368faacac7
This commit reverts5aaefa51(and also partly7f285f48e7andb6d75682f9, which were related to the original commit). As landed,5aaefa51had unintended consequences on some downstream bots and didn't have proper coverage upstream due to a few subtle things. Implementing this is something we should do in libc++, however we'll first need to address a few issues listed in https://reviews.llvm.org/D106124#3349710. Differential Revision: https://reviews.llvm.org/D120683
353 lines
12 KiB
C++
353 lines
12 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_SUBTRACT_WITH_CARRY_ENGINE_H
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#define _LIBCPP___RANDOM_SUBTRACT_WITH_CARRY_ENGINE_H
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#include <__algorithm/equal.h>
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#include <__algorithm/min.h>
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#include <__config>
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#include <__random/is_seed_sequence.h>
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#include <__random/linear_congruential_engine.h>
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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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template<class _UIntType, size_t __w, size_t __s, size_t __r>
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class _LIBCPP_TEMPLATE_VIS subtract_with_carry_engine;
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template<class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
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bool
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operator==(
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const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x,
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const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __y);
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template<class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
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_LIBCPP_INLINE_VISIBILITY
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bool
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operator!=(
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const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x,
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const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __y);
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template <class _CharT, class _Traits,
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class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
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basic_ostream<_CharT, _Traits>&
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operator<<(basic_ostream<_CharT, _Traits>& __os,
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const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x);
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template <class _CharT, class _Traits,
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class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
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basic_istream<_CharT, _Traits>&
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operator>>(basic_istream<_CharT, _Traits>& __is,
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subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x);
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template<class _UIntType, size_t __w, size_t __s, size_t __r>
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class _LIBCPP_TEMPLATE_VIS subtract_with_carry_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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result_type __x_[__r];
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result_type __c_;
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size_t __i_;
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static _LIBCPP_CONSTEXPR const result_type _Dt = numeric_limits<result_type>::digits;
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static_assert( 0 < __w, "subtract_with_carry_engine invalid parameters");
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static_assert(__w <= _Dt, "subtract_with_carry_engine invalid parameters");
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static_assert( 0 < __s, "subtract_with_carry_engine invalid parameters");
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static_assert(__s < __r, "subtract_with_carry_engine invalid parameters");
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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, "subtract_with_carry_engine invalid parameters");
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// engine characteristics
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static _LIBCPP_CONSTEXPR const size_t word_size = __w;
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static _LIBCPP_CONSTEXPR const size_t short_lag = __s;
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static _LIBCPP_CONSTEXPR const size_t long_lag = __r;
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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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static _LIBCPP_CONSTEXPR const result_type default_seed = 19780503u;
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// constructors and seeding functions
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#ifndef _LIBCPP_CXX03_LANG
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_LIBCPP_INLINE_VISIBILITY
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subtract_with_carry_engine() : subtract_with_carry_engine(default_seed) {}
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_LIBCPP_INLINE_VISIBILITY
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explicit subtract_with_carry_engine(result_type __sd) { seed(__sd); }
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#else
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_LIBCPP_INLINE_VISIBILITY
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explicit subtract_with_carry_engine(result_type __sd = default_seed) {
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seed(__sd);
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}
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#endif
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template<class _Sseq>
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_LIBCPP_INLINE_VISIBILITY
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explicit subtract_with_carry_engine(_Sseq& __q,
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typename enable_if<__is_seed_sequence<_Sseq, subtract_with_carry_engine>::value>::type* = 0)
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{seed(__q);}
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_LIBCPP_INLINE_VISIBILITY
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void seed(result_type __sd = default_seed)
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{seed(__sd, integral_constant<unsigned, 1 + (__w - 1) / 32>());}
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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, subtract_with_carry_engine>::value,
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void
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>::type
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seed(_Sseq& __q)
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{__seed(__q, integral_constant<unsigned, 1 + (__w - 1) / 32>());}
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// generating functions
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result_type operator()();
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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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template<class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
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friend
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bool
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operator==(
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const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x,
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const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __y);
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template<class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
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friend
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bool
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operator!=(
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const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x,
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const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __y);
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template <class _CharT, class _Traits,
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class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
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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 subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x);
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template <class _CharT, class _Traits,
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class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
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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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subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x);
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private:
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void seed(result_type __sd, integral_constant<unsigned, 1>);
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void seed(result_type __sd, integral_constant<unsigned, 2>);
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template<class _Sseq>
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void __seed(_Sseq& __q, integral_constant<unsigned, 1>);
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template<class _Sseq>
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void __seed(_Sseq& __q, integral_constant<unsigned, 2>);
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};
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template<class _UIntType, size_t __w, size_t __s, size_t __r>
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_LIBCPP_CONSTEXPR const size_t subtract_with_carry_engine<_UIntType, __w, __s, __r>::word_size;
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template<class _UIntType, size_t __w, size_t __s, size_t __r>
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_LIBCPP_CONSTEXPR const size_t subtract_with_carry_engine<_UIntType, __w, __s, __r>::short_lag;
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template<class _UIntType, size_t __w, size_t __s, size_t __r>
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_LIBCPP_CONSTEXPR const size_t subtract_with_carry_engine<_UIntType, __w, __s, __r>::long_lag;
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template<class _UIntType, size_t __w, size_t __s, size_t __r>
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_LIBCPP_CONSTEXPR const typename subtract_with_carry_engine<_UIntType, __w, __s, __r>::result_type
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subtract_with_carry_engine<_UIntType, __w, __s, __r>::default_seed;
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template<class _UIntType, size_t __w, size_t __s, size_t __r>
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void
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subtract_with_carry_engine<_UIntType, __w, __s, __r>::seed(result_type __sd,
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integral_constant<unsigned, 1>)
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{
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linear_congruential_engine<result_type, 40014u, 0u, 2147483563u>
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__e(__sd == 0u ? default_seed : __sd);
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for (size_t __i = 0; __i < __r; ++__i)
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__x_[__i] = static_cast<result_type>(__e() & _Max);
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__c_ = __x_[__r-1] == 0;
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__i_ = 0;
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}
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template<class _UIntType, size_t __w, size_t __s, size_t __r>
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void
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subtract_with_carry_engine<_UIntType, __w, __s, __r>::seed(result_type __sd,
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integral_constant<unsigned, 2>)
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{
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linear_congruential_engine<result_type, 40014u, 0u, 2147483563u>
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__e(__sd == 0u ? default_seed : __sd);
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for (size_t __i = 0; __i < __r; ++__i)
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{
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result_type __e0 = __e();
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__x_[__i] = static_cast<result_type>(
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(__e0 + ((uint64_t)__e() << 32)) & _Max);
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}
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__c_ = __x_[__r-1] == 0;
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__i_ = 0;
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}
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template<class _UIntType, size_t __w, size_t __s, size_t __r>
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template<class _Sseq>
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void
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subtract_with_carry_engine<_UIntType, __w, __s, __r>::__seed(_Sseq& __q,
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integral_constant<unsigned, 1>)
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{
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const unsigned __k = 1;
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uint32_t __ar[__r * __k];
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__q.generate(__ar, __ar + __r * __k);
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for (size_t __i = 0; __i < __r; ++__i)
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__x_[__i] = static_cast<result_type>(__ar[__i] & _Max);
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__c_ = __x_[__r-1] == 0;
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__i_ = 0;
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}
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template<class _UIntType, size_t __w, size_t __s, size_t __r>
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template<class _Sseq>
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void
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subtract_with_carry_engine<_UIntType, __w, __s, __r>::__seed(_Sseq& __q,
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integral_constant<unsigned, 2>)
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{
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const unsigned __k = 2;
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uint32_t __ar[__r * __k];
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__q.generate(__ar, __ar + __r * __k);
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for (size_t __i = 0; __i < __r; ++__i)
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__x_[__i] = static_cast<result_type>(
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(__ar[2 * __i] + ((uint64_t)__ar[2 * __i + 1] << 32)) & _Max);
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__c_ = __x_[__r-1] == 0;
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__i_ = 0;
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}
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template<class _UIntType, size_t __w, size_t __s, size_t __r>
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_UIntType
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subtract_with_carry_engine<_UIntType, __w, __s, __r>::operator()()
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{
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const result_type& __xs = __x_[(__i_ + (__r - __s)) % __r];
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result_type& __xr = __x_[__i_];
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result_type __new_c = __c_ == 0 ? __xs < __xr : __xs != 0 ? __xs <= __xr : 1;
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__xr = (__xs - __xr - __c_) & _Max;
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__c_ = __new_c;
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__i_ = (__i_ + 1) % __r;
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return __xr;
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}
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template<class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
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bool
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operator==(
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const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x,
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const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __y)
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{
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if (__x.__c_ != __y.__c_)
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return false;
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if (__x.__i_ == __y.__i_)
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return _VSTD::equal(__x.__x_, __x.__x_ + _Rp, __y.__x_);
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if (__x.__i_ == 0 || __y.__i_ == 0)
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{
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size_t __j = _VSTD::min(_Rp - __x.__i_, _Rp - __y.__i_);
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if (!_VSTD::equal(__x.__x_ + __x.__i_, __x.__x_ + __x.__i_ + __j,
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__y.__x_ + __y.__i_))
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return false;
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if (__x.__i_ == 0)
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return _VSTD::equal(__x.__x_ + __j, __x.__x_ + _Rp, __y.__x_);
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return _VSTD::equal(__x.__x_, __x.__x_ + (_Rp - __j), __y.__x_ + __j);
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}
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if (__x.__i_ < __y.__i_)
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{
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size_t __j = _Rp - __y.__i_;
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if (!_VSTD::equal(__x.__x_ + __x.__i_, __x.__x_ + (__x.__i_ + __j),
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__y.__x_ + __y.__i_))
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return false;
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if (!_VSTD::equal(__x.__x_ + (__x.__i_ + __j), __x.__x_ + _Rp,
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__y.__x_))
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return false;
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return _VSTD::equal(__x.__x_, __x.__x_ + __x.__i_,
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__y.__x_ + (_Rp - (__x.__i_ + __j)));
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}
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size_t __j = _Rp - __x.__i_;
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if (!_VSTD::equal(__y.__x_ + __y.__i_, __y.__x_ + (__y.__i_ + __j),
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__x.__x_ + __x.__i_))
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return false;
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if (!_VSTD::equal(__y.__x_ + (__y.__i_ + __j), __y.__x_ + _Rp,
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__x.__x_))
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return false;
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return _VSTD::equal(__y.__x_, __y.__x_ + __y.__i_,
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__x.__x_ + (_Rp - (__y.__i_ + __j)));
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}
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template<class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
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inline _LIBCPP_INLINE_VISIBILITY
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bool
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operator!=(
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const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x,
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const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __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 _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
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basic_ostream<_CharT, _Traits>&
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operator<<(basic_ostream<_CharT, _Traits>& __os,
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const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __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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__os << __x.__x_[__x.__i_];
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for (size_t __j = __x.__i_ + 1; __j < _Rp; ++__j)
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__os << __sp << __x.__x_[__j];
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for (size_t __j = 0; __j < __x.__i_; ++__j)
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__os << __sp << __x.__x_[__j];
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__os << __sp << __x.__c_;
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return __os;
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}
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template <class _CharT, class _Traits,
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class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
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basic_istream<_CharT, _Traits>&
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operator>>(basic_istream<_CharT, _Traits>& __is,
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subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x)
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{
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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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_UInt __t[_Rp+1];
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for (size_t __i = 0; __i < _Rp+1; ++__i)
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__is >> __t[__i];
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if (!__is.fail())
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{
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for (size_t __i = 0; __i < _Rp; ++__i)
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__x.__x_[__i] = __t[__i];
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__x.__c_ = __t[_Rp];
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__x.__i_ = 0;
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}
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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_SUBTRACT_WITH_CARRY_ENGINE_H
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