1 /* Copyright (C) 2011-2016 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
18
19 #include <math.h>
20 #include "math_private.h"
21 #if defined(__UCLIBC_HAS_FENV__)
22 #include <fenv.h>
23 #endif
24
25 #if !defined __NO_LONG_DOUBLE_MATH
26 /* wrapper log2l(x) */
27 long double
log2l(long double x)28 log2l (long double x)
29 {
30 # if defined(__UCLIBC_HAS_FENV__)
31 if (__builtin_expect (islessequal (x, 0.0L), 0) && _LIB_VERSION != _IEEE_)
32 {
33 if (x == 0.0L)
34 {
35 feraiseexcept (FE_DIVBYZERO);
36 return __kernel_standard_l (x, x, 248); /* log2(0) */
37 }
38 else
39 {
40 feraiseexcept (FE_INVALID);
41 return __kernel_standard_l (x, x, 249); /* log2(x<0) */
42 }
43 }
44 # endif /* __UCLIBC_HAS_FENV__ */
45 return (long double) __ieee754_log2 ((double) x);
46 }
47 #endif /* __NO_LONG_DOUBLE_MATH */
48