| //===----------------------------------------------------------------------===// | |
| // | |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. | |
| // See https://llvm.org/LICENSE.txt for license information. | |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception | |
| // | |
| //===----------------------------------------------------------------------===// | |
| #ifndef _LIBCPP___BIT_BIT_LOG2_H | |
| #define _LIBCPP___BIT_BIT_LOG2_H | |
| #include <__assert> | |
| #include <__bit/countl.h> | |
| #include <__config> | |
| #include <__type_traits/integer_traits.h> | |
| #include <limits> | |
| #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) | |
| # pragma GCC system_header | |
| #endif | |
| _LIBCPP_BEGIN_NAMESPACE_STD | |
| template <class _Tp> | |
| _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp __bit_log2(_Tp __t) _NOEXCEPT { | |
| static_assert(__is_unsigned_integer_v<_Tp>, "__bit_log2 requires an unsigned integer type"); | |
| _LIBCPP_ASSERT_INTERNAL(__t != 0, "logarithm of 0 is undefined"); | |
| return numeric_limits<_Tp>::digits - 1 - std::__countl_zero(__t); | |
| } | |
| _LIBCPP_END_NAMESPACE_STD | |
| #endif // _LIBCPP___BIT_BIT_LOG2_H |