14824e7fdSDimitry Andric //===----------------------------------------------------------------------===// 24824e7fdSDimitry Andric // 34824e7fdSDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 44824e7fdSDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 54824e7fdSDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 64824e7fdSDimitry Andric // 74824e7fdSDimitry Andric //===----------------------------------------------------------------------===// 84824e7fdSDimitry Andric 94824e7fdSDimitry Andric #ifndef _LIBCPP___RANDOM_GENERATE_CANONICAL_H 104824e7fdSDimitry Andric #define _LIBCPP___RANDOM_GENERATE_CANONICAL_H 114824e7fdSDimitry Andric 124824e7fdSDimitry Andric #include <__config> 134824e7fdSDimitry Andric #include <__random/log2.h> 144824e7fdSDimitry Andric #include <cstdint> 154824e7fdSDimitry Andric #include <initializer_list> 164824e7fdSDimitry Andric #include <limits> 174824e7fdSDimitry Andric 184824e7fdSDimitry Andric #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 194824e7fdSDimitry Andric # pragma GCC system_header 204824e7fdSDimitry Andric #endif 214824e7fdSDimitry Andric 224824e7fdSDimitry Andric _LIBCPP_PUSH_MACROS 234824e7fdSDimitry Andric #include <__undef_macros> 244824e7fdSDimitry Andric 254824e7fdSDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD 264824e7fdSDimitry Andric 274824e7fdSDimitry Andric // generate_canonical 284824e7fdSDimitry Andric 294824e7fdSDimitry Andric template <class _RealType, size_t __bits, class _URNG> generate_canonical(_URNG & __g)30*cb14a3feSDimitry Andric_LIBCPP_HIDE_FROM_ABI _RealType generate_canonical(_URNG& __g) { 3106c3fb27SDimitry Andric const size_t __dt = numeric_limits<_RealType>::digits; 3206c3fb27SDimitry Andric const size_t __b = __dt < __bits ? __dt : __bits; 334824e7fdSDimitry Andric #ifdef _LIBCPP_CXX03_LANG 3406c3fb27SDimitry Andric const size_t __log_r = __log2<uint64_t, _URNG::_Max - _URNG::_Min + uint64_t(1)>::value; 354824e7fdSDimitry Andric #else 3606c3fb27SDimitry Andric const size_t __log_r = __log2<uint64_t, _URNG::max() - _URNG::min() + uint64_t(1)>::value; 374824e7fdSDimitry Andric #endif 3806c3fb27SDimitry Andric const size_t __k = __b / __log_r + (__b % __log_r != 0) + (__b == 0); 3906c3fb27SDimitry Andric const _RealType __rp = static_cast<_RealType>(_URNG::max() - _URNG::min()) + _RealType(1); 4006c3fb27SDimitry Andric _RealType __base = __rp; 4106c3fb27SDimitry Andric _RealType __sp = __g() - _URNG::min(); 4206c3fb27SDimitry Andric for (size_t __i = 1; __i < __k; ++__i, __base *= __rp) 4306c3fb27SDimitry Andric __sp += (__g() - _URNG::min()) * __base; 4406c3fb27SDimitry Andric return __sp / __base; 454824e7fdSDimitry Andric } 464824e7fdSDimitry Andric 474824e7fdSDimitry Andric _LIBCPP_END_NAMESPACE_STD 484824e7fdSDimitry Andric 494824e7fdSDimitry Andric _LIBCPP_POP_MACROS 504824e7fdSDimitry Andric 514824e7fdSDimitry Andric #endif // _LIBCPP___RANDOM_GENERATE_CANONICAL_H 52