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_ROTATE_H 10 #define _LIBCPP___BIT_ROTATE_H 11 12 #include <__concepts/arithmetic.h> 13 #include <__config> 14 #include <__type_traits/is_unsigned_integer.h> 15 #include <limits> 16 17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 18 # pragma GCC system_header 19 #endif 20 21 _LIBCPP_BEGIN_NAMESPACE_STD 22 23 template <class _Tp> 24 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp __rotr(_Tp __t, int __cnt) _NOEXCEPT { 25 static_assert(__libcpp_is_unsigned_integer<_Tp>::value, "__rotr requires an unsigned integer type"); 26 const unsigned int __dig = numeric_limits<_Tp>::digits; 27 if ((__cnt % __dig) == 0) 28 return __t; 29 30 if (__cnt < 0) { 31 __cnt *= -1; 32 return (__t << (__cnt % __dig)) | (__t >> (__dig - (__cnt % __dig))); // rotr with negative __cnt is similar to rotl 33 } 34 35 return (__t >> (__cnt % __dig)) | (__t << (__dig - (__cnt % __dig))); 36 } 37 38 template <class _Tp> 39 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp __rotl(_Tp __t, int __cnt) _NOEXCEPT { 40 return std::__rotr(__t, -__cnt); 41 } 42 43 #if _LIBCPP_STD_VER >= 20 44 45 template <__libcpp_unsigned_integer _Tp> 46 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp rotl(_Tp __t, int __cnt) noexcept { 47 return std::__rotl(__t, __cnt); 48 } 49 50 template <__libcpp_unsigned_integer _Tp> 51 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp rotr(_Tp __t, int __cnt) noexcept { 52 return std::__rotr(__t, __cnt); 53 } 54 55 #endif // _LIBCPP_STD_VER >= 20 56 57 _LIBCPP_END_NAMESPACE_STD 58 59 #endif // _LIBCPP___BIT_ROTATE_H 60