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_CEIL_H
10#define _LIBCPP___BIT_BIT_CEIL_H
11
12#include <__assert>
13#include <__bit/countl.h>
14#include <__config>
15#include <__type_traits/integer_traits.h>
16#include <limits>
17
18#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
19#  pragma GCC system_header
20#endif
21
22_LIBCPP_BEGIN_NAMESPACE_STD
23
24#if _LIBCPP_STD_VER >= 17
25
26template <class _Tp>
27[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp __bit_ceil(_Tp __t) noexcept {
28  if (__t < 2)
29    return 1;
30  const unsigned __n = numeric_limits<_Tp>::digits - std::__countl_zero((_Tp)(__t - 1u));
31  _LIBCPP_ASSERT_ARGUMENT_WITHIN_DOMAIN(__n != numeric_limits<_Tp>::digits, "Bad input to bit_ceil");
32
33  if constexpr (sizeof(_Tp) >= sizeof(unsigned))
34    return _Tp{1} << __n;
35  else {
36    const unsigned __extra   = numeric_limits<unsigned>::digits - numeric_limits<_Tp>::digits;
37    const unsigned __ret_val = 1u << (__n + __extra);
38    return (_Tp)(__ret_val >> __extra);
39  }
40}
41
42#  if _LIBCPP_STD_VER >= 20
43
44template <__unsigned_integer _Tp>
45[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp bit_ceil(_Tp __t) noexcept {
46  return std::__bit_ceil(__t);
47}
48
49#  endif // _LIBCPP_STD_VER >= 20
50#endif   // _LIBCPP_STD_VER >= 17
51
52_LIBCPP_END_NAMESPACE_STD
53
54#endif // _LIBCPP___BIT_BIT_CEIL_H