// Copyright 1998-2015 Epic Games, Inc. All Rights Reserved.

/*=============================================================================
	HlslUtils.cpp - Utils for HLSL.
=============================================================================*/

#include "ShaderCompilerCommon.h"
#include "HlslUtils.h"

namespace CrossCompiler
{
	namespace Memory
	{
		static struct FPagePoolInstance
		{
			~FPagePoolInstance()
			{
				check(UsedPages.Num() == 0);
				for (int32 Index = 0; Index < FreePages.Num(); ++Index)
				{
					delete FreePages[Index];
				}
			}

			FPage* AllocatePage()
			{
				FScopeLock ScopeLock(&CriticalSection);

				if (FreePages.Num() == 0)
				{
					FreePages.Add(new FPage(PageSize));
				}

				auto* Page = FreePages.Last();
				FreePages.RemoveAt(FreePages.Num() - 1, 1, false);
				UsedPages.Add(Page);
				return Page;
			}

			void FreePage(FPage* Page)
			{
				FScopeLock ScopeLock(&CriticalSection);

				int32 Index = UsedPages.Find(Page);
				check(Index >= 0);
				UsedPages.RemoveAt(Index, 1, false);
				FreePages.Add(Page);
			}

			TArray<FPage*, TInlineAllocator<8> > FreePages;
			TArray<FPage*, TInlineAllocator<8> > UsedPages;

			FCriticalSection CriticalSection;

		} GMemoryPagePool;

		FPage* FPage::AllocatePage()
		{
#if USE_PAGE_POOLING
			return GMemoryPagePool.AllocatePage();
#else
			return new FPage(PageSize);
#endif
		}

		void FPage::FreePage(FPage* Page)
		{
#if USE_PAGE_POOLING
			GMemoryPagePool.FreePage(Page);
#else
			delete Page;
#endif
		}
	}
}