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 <__concepts/arithmetic.h> 15 #include <__config> 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 >= 20 25 26 template <__libcpp_unsigned_integer _Tp> 27 _LIBCPP_NODISCARD_EXT _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_UNCATEGORIZED(__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 #endif // _LIBCPP_STD_VER >= 20 43 44 _LIBCPP_END_NAMESPACE_STD 45 46 #endif // _LIBCPP___BIT_BIT_CEIL_H 47