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/* mpfr_get_q -- get a multiple-precision rational from
a floating-point number
Copyright 2004, 2006-2020 Free Software Foundation, Inc.
Contributed by the AriC and Caramba projects, INRIA.
This file is part of the GNU MPFR Library.
The GNU MPFR Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 3 of the License, or (at your
option) any later version.
The GNU MPFR Library 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 Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see
https://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
#include "mpfr-impl.h"
#ifndef MPFR_USE_MINI_GMP
/* part of the code was copied from get_z.c */
void
mpfr_get_q (mpq_ptr q, mpfr_srcptr f)
{
mpfr_exp_t exp;
mpz_ptr u = mpq_numref (q);
mpz_ptr v = mpq_denref (q);
/* v is set to 1 and will not be changed directly.
This ensures that q will be canonical. */
mpz_set_ui (v, 1);
if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (f)))
{
if (MPFR_UNLIKELY (MPFR_NOTZERO (f)))
MPFR_SET_ERANGEFLAG ();
mpz_set_ui (u, 0);
/* The ternary value is 0 even for infinity. Giving the rounding
direction in this case would not make much sense anyway, and
the direction would not necessarily match rnd. */
}
else
{
exp = mpfr_get_z_2exp (u, f);
if (exp >= 0)
{
MPFR_ASSERTN (exp <= (mp_bitcnt_t) -1);
mpz_mul_2exp (u, u, exp);
}
else /* exp < 0 */
{
MPFR_ASSERTN (-exp <= (mp_bitcnt_t) -1);
mpq_div_2exp (q, q, -exp);
}
}
}
#endif
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