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8248862: Implement Enhanced Pseudo-Random Number Generators

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Reviewed-by: darcy
This commit is contained in:
Jim Laskey 2021-04-05 16:29:18 +00:00
parent 39719da9d1
commit a0ec2cb289
27 changed files with 11384 additions and 1772 deletions
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src/java.base/share/classes/java/util/random/RandomGenerator.java Normal file
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src/java.base/share/classes/java/util/random/RandomGeneratorFactory.java Normal file
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/*
* Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.util.random;
import java.lang.reflect.Constructor;
import java.math.BigInteger;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.Objects;
import java.util.function.Function;
import java.util.Map;
import java.util.random.RandomGenerator.ArbitrarilyJumpableGenerator;
import java.util.random.RandomGenerator.JumpableGenerator;
import java.util.random.RandomGenerator.LeapableGenerator;
import java.util.random.RandomGenerator.SplittableGenerator;
import java.util.random.RandomGenerator.StreamableGenerator;
import java.util.ServiceLoader;
import java.util.ServiceLoader.Provider;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import jdk.internal.util.random.RandomSupport.RandomGeneratorProperties;
/**
* This is a factory class for generating multiple random number generators
* of a specific <a href="package-summary.html#algorithms">algorithm</a>.
* {@link RandomGeneratorFactory} also provides
* methods for selecting random number generator algorithms.
*
* A specific {@link RandomGeneratorFactory} can be located by using the
* {@link RandomGeneratorFactory#of(String)} method, where the argument string
* is the name of the <a href="package-summary.html#algorithms">algorithm</a>
* required. The method
* {@link RandomGeneratorFactory#all()} produces a non-empty {@link Stream} of all available
* {@link RandomGeneratorFactory RandomGeneratorFactorys} that can be searched
* to locate a {@link RandomGeneratorFactory} suitable to the task.
*
* There are three methods for constructing a RandomGenerator instance,
* depending on the type of initial seed required.
* {@link RandomGeneratorFactory#create(long)} is used for long
* seed construction,
* {@link RandomGeneratorFactory#create(byte[])} is used for byte[]
* seed construction, and
* {@link RandomGeneratorFactory#create()} is used for random seed
* construction. Example;
*
* <pre>{@code
* RandomGeneratorFactory<RandomGenerator> factory = RandomGeneratorFactory.of("Random");
*
* for (int i = 0; i < 10; i++) {
* new Thread(() -> {
* RandomGenerator random = factory.create(100L);
* System.out.println(random.nextDouble());
* }).start();
* }
* }</pre>
*
* RandomGeneratorFactory also provides methods describing the attributes (or properties)
* of a generator and can be used to select random number generator
* <a href="package-summary.html#algorithms">algorithms</a>.
* These methods are typically used in
* conjunction with {@link RandomGeneratorFactory#all()}. In this example, the code
* locates the {@link RandomGeneratorFactory} that produces
* {@link RandomGenerator RandomGenerators}
* with the highest number of state bits.
*
* <pre>{@code
* RandomGeneratorFactory<RandomGenerator> best = RandomGeneratorFactory.all()
* .sorted(Comparator.comparingInt(RandomGenerator::stateBits).reversed())
* .findFirst()
* .orElse(RandomGeneratorFactory.of("Random"));
* System.out.println(best.name() + " in " + best.group() + " was selected");
*
* RandomGenerator rng = best.create();
* System.out.println(rng.nextLong());
* }</pre>
*
* @since 17
*
* @see java.util.random
*
*/
public final class RandomGeneratorFactory<T extends RandomGenerator> {
/**
* Instance provider class of random number algorithm.
*/
private final Provider<? extends RandomGenerator> provider;
/**
* Provider RandomGeneratorProperties annotation.
*/
private volatile RandomGeneratorProperties properties;
/**
* Default provider constructor.
*/
private volatile Constructor<T> ctor;
/**
* Provider constructor with long seed.
*/
private Constructor<T> ctorLong;
/**
* Provider constructor with byte[] seed.
*/
private Constructor<T> ctorBytes;
private static class FactoryMapHolder {
static final Map<String, Provider<? extends RandomGenerator>> FACTORY_MAP = createFactoryMap();
/**
* Returns the factory map, lazily constructing map on first use.
*
* @return Map of RandomGeneratorFactory classes.
*/
private static Map<String, Provider<? extends RandomGenerator>> createFactoryMap() {
return ServiceLoader
.load(RandomGenerator.class)
.stream()
.filter(p -> !p.type().isInterface())
.collect(Collectors.toMap(p -> p.type().getSimpleName(), Function.identity()));
}
}
/**
* Private constructor.
*
* @param provider Provider class to wrap.
*/
private RandomGeneratorFactory(Provider<? extends RandomGenerator> provider) {
this.provider = provider;
}
/**
* Returns the factory map, lazily constructing map on first call.
*
* @return Map of RandomGeneratorFactory classes.
*/
private static Map<String, Provider<? extends RandomGenerator>> getFactoryMap() {
return FactoryMapHolder.FACTORY_MAP;
}
/**
* Return the annotation for the specified provider.
*
* @return RandomGeneratorProperties annotation for the specified provider.
*/
private RandomGeneratorProperties getProperties() {
if (properties == null) {
synchronized (provider) {
if (properties == null) {
properties = provider.type().getDeclaredAnnotation(RandomGeneratorProperties.class);
Objects.requireNonNull(properties, provider.type() + " missing annotation");
}
}
}
return properties;
}
/**
* Return true if the provider is a subclass of the category.
*
* @param category Interface category, sub-interface of {@link RandomGenerator}.
*
* @return true if the provider is a subclass of the category.
*/
private boolean isSubclass(Class<? extends RandomGenerator> category) {
return isSubclass(category, provider);
}
/**
* Return true if the provider is a subclass of the category.
*
* @param category Interface category, sub-interface of {@link RandomGenerator}.
* @param provider Provider that is being filtered.
*
* @return true if the provider is a subclass of the category.
*/
private static boolean isSubclass(Class<? extends RandomGenerator> category,
Provider<? extends RandomGenerator> provider) {
return provider != null && category.isAssignableFrom(provider.type());
}
/**
* Returns the provider matching name and category.
*
* @param name Name of RandomGenerator
* @param category Interface category, sub-interface of {@link RandomGenerator}.
*
* @return A provider matching name and category.
*
* @throws IllegalArgumentException if provider is not a subclass of category.
*/
private static Provider<? extends RandomGenerator> findProvider(String name,
Class<? extends RandomGenerator> category)
throws IllegalArgumentException {
Map<String, Provider<? extends RandomGenerator>> fm = getFactoryMap();
Provider<? extends RandomGenerator> provider = fm.get(name);
if (provider == null) {
throw new IllegalArgumentException("No implementation of the random number generator algorithm \"" +
name +
"\" is available");
} else if (!isSubclass(category, provider)) {
throw new IllegalArgumentException("The random number generator algorithm \"" +
name +
"\" is not implemented with the interface \"" +
category.getSimpleName() +
"\"");
}
return provider;
}
/**
* Returns a {@link RandomGenerator} that utilizes the {@code name}
* <a href="package-summary.html#algorithms">algorithm</a>.
*
* @param name Name of random number algorithm to use
* @param category Sub-interface of {@link RandomGenerator} to type check
* @param <T> Sub-interface of {@link RandomGenerator} to produce
*
* @return An instance of {@link RandomGenerator}
*
* @throws IllegalArgumentException when either the name or category is null
*/
static <T extends RandomGenerator> T of(String name, Class<T> category)
throws IllegalArgumentException {
@SuppressWarnings("unchecked")
T uncheckedRandomGenerator = (T)findProvider(name, category).get();
return uncheckedRandomGenerator;
}
/**
* Returns a {@link RandomGeneratorFactory} that will produce instances
* of {@link RandomGenerator} that utilizes the named algorithm.
*
* @param name Name of random number algorithm to use
* @param category Sub-interface of {@link RandomGenerator} to type check
* @param <T> Sub-interface of {@link RandomGenerator} to produce
*
* @return Factory of {@link RandomGenerator}
*
* @throws IllegalArgumentException when either the name or category is null
*/
static <T extends RandomGenerator> RandomGeneratorFactory<T> factoryOf(String name, Class<T> category)
throws IllegalArgumentException {
Provider<? extends RandomGenerator> uncheckedProvider = findProvider(name, category);
return new RandomGeneratorFactory<>(uncheckedProvider);
}
/**
* Fetch the required constructors for class of random number algorithm.
*
* @param randomGeneratorClass class of random number algorithm (provider)
*/
private void getConstructors(Class<? extends RandomGenerator> randomGeneratorClass) {
if (ctor == null) {
synchronized (provider) {
if (ctor == null) {
PrivilegedExceptionAction<Constructor<?>[]> ctorAction = randomGeneratorClass::getConstructors;
try {
Constructor<?>[] ctors = AccessController.doPrivileged(ctorAction);
Constructor<T> tmpCtor = null;
Constructor<T> tmpCtorLong = null;
Constructor<T> tmpCtorBytes = null;
for (Constructor<?> ctorGeneric : ctors) {
@SuppressWarnings("unchecked")
Constructor<T> ctorSpecific = (Constructor<T>) ctorGeneric;
final Class<?>[] parameterTypes = ctorSpecific.getParameterTypes();
if (parameterTypes.length == 0) {
tmpCtor = ctorSpecific;
} else if (parameterTypes.length == 1) {
Class<?> argType = parameterTypes[0];
if (argType == long.class) {
tmpCtorLong = ctorSpecific;
} else if (argType == byte[].class) {
tmpCtorBytes = ctorSpecific;
}
}
}
if (tmpCtor == null) {
throw new IllegalStateException("Random algorithm " + name() + " is missing a default constructor");
}
// Store specialized constructors first, guarded by ctor
ctorBytes = tmpCtorBytes;
ctorLong = tmpCtorLong;
ctor = tmpCtor;
} catch (PrivilegedActionException ex) {
// Do nothing
}
}
}
}
}
/**
* Ensure all the required constructors are fetched.
*/
private void ensureConstructors() {
getConstructors(provider.type());
}
/**
* Returns a {@link RandomGeneratorFactory} that can produce instances of
* {@link RandomGenerator} that utilize the {@code name}
* <a href="package-summary.html#algorithms">algorithm</a>.
*
* @implSpec Availability is determined by RandomGeneratorFactory using the
* service provider API to locate implementations of the RandomGenerator interface.
*
* @param name Name of random number generator
* <a href="package-summary.html#algorithms">algorithm</a>
* @param <T> Sub-interface of {@link RandomGenerator} to produce
*
* @return {@link RandomGeneratorFactory} of {@link RandomGenerator}
*
* @throws NullPointerException if name is null
* @throws IllegalArgumentException if the named algorithm is not found
*/
public static <T extends RandomGenerator> RandomGeneratorFactory<T> of(String name) {
Objects.requireNonNull(name);
@SuppressWarnings("unchecked")
RandomGeneratorFactory<T> factory =
(RandomGeneratorFactory<T>)factoryOf(name, RandomGenerator.class);
return factory;
}
/**
* Returns a {@link RandomGeneratorFactory} meeting the minimal requirement
* of having an algorithm whose state bits are greater than or equal 64.
*
* @implSpec Since algorithms will improve over time, there is no
* guarantee that this method will return the same algorithm over time.
*
* @return a {@link RandomGeneratorFactory}
*/
public static RandomGeneratorFactory<RandomGenerator> getDefault() {
return factoryOf("L32X64MixRandom", RandomGenerator.class);
}
/**
* Returns a stream of matching Providers.
*
* @param category {@link RandomGenerator} sub-interface class to filter
* @param <T> {@link RandomGenerator} sub-interface return type
*
* RandomGenerators that are marked as deprecated or are not properly configured are not included in the result.
*
* @implSpec Availability is determined by RandomGeneratorFactory using the service provider API
* to locate implementations of the RandomGenerator interface.
*
* @return Stream of matching {@link RandomGeneratorFactory RandomGeneratorFactory(s)}.
*
* @hidden
*/
public static <T extends RandomGenerator> Stream<RandomGeneratorFactory<T>> all(Class<T> category) {
Map<String, Provider<? extends RandomGenerator>> fm = getFactoryMap();
return fm.values()
.stream()
.filter(p -> isSubclass(category, p) &&
!p.type().isAnnotationPresent(Deprecated.class) &&
p.type().isAnnotationPresent(RandomGeneratorProperties.class))
.map(RandomGeneratorFactory::new);
}
/**
* Returns a non-empty stream of available {@link RandomGeneratorFactory RandomGeneratorFactory(s)}.
*
* RandomGenerators that are marked as deprecated or are not properly configured are not included in the result.
*
* @implSpec Availability is determined by RandomGeneratorFactory using the service provider API
* to locate implementations of the RandomGenerator interface.
*
* @return a non-empty stream of all available {@link RandomGeneratorFactory RandomGeneratorFactory(s)}.
*/
public static Stream<RandomGeneratorFactory<RandomGenerator>> all() {
Map<String, Provider<? extends RandomGenerator>> fm = getFactoryMap();
return fm.values()
.stream()
.filter(p -> !p.type().isAnnotationPresent(Deprecated.class) &&
p.type().isAnnotationPresent(RandomGeneratorProperties.class))
.map(RandomGeneratorFactory::new);
}
/**
* Return the name of the <a href="package-summary.html#algorithms">algorithm</a>
* used by the random number generator.
*
* @return Name of the <a href="package-summary.html#algorithms">algorithm</a>.
*/
public String name() {
return provider.type().getSimpleName();
}
/**
* Return the group name of the <a href="package-summary.html#algorithms">algorithm</a>
* used by the random number generator.
*
* @return Group name of the <a href="package-summary.html#algorithms">algorithm</a>.
*/
public String group() {
return getProperties().group();
}
/**
* Returns number of bits used by the <a href="package-summary.html#algorithms">algorithm</a>
* to maintain state of seed.
*
* @return number of bits used by the <a href="package-summary.html#algorithms">algorithm</a>
* to maintain state of seed.
*/
public int stateBits() {
RandomGeneratorProperties properties = getProperties();
int i = properties.i();
int k = properties.k();
return i == 0 && k == 0 ? Integer.MAX_VALUE : i + k;
}
/**
* Returns the equidistribution of the <a href="package-summary.html#algorithms">algorithm</a>.
*
* @return the equidistribution of the <a href="package-summary.html#algorithms">algorithm</a>.
*/
public int equidistribution() {
return getProperties().equidistribution();
}
/**
* Return the period of the <a href="package-summary.html#algorithms">algorithm</a>
* used by the random number generator.
* Returns BigInteger.ZERO if period is not determinable.
*
* @return BigInteger period.
*/
public BigInteger period() {
RandomGeneratorProperties properties = getProperties();
int i = properties.i();
int j = properties.j();
int k = properties.k();
if (i == 0 && j == 0 && k == 0) {
return BigInteger.ZERO;
} else {
return BigInteger.ONE.shiftLeft(i).subtract(BigInteger.valueOf(j)).shiftLeft(k);
}
}
/**
* Return true if random generator is computed using an arithmetic
* <a href="package-summary.html#algorithms">algorithm</a>
* and is statistically deterministic.
*
* @return true if random generator is statistical.
*/
public boolean isStatistical() {
return !getProperties().isStochastic();
}
/**
* Return true if random generator is computed using external or entropic
* sources as inputs.
*
* @return true if random generator is stochastic.
*/
public boolean isStochastic() {
return getProperties().isStochastic();
}
/**
* Return true if random generator uses a hardware device (HRNG) to produce
* entropic input.
*
* @return true if random generator is generated by hardware.
*/
public boolean isHardware() {
return getProperties().isHardware();
}
/**
* Return true if random generator can jump an arbitrarily specified distant
* point in the state cycle.
*
* @return true if random generator is arbitrarily jumpable.
*/
public boolean isArbitrarilyJumpable() {
return isSubclass(ArbitrarilyJumpableGenerator.class);
}
/**
* Return true if random generator can jump a specified distant point in
* the state cycle.
*
* @return true if random generator is jumpable.
*/
public boolean isJumpable() {
return isSubclass(JumpableGenerator.class);
}
/**
* Return true if random generator is jumpable and can leap to a very distant
* point in the state cycle.
*
* @return true if random generator is leapable.
*/
public boolean isLeapable() {
return isSubclass(LeapableGenerator.class);
}
/**
* Return true if random generator can be cloned into a separate object with
* the same properties but positioned further in the state cycle.
*
* @return true if random generator is splittable.
*/
public boolean isSplittable() {
return isSubclass(SplittableGenerator.class);
}
/**
* Return true if random generator can be used to create
* {@link java.util.stream.Stream Streams} of random numbers.
*
* @return true if random generator is streamable.
*/
public boolean isStreamable() {
return isSubclass(StreamableGenerator.class);
}
/**
* Return true if the implementation of RandomGenerator (algorithm) has been
* marked for deprecation.
*
* @implNote Random number generator algorithms evolve over time; new
* algorithms will be introduced and old algorithms will
* lose standing. If an older algorithm is deemed unsuitable
* for continued use, it will be marked as deprecated to indicate
* that it may be removed at some point in the future.
*
* @return true if the implementation of RandomGenerator (algorithm) has been
* marked for deprecation
*/
public boolean isDeprecated() {
return provider.type().isAnnotationPresent(Deprecated.class);
}
/**
* Create an instance of {@link RandomGenerator} based on
* <a href="package-summary.html#algorithms">algorithm</a> chosen.
*
* @return new in instance of {@link RandomGenerator}.
*
*/
public T create() {
try {
ensureConstructors();
return ctor.newInstance();
} catch (Exception ex) {
// Should never happen.
throw new IllegalStateException("Random algorithm " + name() + " is missing a default constructor", ex);
}
}
/**
* Create an instance of {@link RandomGenerator} based on
* <a href="package-summary.html#algorithms">algorithm</a> chosen
* providing a starting long seed. If long seed is not supported by an
* algorithm then the no argument form of create is used.
*
* @param seed long random seed value.
*
* @return new in instance of {@link RandomGenerator}.
*/
public T create(long seed) {
try {
ensureConstructors();
return ctorLong.newInstance(seed);
} catch (Exception ex) {
return create();
}
}
/**
* Create an instance of {@link RandomGenerator} based on
* <a href="package-summary.html#algorithms">algorithm</a> chosen
* providing a starting byte[] seed. If byte[] seed is not supported by an
* <a href="package-summary.html#algorithms">algorithm</a> then the no
* argument form of create is used.
*
* @param seed byte array random seed value.
*
* @return new in instance of {@link RandomGenerator}.
*
* @throws NullPointerException if seed is null.
*/
public T create(byte[] seed) {
Objects.requireNonNull(seed, "seed must not be null");
try {
ensureConstructors();
return ctorBytes.newInstance(seed);
} catch (Exception ex) {
return create();
}
}
}

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src/java.base/share/classes/java/util/random/package-info.java Normal file
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/*
* Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/**
* This package contains classes and interfaces that support a generic API
* for random number generation.
*
* <p>These classes and interfaces support the definition and use of "random
* generators", a term covering what have traditionally been called "random
* number generators" as well as generators of other sorts of randomly chosen
* values (eg. booleans). These classes and interfaces cover not only
* deterministic (pseudorandom) algorithms but also generators of values that
* use some "truly random" physical source (stochastic algorithms perhaps making
* use of thermal noise, for example, or quantum-mechanical effects).
*
* <p> The principal interface is {@link RandomGenerator}, which provides
* methods for requesting individual values of type {@code int}, {@code long},
* {@code float}, {@code double}, or {@code boolean} chosen pseudorandomly
* from a uniform distribution; methods for requesting values of type
* {@code double} chosen pseudorandomly from a normal distribution or from an
* exponential distribution; and methods for creating streams of values of type
* {@code int}, {@code long}, or {@code double} chosen pseudorandomly from a
* uniform distribution (such streams are spliterator-based, allowing for
* parallel processing of their elements). There are also static factory methods
* for creating an instance of a specific random number generator algorithm
* given its name.
*
* <p> The principal supporting class is {@link RandomGeneratorFactory}. This
* can be used to generate multiple random number generators for a specific
* algorithm. {@link RandomGeneratorFactory} also provides methods for
* selecting random number generator algorithms. RandomGeneratorFactory
* registers implementations of {@link RandomGenerator} interface using the
* service provider API.
*
* <p> An important subsidiary interface is
* {@link RandomGenerator.StreamableGenerator}, which provides methods for
* creating spliterator-based streams of {@link RandomGenerator} objects,
* allowing for parallel processing of these objects using multiple threads.
* Unlike {@link java.util.Random}, most implementations of
* {@link RandomGenerator} are <i>not</i> thread-safe. The intent is that
* instances should not be shared among threads; rather, each thread should have
* its own random generator(s) to use. The various pseudorandom algorithms
* provided by this package are designed so that multiple instances will (with
* very high probability) behave as if statistically independent.
*
* <p> For many purposes, these are the only two interfaces that a consumer of
* pseudorandom values will need. There are also some more specialized
* interfaces that describe more specialized categories of random number
* generators {@link RandomGenerator.SplittableGenerator SplittableGenerator},
* {@link RandomGenerator.JumpableGenerator JumpableGenerator},
* {@link RandomGenerator.LeapableGenerator LeapableGenerator}, and
* {@link RandomGenerator.ArbitrarilyJumpableGenerator ArbitrarilyJumpableGenerator}
* that have specific strategies for creating statistically independent instances.
*
* <h2>Using the Random Number Generator Interfaces</h2>
*
* To get started, an application should first create one instance of a
* generator class. Assume that the contents of the package
* {@link java.util.random} has been imported:
*
* <blockquote>{@code import java.util.random.*;}</blockquote>
*
* Then one can choose a specific implementation by giving the name of a generator
* algorithm to the static method {@link RandomGenerator#of}, in which case the
* no-arguments constructor for that implementation is used:
*
* <blockquote>{@code RandomGenerator g = RandomGenerator.of("L64X128MixRandom");}</blockquote>
*
* For a single-threaded application, this is all that is needed. One can then
* invoke methods of {@code g} such as
* {@link RandomGenerator#nextLong nextLong()},
* {@link RandomGenerator#nextInt nextInt()},
* {@link RandomGenerator#nextFloat nextFloat()},
* {@link RandomGenerator#nextDouble nextDouble()} and
* {@link RandomGenerator#nextBoolean nextBoolean()} to generate individual
* randomly chosen values. One can also use the methods
* {@link RandomGenerator#ints ints()}, {@link RandomGenerator#longs longs()}
* and {@link RandomGenerator#doubles doubles()} to create streams of randomly
* chosen values. The methods
* {@link RandomGenerator#nextGaussian nextGaussian()} and
* {@link RandomGenerator#nextExponential nextExponential()} draw floating-point
* values from nonuniform distributions.
*
* <p> For a multi-threaded application, one can repeat the preceding steps
* to create additional {@linkplain RandomGenerator RandomGenerators}, but
* often it is preferable to use methods of the one single initially
* created generator to create others like it. (One reason is that some
* generator algorithms, if asked to create a new set of generators all at
* once, can make a special effort to ensure that the new generators are
* statistically independent.) If the initial generator implements the
* interface {@link RandomGenerator.StreamableGenerator}, then the method
* {@link RandomGenerator.StreamableGenerator#rngs rngs()} can be used to
* create a stream of generators. If this is a parallel stream, then it is
* easy to get parallel execution by using the
* {@link java.util.stream.Stream#map map()} method on the stream.
* <p> For a multi-threaded application that forks new threads dynamically,
* another approach is to use an initial generator that implements the interface
* {@link RandomGenerator.SplittableGenerator}, which is then considered to
* "belong" to the initial thread for its exclusive use; then whenever any
* thread needs to fork a new thread, it first uses the
* {@link RandomGenerator.SplittableGenerator#split split()} method of its own
* generator to create a new generator, which is then passed to the newly
* created thread for exclusive use by that new thread.
*
*
* <h2>Choosing a Random Number Generator Algorithm</h2>
*
* <p> There are three groups of random number generator algorithm provided
* in Java; Legacy group, LXM group and Xoroshiro/Xoshiro group.
*
* <p> The legacy group includes random number generators that existed
* before JDK 17; Random, ThreadLocalRandom, SplittableRandom and
* SecureRandom. Random (LCG) is the weakest of available algorithms and it
* is recommended that users migrate to newer algorithms. If an application
* requires a random number generator algorithm that is cryptographically
* secure, then it should continue to use an instance of the class {@link
* java.security.SecureRandom}.
*
* <p> The algorithms in the LXM group use a similar algorithm. The parameters
* of the algorithm can be found in algorithm name. The numbers indicate the
* number of bits in the lower and upper state bits respectively. Mix indicates
* the algorithm uses mix congruency. StarStar indicates use a double
* multiplier.
*
* <p> The algorithms in the Xoroshiro/Xoshiro are more traditional algorithms
* where the number in the name indicates the period.
*
* <p> For applications (such as physical simulation, machine learning, and
* games) that do not require a cryptographically secure algorithm, this package
* provides multiple implementations of interface {@link RandomGenerator} that
* provide trade-offs among speed, space, period, accidental correlation, and
* equidistribution properties.
*
* <p> For applications with no special requirements,
* {@code L64X128MixRandom} has a good balance among speed, space,
* and period, and is suitable for both single-threaded and multi-threaded
* applications when used properly (a separate instance for each thread).
*
* <p> If the application uses only a single thread, then
* {@code Xoroshiro128PlusPlus} is even smaller and faster, and
* certainly has a sufficiently long period.
*
* <p> For an application running in a 32-bit hardware environment and using
* only one thread or a small number of threads, {@code L32X64MixRandom} may be a good
* choice.
*
* <p> For an application that uses many threads that are allocated in one batch
* at the start of the computation, either a "jumpable" generator such as
* {@code Xoroshiro128PlusPlus} or
* {@code Xoshiro256PlusPlus} may be used, or a "splittable"
* generator such as {@code L64X128MixRandom} or
* {@code L64X256MixRandom} may be used.
*
* <p> For an application that creates many threads dynamically, perhaps through
* the use of spliterators, a "splittable" generator such as
* {@code L64X128MixRandom} or {@code L64X256MixRandom} is
* recommended. If the number of generators created dynamically may
* be very large (millions or more), then using generators such as
* {@code L128X128MixRandom} or {@code L128X256MixRandom},
* which use a 128-bit parameter rather than a 64-bit parameter for their LCG
* subgenerator, will make it much less likely that two instances use the same
* state cycle.
*
* <p> For an application that uses tuples of consecutively generated values, it
* may be desirable to use a generator that is <i>k</i>-equidistributed such
* that <i>k</i> is at least as large as the length of the tuples being
* generated. The generator {@code L64X256MixRandom} is provably
* 4-equidistributed, and {@code L64X1024MixRandom} is provably
* 16-equidistributed.
*
* <p> For applications that generate large permutations, it may be best to use
* a generator whose period is much larger than the total number of possible
* permutations; otherwise it will be impossible to generate some of the
* intended permutations. For example, if the goal is to shuffle a deck of 52
* cards, the number of possible permutations is 52! (52 factorial), which is
* larger than 2<sup>225</sup> (but smaller than 2<sup>226</sup>), so it may be
* best to use a generator whose period at least 2<sup>256</sup>, such as
* {@code L64X256MixRandom} or {@code L64X1024MixRandom}
* or {@code L128X256MixRandom} or
* {@code L128X1024MixRandom}. (It is of course also necessary to
* provide sufficiently many seed bits when the generator is initialized, or
* else it will still be impossible to generate some of the intended
* permutations.)
*
*
* <h2><a id="algorithms">Random Number Generator Algorithms Available</a></h2>
*
* These algorithms [in the table below] must be found with the current version
* of Java SE. A particular JDK implementation may recognize additional
* algorithms; check the JDK's documentation for details. The set of algorithm
* required by Java SE may be updated by changes to the Java SE specification.
* Over time, new algorithms may be added and old algorithms may be removed.
* <p>In addition, as another life-cycle phase, an algorithm may be {@linkplain
* RandomGeneratorFactory#isDeprecated() deprecated}. A deprecated algorithm is
* not recommended for use. If a required algorithm is deprecated, it may be
* removed in a future release. Due to advances in random number generator
* algorithm development and analysis, an algorithm may be deprecated during the
* lifetime of a particular Java SE release. Changing the deprecation status of
* an algorithm is <em>not</em> a specification change.
*
* <table style="padding:0px 20px 0px 0px">
* <caption>Available Algorithms</caption>
* <thead>
* <tr>
* <th style="text-align:left">Algorithm</th>
* <th style="text-align:left">Group</th>
* <th style="text-align:left">Period</th>
* <th style="text-align:right">StateBits</th>
* <th style="text-align:right">Equidistribution</th>
* </tr>
* </thead>
* <tbody>
* <tr>
* <td style="text-align:left">L128X1024MixRandom</td>
* <td style="text-align:left">LXM</td>
* <td style="text-align:left">BigInteger.ONE.shiftLeft(N*64).subtract(BigInteger.ONE).shiftLeft(128)</td>
* <td style="text-align:right">1152</td>
* <td style="text-align:right">1</td>
* </tr>
* <tr>
* <td style="text-align:left">L128X128MixRandom</td>
* <td style="text-align:left">LXM</td>
* <td style="text-align:left">BigInteger.ONE.shiftLeft(128).subtract(BigInteger.ONE).shiftLeft(128)</td>
* <td style="text-align:right">256</td>
* <td style="text-align:right">1</td>
* </tr>
* <tr>
* <td style="text-align:left">L128X256MixRandom</td>
* <td style="text-align:left">LXM</td>
* <td style="text-align:left">BigInteger.ONE.shiftLeft(256).subtract(BigInteger.ONE).shiftLeft(128)</td>
* <td style="text-align:right">384</td>
* <td style="text-align:right">1</td>
* </tr>
* <tr>
* <td style="text-align:left">L32X64MixRandom</td>
* <td style="text-align:left">LXM</td>
* <td style="text-align:left">BigInteger.ONE.shiftLeft(64).subtract(BigInteger.ONE).shiftLeft(32)</td>
* <td style="text-align:right">96</td>
* <td style="text-align:right">1</td>
* </tr>
* <tr>
* <td style="text-align:left">L64X1024MixRandom</td>
* <td style="text-align:left">LXM</td>
* <td style="text-align:left">BigInteger.ONE.shiftLeft(N*64).subtract(BigInteger.ONE).shiftLeft(64)</td>
* <td style="text-align:right">1088</td>
* <td style="text-align:right">16</td>
* </tr>
* <tr>
* <td style="text-align:left">L64X128MixRandom</td>
* <td style="text-align:left">LXM</td>
* <td style="text-align:left">BigInteger.ONE.shiftLeft(128).subtract(BigInteger.ONE).shiftLeft(64)</td>
* <td style="text-align:right">192</td>
* <td style="text-align:right">1</td>
* </tr>
* <tr>
* <td style="text-align:left">L64X128StarStarRandom</td>
* <td style="text-align:left">LXM</td>
* <td style="text-align:left">BigInteger.ONE.shiftLeft(128).subtract(BigInteger.ONE).shiftLeft(64)</td>
* <td style="text-align:right">192</td>
* <td style="text-align:right">1</td>
* </tr>
* <tr>
* <td style="text-align:left">L64X256MixRandom</td>
* <td style="text-align:left">LXM</td>
* <td style="text-align:left">BigInteger.ONE.shiftLeft(256).subtract(BigInteger.ONE).shiftLeft(64)</td>
* <td style="text-align:right">320</td>
* <td style="text-align:right">4</td>
* </tr>
* <tr>
* <td style="text-align:left">Random</td>
* <td style="text-align:left">Legacy</td>
* <td style="text-align:left">BigInteger.ONE.shiftLeft(48)</td>
* <td style="text-align:right">48</td>
* <td style="text-align:right">0</td>
* </tr>
* <tr>
* <td style="text-align:left">SplittableRandom</td>
* <td style="text-align:left">Legacy</td>
* <td style="text-align:left">BigInteger.ONE.shiftLeft(64)</td>
* <td style="text-align:right">64</td>
* <td style="text-align:right">1</td>
* </tr>
* <tr>
* <td style="text-align:left">ThreadLocalRandom <sup>*</sup></td>
* <td style="text-align:left">Legacy</td>
* <td style="text-align:left">BigInteger.ONE.shiftLeft(64)</td>
* <td style="text-align:right">64</td>
* <td style="text-align:right">1</td>
* </tr>
* <tr>
* <td style="text-align:left">Xoroshiro128PlusPlus</td>
* <td style="text-align:left">Xoroshiro</td>
* <td style="text-align:left">BigInteger.ONE.shiftLeft(128).subtract(BigInteger.ONE)</td>
* <td style="text-align:right">128</td>
* <td style="text-align:right">2</td>
* </tr>
* <tr>
* <td style="text-align:left">Xoshiro256PlusPlus</td>
* <td style="text-align:left">Xoshiro</td>
* <td style="text-align:left">BigInteger.ONE.shiftLeft(256).subtract(BigInteger.ONE)</td>
* <td style="text-align:right">256</td>
* <td style="text-align:right">4</td>
* </tr>
* </tbody>
* </table>
*
* <p><sup>*</sup> ThreadLocalRandom can only be accessed via
* {@link java.util.concurrent.ThreadLocalRandom#current()}.
*
* <h2>Categories of Random Number Generator Algorithms</h2>
*
* Historically, most pseudorandom generator algorithms have been based on some
* sort of finite-state machine with a single, large cycle of states; when it is
* necessary to have multiple threads use the same algorithm simultaneously, the
* usual technique is to arrange for each thread to traverse a different region
* of the state cycle. These regions may be doled out to threads by starting
* with a single initial state and then using a "jump function" that travels a
* long distance around the cycle (perhaps 2<sup>64</sup> steps or more); the
* jump function is applied repeatedly and sequentially, to identify widely
* spaced states that are then doled out, one to each thread, to serve as the
* initial state for the generator to be used by that thread. This strategy is
* supported by the interface {@link RandomGenerator.JumpableGenerator}.
* Sometimes it is desirable to support two levels of jumping (by long distances
* and by <i>really</i> long distances); this strategy is supported by the
* interface {@link RandomGenerator.LeapableGenerator}. There is also an interface
* {@link RandomGenerator.ArbitrarilyJumpableGenerator} for algorithms that allow
* jumping along the state cycle by any user-specified distance. In this package,
* implementations of these interfaces include
* "Xoroshiro128PlusPlus", and
* "Xoshiro256PlusPlus".
*
* <p> A more recent category of "splittable" pseudorandom generator algorithms
* uses a large family of state cycles and makes some attempt to ensure that
* distinct instances use different state cycles; but even if two instances
* "accidentally" use the same state cycle, they are highly likely to traverse
* different regions parts of that shared state cycle. This strategy is
* supported by the interface {@link RandomGenerator.SplittableGenerator}.
* In this package, implementations of this interface include
* "L32X64MixRandom",
* "L64X128StarStarRandom",
* "L64X128MixRandom",
* "L64X256MixRandom",
* "L64X1024MixRandom",
* "L128X128MixRandom",
* "L128X256MixRandom", and
* "L128X1024MixRandom"; note that the class
* {@link java.util.SplittableRandom} also implements this interface.
*
*
* <h2>The LXM Family of Random Number Generator Algorithms</h2>
*
* The structure of the central nextLong (or nextInt) method of an LXM
* algorithm follows a suggestion in December 2017 by Sebastiano Vigna
* that using one LCG subgenerator and one xor-based subgenerator (rather
* than two LCG subgenerators) would provide a longer period, superior
* equidistribution, scalability, and better quality. Each of the
* specific implementations here combines one of the best currently known
* xor-based generators (xoroshiro or xoshiro, described by Blackman and
* Vigna in "Scrambled Linear Pseudorandom Number Generators", ACM
* Trans. Math. Softw., 2021) with an LCG that uses one of the best
* currently known multipliers (found by a search for better multipliers
* in 2019 by Steele and Vigna), and then applies a mixing function
* identified by Doug Lea. Testing has confirmed that the LXM algorithm
* is far superior in quality to the SplitMix algorithm (2014) used by
* SplittableRandom.
*
* Each class with a name of the form {@code L}<i>p</i>{@code X}<i>q</i>{@code
* SomethingRandom} uses some specific member of the LXM family of random number
* algorithms; "LXM" is short for "LCG, Xorshift, Mixing function". Every LXM
* generator consists of two subgenerators; one is an LCG (Linear Congruential
* Generator) and the other is an Xorshift generator. Each output of an LXM
* generator is the result of combining state from the LCG with state from the
* Xorshift generator by using a Mixing function (and then the state of the LCG
* and the state of the Xorshift generator are advanced).
*
* <p> The LCG subgenerator has an update step of the form {@code s = m*s + a},
* where {@code s}, {@code m}, and {@code a} are all binary integers of the same
* size, each having <i>p</i> bits; {@code s} is the mutable state, the
* multiplier {@code m} is fixed (the same for all instances of a class) and the
* addend {@code a} is a parameter (a final field of the instance). The
* parameter {@code a} is required to be odd (this allows the LCG to have the
* maximal period, namely 2<sup><i>p</i></sup>); therefore there are
* 2<sup><i>p</i>&minus;1</sup> distinct choices of parameter. (When the size of
* {@code s} is 128 bits, then we use the name "{@code sh}" below to refer to
* the high half of {@code s}, that is, the high-order 64 bits of {@code s}.)
*
* <p> The Xorshift subgenerator can in principle be any one of a wide variety
* of xorshift algorithms; in this package it is always either
* {@code xoroshiro128}, {@code xoshiro256}, or {@code xoroshiro1024}, in each
* case without any final scrambler such as "+" or "**". Its state consists of
* some fixed number of {@code int} or {@code long} fields, generally named
* {@code x0}, {@code x1}, and so on, which can take on any values provided that
* they are not all zero. The collective total size of these fields is <i>q</i>
* bits; therefore the period of this subgenerator is
* 2<sup><i>q</i></sup>&minus;1.
*
* <p> Because the periods 2<sup><i>p</i></sup> and 2<sup><i>q</i></sup>&minus;1
* of the two subgenerators are relatively prime, the <em>period</em> of any
* single instance of an LXM algorithm (the length of the series of generated
* values before it repeats) is the product of the periods of the subgenerators,
* that is, 2<sup><i>p</i></sup>(2<sup><i>q</i></sup>&minus;1), which is just
* slightly smaller than 2<sup>(<i>p</i>+<i>q</i>)</sup>. Moreover, if two
* distinct instances of the same LXM algorithm have different {@code a}
* parameters, then their cycles of produced values will be different.
*
* <p> Generally speaking, among the "{@code L}<i>p</i>{@code X}<i>q</i>"
* generators, the memory required for an instance is 2<i>p</i>+<i>q</i> bits.
* (If <i>q</i> is 1024 or larger, the Xorshift state is represented as an
* array, so additional bits are needed for the array object header, and another
* 32 bits are used for an array index.)
*
* <p> Larger values of <i>p</i> imply a lower probability that two distinct
* instances will traverse the same state cycle, and larger values of <i>q</i>
* imply that the generator is equidistributed in a larger number of dimensions
* (this is provably true when <i>p</i> is 64, and conjectured to be
* approximately true when <i>p</i> is 128). A class with "{@code Mix}" in its
* name uses a fairly strong mixing function with excellent avalanche
* characteristics; a class with "{@code StarStar}" in its name uses a weaker
* but faster mixing function.
*
* <p> The specific LXM algorithms used in this package are all chosen so that
* the 64-bit values produced by the {@link RandomGenerator#nextLong nextLong()}
* method are exactly equidistributed (for example, for any specific instance of
* "L64X128MixRandom", over the course of its cycle each of the
* 2<sup>64</sup> possible {@code long} values will be produced
* 2<sup>128</sup>&minus;1 times). The values produced by the
* {@link RandomGenerator#nextInt nextInt()},
* {@link RandomGenerator#nextFloat nextFloat()}, and
* {@link RandomGenerator#nextDouble nextDouble()} methods are likewise exactly
* equidistributed. Some algorithms provide a further guarantee of
* <i>k</i>-equidistribution for some <i>k</i> greater than 1, meaning that successive
* non-overlapping <i>k</i>-tuples of 64-bit values produced by the
* {@link RandomGenerator#nextLong nextLong()} method are exactly
* equidistributed (equally likely to occur).
*
* <p> The following table gives the period, state size (in bits), parameter
* size (in bits, including the low-order bit that is required always to be a
* 1-bit), and equidistribution property for each of the specific LXM algorithms
* used in this package.
*
* <table style="padding:0px 20px 0px 0px">
* <caption>Algorithm Properties</caption>
* <thead>
* <tr><th style="text-align:left">Implementation</th>
* <th style="text-align:right">Period</th>
* <th style="text-align:right">State size</th>
* <th style="text-align:right">Parameter size</th>
* <th style="text-align:left">{@link RandomGenerator#nextLong nextLong()} values are</th></tr>
* </thead>
* <tbody>
* <tr><td style="text-align:left">"L32X64MixRandom"</td>
* <td style="text-align:right">2<sup>32</sup>(2<sup>64</sup>&minus;1)</td>
* <td style="text-align:right">96 bits</td>
* <td style="text-align:right">32 bits</td>
* <td style="text-align:left"></td></tr>
* <tr><td style="text-align:left">"L64X128StarStarRandom"</td>
* <td style="text-align:right">2<sup>64</sup>(2<sup>128</sup>&minus;1)</td>
* <td style="text-align:right">192 bits</td>
* <td style="text-align:right">64 bits</td>
* <td style="text-align:left">2-equidistributed and exactly equidistributed</td></tr>
* <tr><td style="text-align:left">"L64X128MixRandom"</td>
* <td style="text-align:right">2<sup>64</sup>(2<sup>128</sup>&minus;1)</td>
* <td style="text-align:right">192 bits</td>
* <td style="text-align:right">64 bits</td>
* <td style="text-align:left">2-equidistributed and exactly equidistributed</td></tr>
* <tr><td style="text-align:left">"L64X256MixRandom"</td>
* <td style="text-align:right">2<sup>64</sup>(2<sup>256</sup>&minus;1)</td>
* <td style="text-align:right">320 bits</td>
* <td style="text-align:right">64 bits</td>
* <td style="text-align:left">4-equidistributed and exactly equidistributed</td></tr>
* <tr><td style="text-align:left">"L64X1024MixRandom"</td>
* <td style="text-align:right">2<sup>64</sup>(2<sup>1024</sup>&minus;1)</td>
* <td style="text-align:right">1088 bits</td>
* <td style="text-align:right">64 bits</td>
* <td style="text-align:left">16-equidistributed and exactly equidistributed</td></tr>
* <tr><td style="text-align:left">"L128X128MixRandom"</td>
* <td style="text-align:right">2<sup>128</sup>(2<sup>128</sup>&minus;1)</td>
* <td style="text-align:right">256 bits</td>
* <td style="text-align:right">128 bits</td>
* <td style="text-align:left">exactly equidistributed</td></tr>
* <tr><td style="text-align:left">"L128X256MixRandom"</td>
* <td style="text-align:right">2<sup>128</sup>(2<sup>256</sup>&minus;1)</td>
* <td style="text-align:right">384 bits</td>
* <td style="text-align:right">128 bits</td>
* <td style="text-align:left">exactly equidistributed</td></tr>
* <tr><td style="text-align:left">"L128X1024MixRandom"</td>
* <td style="text-align:right">2<sup>128</sup>(2<sup>1024</sup>&minus;1)</td>
* <td style="text-align:right">1152 bits</td>
* <td style="text-align:right">128 bits</td>
* <td style="text-align:left">exactly equidistributed</td></tr>
* </tbody>
* </table>
*
* For the algorithms listed above whose names begin with {@code L32}, the
* 32-bit values produced by the {@link RandomGenerator#nextInt nextInt()}
* method are exactly equidistributed, but the 64-bit values produced by the
* {@link RandomGenerator#nextLong nextLong()} method are not exactly
* equidistributed.
*
* <p> For the algorithms listed above whose names begin with {@code L64} or
* {@code L128}, the 64-bit values produced by the
* {@link RandomGenerator#nextLong nextLong()} method are <i>exactly
* equidistributed</i>: every instance, over the course of its cycle, will
* produce each of the 2<sup>64</sup> possible {@code long} values exactly the
* same number of times. For example, any specific instance of
* "L64X256MixRandom", over the course of its cycle each of the
* 2<sup>64</sup> possible {@code long} values will be produced
* 2<sup>256</sup>&minus;1 times. The values produced by the
* {@link RandomGenerator#nextInt nextInt()},
* {@link RandomGenerator#nextFloat nextFloat()}, and
* {@link RandomGenerator#nextDouble nextDouble()} methods are likewise exactly
* equidistributed.
*
* <p> In addition, for the algorithms listed above whose names begin with
* {@code L64}, the 64-bit values produced by the
* {@link RandomGenerator#nextLong nextLong()} method are
* <i>k</i>-equidistributed (but not exactly <i>k</i>-equidistributed). To be
* precise, and taking "L64X256MixRandom" as an example: for
* any specific instance of "L64X256MixRandom", consider the
* (overlapping) length-4 subsequences of the cycle of 64-bit values produced by
* {@link RandomGenerator#nextLong nextLong()} (assuming no other methods are
* called that would affect the state). There are
* 2<sup>64</sup>(2<sup>256</sup>&minus;1) such subsequences, and each
* subsequence, which consists of 4 64-bit values, can have one of
* 2<sup>256</sup> values. Of those 2<sup>256</sup> subsequence values, nearly
* all of them (2<sup>256</sup>%minus;2<sup>64</sup>) occur 2<sup>64</sup> times
* over the course of the entire cycle, and the other 2<sup>64</sup> subsequence
* values occur only 2<sup>64</sup>&minus;1 times. So the ratio of the
* probability of getting any specific one of the less common subsequence values
* and the probability of getting any specific one of the more common
* subsequence values is 1&minus;2<sup>-64</sup>. (Note that the set of
* 2<sup>64</sup> less-common subsequence values will differ from one instance
* of "L64X256MixRandom" to another, as a function of the
* additive parameter of the LCG.) The values produced by the
* {@link RandomGenerator#nextInt nextInt()},
* {@link RandomGenerator#nextFloat nextFloat()}, and
* {@link RandomGenerator#nextDouble nextDouble()} methods are likewise
* 4-equidistributed (but not exactly 4-equidistributed).
*
* <p> The next table gives the LCG multiplier value, the name of the specific
* Xorshift algorithm used, the specific numeric parameters for that Xorshift
* algorithm, and the mixing function for each of the specific LXM algorithms
* used in this package. (Note that the multiplier used for the 128-bit LCG
* cases is 65 bits wide, so the constant {@code 0x1d605bbb58c8abbfdL} shown in
* the table cannot actually be used in code; instead, only the 64 low-order
* bits {@code 0xd605bbb58c8abbfdL} are represented in the source code, and the
* missing 1-bit is handled through special coding of the multiply-add algorithm
* used in the LCG.)
*
* <table style="padding:0px 20px 0px 0px">
* <caption>LXM Multipliers</caption>
* <thead>
* <tr><th style="text-align:left">Implementation</th>
* <th style="text-align:right">LCG multiplier {@code m}</th>
* <th style="text-align:left">Xorshift algorithm</th>
* <th style="text-align:left">Xorshift parameters</th>
* <th style="text-align:left">Mixing function</th></tr>
* </thead>
* <tbody>
* <tr><td style="text-align:left">"L32X64MixRandom"</td>
* <td style="text-align:right">{@code 0xadb4a92d}</td>
* <td style="text-align:left">{@code xoroshiro64}, version 1.0</td>
* <td style="text-align:left">{@code (26, 9, 13)}</td>
* <td style="text-align:left">mixLea32{@code (s+x0)}</td></tr>
* <tr><td style="text-align:left">"L64X128StarStarRandom" </td>
* <td style="text-align:right">{@code 0xd1342543de82ef95L}</td>
* <td style="text-align:left">{@code xoroshiro128}, version 1.0</td>
* <td style="text-align:left">{@code (24, 16, 37)}</td>
* <td style="text-align:left">{@code Long.rotateLeft((s+x0)* 5, 7) * 9}</td></tr>
* <tr><td style="text-align:left">"L64X128MixRandom"</td>
* <td style="text-align:right">{@code 0xd1342543de82ef95L}</td>
* <td style="text-align:left">{@code xoroshiro128}, version 1.0</td>
* <td style="text-align:left">{@code (24, 16, 37)}</td>
* <td style="text-align:left">mixLea32{@code (s+x0)}</td></tr>
* <tr><td style="text-align:left">"L64X256MixRandom"</td>
* <td style="text-align:right">{@code 0xd1342543de82ef95L}</td>
* <td style="text-align:left">{@code xoshiro256}, version 1.0</td>
* <td style="text-align:left">{@code (17, 45)}</td>
* <td style="text-align:left">mixLea32{@code (s+x0)}</td></tr>
* <tr><td style="text-align:left">"L64X1024MixRandom"</td>
* <td style="text-align:right">{@code 0xd1342543de82ef95L}</td>
* <td style="text-align:left">{@code xoroshiro1024}, version 1.0</td>
* <td style="text-align:left">{@code (25, 27, 36)}</td>
* <td style="text-align:left">mixLea32{@code (s+x0)}</td></tr>
* <tr><td style="text-align:left">"L128X128MixRandom"</td>
* <td style="text-align:right">{@code 0x1d605bbb58c8abbfdL}</td>
* <td style="text-align:left">{@code xoroshiro128}, version 1.0</td>
* <td style="text-align:left">{@code (24, 16, 37)}</td>
* <td style="text-align:left">mixLea32{@code (sh+x0)}</td></tr>
* <tr><td style="text-align:left">"L128X256MixRandom"</td>
* <td style="text-align:right">{@code 0x1d605bbb58c8abbfdL}</td>
* <td style="text-align:left">{@code xoshiro256}, version 1.0</td>
* <td style="text-align:left">{@code (17, 45)}</td>
* <td style="text-align:left">mixLea32{@code (sh+x0)}</td></tr>
* <tr><td style="text-align:left">"L128X1024MixRandom"</td>
* <td style="text-align:right">{@code 0x1d605bbb58c8abbfdL}</td>
* <td style="text-align:left">{@code xoroshiro1024}, version 1.0</td>
* <td style="text-align:left">{@code (25, 27, 36)}</td>
* <td style="text-align:left">mixLea32{@code (sh+x0)}</td></tr>
* </tbody>
* </table>
*
* @since 17
*/
package java.util.random;