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/* Floating-point exponent.
Copyright (C) 2012-2022 Free Software Foundation, Inc.
This file 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.
This file 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 this program. If not, see <https://www.gnu.org/licenses/>. */
#if ! (defined USE_LONG_DOUBLE || defined USE_FLOAT)
# include <config.h>
#endif
/* Specification. */
#include <math.h>
#ifdef USE_LONG_DOUBLE
# define LOGB logbl
# define DOUBLE long double
# define L_(literal) literal##L
# define HUGEVAL HUGE_VALL
# define FREXP frexpl
# define ISNAN isnanl
#elif ! defined USE_FLOAT
# define LOGB logb
# define DOUBLE double
# define L_(literal) literal
# define HUGEVAL HUGE_VAL
# define FREXP frexp
# define ISNAN isnand
#else /* defined USE_FLOAT */
# define LOGB logbf
# define DOUBLE float
# define L_(literal) literal##f
# define HUGEVAL HUGE_VALF
# define FREXP frexpf
# define ISNAN isnanf
#endif
DOUBLE
LOGB (DOUBLE x)
{
if (isfinite (x))
{
if (x == L_(0.0))
/* Return -Infinity. */
return - HUGEVAL;
else
{
int e;
(void) FREXP (x, &e);
return (DOUBLE) (e - 1);
}
}
else
{
if (ISNAN (x))
return x; /* NaN */
else
/* Return +Infinity. */
return HUGEVAL;
}
}
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