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/* Compute 2^x.
Copyright (C) 2012-2018 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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>
#include <math-underflow.h>
#include <float.h>
FLOAT
M_DECL_FUNC (__ieee754_exp2) (FLOAT x)
{
if (__glibc_likely (isless (x, (FLOAT) M_MAX_EXP)))
{
if (__builtin_expect (isgreaterequal (x, (FLOAT) (M_MIN_EXP - M_MANT_DIG
- 1)), 1))
{
int intx = (int) x;
FLOAT fractx = x - intx;
FLOAT result;
if (M_FABS (fractx) < M_EPSILON / 4)
result = M_SCALBN (1 + fractx, intx);
else
result = M_SCALBN (M_EXP (M_MLIT (M_LN2) * fractx), intx);
math_check_force_underflow_nonneg (result);
return result;
}
else
{
/* Underflow or exact zero. */
if (isinf (x))
return 0;
else
return M_MIN * M_MIN;
}
}
else
/* Infinity, NaN or overflow. */
return M_MAX * x;
}
declare_mgen_finite_alias (__ieee754_exp2, __exp2)
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