bit_floor.h 945 B

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  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. #ifndef _LIBCPP___BIT_BIT_FLOOR_H
  9. #define _LIBCPP___BIT_BIT_FLOOR_H
  10. #include <__bit/bit_log2.h>
  11. #include <__concepts/arithmetic.h>
  12. #include <__config>
  13. #include <limits>
  14. #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  15. # pragma GCC system_header
  16. #endif
  17. _LIBCPP_BEGIN_NAMESPACE_STD
  18. #if _LIBCPP_STD_VER >= 20
  19. template <__libcpp_unsigned_integer _Tp>
  20. _LIBCPP_HIDE_FROM_ABI constexpr _Tp bit_floor(_Tp __t) noexcept {
  21. return __t == 0 ? 0 : _Tp{1} << std::__bit_log2(__t);
  22. }
  23. #endif // _LIBCPP_STD_VER >= 20
  24. _LIBCPP_END_NAMESPACE_STD
  25. #endif // _LIBCPP___BIT_BIT_FLOOR_H