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/*
Copyright (C) 2009 William Hart
Copyright (C) 2012 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 "gmpcompat.h"
#include "fmpz.h"
void
fmpz_mul_tdiv_q_2exp(fmpz_t f, const fmpz_t g, const fmpz_t h, ulong exp)
{
fmpz c1, c2;
mpz_ptr mf;
c1 = *g;
if (!COEFF_IS_MPZ(c1)) /* g is small */
{
fmpz_mul_si_tdiv_q_2exp(f, h, c1, exp);
return;
}
c2 = *h; /* save h in case it is aliased with f */
if (c2 == WORD(0)) /* special case, h = 0 */
{
fmpz_zero(f);
return;
}
mf = _fmpz_promote(f); /* h is saved, g is already large */
if (!COEFF_IS_MPZ(c2)) /* g is large, h is small */
flint_mpz_mul_si(mf, COEFF_TO_PTR(c1), c2);
else /* c1 and c2 are large */
mpz_mul(mf, COEFF_TO_PTR(c1), COEFF_TO_PTR(c2));
mpz_tdiv_q_2exp(mf, mf, exp);
_fmpz_demote_val(f); /* division may make value small */
}