#include <Compression.h>

Static Public Member Functions
static CORE_API uint32	GetCompressorVersion (FName FormatName)

static CORE_API bool	CompressMemoryBound (FName InFormatName, int64 &OutBufferSizeRequired, int64 InUncompressedSizeBytes, uintptr_t InCompressionData=0)

static CORE_API int32	CompressMemoryBound (FName FormatName, int32 UncompressedSize, ECompressionFlags Flags=COMPRESS_NoFlags, int32 CompressionData=0)

static CORE_API bool	GetMaximumCompressedSize (FName InFormatName, int64 &OutMaxCompressedSize, int64 InUncompressedSizeBytes, uintptr_t InCompressionData=0)

static CORE_API int32	GetMaximumCompressedSize (FName FormatName, int32 UncompressedSize, ECompressionFlags Flags=COMPRESS_NoFlags, int32 CompressionData=0)

static CORE_API bool	CompressMemory (FName FormatName, void CompressedBuffer, int64 &CompressedSize, const void UncompressedBuffer, int64 UncompressedSize, ECompressionFlags Flags=COMPRESS_NoFlags, uintptr_t CompressionData=0)

static CORE_API bool	CompressMemory (FName FormatName, void CompressedBuffer, int32 &CompressedSize, const void UncompressedBuffer, int32 UncompressedSize, ECompressionFlags Flags=COMPRESS_NoFlags, int32 CompressionData=0)

static CORE_API 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)

static CORE_API bool	CompressMemoryIfWorthDecompressing (FName FormatName, int32 MinBytesSaved, int32 MinPercentSaved, void CompressedBuffer, int32 &CompressedSize, const void UncompressedBuffer, int32 UncompressedSize, ECompressionFlags Flags=COMPRESS_NoFlags, int32 CompressionData=0)

static CORE_API bool	UncompressMemory (FName FormatName, void UncompressedBuffer, int64 UncompressedSize, const void CompressedBuffer, int64 CompressedSize, ECompressionFlags Flags=COMPRESS_NoFlags, uintptr_t CompressionData=0)

static CORE_API bool	UncompressMemoryStream (FName FormatName, void UncompressedBuffer, int64 UncompressedSize, IMemoryReadStream Stream, int64 StreamOffset, int64 CompressedSize, ECompressionFlags Flags=COMPRESS_NoFlags, uintptr_t CompressionData=0)

static CORE_API FString	GetCompressorDDCSuffix (FName FormatName)

static CORE_API bool	IsFormatValid (FName FormatName)

static CORE_API bool	VerifyCompressionFlagsValid (int32 InCompressionFlags)

static CORE_API FName	GetCompressionFormatFromDeprecatedFlags (ECompressionFlags DeprecatedFlags)

Static Public Attributes
static CORE_API TAtomic< uint64 >	CompressorTimeCycles

static CORE_API TAtomic< uint64 >	CompressorSrcBytes

static CORE_API TAtomic< uint64 >	CompressorDstBytes

Member Function Documentation

◆ CompressMemory() [1/2]

bool FCompression::CompressMemory	(	FName	FormatName,
		void *	CompressedBuffer,
		int32 &	CompressedSize,
		const void *	UncompressedBuffer,
		int32	UncompressedSize,
		ECompressionFlags	Flags = `COMPRESS_NoFlags`,
		int32	CompressionData = `0`
	)

static

◆ CompressMemory() [2/2]

bool FCompression::CompressMemory	(	FName	FormatName,
		void *	CompressedBuffer,
		int64 &	CompressedSize,
		const void *	UncompressedBuffer,
		int64	UncompressedSize,
		ECompressionFlags	Flags = `COMPRESS_NoFlags`,
		uintptr_t	CompressionData = `0`
	)

static

Thread-safe abstract compression routine. Compresses memory from uncompressed buffer and writes it to compressed buffer. Updates CompressedSize with size of compressed data. Compression controlled by the passed in flags. CompressMemory is expected to return true and write valid data even if it expanded bytes. Always check CompressedSize >= UncompressedSize and fall back to uncompressed, or use CompressMemoryIfWorthDecompressing

Parameters

FormatName	Name of the compression format
CompressedBuffer	Buffer compressed data is going to be written to
CompressedSize	[in/out] Size of CompressedBuffer, at exit will be size of compressed data
UncompressedBuffer	Buffer containing uncompressed data
UncompressedSize	Size of uncompressed data in bytes
Flags	Flags to control what method to use and optionally control memory vs speed
CompressionData	Additional compression parameter - see comments a top of FCompression struct.

Returns: true if compression succeeds, false if it fails because CompressedBuffer was too small or other reasons

◆ CompressMemoryBound() [1/2]

int32 FCompression::CompressMemoryBound	(	FName	FormatName,
		int32	UncompressedSize,
		ECompressionFlags	Flags = `COMPRESS_NoFlags`,
		int32	CompressionData = `0`
	)

static

◆ CompressMemoryBound() [2/2]

bool FCompression::CompressMemoryBound	(	FName	InFormatName,
		int64 &	OutBufferSizeRequired,
		int64	InUncompressedSizeBytes,
		uintptr_t	InCompressionData = `0`
	)

static

Thread-safe abstract compression routine to query buffer requirements for a compression operation. This is the minimize size to allocate the buffer for CompressMemory (encoding). Use GetMaximumCompressedSize at decode to know how large a compressed buffer may be.

Despite the name, this has nothing to do with how much memory will be allocated during compression.

Parameters

FormatName	Name of the compression format
UncompressedSize	Size of uncompressed data in bytes
CompressionData	Additional compression parameter - see comments a top of FCompression struct.
OutBufferSizeRequired	The maximum possible bytes needed for compression of a data buffer of the given size.

Returns: false if the bounds couldn't be determined - e.g. the format is unknown or the size isn't supported by the format.

◆ CompressMemoryIfWorthDecompressing() [1/2]

bool FCompression::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`
	)

static

Same as CompressMemory but evaluates if the compression gain is worth the runtime decode time.

Parameters

FormatName	Name of the compression format
bOutWasCompressed	[out] Whether the compression was worth it. The data is still compressed.
MinBytesSaved	Minimum amount of bytes which should be saved when performing compression, otherwise false is returned
MinPercentSaved	Minimum percentage of the buffer which should be saved when performing compression, otherwise false is returned
CompressedBuffer	Buffer compressed data is going to be written to
CompressedSize	[in/out] Size of CompressedBuffer, at exit will be size of compressed data
UncompressedBuffer	Buffer containing uncompressed data
UncompressedSize	Size of uncompressed data in bytes
Flags	Flags to control what method to use and optionally control memory vs speed
CompressionData	Additional compression parameter - see comments a top of FCompression struct.

Returns: true if compression succeeds, false if it fails because CompressedBuffer was too small or other reasons

◆ CompressMemoryIfWorthDecompressing() [2/2]

bool FCompression::CompressMemoryIfWorthDecompressing	(	FName	FormatName,
		int32	MinBytesSaved,
		int32	MinPercentSaved,
		void *	CompressedBuffer,
		int32 &	CompressedSize,
		const void *	UncompressedBuffer,
		int32	UncompressedSize,
		ECompressionFlags	Flags = `COMPRESS_NoFlags`,
		int32	CompressionData = `0`
	)

static

◆ GetCompressionFormatFromDeprecatedFlags()

FName FCompression::GetCompressionFormatFromDeprecatedFlags ( ECompressionFlags DeprecatedFlags )

static

◆ GetCompressorDDCSuffix()

FString FCompression::GetCompressorDDCSuffix ( FName FormatName )

static

Returns a string which can be used to identify if a format has become out of date

Parameters

FormatName name of the format to retrieve the DDC suffix for

Returns: unique DDC key string which will be different when the format is changed / updated

◆ GetCompressorVersion()

uint32 FCompression::GetCompressorVersion ( FName FormatName )

static

Returns a version number for a specified format

Parameters

FormatName Compressor format name (eg NAME_Zlib)

Returns: An interpretation of an internal version number for a specific format (different formats will have different layouts) this should change if a version is updated

◆ GetMaximumCompressedSize() [1/2]

int32 FCompression::GetMaximumCompressedSize	(	FName	FormatName,
		int32	UncompressedSize,
		ECompressionFlags	Flags = `COMPRESS_NoFlags`,
		int32	CompressionData = `0`
	)

static

◆ GetMaximumCompressedSize() [2/2]

bool FCompression::GetMaximumCompressedSize	(	FName	InFormatName,
		int64 &	OutMaxCompressedSize,
		int64	InUncompressedSizeBytes,
		uintptr_t	InCompressionData = `0`
	)

static

Thread-safe abstract compression routine to query maximum compressed size that could be made. This is used for making buffers that could hold any compressed buffer that started uncompressed with the given size. It's distinct from the buffer needed to compress! If you are calling CompressMemory then you need to pass a buffer sized based on CompressMemoryBound!

CompressMemoryBound is strictly greater equal GetMaximumCompressedSize.

Parameters

FormatName	Name of the compression format
OutMaxCompressedSize	The maximum possible size of valid compressed data made by this format
InUncompressedSizeBytes	Size of uncompressed data in bytes
CompressionData	Additional compression parameter - see comments a top of FCompression struct.

Returns: success

◆ IsFormatValid()

bool FCompression::IsFormatValid ( FName FormatName )

static

Checks to see if a format will be usable, so that a fallback can be used

Parameters

FormatName The name of the format to test

◆ UncompressMemory()

bool FCompression::UncompressMemory	(	FName	FormatName,
		void *	UncompressedBuffer,
		int64	UncompressedSize,
		const void *	CompressedBuffer,
		int64	CompressedSize,
		ECompressionFlags	Flags = `COMPRESS_NoFlags`,
		uintptr_t	CompressionData = `0`
	)

static

Thread-safe abstract decompression routine. Uncompresses memory from compressed buffer and writes it to uncompressed buffer. UncompressedSize is expected to be the exact size of the data after decompression.

Parameters

FormatName	Name of the compression format
UncompressedBuffer	Buffer containing uncompressed data
UncompressedSize	Size of uncompressed data in bytes
CompressedBuffer	Buffer compressed data is going to be read from
CompressedSize	Size of CompressedBuffer data in bytes
Flags	Flags to control what method to use to decompress
CompressionData	Additional decompression parameter (specifies BitWindow value for ZLIB compression format)

Returns: true if compression succeeds, false if it fails because CompressedBuffer was too small or other reasons

◆ UncompressMemoryStream()

bool FCompression::UncompressMemoryStream	(	FName	FormatName,
		void *	UncompressedBuffer,
		int64	UncompressedSize,
		IMemoryReadStream *	Stream,
		int64	StreamOffset,
		int64	CompressedSize,
		ECompressionFlags	Flags = `COMPRESS_NoFlags`,
		uintptr_t	CompressionData = `0`
	)

static

Wraps UncompressMemory to provide access with a IMemoryReadStream interface, attempting to avoid copying in to a contiguous buffer doe decompression if the format supports it. If not, a CompressedSize temp buffer will be allocated.

◆ VerifyCompressionFlagsValid()

bool FCompression::VerifyCompressionFlagsValid ( int32 InCompressionFlags )

static

Verifies if the passed in value represents valid compression flags

Parameters

InCompressionFlags Value to test

Member Data Documentation

◆ CompressorDstBytes

TAtomic< uint64 > FCompression::CompressorDstBytes

static

Number of bytes after compression.

Nubmer of bytes after compression.

◆ CompressorSrcBytes

TAtomic< uint64 > FCompression::CompressorSrcBytes

static

Number of bytes before compression.

◆ CompressorTimeCycles

TAtomic< uint64 > FCompression::CompressorTimeCycles

static

CompressionData is per-compressor data passed through this API and is interpreted by the codecs. For builtins: NAME_Zlib BitWindow NAME_LZ4 Unused NAME_Gzip Unused NAME_Oodle Unused Time spent compressing data in cycles.

Time spent compressing data in cycles.

The documentation for this struct was generated from the following files:

Engine/Source/Runtime/Core/Public/Misc/Compression.h
Engine/Source/Runtime/Core/Private/Misc/Compression.cpp

Static Public Member Functions

Static Public Attributes

Member Function Documentation

◆ CompressMemory() [1/2]

◆ CompressMemory() [2/2]

◆ CompressMemoryBound() [1/2]

◆ CompressMemoryBound() [2/2]

◆ CompressMemoryIfWorthDecompressing() [1/2]

◆ CompressMemoryIfWorthDecompressing() [2/2]

◆ GetCompressionFormatFromDeprecatedFlags()

◆ GetCompressorDDCSuffix()

◆ GetCompressorVersion()

◆ GetMaximumCompressedSize() [1/2]

◆ GetMaximumCompressedSize() [2/2]

◆ IsFormatValid()

◆ UncompressMemory()

◆ UncompressMemoryStream()

◆ VerifyCompressionFlagsValid()

Member Data Documentation

◆ CompressorDstBytes

◆ CompressorSrcBytes

◆ CompressorTimeCycles