| //===----------------------------------------------------------------------===// |
| // |
| // 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 |
