__cxx03/__bit/has_single_bit.h

0001 //===----------------------------------------------------------------------===//
0002 //
0003 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0004 // See https://llvm.org/LICENSE.txt for license information.
0005 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0006 //
0007 //===----------------------------------------------------------------------===//
0008
0009 #ifndef _LIBCPP___CXX03___BIT_HAS_SINGLE_BIT_H
0010 #define _LIBCPP___CXX03___BIT_HAS_SINGLE_BIT_H
0011
0012 #include <__cxx03/__concepts/arithmetic.h>
0013 #include <__cxx03/__config>
0014
0015 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0016 #  pragma GCC system_header
0017 #endif
0018
0019 _LIBCPP_PUSH_MACROS
0020 #include <__cxx03/__undef_macros>
0021
0022 #if _LIBCPP_STD_VER >= 20
0023
0024 _LIBCPP_BEGIN_NAMESPACE_STD
0025
0026 template <__libcpp_unsigned_integer _Tp>
0027 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool has_single_bit(_Tp __t) noexcept {
0028   return __t != 0 && (((__t & (__t - 1)) == 0));
0029 }
0030
0031 _LIBCPP_END_NAMESPACE_STD
0032
0033 #endif // _LIBCPP_STD_VER >= 20
0034
0035 _LIBCPP_POP_MACROS
0036
0037 #endif // _LIBCPP___CXX03___BIT_HAS_SINGLE_BIT_H