org.gridfour.lsop

Class LsHeader

java.lang.Object

org.gridfour.lsop.LsHeader

public class LsHeader
extends Object

Provides utilities for reading the LsHeader from a packing.

Currently, the header definition is hard-wired for 8 predictor coefficients. But this value is subject to change in the future.

Field Summary

Fields

Modifier and Type	Field and Description
protected int	codecIndex
static int	COMPRESSION_TYPE_DEFLATE
static int	COMPRESSION_TYPE_HUFFMAN
protected int	compressionType
protected int	headerSize
protected int	nCoefficients
protected int	nInitializerCodes
protected int	nInteriorCodes
protected int	seed
protected float[]	u

Constructor Summary

Constructors

Constructor and Description
LsHeader(byte[] packing, int packingOffset) Constructs a instance populated with parameters extracted from the packing

Method Summary

Modifier and Type	Method and Description
int	getCodecIndex() Get the codec index from the packing
int	getCodedInitializerLength() Get the length of the encoded text (M32 codes) for the initializers
int	getCodedInteriorLength() Get the length of the encoded text (M32 codes) for the interior.
int	getCompressionType() Indicates whether the data was compresses using Huffman coding or Deflate.
int	getHeaderSize() Get the size of the header, in bytes
float[]	getOptimalPredictorCoefficients() Get the optimal predictor coefficients from the packing
int	getPredictorCoefficientCount() Gets the number of predictors coefficients defined for the encoding
int	getSeed() Get the seed value from the packing
static byte[]	packHeader(int codecIndex, int nCoefficients, int seed, float[] u, int nInitializationCodes, int nInteriorCodes, int compressionTypeCode) Packs the metadata ("header") for a LSOP compression into an array of bytes
static byte[]	packHeader(int codecIndex, LsOptimalPredictorResult result, int compressionTypeCode)

Methods inherited from class java.lang.Object

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

Field Detail

COMPRESSION_TYPE_HUFFMAN

public static final int COMPRESSION_TYPE_HUFFMAN

See Also:

Constant Field Values

COMPRESSION_TYPE_DEFLATE

public static final int COMPRESSION_TYPE_DEFLATE

See Also:

Constant Field Values

codecIndex

protected final int codecIndex

nCoefficients

protected final int nCoefficients

seed

protected final int seed

u

protected final float[] u

nInitializerCodes

protected final int nInitializerCodes

nInteriorCodes

protected final int nInteriorCodes

compressionType

protected final int compressionType

headerSize

protected final int headerSize

Constructor Detail

LsHeader

public LsHeader(byte[] packing,
                int packingOffset)

Constructs a instance populated with parameters extracted from the packing

Parameters:

packing - an array of bytes containing the encoded parameters; it is assumed that the packing is at least as long as the required storage

packingOffset - the starting position within the encoded packing

Method Detail

packHeader

public static byte[] packHeader(int codecIndex,
                                int nCoefficients,
                                int seed,
                                float[] u,
                                int nInitializationCodes,
                                int nInteriorCodes,
                                int compressionTypeCode)

Packs the metadata ("header") for a LSOP compression into an array of bytes

Parameters:

codecIndex - the index of the CODEC as defined by the calling application.

nCoefficients - the number of coefficients

seed - the seed value

u - the compression coefficients, should be dimensioned to at least nCoefficients

nInitializationCodes - the number of M32 codes in the initializer

nInteriorCodes - the number of M32 codes in the interior

compressionTypeCode - indicates which standard compression method (Huffman or Deflate) was used to compress the M32 code sequence

Returns:

an array in the exact size of the packing.

packHeader

public static byte[] packHeader(int codecIndex,
                                LsOptimalPredictorResult result,
                                int compressionTypeCode)

getCodecIndex

public int getCodecIndex()

Get the codec index from the packing

Returns:

the codecIndex

getPredictorCoefficientCount

public int getPredictorCoefficientCount()

Gets the number of predictors coefficients defined for the encoding

Returns:

a positive integer (currently, 8 or 12)

getSeed

public int getSeed()

Get the seed value from the packing

Returns:

the seed

getOptimalPredictorCoefficients

public float[] getOptimalPredictorCoefficients()

Get the optimal predictor coefficients from the packing

Returns:

the u

getCodedInitializerLength

public int getCodedInitializerLength()

Get the length of the encoded text (M32 codes) for the initializers

Returns:

a positive integer greater than zero, in bytes

getCodedInteriorLength

public int getCodedInteriorLength()

Get the length of the encoded text (M32 codes) for the interior.

Returns:

a positive integer greater than zero, in bytes

getCompressionType

public int getCompressionType()

Indicates whether the data was compresses using Huffman coding or Deflate.

Returns:

a value of zero (for Huffman coding) or 1 (for Deflate).

getHeaderSize

public int getHeaderSize()

Get the size of the header, in bytes

Returns:

a positive integer (47 at this time, subject to change in future)