Lz4Decompressor Class Reference

Decompress data using the LZ4 algorithm created by Yann Collet. More...

#include <Lz4Decompressor.h>

Public Types
enum	Result { Success, IOError, InvalidArgument, NotSupported }
	Result codes. More...

Public Member Functions
	Lz4Decompressor (const void *data, const Size size)
	Constructor function. More...
Result	initialize ()
	Initialize the decompressor. More...
u64	getUncompressedSize () const
	Get size of the uncompressed data. More...
Result	read (void *buffer, const Size size) const
	Reads compressed data. More...

Private Types
enum	FrameFlgFields {   FrameDictIdShift = 0, FrameContentChkShift = 2, FrameContentSzShift = 3, FrameBlockChkShift = 4,   FrameBlockIndShift = 5, FrameVersionShift = 6 }
	Frame FLG Field Shift values. More...

Private Member Functions
const u32	decompress (const u8 *input, const Size inputSize, u8 *output, const Size outputSize) const
	Decompress a block of compressed data. More...
const u32	integerDecode (const u32 initial, const u8 *next, Size &byteCount) const
	Decode input data as integer (little-endian, 32-bit unsigned) More...

Private Attributes
const u8 *	m_inputData
	Compressed input data. More...
const Size	m_inputSize
	Total size in bytes of the compressed input data. More...
Size	m_frameDescSize
	Size of the frame descriptor in bytes. More...
bool	m_blockChecksums
	True if blocks have checksums enabled. More...
bool	m_contentChecksum
	True if the input data buffer contains content checksum. More...
u64	m_contentSize
	Content size as specified in the frame header. More...
Size	m_blockMaximumSize
	Maximum block size in bytes of the uncompressed content. More...

Static Private Attributes
static const u32	FrameMagic = 0x184D2204
	Magic number value marks the start of the frame header. More...
static const u8	FrameVersion = 0x01
	Current supported version of the LZ4 algorithm. More...
static const u32	EndMark = 0x00000000
	EndMark marks the end of the data stream. More...

Detailed Description

Decompress data using the LZ4 algorithm created by Yann Collet.

See also

http://www.lz4.org

https://lz4.github.io/lz4/

https://en.wikipedia.org/wiki/LZ4_(compression_algorithm)

Definition at line 39 of file Lz4Decompressor.h.

Member Enumeration Documentation

FrameFlgFields

enum Lz4Decompressor::FrameFlgFields

private

Frame FLG Field Shift values.

Enumerator
FrameDictIdShift
FrameContentChkShift
FrameContentSzShift
FrameBlockChkShift
FrameBlockIndShift
FrameVersionShift

Definition at line 49 of file Lz4Decompressor.h.

Result

enum Lz4Decompressor::Result

Result codes.

Enumerator
Success
IOError
InvalidArgument
NotSupported

Definition at line 70 of file Lz4Decompressor.h.

Constructor & Destructor Documentation

Lz4Decompressor()

Lz4Decompressor::Lz4Decompressor	(	const void *	data,
		const Size	size
	)

Constructor function.

Parameters

data	Input data buffer
size	Size in bytes of the input buffer

Definition at line 24 of file Lz4Decompressor.cpp.

Member Function Documentation

decompress()

const u32 Lz4Decompressor::decompress ( const u8 *  input, const Size  inputSize, u8 *  output, const Size  outputSize  ) const

private

Decompress a block of compressed data.

Parameters

input	Compressed block data
inputSize	Number of compressed bytes
output	Output buffer to decompress to
outputSize	Maximum number of bytes to decompress

Returns

Number of bytes decompressed

Definition at line 204 of file Lz4Decompressor.cpp.

References assert, MemoryBlock::copy(), DEBUG, integerDecode(), m_blockMaximumSize, and readLe16().

Referenced by read().

getUncompressedSize()

u64 Lz4Decompressor::getUncompressedSize

(

)

const

Get size of the uncompressed data.

Returns

Total size in bytes

Definition at line 125 of file Lz4Decompressor.cpp.

References m_contentSize.

Referenced by Decompress::decompressFile(), forkexec(), MpiTarget::initializeMaster(), CoreServer::loadKernel(), RecoveryServer::reloadProgram(), and MpiProxy::startRemoteProcess().

initialize()

Lz4Decompressor::Result Lz4Decompressor::initialize

(

)

Initialize the decompressor.

Returns

Result code

Definition at line 35 of file Lz4Decompressor.cpp.

References ERROR, FrameBlockChkShift, FrameBlockIndShift, FrameContentChkShift, FrameContentSzShift, FrameDictIdShift, FrameMagic, FrameVersion, FrameVersionShift, InvalidArgument, KiloByte, m_blockChecksums, m_blockMaximumSize, m_contentChecksum, m_contentSize, m_frameDescSize, m_inputData, m_inputSize, MegaByte, NotSupported, readLe32(), readLe64(), and Success.

Referenced by Decompress::decompressFile(), forkexec(), MpiTarget::initializeMaster(), CoreServer::loadKernel(), RecoveryServer::reloadProgram(), and MpiProxy::startRemoteProcess().

integerDecode()

const u32 Lz4Decompressor::integerDecode ( const u32  initial, const u8 *  next, Size &  byteCount  ) const

inlineprivate

Decode input data as integer (little-endian, 32-bit unsigned)

Parameters

initial	The initial integer value to use
next	Pointer to next data to decode as integer
byteCount	On output contains the number of bytes decoded

Returns

Decoded unsigned 32-bit integer value

Definition at line 179 of file Lz4Decompressor.cpp.

Referenced by decompress().

read()

Lz4Decompressor::Result Lz4Decompressor::read	(	void *	buffer,
		const Size	size
	)		const

Reads compressed data.

Parameters

buffer	Output buffer.
size	Number of bytes of uncompressed data to copy.

Returns

Result code

Definition at line 130 of file Lz4Decompressor.cpp.

References assert, MemoryBlock::copy(), decompress(), EndMark, m_blockChecksums, m_blockMaximumSize, m_frameDescSize, m_inputData, m_inputSize, readLe32(), and Success.

Referenced by Decompress::decompressFile(), forkexec(), MpiTarget::initializeMaster(), CoreServer::loadKernel(), RecoveryServer::reloadProgram(), and MpiProxy::startRemoteProcess().

Field Documentation

EndMark

const u32 Lz4Decompressor::EndMark = 0x00000000

staticprivate

EndMark marks the end of the data stream.

Definition at line 63 of file Lz4Decompressor.h.

Referenced by read().

FrameMagic

const u32 Lz4Decompressor::FrameMagic = 0x184D2204

staticprivate

Magic number value marks the start of the frame header.

Definition at line 44 of file Lz4Decompressor.h.

Referenced by initialize().

FrameVersion

const u8 Lz4Decompressor::FrameVersion = 0x01

staticprivate

Current supported version of the LZ4 algorithm.

Definition at line 60 of file Lz4Decompressor.h.

Referenced by initialize().

m_blockChecksums

bool Lz4Decompressor::m_blockChecksums

private

True if blocks have checksums enabled.

Definition at line 154 of file Lz4Decompressor.h.

Referenced by initialize(), and read().

m_blockMaximumSize

Size Lz4Decompressor::m_blockMaximumSize

private

Maximum block size in bytes of the uncompressed content.

Definition at line 163 of file Lz4Decompressor.h.

Referenced by decompress(), initialize(), and read().

m_contentChecksum

bool Lz4Decompressor::m_contentChecksum

private

True if the input data buffer contains content checksum.

Definition at line 157 of file Lz4Decompressor.h.

Referenced by initialize().

m_contentSize

u64 Lz4Decompressor::m_contentSize

private

Content size as specified in the frame header.

Definition at line 160 of file Lz4Decompressor.h.

Referenced by getUncompressedSize(), and initialize().

m_frameDescSize

Size Lz4Decompressor::m_frameDescSize

private

Size of the frame descriptor in bytes.

Definition at line 151 of file Lz4Decompressor.h.

Referenced by initialize(), and read().

m_inputData

const u8* Lz4Decompressor::m_inputData

private

Compressed input data.

Definition at line 145 of file Lz4Decompressor.h.

Referenced by initialize(), and read().

m_inputSize

const Size Lz4Decompressor::m_inputSize

private

Total size in bytes of the compressed input data.

Definition at line 148 of file Lz4Decompressor.h.

Referenced by initialize(), and read().

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

• lib/libexec/Lz4Decompressor.h
• lib/libexec/Lz4Decompressor.cpp