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/* Copyright (C) 2011-2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.
The GNU C 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 2.1 of the License, or (at your option) any later version.
The GNU C 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 C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <inttypes.h>
#include <math.h>
#include <math_private.h>
#include <libm-alias-double.h>
/*
* for non-zero, finite x
* x = frexp(arg,&exp);
* return a double fp quantity x such that 0.5 <= |x| <1.0
* and the corresponding binary exponent "exp". That is
* arg = x*2^exp.
* If arg is inf, 0.0, or NaN, then frexp(arg,&exp) returns arg
* with *exp=0.
*/
double
__frexp (double x, int *eptr)
{
int64_t ix;
EXTRACT_WORDS64 (ix, x);
int32_t ex = 0x7ff & (ix >> 52);
int e = 0;
if (__glibc_likely (ex != 0x7ff && x != 0.0))
{
/* Not zero and finite. */
e = ex - 1022;
if (__glibc_unlikely (ex == 0))
{
/* Subnormal. */
x *= 0x1p54;
EXTRACT_WORDS64 (ix, x);
ex = 0x7ff & (ix >> 52);
e = ex - 1022 - 54;
}
ix = (ix & INT64_C (0x800fffffffffffff)) | INT64_C (0x3fe0000000000000);
INSERT_WORDS64 (x, ix);
}
else
/* Quiet signaling NaNs. */
x += x;
*eptr = e;
return x;
}
libm_alias_double (__frexp, frexp)
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