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