Package com.scurrilous.circe

Interface IncrementalLongHash

All Superinterfaces:

Hash, StatelessHash, StatelessLongHash

All Known Implementing Classes:

AbstractIncrementalLongHash, AbstractLongCrc, NormalLongCrc, ReflectedLongCrc

public interface IncrementalLongHash
extends StatelessLongHash

Incremental stateless long integer hash function, which has the property that its output is the same as (or easily derivable from) its state. Specifically, for any sequence M partitioned arbitrarily into two subsequences M₁ M₂:

 h(M) = h'(h(M1), M2)
 

where h corresponds to the calculate function and h' corresponds to the resume(long, byte[]) function.

Note that stateful hash functions obtained from incremental stateless hash functions are also incremental.

Method Summary

Modifier and Type	Method	Description
long	resume(long current, byte[] input)	Evaluates this hash function as if the entire given input array were appended to the previously hashed input.
long	resume(long 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.
long	resume(long 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.
long	resume(long 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.

Methods inherited from interface com.scurrilous.circe.Hash

algorithm, length, supportsUnsafe

Methods inherited from interface com.scurrilous.circe.StatelessLongHash

calculate, calculate, calculate, calculate, createStateful

Method Detail

resume

long resume(long current,
            byte[] input)

Evaluates this hash function as if the entire given input array were appended to the previously hashed input.

Parameters:

current - the hash output for input hashed so far

input - the input array

Returns:

the output of the hash function for the concatenated input

resume

long resume(long 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.

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

Throws:

java.lang.IndexOutOfBoundsException - if index is negative or index + length is greater than the array length

resume

long resume(long 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. This method leaves the buffer position at the limit.

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

long resume(long 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. The arguments are generally not checked in any way and will likely lead to a VM crash or undefined results if invalid.

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

Throws:

java.lang.UnsupportedOperationException - if this function does not support unsafe memory access

See Also:

Hash.supportsUnsafe()