Package com.scurrilous.circe.crc

Class Sse42Crc32C

java.lang.Object

com.scurrilous.circe.impl.AbstractIncrementalIntHash

com.scurrilous.circe.crc.Sse42Crc32C

All Implemented Interfaces:

Hash, IncrementalIntHash, StatelessHash, StatelessIntHash

public final class Sse42Crc32C
extends AbstractIncrementalIntHash
implements IncrementalIntHash

Implementation of CRC-32C using the SSE 4.2 CRC instruction.

Constructor Summary

Constructors

Constructor	Description
Sse42Crc32C()
Sse42Crc32C(int[] chunkWords)

Method Summary

Modifier and Type	Method	Description
java.lang.String	algorithm()	Returns the canonical name of this hash algorithm.
int	calculate(long address, long length)	Evaluates this hash function for the memory with the given address and length.
protected void	finalize()
protected int	initial()	The initial state of the hash function, which is the same as the output value for an empty input sequence.
static boolean	isSupported()	Returns whether SSE 4.2 CRC-32C is supported on this system.
int	length()	Returns the length in bytes of the output of this hash function.
int	resume(int current, long address, long length)	Evaluates this hash function as if the memory with the given address and length were appended to the previously hashed input.
int	resume(int current, java.nio.ByteBuffer input)	Evaluates this hash function as if the remaining contents of the given input buffer were appended to the previously hashed input.
protected int	resumeUnchecked(int current, byte[] input, int index, int length)	Evaluates this hash function as if the given range of the given input array were appended to the previously hashed input.
boolean	supportsUnsafe()	Returns whether this hash function supports unsafe access to arbitrary memory addresses using methods such as StatefulHash.update(long, long), StatelessIntHash.calculate(long, long), or IncrementalIntHash.resume(int, long, long).

Methods inherited from class com.scurrilous.circe.impl.AbstractIncrementalIntHash

calculate, calculate, calculate, createStateful, resume, resume

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.scurrilous.circe.IncrementalIntHash

resume, resume

Methods inherited from interface com.scurrilous.circe.StatelessIntHash

calculate, calculate, calculate, createStateful

Constructor Detail

Sse42Crc32C

Sse42Crc32C()

Sse42Crc32C

public Sse42Crc32C(int[] chunkWords)

Method Detail

isSupported

public static boolean isSupported()

Returns whether SSE 4.2 CRC-32C is supported on this system.

Returns:

true if this class is supported, false if not

finalize

protected void finalize()

Overrides:

finalize in class java.lang.Object

algorithm

public java.lang.String algorithm()

Description copied from interface: Hash

Returns the canonical name of this hash algorithm.

Specified by:

algorithm in interface Hash

Returns:

the name of this hash algorithm

length

public int length()

Description copied from interface: Hash

Returns the length in bytes of the output of this hash function.

Specified by:

length in interface Hash

Returns:

the hash length in bytes

supportsUnsafe

public boolean supportsUnsafe()

Description copied from interface: Hash

Returns whether this hash function supports unsafe access to arbitrary memory addresses using methods such as StatefulHash.update(long, long), StatelessIntHash.calculate(long, long), or IncrementalIntHash.resume(int, long, long). Such functions are generally implemented in native code.

Specified by:

supportsUnsafe in interface Hash

Overrides:

supportsUnsafe in class AbstractIncrementalIntHash

Returns:

true if unsafe access is supported, false if not

calculate

public int calculate(long address,
                     long length)

Description copied from interface: StatelessIntHash

Evaluates this hash function for the memory with the given address and length. The arguments are generally not checked in any way and will likely lead to a VM crash or undefined results if invalid.

Specified by:

calculate in interface StatelessIntHash

Overrides:

calculate in class AbstractIncrementalIntHash

Parameters:

address - the base address of the input

length - the length of the input

Returns:

the output of the hash function

See Also:

Hash.supportsUnsafe()

resume

public int resume(int current,
                  java.nio.ByteBuffer input)

Description copied from interface: IncrementalIntHash

Evaluates this hash function as if the remaining contents of the given input buffer were appended to the previously hashed input. This method leaves the buffer position at the limit.

Specified by:

resume in interface IncrementalIntHash

Overrides:

resume in class AbstractIncrementalIntHash

Parameters:

current - the hash output for input hashed so far

input - the input buffer

Returns:

the output of the hash function for the concatenated input

resume

public int resume(int current,
                  long address,
                  long length)

Description copied from interface: IncrementalIntHash

Evaluates this hash function as if the memory with the given address and length were appended to the previously hashed input. The arguments are generally not checked in any way and will likely lead to a VM crash or undefined results if invalid.

Specified by:

resume in interface IncrementalIntHash

Overrides:

resume in class AbstractIncrementalIntHash

Parameters:

current - the hash output for input hashed so far

address - the base address of the input

length - the length of the input

Returns:

the output of the hash function for the concatenated input

See Also:

Hash.supportsUnsafe()

initial

protected int initial()

Description copied from class: AbstractIncrementalIntHash

The initial state of the hash function, which is the same as the output value for an empty input sequence.

Specified by:

initial in class AbstractIncrementalIntHash

Returns:

the initial hash state/output

resumeUnchecked

protected int resumeUnchecked(int current,
                              byte[] input,
                              int index,
                              int length)

Description copied from class: AbstractIncrementalIntHash

Evaluates this hash function as if the given range of the given input array were appended to the previously hashed input. The index and length parameters have already been validated.

Specified by:

resumeUnchecked in class AbstractIncrementalIntHash

Parameters:

current - the hash output for input hashed so far

input - the input array

index - the starting index of the first input byte

length - the length of the input range

Returns:

the output of the hash function for the concatenated input