com.ning.compress.lzf

Class ChunkDecoder

java.lang.Object

com.ning.compress.lzf.ChunkDecoder

Direct Known Subclasses:

UnsafeChunkDecoder, VanillaChunkDecoder

public abstract class ChunkDecoder
extends Object

Decoder that handles decoding of sequence of encoded LZF chunks, combining them into a single contiguous result byte array.

Note that instances have no state, so they are fully thread-safe and reusable.

Author:

Tatu Saloranta (tatu.saloranta@iki.fi)

Field Summary

Fields

Modifier and Type	Field and Description
protected static byte	BYTE_NULL
protected static int	HEADER_BYTES

Constructor Summary

Constructors

Constructor and Description
ChunkDecoder()

Method Summary

Modifier and Type	Method and Description
protected void	_reportArrayOverflow(byte[] targetBuffer, int outPtr, int dataLen) Helper method called when it is determined that the target buffer can not hold all data to copy or uncompress
protected void	_reportCorruptHeader()
static int	calculateUncompressedSize(byte[] data, int ptr, int length) Helper method that will calculate total uncompressed size, for sequence of one or more LZF blocks stored in given byte array.
byte[]	decode(byte[] inputBuffer) Method for decompressing a block of input data encoded in LZF block structure (compatible with lzf command line utility), and can consist of any number of blocks.
int	decode(byte[] inputBuffer, byte[] targetBuffer) Method for decompressing a block of input data encoded in LZF block structure (compatible with lzf command line utility), and can consist of any number of blocks.
byte[]	decode(byte[] inputBuffer, int inputPtr, int inputLen) Method for decompressing a block of input data encoded in LZF block structure (compatible with lzf command line utility), and can consist of any number of blocks.
int	decode(byte[] sourceBuffer, int inPtr, int inLength, byte[] targetBuffer) Method for decompressing a block of input data encoded in LZF block structure (compatible with LZF command line utility), and can consist of any number of blocks.
abstract void	decodeChunk(byte[] in, int inPos, byte[] out, int outPos, int outEnd) Main decode method for individual chunks.
abstract int	decodeChunk(InputStream is, byte[] inputBuffer, byte[] outputBuffer) Main decode from a stream.
protected static void	readFully(InputStream is, boolean compressed, byte[] outputBuffer, int offset, int len)
protected static int	readHeader(InputStream is, byte[] inputBuffer) Helper method to forcibly load header bytes that must be read before chunk can be handled.
protected static void	skipFully(InputStream is, int amount)
abstract int	skipOrDecodeChunk(InputStream is, byte[] inputBuffer, byte[] outputBuffer, long maxToSkip)
protected static int	uint16(byte[] data, int ptr)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

BYTE_NULL

protected static final byte BYTE_NULL

See Also:

Constant Field Values

HEADER_BYTES

protected static final int HEADER_BYTES

See Also:

Constant Field Values

Constructor Detail

ChunkDecoder

public ChunkDecoder()

Method Detail

decode

public final byte[] decode(byte[] inputBuffer)
                    throws LZFException

Method for decompressing a block of input data encoded in LZF block structure (compatible with lzf command line utility), and can consist of any number of blocks. Note that input MUST consists of a sequence of one or more complete chunks; partial chunks can not be handled.

Throws:

LZFException

decode

public final byte[] decode(byte[] inputBuffer,
                           int inputPtr,
                           int inputLen)
                    throws LZFException

Method for decompressing a block of input data encoded in LZF block structure (compatible with lzf command line utility), and can consist of any number of blocks. Note that input MUST consists of a sequence of one or more complete chunks; partial chunks can not be handled.

Throws:

LZFException

decode

public final int decode(byte[] inputBuffer,
                        byte[] targetBuffer)
                 throws LZFException

Method for decompressing a block of input data encoded in LZF block structure (compatible with lzf command line utility), and can consist of any number of blocks. Note that input MUST consists of a sequence of one or more complete chunks; partial chunks can not be handled.

Throws:

LZFException

decode

public int decode(byte[] sourceBuffer,
                  int inPtr,
                  int inLength,
                  byte[] targetBuffer)
           throws LZFException

Method for decompressing a block of input data encoded in LZF block structure (compatible with LZF command line utility), and can consist of any number of blocks. Note that input MUST consists of a sequence of one or more complete chunks; partial chunks can not be handled.

Throws:

LZFException

decodeChunk

public abstract int decodeChunk(InputStream is,
                                byte[] inputBuffer,
                                byte[] outputBuffer)
                         throws IOException

Main decode from a stream. Decompressed bytes are placed in the outputBuffer, inputBuffer is a "scratch-area".

Parameters:

is - An input stream of LZF compressed bytes

inputBuffer - A byte array used as a scratch area.

outputBuffer - A byte array in which the result is returned

Returns:

The number of bytes placed in the outputBuffer.

Throws:

IOException

decodeChunk

public abstract void decodeChunk(byte[] in,
                                 int inPos,
                                 byte[] out,
                                 int outPos,
                                 int outEnd)
                          throws LZFException

Main decode method for individual chunks.

Throws:

LZFException

skipOrDecodeChunk

public abstract int skipOrDecodeChunk(InputStream is,
                                      byte[] inputBuffer,
                                      byte[] outputBuffer,
                                      long maxToSkip)
                               throws IOException

Returns:

If positive number, number of bytes skipped; if -1, end-of-stream was reached; otherwise, amount of content decoded (using formula of returnValue = -(decodedAmount + 2))

Throws:

IOException

calculateUncompressedSize

public static int calculateUncompressedSize(byte[] data,
                                            int ptr,
                                            int length)
                                     throws LZFException

Helper method that will calculate total uncompressed size, for sequence of one or more LZF blocks stored in given byte array. Will do basic sanity checking, so that this method can be called to verify against some types of corruption.

Throws:

LZFException

uint16

protected static final int uint16(byte[] data,
                                  int ptr)

readHeader

protected static final int readHeader(InputStream is,
                                      byte[] inputBuffer)
                               throws IOException

Helper method to forcibly load header bytes that must be read before chunk can be handled.

Throws:

IOException

readFully

protected static final void readFully(InputStream is,
                                      boolean compressed,
                                      byte[] outputBuffer,
                                      int offset,
                                      int len)
                               throws IOException

Throws:

IOException

skipFully

protected static final void skipFully(InputStream is,
                                      int amount)
                               throws IOException

Throws:

IOException

_reportCorruptHeader

protected void _reportCorruptHeader()
                             throws LZFException

Throws:

LZFException

_reportArrayOverflow

protected void _reportArrayOverflow(byte[] targetBuffer,
                                    int outPtr,
                                    int dataLen)
                             throws LZFException

Helper method called when it is determined that the target buffer can not hold all data to copy or uncompress

Throws:

LZFException