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/* mpfr_frexp -- convert to integral and fractional parts
Copyright 2011-2020 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"
int
mpfr_frexp (mpfr_exp_t *exp, mpfr_ptr y, mpfr_srcptr x, mpfr_rnd_t rnd)
{
int inex;
mpfr_flags_t saved_flags = __gmpfr_flags;
MPFR_BLOCK_DECL (flags);
MPFR_LOG_FUNC
(("x[%Pu]=%.*Rg rnd=%d", mpfr_get_prec (x), mpfr_log_prec, x, rnd),
("y[%Pu]=%.*Rg exp=%" MPFR_EXP_FSPEC "d inex=%d", mpfr_get_prec (y),
mpfr_log_prec, y, (mpfr_eexp_t) *exp, inex));
if (MPFR_UNLIKELY(MPFR_IS_SINGULAR(x)))
{
if (MPFR_IS_NAN(x))
{
MPFR_SET_NAN(y);
MPFR_RET_NAN; /* exp is unspecified */
}
else if (MPFR_IS_INF(x))
{
MPFR_SET_INF(y);
MPFR_SET_SAME_SIGN(y,x);
MPFR_RET(0); /* exp is unspecified */
}
else
{
MPFR_SET_ZERO(y);
MPFR_SET_SAME_SIGN(y,x);
*exp = 0;
MPFR_RET(0);
}
}
MPFR_BLOCK (flags, inex = mpfr_set (y, x, rnd));
__gmpfr_flags = saved_flags;
/* Possible overflow due to the rounding, no possible underflow. */
if (MPFR_UNLIKELY (MPFR_OVERFLOW (flags)))
{
int inex2;
/* An overflow here means that the exponent of y would be larger than
the one of x, thus x would be rounded to the next power of 2, and
the returned y should be 1/2 in absolute value, rounded (i.e. with
possible underflow or overflow). This also implies that x and y are
different objects, so that the exponent of x has not been lost. */
MPFR_LOG_MSG (("Internal overflow\n", 0));
MPFR_ASSERTD (x != y);
*exp = MPFR_GET_EXP (x) + 1;
inex2 = mpfr_set_si_2exp (y, MPFR_INT_SIGN (x), -1, rnd);
MPFR_LOG_MSG (("inex=%d inex2=%d\n", inex, inex2));
if (inex2 != 0)
inex = inex2;
MPFR_RET (inex);
}
*exp = MPFR_GET_EXP (y);
/* Do not use MPFR_SET_EXP because the range has not been checked yet. */
MPFR_EXP (y) = 0;
return mpfr_check_range (y, inex, rnd);
}
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