libcxx/include/__cxx03/__bit/has_single_bit.h

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef _LIBCPP___BIT_HAS_SINGLE_BIT_H
  10 #define _LIBCPP___BIT_HAS_SINGLE_BIT_H
  11
  12 #include <__cxx03/__concepts/arithmetic.h>
  13 #include <__cxx03/__config>
  14
  15 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  16 #  pragma GCC system_header
  17 #endif
  18
  19 _LIBCPP_PUSH_MACROS
  20 #include <__cxx03/__undef_macros>
  21
  22 #if _LIBCPP_STD_VER >= 20
  23
  24 _LIBCPP_BEGIN_NAMESPACE_STD
  25
  26 template <__libcpp_unsigned_integer _Tp>
  27 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool has_single_bit(_Tp __t) noexcept {
  28   return __t != 0 && (((__t & (__t - 1)) == 0));
  29 }
  30
  31 _LIBCPP_END_NAMESPACE_STD
  32
  33 #endif // _LIBCPP_STD_VER >= 20
  34
  35 _LIBCPP_POP_MACROS
  36
  37 #endif // _LIBCPP___BIT_HAS_SINGLE_BIT_H