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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-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef _LIBCPP___RANDOM_GENERATE_CANONICAL_H10#define _LIBCPP___RANDOM_GENERATE_CANONICAL_H11 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_header20#endif21 22_LIBCPP_PUSH_MACROS23#include <__undef_macros>24 25_LIBCPP_BEGIN_NAMESPACE_STD26 27// generate_canonical28 29template <class _RealType, size_t __bits, class _URNG>30_LIBCPP_HIDE_FROM_ABI _RealType generate_canonical(_URNG& __g) {31 const size_t __dt = numeric_limits<_RealType>::digits;32 const size_t __b = __dt < __bits ? __dt : __bits;33#ifdef _LIBCPP_CXX03_LANG34 const size_t __log_r = __log2<uint64_t, _URNG::_Max - _URNG::_Min + uint64_t(1)>::value;35#else36 const size_t __log_r = __log2<uint64_t, _URNG::max() - _URNG::min() + uint64_t(1)>::value;37#endif38 const size_t __k = __b / __log_r + (__b % __log_r != 0) + (__b == 0);39 const _RealType __rp = static_cast<_RealType>(_URNG::max() - _URNG::min()) + _RealType(1);40 _RealType __base = __rp;41 _RealType __sp = __g() - _URNG::min();42 for (size_t __i = 1; __i < __k; ++__i, __base *= __rp)43 __sp += (__g() - _URNG::min()) * __base;44 return __sp / __base;45}46 47_LIBCPP_END_NAMESPACE_STD48 49_LIBCPP_POP_MACROS50 51#endif // _LIBCPP___RANDOM_GENERATE_CANONICAL_H52