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_WIDTH_H
10 #define _LIBCPP___BIT_BIT_WIDTH_H
11 
12 #include <__bit/bit_log2.h>
13 #include <__concepts/arithmetic.h>
14 #include <__config>
15 
16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
17 #  pragma GCC system_header
18 #endif
19 
20 #if _LIBCPP_STD_VER >= 20
21 
22 _LIBCPP_BEGIN_NAMESPACE_STD
23 
24 template <__libcpp_unsigned_integer _Tp>
25 _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr int bit_width(_Tp __t) noexcept {
26   return __t == 0 ? 0 : std::__bit_log2(__t) + 1;
27 }
28 
29 _LIBCPP_END_NAMESPACE_STD
30 
31 #endif // _LIBCPP_STD_VER >= 20
32 
33 #endif // _LIBCPP___BIT_BIT_WIDTH_H
34