272 lines
9.2 KiB
C++
272 lines
9.2 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___RANDOM_INDEPENDENT_BITS_ENGINE_H
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#define _LIBCPP___RANDOM_INDEPENDENT_BITS_ENGINE_H
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#include <__config>
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#include <__random/is_seed_sequence.h>
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#include <__random/log2.h>
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#include <__utility/move.h>
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#include <iosfwd>
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#include <limits>
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#include <type_traits>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_PUSH_MACROS
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#include <__undef_macros>
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_LIBCPP_BEGIN_NAMESPACE_STD
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template<class _Engine, size_t __w, class _UIntType>
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class _LIBCPP_TEMPLATE_VIS independent_bits_engine
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{
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template <class _UInt, _UInt _R0, size_t _Wp, size_t _Mp>
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class __get_n
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{
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static _LIBCPP_CONSTEXPR const size_t _Dt = numeric_limits<_UInt>::digits;
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static _LIBCPP_CONSTEXPR const size_t _Np = _Wp / _Mp + (_Wp % _Mp != 0);
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static _LIBCPP_CONSTEXPR const size_t _W0 = _Wp / _Np;
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static _LIBCPP_CONSTEXPR const _UInt _Y0 = _W0 >= _Dt ? 0 : (_R0 >> _W0) << _W0;
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public:
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static _LIBCPP_CONSTEXPR const size_t value = _R0 - _Y0 > _Y0 / _Np ? _Np + 1 : _Np;
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};
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public:
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// types
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typedef _UIntType result_type;
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private:
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_Engine __e_;
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static _LIBCPP_CONSTEXPR const result_type _Dt = numeric_limits<result_type>::digits;
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static_assert( 0 < __w, "independent_bits_engine invalid parameters");
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static_assert(__w <= _Dt, "independent_bits_engine invalid parameters");
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typedef typename _Engine::result_type _Engine_result_type;
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typedef typename conditional
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<
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sizeof(_Engine_result_type) <= sizeof(result_type),
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result_type,
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_Engine_result_type
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>::type _Working_result_type;
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#ifdef _LIBCPP_CXX03_LANG
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static const _Working_result_type _Rp = _Engine::_Max - _Engine::_Min
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+ _Working_result_type(1);
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#else
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static _LIBCPP_CONSTEXPR const _Working_result_type _Rp = _Engine::max() - _Engine::min()
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+ _Working_result_type(1);
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#endif
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static _LIBCPP_CONSTEXPR const size_t __m = __log2<_Working_result_type, _Rp>::value;
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static _LIBCPP_CONSTEXPR const size_t __n = __get_n<_Working_result_type, _Rp, __w, __m>::value;
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static _LIBCPP_CONSTEXPR const size_t __w0 = __w / __n;
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static _LIBCPP_CONSTEXPR const size_t __n0 = __n - __w % __n;
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static _LIBCPP_CONSTEXPR const size_t _WDt = numeric_limits<_Working_result_type>::digits;
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static _LIBCPP_CONSTEXPR const size_t _EDt = numeric_limits<_Engine_result_type>::digits;
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static _LIBCPP_CONSTEXPR const _Working_result_type __y0 = __w0 >= _WDt ? 0 :
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(_Rp >> __w0) << __w0;
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static _LIBCPP_CONSTEXPR const _Working_result_type __y1 = __w0 >= _WDt - 1 ? 0 :
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(_Rp >> (__w0+1)) << (__w0+1);
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static _LIBCPP_CONSTEXPR const _Engine_result_type __mask0 = __w0 > 0 ?
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_Engine_result_type(~0) >> (_EDt - __w0) :
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_Engine_result_type(0);
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static _LIBCPP_CONSTEXPR const _Engine_result_type __mask1 = __w0 < _EDt - 1 ?
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_Engine_result_type(~0) >> (_EDt - (__w0 + 1)) :
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_Engine_result_type(~0);
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public:
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static _LIBCPP_CONSTEXPR const result_type _Min = 0;
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static _LIBCPP_CONSTEXPR const result_type _Max = __w == _Dt ? result_type(~0) :
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(result_type(1) << __w) - result_type(1);
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static_assert(_Min < _Max, "independent_bits_engine invalid parameters");
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// engine characteristics
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_LIBCPP_INLINE_VISIBILITY
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static _LIBCPP_CONSTEXPR result_type min() { return _Min; }
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_LIBCPP_INLINE_VISIBILITY
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static _LIBCPP_CONSTEXPR result_type max() { return _Max; }
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// constructors and seeding functions
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_LIBCPP_INLINE_VISIBILITY
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independent_bits_engine() {}
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_LIBCPP_INLINE_VISIBILITY
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explicit independent_bits_engine(const _Engine& __e)
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: __e_(__e) {}
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#ifndef _LIBCPP_CXX03_LANG
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_LIBCPP_INLINE_VISIBILITY
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explicit independent_bits_engine(_Engine&& __e)
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: __e_(_VSTD::move(__e)) {}
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#endif // _LIBCPP_CXX03_LANG
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_LIBCPP_INLINE_VISIBILITY
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explicit independent_bits_engine(result_type __sd) : __e_(__sd) {}
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template<class _Sseq>
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_LIBCPP_INLINE_VISIBILITY
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explicit independent_bits_engine(_Sseq& __q,
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typename enable_if<__is_seed_sequence<_Sseq, independent_bits_engine>::value &&
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!is_convertible<_Sseq, _Engine>::value>::type* = 0)
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: __e_(__q) {}
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_LIBCPP_INLINE_VISIBILITY
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void seed() {__e_.seed();}
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_LIBCPP_INLINE_VISIBILITY
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void seed(result_type __sd) {__e_.seed(__sd);}
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template<class _Sseq>
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_LIBCPP_INLINE_VISIBILITY
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typename enable_if
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<
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__is_seed_sequence<_Sseq, independent_bits_engine>::value,
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void
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>::type
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seed(_Sseq& __q) {__e_.seed(__q);}
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// generating functions
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_LIBCPP_INLINE_VISIBILITY
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result_type operator()() {return __eval(integral_constant<bool, _Rp != 0>());}
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_LIBCPP_INLINE_VISIBILITY
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void discard(unsigned long long __z) {for (; __z; --__z) operator()();}
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// property functions
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_LIBCPP_INLINE_VISIBILITY
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const _Engine& base() const _NOEXCEPT {return __e_;}
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template<class _Eng, size_t _Wp, class _UInt>
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friend
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bool
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operator==(
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const independent_bits_engine<_Eng, _Wp, _UInt>& __x,
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const independent_bits_engine<_Eng, _Wp, _UInt>& __y);
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template<class _Eng, size_t _Wp, class _UInt>
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friend
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bool
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operator!=(
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const independent_bits_engine<_Eng, _Wp, _UInt>& __x,
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const independent_bits_engine<_Eng, _Wp, _UInt>& __y);
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template <class _CharT, class _Traits,
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class _Eng, size_t _Wp, class _UInt>
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friend
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basic_ostream<_CharT, _Traits>&
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operator<<(basic_ostream<_CharT, _Traits>& __os,
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const independent_bits_engine<_Eng, _Wp, _UInt>& __x);
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template <class _CharT, class _Traits,
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class _Eng, size_t _Wp, class _UInt>
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friend
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basic_istream<_CharT, _Traits>&
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operator>>(basic_istream<_CharT, _Traits>& __is,
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independent_bits_engine<_Eng, _Wp, _UInt>& __x);
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private:
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_LIBCPP_INLINE_VISIBILITY
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result_type __eval(false_type);
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result_type __eval(true_type);
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template <size_t __count>
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_LIBCPP_INLINE_VISIBILITY
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static
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typename enable_if
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<
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__count < _Dt,
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result_type
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>::type
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__lshift(result_type __x) {return __x << __count;}
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template <size_t __count>
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_LIBCPP_INLINE_VISIBILITY
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static
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typename enable_if
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<
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(__count >= _Dt),
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result_type
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>::type
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__lshift(result_type) {return result_type(0);}
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};
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template<class _Engine, size_t __w, class _UIntType>
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inline
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_UIntType
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independent_bits_engine<_Engine, __w, _UIntType>::__eval(false_type)
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{
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return static_cast<result_type>(__e_() & __mask0);
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}
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template<class _Engine, size_t __w, class _UIntType>
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_UIntType
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independent_bits_engine<_Engine, __w, _UIntType>::__eval(true_type)
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{
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result_type _Sp = 0;
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for (size_t __k = 0; __k < __n0; ++__k)
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{
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_Engine_result_type __u;
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do
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{
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__u = __e_() - _Engine::min();
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} while (__u >= __y0);
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_Sp = static_cast<result_type>(__lshift<__w0>(_Sp) + (__u & __mask0));
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}
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for (size_t __k = __n0; __k < __n; ++__k)
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{
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_Engine_result_type __u;
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do
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{
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__u = __e_() - _Engine::min();
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} while (__u >= __y1);
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_Sp = static_cast<result_type>(__lshift<__w0+1>(_Sp) + (__u & __mask1));
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}
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return _Sp;
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}
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template<class _Eng, size_t _Wp, class _UInt>
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inline _LIBCPP_INLINE_VISIBILITY
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bool
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operator==(
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const independent_bits_engine<_Eng, _Wp, _UInt>& __x,
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const independent_bits_engine<_Eng, _Wp, _UInt>& __y)
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{
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return __x.base() == __y.base();
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}
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template<class _Eng, size_t _Wp, class _UInt>
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inline _LIBCPP_INLINE_VISIBILITY
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bool
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operator!=(
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const independent_bits_engine<_Eng, _Wp, _UInt>& __x,
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const independent_bits_engine<_Eng, _Wp, _UInt>& __y)
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{
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return !(__x == __y);
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}
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template <class _CharT, class _Traits,
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class _Eng, size_t _Wp, class _UInt>
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basic_ostream<_CharT, _Traits>&
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operator<<(basic_ostream<_CharT, _Traits>& __os,
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const independent_bits_engine<_Eng, _Wp, _UInt>& __x)
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{
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return __os << __x.base();
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}
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template <class _CharT, class _Traits,
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class _Eng, size_t _Wp, class _UInt>
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basic_istream<_CharT, _Traits>&
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operator>>(basic_istream<_CharT, _Traits>& __is,
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independent_bits_engine<_Eng, _Wp, _UInt>& __x)
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{
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_Eng __e;
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__is >> __e;
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if (!__is.fail())
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__x.__e_ = __e;
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return __is;
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}
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___RANDOM_INDEPENDENT_BITS_ENGINE_H
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