__cxx03/__bit/bit_width.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_BIT_WIDTH_H
0010 #define _LIBCPP___CXX03___BIT_BIT_WIDTH_H
0011
0012 #include <__cxx03/__bit/bit_log2.h>
0013 #include <__cxx03/__concepts/arithmetic.h>
0014 #include <__cxx03/__config>
0015
0016 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0017 #  pragma GCC system_header
0018 #endif
0019
0020 #if _LIBCPP_STD_VER >= 20
0021
0022 _LIBCPP_BEGIN_NAMESPACE_STD
0023
0024 template <__libcpp_unsigned_integer _Tp>
0025 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr int bit_width(_Tp __t) noexcept {
0026   return __t == 0 ? 0 : std::__bit_log2(__t) + 1;
0027 }
0028
0029 _LIBCPP_END_NAMESPACE_STD
0030
0031 #endif // _LIBCPP_STD_VER >= 20
0032
0033 #endif // _LIBCPP___CXX03___BIT_BIT_WIDTH_H