JDK 17 jdk.random.jmod - JDK Random Module
JDK 17 jdk.random.jmod is the JMOD file for JDK 17 Random module.
JDK 17 Random module compiled class files are stored in \fyicenter\jdk-17.0.5\jmods\jdk.random.jmod.
JDK 17 Random module compiled class files are also linked and stored in the \fyicenter\jdk-17.0.5\lib\modules JImage file.
JDK 17 Random module source code files are stored in \fyicenter\jdk-17.0.5\lib\src.zip\jdk.random.
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⏎ jdk/random/Xoroshiro128PlusPlus.java
/*
* Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package jdk.random;
import java.util.concurrent.atomic.AtomicLong;
import java.util.random.RandomGenerator;
import java.util.random.RandomGenerator.LeapableGenerator;
import jdk.internal.util.random.RandomSupport;
import jdk.internal.util.random.RandomSupport.RandomGeneratorProperties;
/**
* A "jumpable and leapable" pseudorandom number generator (PRNG) whose period
* is roughly 2<sup>128</sup>. Class {@link Xoroshiro128PlusPlus} implements
* interfaces {@link RandomGenerator} and {@link LeapableGenerator},
* and therefore supports methods for producing pseudorandomly chosen
* numbers of type {@code int}, {@code long}, {@code float}, and {@code double}
* as well as creating new {@link Xoroshiro128PlusPlus} objects
* by "jumping" or "leaping".
* <p>
* The class {@link Xoroshiro128PlusPlus} uses the {@code xoroshiro128} algorithm
* (parameters 49, 21, 28) with the "++" scrambler that computes
* {@code Long.rotateLeft(s0 + s1, 17) + s0}.
* (See David Blackman and Sebastiano Vigna, "Scrambled Linear Pseudorandom
* Number Generators," ACM Transactions on Mathematical Software, 2021.)
* Its state consists of two {@code long} fields {@code x0} and {@code x1},
* which can take on any values provided that they are not both zero.
* The period of this generator is 2<sup>128</sup>-1.
* <p>
* The 64-bit values produced by the {@code nextLong()} method are equidistributed.
* To be precise, over the course of the cycle of length 2<sup>128</sup>-1,
* each nonzero {@code long} value is generated 2<sup>64</sup> times,
* but the value 0 is generated only 2<sup>64</sup>-1 times.
* The values produced by the {@code nextInt()}, {@code nextFloat()}, and {@code nextDouble()}
* methods are likewise equidistributed.
* <p>
* Instances {@link Xoroshiro128PlusPlus} are <em>not</em> thread-safe.
* They are designed to be used so that each thread as its own instance.
* The methods {@link #jump} and {@link #leap} and {@link #jumps} and {@link #leaps}
* can be used to construct new instances of {@link Xoroshiro128PlusPlus} that traverse
* other parts of the state cycle.
* <p>
* Instances of {@link Xoroshiro128PlusPlus} are not cryptographically
* secure. Consider instead using {@link java.security.SecureRandom}
* in security-sensitive applications. Additionally,
* default-constructed instances do not use a cryptographically random
* seed unless the {@linkplain System#getProperty system property}
* {@code java.util.secureRandomSeed} is set to {@code true}.
*
* @since 17
*
*/
@RandomGeneratorProperties(
name = "Xoroshiro128PlusPlus",
group = "Xoroshiro",
i = 128, j = 1, k = 0,
equidistribution = 1
)
public final class Xoroshiro128PlusPlus implements LeapableGenerator {
/*
* Implementation Overview.
*
* This is an implementation of the xoroshiro128++ algorithm version 1.0,
* written in 2019 by David Blackman and Sebastiano Vigna (vigna@acm.org).
*
* The jump operation moves the current generator forward by 2*64
* steps; this has the same effect as calling nextLong() 2**64
* times, but is much faster. Similarly, the leap operation moves
* the current generator forward by 2*96 steps; this has the same
* effect as calling nextLong() 2**96 times, but is much faster.
* The copy method may be used to make a copy of the current
* generator. Thus one may repeatedly and cumulatively copy and
* jump to produce a sequence of generators whose states are well
* spaced apart along the overall state cycle (indeed, the jumps()
* and leaps() methods each produce a stream of such generators).
* The generators can then be parceled out to other threads.
*
* File organization: First the non-public methods that constitute the
* main algorithm, then the public methods. Note that many methods are
* defined by classes {@link AbstractJumpableGenerator} and {@link AbstractGenerator}.
*/
/* ---------------- static fields ---------------- */
/**
* Group name.
*/
private static final String GROUP = "Xoroshiro";
/**
* The seed generator for default constructors.
*/
private static final AtomicLong defaultGen = new AtomicLong(RandomSupport.initialSeed());
/* ---------------- instance fields ---------------- */
/**
* The per-instance state.
* At least one of the two fields x0 and x1 must be nonzero.
*/
private long x0, x1;
/* ---------------- constructors ---------------- */
/**
* Basic constructor that initializes all fields from parameters.
* It then adjusts the field values if necessary to ensure that
* all constraints on the values of fields are met.
*
* @param x0 first word of the initial state
* @param x1 second word of the initial state
*/
public Xoroshiro128PlusPlus(long x0, long x1) {
this.x0 = x0;
this.x1 = x1;
// If x0 and x1 are both zero, we must choose nonzero values.
if ((x0 | x1) == 0) {
this.x0 = RandomSupport.GOLDEN_RATIO_64;
this.x1 = RandomSupport.SILVER_RATIO_64;
}
}
/**
* Creates a new instance of {@link Xoroshiro128PlusPlus} using the
* specified {@code long} value as the initial seed. Instances of
* {@link Xoroshiro128PlusPlus} created with the same seed in the same
* program generate identical sequences of values.
*
* @param seed the initial seed
*/
public Xoroshiro128PlusPlus(long seed) {
// Using a value with irregularly spaced 1-bits to xor the seed
// argument tends to improve "pedestrian" seeds such as 0 or
// other small integers. We may as well use SILVER_RATIO_64.
//
// The x values are then filled in as if by a SplitMix PRNG with
// GOLDEN_RATIO_64 as the gamma value and Stafford13 as the mixer.
this(RandomSupport.mixStafford13(seed ^= RandomSupport.SILVER_RATIO_64),
RandomSupport.mixStafford13(seed + RandomSupport.GOLDEN_RATIO_64));
}
/**
* Creates a new instance of {@link Xoroshiro128PlusPlus} that is likely to
* generate sequences of values that are statistically independent
* of those of any other instances in the current program execution,
* but may, and typically does, vary across program invocations.
*/
public Xoroshiro128PlusPlus() {
// Using GOLDEN_RATIO_64 here gives us a good Weyl sequence of values.
this(defaultGen.getAndAdd(RandomSupport.GOLDEN_RATIO_64));
}
/**
* Creates a new instance of {@link Xoroshiro128PlusPlus} using the specified array of
* initial seed bytes. Instances of {@link Xoroshiro128PlusPlus} created with the same
* seed array in the same program execution generate identical sequences of values.
*
* @param seed the initial seed
*/
public Xoroshiro128PlusPlus(byte[] seed) {
// Convert the seed to 2 long values, which are not both zero.
long[] data = RandomSupport.convertSeedBytesToLongs(seed, 2, 2);
long x0 = data[0], x1 = data[1];
this.x0 = x0;
this.x1 = x1;
}
/* ---------------- public methods ---------------- */
public Xoroshiro128PlusPlus copy() {
return new Xoroshiro128PlusPlus(x0, x1);
}
/*
* The following two comments are quoted from http://prng.di.unimi.it/xoroshiro128plusplus.c
*/
/*
* To the extent possible under law, the author has dedicated all copyright
* and related and neighboring rights to this software to the public domain
* worldwide. This software is distributed without any warranty.
* <p>
* See http://creativecommons.org/publicdomain/zero/1.0/.
*/
/*
* This is xoroshiro128++ 1.0, one of our all-purpose, rock-solid,
* small-state generators. It is extremely (sub-ns) fast and it passes all
* tests we are aware of, but its state space is large enough only for
* mild parallelism.
* <p>
* For generating just floating-point numbers, xoroshiro128+ is even
* faster (but it has a very mild bias, see notes in the comments).
* <p>
* The state must be seeded so that it is not everywhere zero. If you have
* a 64-bit seed, we suggest to seed a splitmix64 generator and use its
* output to fill s.
*/
@Override
public long nextLong() {
final long s0 = x0;
long s1 = x1;
// Compute the result based on current state information
// (this allows the computation to be overlapped with state update).
final long result = Long.rotateLeft(s0 + s1, 17) + s0; // "plusplus" scrambler
s1 ^= s0;
x0 = Long.rotateLeft(s0, 49) ^ s1 ^ (s1 << 21); // a, b
x1 = Long.rotateLeft(s1, 28); // c
return result;
}
@Override
public double jumpDistance() {
return 0x1.0p64;
}
@Override
public double leapDistance() {
return 0x1.0p96;
}
private static final long[] JUMP_TABLE = { 0x2bd7a6a6e99c2ddcL, 0x0992ccaf6a6fca05L };
private static final long[] LEAP_TABLE = { 0x360fd5f2cf8d5d99L, 0x9c6e6877736c46e3L };
@Override
public void jump() {
jumpAlgorithm(JUMP_TABLE);
}
@Override
public void leap() {
jumpAlgorithm(LEAP_TABLE);
}
private void jumpAlgorithm(long[] table) {
long s0 = 0, s1 = 0;
for (int i = 0; i < table.length; i++) {
for (int b = 0; b < 64; b++) {
if ((table[i] & (1L << b)) != 0) {
s0 ^= x0;
s1 ^= x1;
}
nextLong();
}
}
x0 = s0;
x1 = s1;
}
}
⏎ jdk/random/Xoroshiro128PlusPlus.java
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