* g is small */
{
fmpz_set_si(f, c1 / h);
}
else /* g is large */
{
__mpz_struct * mpz_ptr = _fmpz_promote(f);
if (h > 0)
{
flint_mpz_divexact_ui(mpz_ptr, COEFF_TO_PTR(c1), h);
_fmpz_demote_val(f); /* division by h may result in small value */
}
else
{
flint_mpz_divexact_ui(mpz_ptr, COEFF_TO_PTR(c1), -h);
_fmpz_demote_val(f); /* division by h may result in small value */
fmpz_neg(f, f);
}
}
}