Pirama Arumuga Nainar | d285ad0 | 2022-02-08 09:26:56 -0800 | [diff] [blame] | 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___RANDOM_GENERATE_CANONICAL_H |
| 10 | #define _LIBCPP___RANDOM_GENERATE_CANONICAL_H |
| 11 | |
| 12 | #include <__config> |
| 13 | #include <__random/log2.h> |
| 14 | #include <cstdint> |
| 15 | #include <initializer_list> |
| 16 | #include <limits> |
| 17 | |
| 18 | #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) |
| 19 | #pragma GCC system_header |
| 20 | #endif |
| 21 | |
| 22 | _LIBCPP_PUSH_MACROS |
| 23 | #include <__undef_macros> |
| 24 | |
| 25 | _LIBCPP_BEGIN_NAMESPACE_STD |
| 26 | |
| 27 | // generate_canonical |
| 28 | |
| 29 | template<class _RealType, size_t __bits, class _URNG> |
| 30 | _RealType |
| 31 | generate_canonical(_URNG& __g) |
| 32 | { |
| 33 | const size_t _Dt = numeric_limits<_RealType>::digits; |
| 34 | const size_t __b = _Dt < __bits ? _Dt : __bits; |
| 35 | #ifdef _LIBCPP_CXX03_LANG |
| 36 | const size_t __logR = __log2<uint64_t, _URNG::_Max - _URNG::_Min + uint64_t(1)>::value; |
| 37 | #else |
| 38 | const size_t __logR = __log2<uint64_t, _URNG::max() - _URNG::min() + uint64_t(1)>::value; |
| 39 | #endif |
| 40 | const size_t __k = __b / __logR + (__b % __logR != 0) + (__b == 0); |
| 41 | const _RealType _Rp = static_cast<_RealType>(_URNG::max() - _URNG::min()) + _RealType(1); |
| 42 | _RealType __base = _Rp; |
| 43 | _RealType _Sp = __g() - _URNG::min(); |
| 44 | for (size_t __i = 1; __i < __k; ++__i, __base *= _Rp) |
| 45 | _Sp += (__g() - _URNG::min()) * __base; |
| 46 | return _Sp / __base; |
| 47 | } |
| 48 | |
| 49 | _LIBCPP_END_NAMESPACE_STD |
| 50 | |
| 51 | _LIBCPP_POP_MACROS |
| 52 | |
| 53 | #endif // _LIBCPP___RANDOM_GENERATE_CANONICAL_H |