Class XoShiRo128Plus

java.lang.Object

org.apache.commons.rng.core.BaseProvider

org.apache.commons.rng.core.source32.IntProvider

org.apache.commons.rng.core.source32.XoShiRo128Plus

All Implemented Interfaces:

RandomIntSource, JumpableUniformRandomProvider, LongJumpableUniformRandomProvider, RestorableUniformRandomProvider, UniformRandomProvider

public class XoShiRo128Plus
extends IntProvider

A fast 32-bit generator suitable for float generation. This is slightly faster than the all-purpose generator XoShiRo128StarStar.

This is a member of the Xor-Shift-Rotate family of generators. Memory footprint is 128 bits.

Since:

1.3

See Also:

• Original source code
• xorshiro / xoroshiro generators

Field Summary

Fields

Modifier and Type	Field	Description
protected int	state0	State 0 of the generator.
protected int	state1	State 1 of the generator.
protected int	state2	State 2 of the generator.
protected int	state3	State 3 of the generator.

Constructor Summary

Constructors

Modifier	Constructor	Description
	XoShiRo128Plus(int[] seed)	Creates a new instance.
	XoShiRo128Plus(int seed0, int seed1, int seed2, int seed3)	Creates a new instance using a 4 element seed.
protected	XoShiRo128Plus(XoShiRo128Plus source)	Creates a copy instance.

Method Summary

Modifier and Type	Method	Description
protected XoShiRo128Plus	copy()	Create a copy.
protected byte[]	getStateInternal()	Creates a snapshot of the RNG state.
UniformRandomProvider	jump()	Creates a copy of the UniformRandomProvider and then advances the state of the current instance.
JumpableUniformRandomProvider	longJump()	Creates a copy of the JumpableUniformRandomProvider and then advances the state of the current instance.
int	next()	Return the next random value.
protected int	nextOutput()	Use the current state to compute the next output from the generator.
protected void	setStateInternal(byte[] s)	Resets the RNG to the given state.

Methods inherited from class IntProvider

nextBoolean, nextBytes, nextBytes, nextDouble, nextInt, nextLong, resetCachedState

Methods inherited from class BaseProvider

checkIndex, checkStateSize, composeStateInternal, extendSeed, extendSeed, fillState, fillState, restoreState, saveState, splitStateInternal, toString

Methods inherited from class Object

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

Methods inherited from interface JumpableUniformRandomProvider

jumps, jumps

Methods inherited from interface LongJumpableUniformRandomProvider

longJumps, longJumps

Methods inherited from interface UniformRandomProvider

doubles, doubles, doubles, doubles, ints, ints, ints, ints, longs, longs, longs, longs, nextBoolean, nextBytes, nextBytes, nextDouble, nextDouble, nextDouble, nextFloat, nextFloat, nextFloat, nextInt, nextInt, nextInt, nextLong, nextLong, nextLong

Field Details

state0

protected int state0

State 0 of the generator.

state1

protected int state1

State 1 of the generator.

state2

protected int state2

State 2 of the generator.

state3

protected int state3

State 3 of the generator.

Constructor Details

XoShiRo128Plus

public XoShiRo128Plus(int[] seed)

Creates a new instance.

Parameters:

seed - Initial seed. If the length is larger than 4, only the first 4 elements will be used; if smaller, the remaining elements will be automatically set. A seed containing all zeros will create a non-functional generator.

XoShiRo128Plus

public XoShiRo128Plus(int seed0,
 int seed1,
 int seed2,
 int seed3)

Creates a new instance using a 4 element seed. A seed containing all zeros will create a non-functional generator.

Parameters:

seed0 - Initial seed element 0.

seed1 - Initial seed element 1.

seed2 - Initial seed element 2.

seed3 - Initial seed element 3.

XoShiRo128Plus

protected XoShiRo128Plus(XoShiRo128Plus source)

Creates a copy instance.

Parameters:

source - Source to copy.

Method Details

nextOutput

protected int nextOutput()

Use the current state to compute the next output from the generator. The output function shall vary with respect to different generators. This method is called from RandomIntSource.next() before the current state is updated.

Returns:

the next output

copy

protected XoShiRo128Plus copy()

Create a copy.

Returns:

the copy

getStateInternal

protected byte[] getStateInternal()

Creates a snapshot of the RNG state.

Overrides:

getStateInternal in class IntProvider

Returns:

the internal state.

setStateInternal

protected void setStateInternal(byte[] s)

Resets the RNG to the given state.

Overrides:

setStateInternal in class IntProvider

Parameters:

s - State (previously obtained by a call to BaseProvider.getStateInternal()).

See Also:

• BaseProvider.checkStateSize(byte[],int)

next

public int next()

Return the next random value.

Specified by:

next in interface RandomIntSource

Returns:

the next random value.

jump

public UniformRandomProvider jump()

Creates a copy of the UniformRandomProvider and then advances the state of the current instance. The copy is returned.

The current state will be advanced in a single operation by the equivalent of a number of sequential calls to a method that updates the state of the provider. The size of the jump is implementation dependent.

Repeat invocations of this method will create a series of generators that are uniformly spaced at intervals of the output sequence. Each generator provides non-overlapping output for the length of the jump for use in parallel computations.

The jump size is the equivalent of 2⁶⁴ calls to nextInt(). It can provide up to 2⁶⁴ non-overlapping subsequences.

Specified by:

jump in interface JumpableUniformRandomProvider

Returns:

A copy of the current state.

longJump

public JumpableUniformRandomProvider longJump()

Creates a copy of the JumpableUniformRandomProvider and then advances the state of the current instance. The copy is returned.

The current state will be advanced in a single operation by the equivalent of a number of sequential calls to a method that updates the state of the provider. The size of the long jump is implementation dependent.

Repeat invocations of this method will create a series of generators that are uniformly spaced at intervals of the output sequence. Each generator provides non-overlapping output for the length of the long jump for use in parallel computations.

The returned copy may be jumped m / n times before overlap with the current instance where m is the long jump length and n is the jump length of the JumpableUniformRandomProvider.jump() method.

The jump size is the equivalent of 2⁹⁶ calls to nextLong(). It can provide up to 2³² non-overlapping subsequences of length 2⁹⁶; each subsequence can provide up to 2³² non-overlapping subsequences of length 2⁶⁴ using the JumpableUniformRandomProvider.jump() method.

Specified by:

longJump in interface LongJumpableUniformRandomProvider

Returns:

A copy of the current state.