Package squidpony.squidmath

Class PointHash

java.lang.Object

squidpony.squidmath.IPointHash.LongImpl

squidpony.squidmath.PointHash

All Implemented Interfaces:

IPointHash

public final class PointHash
extends IPointHash.LongImpl

A group of similar methods for getting hashes of points based on long coordinates in 2, 3, 4, or 6 dimensions and a long for state. Internally, the methods here are based on a simplified version of Hive from CrossHash; this version does not include the somewhat-involved finalization step. Omitting finalization helps this class be somewhat faster, but also makes it so it doesn't avalanche very well. Avalanche refers to the property of a hash where one changed bit in the input(s) or state has a chance to change any of the output's bits, and should usually change about 50% of them. You can call avalanche(long) on the result of a hashAll() call to put the finalization step back. This has rather good quality when avalanche(long) is used, but most usage will not be able to discern a difference between the quality of this (with or without avalanche) and the quality of HastyPointHash, where HastyPointHash is a fair amount faster. If your state and input are ints anyway, consider IntPointHash, since it's faster than the long-based hashes and still has perfectly fine quality.
This implements IPointHash and has a long it uses internally for state, exposed by getState().

Nested Class Summary

Nested classes/interfaces inherited from interface squidpony.squidmath.IPointHash

IPointHash.IntImpl, IPointHash.LongImpl

Field Summary

Fields inherited from class squidpony.squidmath.IPointHash.LongImpl

state

Constructor Summary

Constructors

Constructor	Description
PointHash()

Method Summary

Modifier and Type	Method	Description
static long	avalanche(long state)	If it's important for some usage that one bit of change in any parameters cause roughly 50% of all bits in the result to change, then you can call this on the output of any hashAll() overload to improve the bit avalanche qualities.
long	getState()
static int	hash256(long x, long y, long state)
static int	hash256(long x, long y, long z, long state)
static int	hash256(long x, long y, long z, long w, long state)
static int	hash256(long x, long y, long z, long w, long u, long v, long state)
static int	hash32(long x, long y, long state)
static int	hash32(long x, long y, long z, long state)
static int	hash32(long x, long y, long z, long w, long state)
static int	hash32(long x, long y, long z, long w, long u, long v, long state)
static int	hash64(long x, long y, long state)
static int	hash64(long x, long y, long z, long state)
static int	hash64(long x, long y, long z, long w, long state)
static int	hash64(long x, long y, long z, long w, long u, long v, long state)
static long	hashAll(long x, long y, long state)
static long	hashAll(long x, long y, long z, long state)
static long	hashAll(long x, long y, long z, long w, long state)
static long	hashAll(long x, long y, long z, long w, long u, long v, long state)
int	hashWithState(int x, int y, int state)
int	hashWithState(int x, int y, int z, int state)
int	hashWithState(int x, int y, int z, int w, int state)
int	hashWithState(int x, int y, int z, int w, int u, int v, int state)

Methods inherited from class squidpony.squidmath.IPointHash.LongImpl

hash, hash, hash, hash, setState, setState

Methods inherited from class java.lang.Object

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

Constructor Details

PointHash

public PointHash()

Method Details

hashWithState

public int hashWithState(int x, int y, int state)

hashWithState

public int hashWithState(int x, int y, int z, int state)

hashWithState

public int hashWithState(int x, int y, int z, int w, int state)

hashWithState

public int hashWithState(int x, int y, int z, int w, int u, int v, int state)

getState

public long getState()

avalanche

public static long avalanche(long state)

If it's important for some usage that one bit of change in any parameters cause roughly 50% of all bits in the result to change, then you can call this on the output of any hashAll() overload to improve the bit avalanche qualities.

Parameters:

state - the output of hashAll() in this class

Returns:

a significantly-mixed-around long obtained from state

hashAll

public static long hashAll(long x, long y, long state)

Parameters:

x -

y -

state -

Returns:

64-bit hash of the x,y point with the given state

hashAll

public static long hashAll(long x, long y, long z, long state)

Parameters:

x -

y -

z -

state -

Returns:

64-bit hash of the x,y,z point with the given state

hashAll

public static long hashAll(long x, long y, long z, long w, long state)

Parameters:

x -

y -

z -

w -

state -

Returns:

64-bit hash of the x,y,z,w point with the given state

hashAll

public static long hashAll(long x, long y, long z, long w, long u, long v, long state)

Parameters:

x -

y -

z -

w -

u -

v -

state -

Returns:

64-bit hash of the x,y,z,w,u,v point with the given state

hash256

public static int hash256(long x, long y, long state)

Parameters:

x -

y -

state -

Returns:

8-bit hash of the x,y point with the given state

hash256

public static int hash256(long x, long y, long z, long state)

Parameters:

x -

y -

z -

state -

Returns:

8-bit hash of the x,y,z point with the given state

hash256

public static int hash256(long x, long y, long z, long w, long state)

Parameters:

x -

y -

z -

w -

state -

Returns:

8-bit hash of the x,y,z,w point with the given state

hash256

public static int hash256(long x, long y, long z, long w, long u, long v, long state)

Parameters:

x -

y -

z -

w -

u -

v -

state -

Returns:

8-bit hash of the x,y,z,w,u,v point with the given state

hash32

public static int hash32(long x, long y, long state)

Parameters:

x -

y -

state -

Returns:

5-bit hash of the x,y point with the given state

hash32

public static int hash32(long x, long y, long z, long state)

Parameters:

x -

y -

z -

state -

Returns:

5-bit hash of the x,y,z point with the given state

hash32

public static int hash32(long x, long y, long z, long w, long state)

Parameters:

x -

y -

z -

w -

state -

Returns:

5-bit hash of the x,y,z,w point with the given state

hash32

public static int hash32(long x, long y, long z, long w, long u, long v, long state)

Parameters:

x -

y -

z -

w -

u -

v -

state -

Returns:

5-bit hash of the x,y,z,w,u,v point with the given state

hash64

public static int hash64(long x, long y, long state)

Parameters:

x -

y -

state -

Returns:

6-bit hash of the x,y point with the given state

hash64

public static int hash64(long x, long y, long z, long state)

Parameters:

x -

y -

z -

state -

Returns:

6-bit hash of the x,y,z point with the given state

hash64

public static int hash64(long x, long y, long z, long w, long state)

Parameters:

x -

y -

z -

w -

state -

Returns:

6-bit hash of the x,y,z,w point with the given state

hash64

public static int hash64(long x, long y, long z, long w, long u, long v, long state)

Parameters:

x -

y -

z -

w -

u -

v -

state -

Returns:

6-bit hash of the x,y,z,w,u,v point with the given state