CompressedGrowableBuffer.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
#include "Containers/Array.h"
#include "UObject/NameTypes.h"
 
struct FCompressedGrowableBuffer
{
public:
    CORE_API FCompressedGrowableBuffer(int32 MaxPendingBufferSize, FName CompressionFormat, ECompressionFlags CompressionFlags=COMPRESS_None);
 
    CORE_API void Lock();
    CORE_API void Unlock();
 
    CORE_API int32 Append( void* Data, int32 Size );
 
    CORE_API void* Access( int32 Offset );
 
    int32 Num() const
    {
        return NumEntries;
    }
 
    SIZE_T GetAllocatedSize() const
    {
        return CompressedBuffer.GetAllocatedSize()
            + PendingCompressionBuffer.GetAllocatedSize()
            + DecompressedBuffer.GetAllocatedSize()
            + BookKeepingInfo.GetAllocatedSize();
    }
 
private:
 
    struct FBufferBookKeeping
    {
        int32 CompressedOffset;
        int32 CompressedSize;
        int32 UncompressedOffset;
        int32 UncompressedSize;
    };
 
    int32                   MaxPendingBufferSize;
    FName               CompressionFormat;
    ECompressionFlags   CompressionFlags;
    int32                   CurrentOffset;
    int32                   NumEntries;
    TArray<uint8>       CompressedBuffer;
    TArray<uint8>       PendingCompressionBuffer;
    TArray<uint8>       DecompressedBuffer;
    int32                   DecompressedBufferBookKeepingInfoIndex;
    TArray<FBufferBookKeeping>  BookKeepingInfo;
};