// Copyright 1998-2019 Epic Games, Inc. All Rights Reserved.

#pragma once


#include "CoreTypes.h"

/**
 * Used to declare an untyped array of data with compile-time alignment.
 * It needs to use template specialization as the MS_ALIGN and GCC_ALIGN macros require literal parameters.
 */
template<int32 Size,uint32 Alignment>
struct TAlignedBytes; // this intentionally won't compile, we don't support the requested alignment

/** Unaligned storage. */
template<int32 Size>
struct TAlignedBytes<Size,1>
{
	uint8 Pad[Size];
};


// C++/CLI doesn't support alignment of native types in managed code, so we enforce that the element
// size is a multiple of the desired alignment
#ifdef __cplusplus_cli
	#define IMPLEMENT_ALIGNED_STORAGE(Align) \
		template<int32 Size>        \
		struct TAlignedBytes<Size,Align> \
		{ \
			uint8 Pad[Size]; \
			static_assert(Size % Align == 0, "CLR interop types must not be aligned."); \
		};
#else
/** A macro that implements TAlignedBytes for a specific alignment. */
#define IMPLEMENT_ALIGNED_STORAGE(Align) \
	template<int32 Size>        \
	struct TAlignedBytes<Size,Align> \
	{ \
		struct MS_ALIGN(Align) TPadding \
		{ \
			uint8 Pad[Size]; \
		} GCC_ALIGN(Align); \
		TPadding Padding; \
	};
#endif

// Implement TAlignedBytes for these alignments.
IMPLEMENT_ALIGNED_STORAGE(16);
IMPLEMENT_ALIGNED_STORAGE(8);
IMPLEMENT_ALIGNED_STORAGE(4);
IMPLEMENT_ALIGNED_STORAGE(2);

#undef IMPLEMENT_ALIGNED_STORAGE

/** An untyped array of data with compile-time alignment and size derived from another type. */
template<typename ElementType>
struct TTypeCompatibleBytes :
	public TAlignedBytes<
		sizeof(ElementType),
		alignof(ElementType)
		>
{
	ElementType*		GetTypedPtr()		{ return (ElementType*)this;  }
	const ElementType*	GetTypedPtr() const	{ return (const ElementType*)this; }
};