317 lines
9.2 KiB
C++
317 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_UNIFORM_INT_DISTRIBUTION_H
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#define _LIBCPP___RANDOM_UNIFORM_INT_DISTRIBUTION_H
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#include <__bits>
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#include <__config>
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#include <cstddef>
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#include <cstdint>
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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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// __independent_bits_engine
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template <unsigned long long _Xp, size_t _Rp>
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struct __log2_imp
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{
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static const size_t value = _Xp & ((unsigned long long)(1) << _Rp) ? _Rp
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: __log2_imp<_Xp, _Rp - 1>::value;
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};
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template <unsigned long long _Xp>
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struct __log2_imp<_Xp, 0>
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{
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static const size_t value = 0;
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};
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template <size_t _Rp>
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struct __log2_imp<0, _Rp>
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{
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static const size_t value = _Rp + 1;
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};
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template <class _UIntType, _UIntType _Xp>
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struct __log2
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{
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static const size_t value = __log2_imp<_Xp,
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sizeof(_UIntType) * __CHAR_BIT__ - 1>::value;
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};
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template<class _Engine, class _UIntType>
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class __independent_bits_engine
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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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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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_Engine& __e_;
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size_t __w_;
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size_t __w0_;
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size_t __n_;
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size_t __n0_;
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_Working_result_type __y0_;
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_Working_result_type __y1_;
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_Engine_result_type __mask0_;
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_Engine_result_type __mask1_;
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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 _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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public:
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// constructors and seeding functions
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__independent_bits_engine(_Engine& __e, size_t __w);
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// generating functions
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result_type operator()() {return __eval(integral_constant<bool, _Rp != 0>());}
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private:
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result_type __eval(false_type);
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result_type __eval(true_type);
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};
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template<class _Engine, class _UIntType>
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__independent_bits_engine<_Engine, _UIntType>
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::__independent_bits_engine(_Engine& __e, size_t __w)
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: __e_(__e),
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__w_(__w)
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{
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__n_ = __w_ / __m + (__w_ % __m != 0);
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__w0_ = __w_ / __n_;
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if (_Rp == 0)
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__y0_ = _Rp;
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else if (__w0_ < _WDt)
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__y0_ = (_Rp >> __w0_) << __w0_;
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else
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__y0_ = 0;
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if (_Rp - __y0_ > __y0_ / __n_)
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{
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++__n_;
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__w0_ = __w_ / __n_;
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if (__w0_ < _WDt)
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__y0_ = (_Rp >> __w0_) << __w0_;
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else
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__y0_ = 0;
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}
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__n0_ = __n_ - __w_ % __n_;
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if (__w0_ < _WDt - 1)
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__y1_ = (_Rp >> (__w0_ + 1)) << (__w0_ + 1);
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else
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__y1_ = 0;
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__mask0_ = __w0_ > 0 ? _Engine_result_type(~0) >> (_EDt - __w0_) :
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_Engine_result_type(0);
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__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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}
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template<class _Engine, class _UIntType>
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inline
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_UIntType
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__independent_bits_engine<_Engine, _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, class _UIntType>
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_UIntType
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__independent_bits_engine<_Engine, _UIntType>::__eval(true_type)
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{
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const size_t _WRt = numeric_limits<result_type>::digits;
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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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if (__w0_ < _WRt)
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_Sp <<= __w0_;
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else
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_Sp = 0;
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_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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if (__w0_ < _WRt - 1)
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_Sp <<= __w0_ + 1;
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else
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_Sp = 0;
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_Sp += __u & __mask1_;
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}
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return _Sp;
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}
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template<class _IntType = int>
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class uniform_int_distribution
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{
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public:
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// types
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typedef _IntType result_type;
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class param_type
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{
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result_type __a_;
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result_type __b_;
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public:
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typedef uniform_int_distribution distribution_type;
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explicit param_type(result_type __a = 0,
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result_type __b = numeric_limits<result_type>::max())
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: __a_(__a), __b_(__b) {}
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result_type a() const {return __a_;}
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result_type b() const {return __b_;}
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friend bool operator==(const param_type& __x, const param_type& __y)
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{return __x.__a_ == __y.__a_ && __x.__b_ == __y.__b_;}
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friend bool operator!=(const param_type& __x, const param_type& __y)
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{return !(__x == __y);}
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};
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private:
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param_type __p_;
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public:
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// constructors and reset functions
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#ifndef _LIBCPP_CXX03_LANG
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uniform_int_distribution() : uniform_int_distribution(0) {}
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explicit uniform_int_distribution(
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result_type __a, result_type __b = numeric_limits<result_type>::max())
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: __p_(param_type(__a, __b)) {}
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#else
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explicit uniform_int_distribution(
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result_type __a = 0,
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result_type __b = numeric_limits<result_type>::max())
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: __p_(param_type(__a, __b)) {}
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#endif
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explicit uniform_int_distribution(const param_type& __p) : __p_(__p) {}
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void reset() {}
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// generating functions
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template<class _URNG> result_type operator()(_URNG& __g)
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{return (*this)(__g, __p_);}
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template<class _URNG> result_type operator()(_URNG& __g, const param_type& __p);
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// property functions
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result_type a() const {return __p_.a();}
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result_type b() const {return __p_.b();}
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param_type param() const {return __p_;}
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void param(const param_type& __p) {__p_ = __p;}
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result_type min() const {return a();}
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result_type max() const {return b();}
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friend bool operator==(const uniform_int_distribution& __x,
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const uniform_int_distribution& __y)
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{return __x.__p_ == __y.__p_;}
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friend bool operator!=(const uniform_int_distribution& __x,
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const uniform_int_distribution& __y)
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{return !(__x == __y);}
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};
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template<class _IntType>
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template<class _URNG>
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typename uniform_int_distribution<_IntType>::result_type
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uniform_int_distribution<_IntType>::operator()(_URNG& __g, const param_type& __p)
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_LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
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{
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typedef typename conditional<sizeof(result_type) <= sizeof(uint32_t),
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uint32_t, uint64_t>::type _UIntType;
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const _UIntType _Rp = _UIntType(__p.b()) - _UIntType(__p.a()) + _UIntType(1);
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if (_Rp == 1)
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return __p.a();
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const size_t _Dt = numeric_limits<_UIntType>::digits;
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typedef __independent_bits_engine<_URNG, _UIntType> _Eng;
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if (_Rp == 0)
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return static_cast<result_type>(_Eng(__g, _Dt)());
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size_t __w = _Dt - __libcpp_clz(_Rp) - 1;
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if ((_Rp & (numeric_limits<_UIntType>::max() >> (_Dt - __w))) != 0)
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++__w;
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_Eng __e(__g, __w);
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_UIntType __u;
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do
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{
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__u = __e();
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} while (__u >= _Rp);
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return static_cast<result_type>(__u + __p.a());
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}
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template <class _CharT, class _Traits, class _IT>
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basic_ostream<_CharT, _Traits>&
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operator<<(basic_ostream<_CharT, _Traits>& __os,
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const uniform_int_distribution<_IT>& __x)
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{
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__save_flags<_CharT, _Traits> __lx(__os);
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typedef basic_ostream<_CharT, _Traits> _Ostream;
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__os.flags(_Ostream::dec | _Ostream::left);
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_CharT __sp = __os.widen(' ');
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__os.fill(__sp);
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return __os << __x.a() << __sp << __x.b();
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}
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template <class _CharT, class _Traits, class _IT>
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basic_istream<_CharT, _Traits>&
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operator>>(basic_istream<_CharT, _Traits>& __is,
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uniform_int_distribution<_IT>& __x)
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{
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typedef uniform_int_distribution<_IT> _Eng;
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typedef typename _Eng::result_type result_type;
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typedef typename _Eng::param_type param_type;
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__save_flags<_CharT, _Traits> __lx(__is);
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typedef basic_istream<_CharT, _Traits> _Istream;
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__is.flags(_Istream::dec | _Istream::skipws);
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result_type __a;
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result_type __b;
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__is >> __a >> __b;
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if (!__is.fail())
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__x.param(param_type(__a, __b));
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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_UNIFORM_INT_DISTRIBUTION_H
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