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_BIT_FLOOR_H 10 #define _LIBCPP___BIT_BIT_FLOOR_H 11 12 #include <__bit/bit_log2.h> 13 #include <__config> 14 #include <__type_traits/integer_traits.h> 15 16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 17 # pragma GCC system_header 18 #endif 19 20 _LIBCPP_BEGIN_NAMESPACE_STD 21 22 #if _LIBCPP_STD_VER >= 20 23 24 template <__unsigned_integer _Tp> bit_floor(_Tp __t)25[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp bit_floor(_Tp __t) noexcept { 26 return __t == 0 ? 0 : _Tp{1} << std::__bit_log2(__t); 27 } 28 29 #endif // _LIBCPP_STD_VER >= 20 30 31 _LIBCPP_END_NAMESPACE_STD 32 33 #endif // _LIBCPP___BIT_BIT_FLOOR_H 34