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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___CXX03___RANDOM_GENERATE_CANONICAL_H10#define _LIBCPP___CXX03___RANDOM_GENERATE_CANONICAL_H11 12#include <__cxx03/__config>13#include <__cxx03/__random/log2.h>14#include <__cxx03/cstdint>15#include <__cxx03/limits>16 17#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)18# pragma GCC system_header19#endif20 21_LIBCPP_PUSH_MACROS22#include <__cxx03/__undef_macros>23 24_LIBCPP_BEGIN_NAMESPACE_STD25 26// generate_canonical27 28template <class _RealType, size_t __bits, class _URNG>29_LIBCPP_HIDE_FROM_ABI _RealType generate_canonical(_URNG& __g) {30 const size_t __dt = numeric_limits<_RealType>::digits;31 const size_t __b = __dt < __bits ? __dt : __bits;32 const size_t __log_r = __log2<uint64_t, _URNG::_Max - _URNG::_Min + uint64_t(1)>::value;33 const size_t __k = __b / __log_r + (__b % __log_r != 0) + (__b == 0);34 const _RealType __rp = static_cast<_RealType>(_URNG::max() - _URNG::min()) + _RealType(1);35 _RealType __base = __rp;36 _RealType __sp = __g() - _URNG::min();37 for (size_t __i = 1; __i < __k; ++__i, __base *= __rp)38 __sp += (__g() - _URNG::min()) * __base;39 return __sp / __base;40}41 42_LIBCPP_END_NAMESPACE_STD43 44_LIBCPP_POP_MACROS45 46#endif // _LIBCPP___CXX03___RANDOM_GENERATE_CANONICAL_H47