xref: /freebsd/contrib/llvm-project/libcxx/include/__bit/has_single_bit.h (revision 0fca6ea1d4eea4c934cfff25ac9ee8ad6fe95583)
1bdd1243dSDimitry Andric //===----------------------------------------------------------------------===//
2bdd1243dSDimitry Andric //
3bdd1243dSDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4bdd1243dSDimitry Andric // See https://llvm.org/LICENSE.txt for license information.
5bdd1243dSDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6bdd1243dSDimitry Andric //
7bdd1243dSDimitry Andric //===----------------------------------------------------------------------===//
8bdd1243dSDimitry Andric 
9bdd1243dSDimitry Andric #ifndef _LIBCPP___BIT_HAS_SINGLE_BIT_H
10bdd1243dSDimitry Andric #define _LIBCPP___BIT_HAS_SINGLE_BIT_H
11bdd1243dSDimitry Andric 
12bdd1243dSDimitry Andric #include <__concepts/arithmetic.h>
13bdd1243dSDimitry Andric #include <__config>
14bdd1243dSDimitry Andric 
15bdd1243dSDimitry Andric #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
16bdd1243dSDimitry Andric #  pragma GCC system_header
17bdd1243dSDimitry Andric #endif
18bdd1243dSDimitry Andric 
19bdd1243dSDimitry Andric _LIBCPP_PUSH_MACROS
20bdd1243dSDimitry Andric #include <__undef_macros>
21bdd1243dSDimitry Andric 
22bdd1243dSDimitry Andric #if _LIBCPP_STD_VER >= 20
23bdd1243dSDimitry Andric 
24bdd1243dSDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD
25bdd1243dSDimitry Andric 
26bdd1243dSDimitry Andric template <__libcpp_unsigned_integer _Tp>
has_single_bit(_Tp __t)27*0fca6ea1SDimitry Andric [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool has_single_bit(_Tp __t) noexcept {
28bdd1243dSDimitry Andric   return __t != 0 && (((__t & (__t - 1)) == 0));
29bdd1243dSDimitry Andric }
30bdd1243dSDimitry Andric 
31bdd1243dSDimitry Andric _LIBCPP_END_NAMESPACE_STD
32bdd1243dSDimitry Andric 
33bdd1243dSDimitry Andric #endif // _LIBCPP_STD_VER >= 20
34bdd1243dSDimitry Andric 
35bdd1243dSDimitry Andric _LIBCPP_POP_MACROS
36bdd1243dSDimitry Andric 
37bdd1243dSDimitry Andric #endif // _LIBCPP___BIT_HAS_SINGLE_BIT_H
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