Compression.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Containers/Map.h"
#include "Containers/UnrealString.h"
#include "CoreTypes.h"
#include "HAL/CriticalSection.h"
#include "Misc/CompressionFlags.h"
#include "Templates/Atomic.h"
#include "UObject/NameTypes.h"
 
class IMemoryReadStream;
template <typename T> class TAtomic;
 
// Define global current platform default to current platform.  
// DEPRECATED, USE NAME_Zlib - was deprecated in 2018, leaving for grep until 5.6 or so.
//#define COMPRESS_Default          COMPRESS_ZLIB
 
#define LOADING_COMPRESSION_CHUNK_SIZE_PRE_369  32768
#define LOADING_COMPRESSION_CHUNK_SIZE          131072
#define SAVING_COMPRESSION_CHUNK_SIZE           LOADING_COMPRESSION_CHUNK_SIZE
 
struct FCompression
{
    CORE_API static TAtomic<uint64> CompressorTimeCycles;
    CORE_API static TAtomic<uint64> CompressorSrcBytes;
    CORE_API static TAtomic<uint64> CompressorDstBytes;
 
 
    CORE_API static uint32 GetCompressorVersion(FName FormatName);
 
    CORE_API static bool CompressMemoryBound(FName InFormatName, int64& OutBufferSizeRequired, int64 InUncompressedSizeBytes, uintptr_t InCompressionData = 0);
 
    // Thunks to the 64 bit, prefer that as this can only Fatal on error!
    CORE_API static int32 CompressMemoryBound(FName FormatName, int32 UncompressedSize, ECompressionFlags Flags = COMPRESS_NoFlags, int32 CompressionData = 0);
    
    CORE_API static bool GetMaximumCompressedSize(FName InFormatName, int64& OutMaxCompressedSize, int64 InUncompressedSizeBytes, uintptr_t InCompressionData=0);
 
    // Thunks to the 64 bit version, prefer that as this can only Fatal on error!
    UE_DEPRECATED(5.5, "Use the 64 bit version")
    CORE_API static int32 GetMaximumCompressedSize(FName FormatName, int32 UncompressedSize, ECompressionFlags Flags = COMPRESS_NoFlags, int32 CompressionData = 0);
 
    CORE_API static bool CompressMemory(FName FormatName, void* CompressedBuffer, int64& CompressedSize, const void* UncompressedBuffer, int64 UncompressedSize, ECompressionFlags Flags = COMPRESS_NoFlags, uintptr_t CompressionData = 0);
 
    // Thunks to 64 bit CompressMemory, favor that.
    CORE_API static bool CompressMemory(FName FormatName, void* CompressedBuffer, int32& CompressedSize, const void* UncompressedBuffer, int32 UncompressedSize, ECompressionFlags Flags = COMPRESS_NoFlags, int32 CompressionData = 0);
    
    CORE_API static bool CompressMemoryIfWorthDecompressing(FName FormatName, bool& bOutWasCompressed, int64 MinBytesSaved, int32 MinPercentSaved, void* CompressedBuffer, int64& CompressedSize, const void* UncompressedBuffer, int64 UncompressedSize, ECompressionFlags Flags = COMPRESS_NoFlags, uintptr_t CompressionData = 0);
 
    // 32 bit thunk. This legacy function doens't separate bOutWasCompressed vs general compress failure and will return false in both cases.
    CORE_API static bool CompressMemoryIfWorthDecompressing(FName FormatName, int32 MinBytesSaved, int32 MinPercentSaved, void* CompressedBuffer, int32& CompressedSize, const void* UncompressedBuffer, int32 UncompressedSize, ECompressionFlags Flags = COMPRESS_NoFlags, int32 CompressionData = 0);
 
    CORE_API static bool UncompressMemory(FName FormatName, void* UncompressedBuffer, int64 UncompressedSize, const void* CompressedBuffer, int64 CompressedSize, ECompressionFlags Flags=COMPRESS_NoFlags, uintptr_t CompressionData=0);
 
    CORE_API static bool UncompressMemoryStream(FName FormatName, void* UncompressedBuffer, int64 UncompressedSize, IMemoryReadStream* Stream, int64 StreamOffset, int64 CompressedSize, ECompressionFlags Flags = COMPRESS_NoFlags, uintptr_t CompressionData = 0);
 
 
    CORE_API static FString GetCompressorDDCSuffix(FName FormatName);
 
    CORE_API static bool IsFormatValid(FName FormatName);
 
    CORE_API static bool VerifyCompressionFlagsValid(int32 InCompressionFlags);
 
    // deprecating this because we "should", but all internal references to these flags were deprecated in 4.21 so hopefully no one is using them anymore!
    UE_DEPRECATED(5.5, "Use the direct FName instead e.g NAME_Oodle")
    CORE_API static FName GetCompressionFormatFromDeprecatedFlags(ECompressionFlags DeprecatedFlags);
 
private:
    
    static struct ICompressionFormat* GetCompressionFormat(FName Method, bool bErrorOnFailure=true);
 
    static TMap<FName, struct ICompressionFormat*> CompressionFormats;
    static FCriticalSection CompressionFormatsCriticalSection;
 
};