//===----------------------------------------------------------------------===//
//
// 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 _LIBCUDACXX___TYPE_TRAITS_ALIGNED_STORAGE_H
#define _LIBCUDACXX___TYPE_TRAITS_ALIGNED_STORAGE_H

#include <cuda/std/detail/__config>

#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
#  pragma GCC system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
#  pragma clang system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
#  pragma system_header
#endif // no system header

#include <cuda/std/__type_traits/conditional.h>
#include <cuda/std/__type_traits/integral_constant.h>
#include <cuda/std/__type_traits/nat.h>
#include <cuda/std/__type_traits/type_list.h>
#include <cuda/std/cstddef>

_LIBCUDACXX_BEGIN_NAMESPACE_STD

template <class _Tp>
struct __align_type
{
  static const size_t value = _LIBCUDACXX_PREFERRED_ALIGNOF(_Tp);
  typedef _Tp type;
};

struct __struct_double
{
  long double __lx;
};
struct __struct_double4
{
  double __lx[4];
};

typedef __type_list<
  __align_type<unsigned char>,
  __type_list<
    __align_type<unsigned short>,
    __type_list<
      __align_type<unsigned int>,
      __type_list<
        __align_type<unsigned long>,
        __type_list<__align_type<unsigned long long>,
                    __type_list<__align_type<double>,
                                __type_list<__align_type<long double>,
                                            __type_list<__align_type<__struct_double>,
                                                        __type_list<__align_type<__struct_double4>,
                                                                    __type_list<__align_type<int*>, __nat>>>>>>>>>>
  __all_types;

template <size_t _Align>
struct _CCCL_ALIGNAS(_Align) __fallback_overaligned
{};

template <class _TL, size_t _Align>
struct __find_pod;

template <class _Hp, size_t _Align>
struct __find_pod<__type_list<_Hp, __nat>, _Align>
{
  typedef __conditional_t<_Align == _Hp::value, typename _Hp::type, __fallback_overaligned<_Align>> type;
};

template <class _Hp, class _Tp, size_t _Align>
struct __find_pod<__type_list<_Hp, _Tp>, _Align>
{
  typedef __conditional_t<_Align == _Hp::value, typename _Hp::type, typename __find_pod<_Tp, _Align>::type> type;
};

template <class _TL, size_t _Len>
struct __find_max_align;

template <class _Hp, size_t _Len>
struct __find_max_align<__type_list<_Hp, __nat>, _Len> : public integral_constant<size_t, _Hp::value>
{};

template <size_t _Len, size_t _A1, size_t _A2>
struct __select_align
{
private:
  static const size_t __min = _A2 < _A1 ? _A2 : _A1;
  static const size_t __max = _A1 < _A2 ? _A2 : _A1;

public:
  static const size_t value = _Len < __max ? __min : __max;
};

template <class _Hp, class _Tp, size_t _Len>
struct __find_max_align<__type_list<_Hp, _Tp>, _Len>
    : public integral_constant<size_t, __select_align<_Len, _Hp::value, __find_max_align<_Tp, _Len>::value>::value>
{};

template <size_t _Len, size_t _Align = __find_max_align<__all_types, _Len>::value>
struct _CCCL_TYPE_VISIBILITY_DEFAULT aligned_storage
{
  typedef typename __find_pod<__all_types, _Align>::type _Aligner;
  union type
  {
    _Aligner __align;
    unsigned char __data[(_Len + _Align - 1) / _Align * _Align];
  };
};

#if _CCCL_STD_VER > 2011
template <size_t _Len, size_t _Align = __find_max_align<__all_types, _Len>::value>
using aligned_storage_t = typename aligned_storage<_Len, _Align>::type;
#endif

#define _CREATE_ALIGNED_STORAGE_SPECIALIZATION(n)               \
  template <size_t _Len>                                        \
  struct _CCCL_TYPE_VISIBILITY_DEFAULT aligned_storage<_Len, n> \
  {                                                             \
    struct _CCCL_ALIGNAS(n) type                                \
    {                                                           \
      unsigned char __lx[(_Len + n - 1) / n * n];               \
    };                                                          \
  }

_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x1);
_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x2);
_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x4);
_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x8);
_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x10);
_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x20);
_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x40);
_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x80);
_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x100);
_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x200);
_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x400);
_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x800);
_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x1000);
_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x2000);
// PE/COFF does not support alignment beyond 8192 (=0x2000)
#if !defined(_WIN32)
_CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x4000);
#endif // !defined(_WIN32)

#undef _CREATE_ALIGNED_STORAGE_SPECIALIZATION

_LIBCUDACXX_END_NAMESPACE_STD

#endif // _LIBCUDACXX___TYPE_TRAITS_ALIGNED_STORAGE_H
