glibc/math/e_scalb.c

55 lines
1.5 KiB
C

/* Copyright (C) 2011-2018 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
<http://www.gnu.org/licenses/>. */
#include <math.h>
#include <math_private.h>
static double
__attribute__ ((noinline))
invalid_fn (double x, double fn)
{
if (rint (fn) != fn)
return (fn - fn) / (fn - fn);
else if (fn > 65000.0)
return __scalbn (x, 65000);
else
return __scalbn (x,-65000);
}
double
__ieee754_scalb (double x, double fn)
{
if (__glibc_unlikely (isnan (x)))
return x * fn;
if (__glibc_unlikely (!isfinite (fn)))
{
if (isnan (fn) || fn > 0.0)
return x * fn;
if (x == 0.0)
return x;
return x / -fn;
}
if (__glibc_unlikely (fabs (fn) >= 0x1p31 || (double) (int) fn != fn))
return invalid_fn (x, fn);
return __scalbn (x, (int) fn);
}
strong_alias (__ieee754_scalb, __scalb_finite)