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//===----------------------------------------------------------------------===//
//
// 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_SEED_SEQ_H
#define _LIBCPP___RANDOM_SEED_SEQ_H
#include <__algorithm/copy.h>
#include <__algorithm/fill.h>
#include <__algorithm/max.h>
#include <__config>
#include <initializer_list>
#include <vector>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
_LIBCPP_BEGIN_NAMESPACE_STD
class _LIBCPP_TEMPLATE_VIS seed_seq
{
public:
// types
typedef uint32_t result_type;
// constructors
_LIBCPP_INLINE_VISIBILITY
seed_seq() _NOEXCEPT {}
#ifndef _LIBCPP_CXX03_LANG
template<class _Tp, __enable_if_t<is_integral<_Tp>::value>* = nullptr>
_LIBCPP_INLINE_VISIBILITY
seed_seq(initializer_list<_Tp> __il) {
__init(__il.begin(), __il.end());
}
#endif // _LIBCPP_CXX03_LANG
template<class _InputIterator>
_LIBCPP_INLINE_VISIBILITY
seed_seq(_InputIterator __first, _InputIterator __last) {
static_assert(is_integral<typename iterator_traits<_InputIterator>::value_type>::value,
"Mandates: iterator_traits<InputIterator>::value_type is an integer type");
__init(__first, __last);
}
// generating functions
template<class _RandomAccessIterator>
void generate(_RandomAccessIterator __first, _RandomAccessIterator __last);
// property functions
_LIBCPP_INLINE_VISIBILITY
size_t size() const _NOEXCEPT {return __v_.size();}
template<class _OutputIterator>
_LIBCPP_INLINE_VISIBILITY
void param(_OutputIterator __dest) const
{_VSTD::copy(__v_.begin(), __v_.end(), __dest);}
seed_seq(const seed_seq&) = delete;
void operator=(const seed_seq&) = delete;
_LIBCPP_INLINE_VISIBILITY
static result_type _Tp(result_type __x) {return __x ^ (__x >> 27);}
private:
template<class _InputIterator>
void __init(_InputIterator __first, _InputIterator __last);
vector<result_type> __v_;
};
template<class _InputIterator>
void
seed_seq::__init(_InputIterator __first, _InputIterator __last)
{
for (_InputIterator __s = __first; __s != __last; ++__s)
__v_.push_back(*__s & 0xFFFFFFFF);
}
template<class _RandomAccessIterator>
void
seed_seq::generate(_RandomAccessIterator __first, _RandomAccessIterator __last)
{
if (__first != __last)
{
_VSTD::fill(__first, __last, 0x8b8b8b8b);
const size_t __n = static_cast<size_t>(__last - __first);
const size_t __s = __v_.size();
const size_t __t = (__n >= 623) ? 11
: (__n >= 68) ? 7
: (__n >= 39) ? 5
: (__n >= 7) ? 3
: (__n - 1) / 2;
const size_t __p = (__n - __t) / 2;
const size_t __q = __p + __t;
const size_t __m = _VSTD::max(__s + 1, __n);
// __k = 0;
{
result_type __r = 1664525 * _Tp(__first[0] ^ __first[__p]
^ __first[__n - 1]);
__first[__p] += __r;
__r += __s;
__first[__q] += __r;
__first[0] = __r;
}
// Initialize indexing terms used with if statements as an optimization to
// avoid calculating modulo n on every loop iteration for each term.
size_t __kmodn = 0; // __k % __n
size_t __k1modn = __n - 1; // (__k - 1) % __n
size_t __kpmodn = __p % __n; // (__k + __p) % __n
size_t __kqmodn = __q % __n; // (__k + __q) % __n
for (size_t __k = 1; __k <= __s; ++__k)
{
if (++__kmodn == __n)
__kmodn = 0;
if (++__k1modn == __n)
__k1modn = 0;
if (++__kpmodn == __n)
__kpmodn = 0;
if (++__kqmodn == __n)
__kqmodn = 0;
result_type __r = 1664525 * _Tp(__first[__kmodn] ^ __first[__kpmodn] ^ __first[__k1modn]);
__first[__kpmodn] += __r;
__r += __kmodn + __v_[__k - 1];
__first[__kqmodn] += __r;
__first[__kmodn] = __r;
}
for (size_t __k = __s + 1; __k < __m; ++__k)
{
if (++__kmodn == __n)
__kmodn = 0;
if (++__k1modn == __n)
__k1modn = 0;
if (++__kpmodn == __n)
__kpmodn = 0;
if (++__kqmodn == __n)
__kqmodn = 0;
result_type __r = 1664525 * _Tp(__first[__kmodn] ^ __first[__kpmodn] ^ __first[__k1modn]);
__first[__kpmodn] += __r;
__r += __kmodn;
__first[__kqmodn] += __r;
__first[__kmodn] = __r;
}
for (size_t __k = __m; __k < __m + __n; ++__k)
{
if (++__kmodn == __n)
__kmodn = 0;
if (++__k1modn == __n)
__k1modn = 0;
if (++__kpmodn == __n)
__kpmodn = 0;
if (++__kqmodn == __n)
__kqmodn = 0;
result_type __r = 1566083941 * _Tp(__first[__kmodn] + __first[__kpmodn] + __first[__k1modn]);
__first[__kpmodn] ^= __r;
__r -= __kmodn;
__first[__kqmodn] ^= __r;
__first[__kmodn] = __r;
}
}
}
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___RANDOM_SEED_SEQ_H
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