Package io.github.pr0methean.betterrandom.prng

Class Cmwc4096Random

java.lang.Object

java.util.Random

io.github.pr0methean.betterrandom.prng.BaseRandom

io.github.pr0methean.betterrandom.prng.Cmwc4096Random

All Implemented Interfaces:

ByteArrayReseedableRandom, EntropyCountingRandom, RepeatableRandom, Dumpable, Serializable

public class Cmwc4096Random
extends BaseRandom

A Java version of George Marsaglia's Complementary Multiply With Carry (CMWC) RNG. This is a very fast PRNG with an extremely long period (2¹³¹¹⁰⁴). It should be used in preference to the MersenneTwisterRandom when a very long period is required.

One potential drawback of this RNG is that it requires significantly more seed data than the other RNGs provided by Uncommons Maths. It requires just over 16 kilobytes, which may be a problem if your are obtaining seed data from a slow or limited entropy source. In contrast, the Mersenne Twister requires only 128 bits of seed data.

NOTE: Because instances of this class require 16-kilobyte seeds, it is not possible to seed this RNG using the setSeed(long) method inherited from Random. Calls to this method will have no effect. Instead the seed must be set by a constructor.

Since:

1.2

Author:

Daniel Dyer

See Also:

Serialized Form

Field Summary

Fields inherited from class io.github.pr0methean.betterrandom.prng.BaseRandom

ENTROPY_OF_DOUBLE, ENTROPY_OF_FLOAT, entropyBits, lock, randomSeeder, seed, superConstructorFinished

Constructor Summary

Constructors

Constructor	Description
Cmwc4096Random()	Creates a new RNG and seeds it using the default seeding strategy.
Cmwc4096Random(byte[] seed)	Creates an RNG and seeds it with the specified seed data.
Cmwc4096Random(SeedGenerator seedGenerator)	Seed the RNG using the provided seed generation strategy.

Method Summary

Modifier and Type	Method	Description
protected MoreObjects.ToStringHelper	addSubclassFields(MoreObjects.ToStringHelper original)	Adds the fields that were not inherited from BaseRandom to the given MoreObjects.ToStringHelper for dumping.
int	getNewSeedLength()	Returns the only supported seed length.
protected int	next(int bits)	Generates the next pseudorandom number.
void	setSeed(long seed)	Reseeds this PRNG using the DefaultSeedGenerator, since it needs a longer seed.
protected void	setSeedInternal(byte[] seed)	Sets the seed, and should be overridden to set other state that derives from the seed.

Methods inherited from class io.github.pr0methean.betterrandom.prng.BaseRandom

checkLength, checkValidRange, creditEntropyForNewSeed, debitEntropy, doubles, doubles, doubles, doubles, dump, entropyOfInt, entropyOfLong, fallbackSetSeedIfInitialized, gaussians, gaussians, getEntropyBits, getRandomSeeder, getSeed, initTransientFields, internalNextGaussian, ints, ints, ints, ints, lockForNextGaussian, longs, longs, longs, longs, nextBoolean, nextBytes, nextDouble, nextDouble, nextDouble, nextDoubleNoEntropyDebit, nextElement, nextElement, nextEnum, nextFloat, nextGaussian, nextInt, nextInt, nextInt, nextLong, nextLong, nextLong, nextLongNoEntropyDebit, preferSeedWithLong, setRandomSeeder, setSeed, supportsMultipleSeedLengths, unlockForNextGaussian, usesParallelStreams, withProbability, withProbabilityInternal

Methods inherited from class java.lang.Object

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

Methods inherited from interface io.github.pr0methean.betterrandom.EntropyCountingRandom

needsReseedingEarly

Constructor Detail

Cmwc4096Random

public Cmwc4096Random()
               throws SeedException

Creates a new RNG and seeds it using the default seeding strategy.

Throws:

SeedException - if any.

Cmwc4096Random

public Cmwc4096Random(SeedGenerator seedGenerator)
               throws SeedException

Seed the RNG using the provided seed generation strategy.

Parameters:

seedGenerator - The seed generation strategy that will provide the seed value for this RNG.

Throws:

SeedException - If there is a problem generating a seed.

Cmwc4096Random

public Cmwc4096Random(byte[] seed)

Creates an RNG and seeds it with the specified seed data.

Parameters:

seed - 16384 bytes of seed data used to initialize the RNG.

Method Detail

addSubclassFields

protected MoreObjects.ToStringHelper addSubclassFields(MoreObjects.ToStringHelper original)

Description copied from class: BaseRandom

Adds the fields that were not inherited from BaseRandom to the given MoreObjects.ToStringHelper for dumping.

Specified by:

addSubclassFields in class BaseRandom

Parameters:

original - a MoreObjects.ToStringHelper object.

Returns:

original with the fields not inherited from BaseRandom written to it.

setSeed

public void setSeed(long seed)

Reseeds this PRNG using the DefaultSeedGenerator, since it needs a longer seed.

Overrides:

setSeed in class BaseRandom

Parameters:

seed - ignored

See Also:

ByteArrayReseedableRandom.preferSeedWithLong()

setSeedInternal

protected void setSeedInternal(byte[] seed)

Description copied from class: BaseRandom

Sets the seed, and should be overridden to set other state that derives from the seed. Called by BaseRandom.setSeed(byte[]), constructors, and readObject(ObjectInputStream). When called after initialization, the BaseRandom.lock is always held.

Overrides:

setSeedInternal in class BaseRandom

Parameters:

seed - The new seed.

next

protected int next(int bits)

Description copied from class: BaseRandom

Generates the next pseudorandom number. Called by all other random-number-generating methods. Should not debit the entropy count, since that's done by the calling methods according to the amount they actually output (see for example BaseRandom.withProbability(double), which uses 53 random bits but outputs only one, and thus debits only 1 bit of entropy).

Specified by:

next in class BaseRandom

getNewSeedLength

public int getNewSeedLength()

Returns the only supported seed length.

Specified by:

getNewSeedLength in interface ByteArrayReseedableRandom

Specified by:

getNewSeedLength in class BaseRandom

Returns:

The desired length of a new byte-array seed.