Package com.linkedin.alpini.base.hash

Class Crc32C

java.lang.Object

com.linkedin.alpini.base.hash.Crc32C

All Implemented Interfaces:

Checksum

public final class Crc32C
extends Object
implements Checksum

A pure-java implementation of the CRC32 checksum that uses the CRC32-C polynomial, the same polynomial used by iSCSI and implemented on many Intel chipsets supporting SSE4.2. This class implementation is copied from the org.iq80.snappy.Crc32C implementation because it was stupidly made package private for no good reason. Note that Java9 will provide its own implementation of CRC32-C which may have scope for native acceleration.

Constructor Summary

Constructors

Constructor	Description
Crc32C()	Create a new PureJavaCrc32 object.

Method Summary

Modifier and Type	Method	Description
int	getIntValue()
int	getMaskedValue()
long	getValue()
static int	mask(int crc)	Return a masked representation of crc.
static int	maskedCrc32c(byte[] data)
static int	maskedCrc32c(byte[] data, int offset, int length)
void	reset()
static int	unmask(int maskedCrc)	Return the crc whose masked representation is masked_crc.
void	update(byte[] b)
void	update(byte[] b, int off, int len)
void	update(int b)

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.zip.Checksum

update

Constructor Details

Crc32C

public Crc32C()

Create a new PureJavaCrc32 object.

Method Details

maskedCrc32c

public static int maskedCrc32c(byte[] data)

maskedCrc32c

public static int maskedCrc32c(byte[] data,
 int offset,
 int length)

mask

public static int mask(int crc)

Return a masked representation of crc.

Motivation: it is problematic to compute the CRC of a string that contains embedded CRCs. Therefore we recommend that CRCs stored somewhere (e.g., in files) should be masked before being stored.

unmask

public static int unmask(int maskedCrc)

Return the crc whose masked representation is masked_crc.

getMaskedValue

public int getMaskedValue()

getIntValue

public int getIntValue()

getValue

public long getValue()

Specified by:

getValue in interface Checksum

reset

public void reset()

Specified by:

reset in interface Checksum

update

public void update(byte[] b)

Specified by:

update in interface Checksum

update

public void update(byte[] b,
 int off,
 int len)

Specified by:

update in interface Checksum

update

public void update(int b)

Specified by:

update in interface Checksum