libcxx/include/__bit/bit_width.h

   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 [[nodiscard]] _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