com.pervasive.datarush.util

Class HashMixer

java.lang.Object

com.pervasive.datarush.util.HashMixer

public final class HashMixer
extends Object

A representation of a partially completed hash of a sequence of values. The internal state contains more bits than the final 32-bit hash code.

This implementation is based on C code placed in the public domain by Bob Jenkins. It is advertised as strong enough to allow the use of hash & mask instead of hash % prime for computing a hash bucket.

Constructor Summary

Constructors

Constructor and Description
HashMixer() Constructs a mixer by initializing the internal state.

Method Summary

Modifier and Type	Method and Description
int	finalMix(int i, int j, int k) Performs the final "mix" of the internal state with the given parameters, resets the state, and returns the resulting hash code.
void	mix(int i, int j, int k) Replicates the computation of Bob Jenkins' "mix" macro.

Methods inherited from class java.lang.Object

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

Constructor Detail

HashMixer

public HashMixer()

Constructs a mixer by initializing the internal state.

Method Detail

mix

public void mix(int i,
                int j,
                int k)

Replicates the computation of Bob Jenkins' "mix" macro.

Parameters:

i - the first input to the macro

j - the second input to the macro

k - the third input to the macro

finalMix

public int finalMix(int i,
                    int j,
                    int k)

Performs the final "mix" of the internal state with the given parameters, resets the state, and returns the resulting hash code.

Parameters:

i - the first four bytes to include

j - the second four bytes to include

k - the final four bytes to include

Returns:

the hash code produced by "mixing" initial state, parameters to each call of mix(int, int, int), and parameters to finalMix(int, int, int)