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 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_LANG 34 const size_t __log_r = __log2<uint64_t, _URNG::_Max - _URNG::_Min + uint64_t(1)>::value; 35#else 36 const size_t __log_r = __log2<uint64_t, _URNG::max() - _URNG::min() + uint64_t(1)>::value; 37#endif 38 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_STD 48 49_LIBCPP_POP_MACROS 50 51#endif // _LIBCPP___RANDOM_GENERATE_CANONICAL_H 52