--- a/src/java.base/share/classes/java/util/random/Xoroshiro128Plus.java Thu Aug 29 11:33:26 2019 -0300
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,300 +0,0 @@
-/*
- * Copyright (c) 2013, 2019, 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.math.BigInteger;
-import java.util.concurrent.atomic.AtomicLong;
-import java.util.random.RandomGenerator.LeapableGenerator;
-
-/**
- * A generator of uniform pseudorandom values applicable for use in
- * (among other contexts) isolated parallel computations that may
- * generate subtasks. Class {@link Xoroshiro128Plus} 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 Xoroshiro128Plus} objects
- * by "jumping" or "leaping".
- * <p>
- * Series of generated values pass the TestU01 BigCrush and PractRand test suites
- * that measure independence and uniformity properties of random number generators,
- * <em>except</em> that it does not pass the binary rank tests of PractRand,
- * which fail due to the lowest bit being an LFSR; all other bits pass all tests.
- * For this reason may be best for some purposes to use this generator to generate
- * pseudorandom {@code int}, {@code float}, and {@code double} values but not
- * {@code long} values. For the same reason, it may be best not to use the
- * method {@code nextGaussian} or {@code nextExponential} with this generator.
- * <p>
- * The class {@link Xoroshiro128Plus} uses the {@code xoroshiro128} algorithm,
- * version 1.0 (parameters 24, 16, 37), with the "+" scrambler
- * (the returned value is the sum of the two state variables {@code x0} and {@code x1}).
- * 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 Xoroshiro128Plus} 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 Xoroshiro128Plus} that traverse
- * other parts of the state cycle.
- * <p>
- * Instances of {@link Xoroshiro128Plus} 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 14
- */
-public final class Xoroshiro128Plus implements LeapableGenerator {
-
- /*
- * Implementation Overview.
- *
- * This is an implementation of the xoroshiro128+ algorithm written
- * in 2016 by David Blackman and Sebastiano Vigna (vigna@acm.org),
- * and updated with improved parameters in 2018.
- * See http://xoshiro.di.unimi.it and these two papers:
- *
- * Sebastiano Vigna. 2016. An Experimental Exploration of Marsaglia's
- * xorshift Generators, Scrambled. ACM Transactions on Mathematical
- * Software 42, 4, Article 30 (June 2016), 23 pages.
- * https://doi.org/10.1145/2845077
- *
- * David Blackman and Sebastiano Vigna. 2018. Scrambled Linear
- * Pseudorandom Number Generators. Computing Research Repository (CoRR).
- * http://arxiv.org/abs/1805.01407
- *
- * 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 ---------------- */
-
- /**
- * The seed generator for default constructors.
- */
- private static final AtomicLong defaultGen = new AtomicLong(RandomSupport.initialSeed());
-
- /*
- * The period of this generator, which is 2**128 - 1.
- */
- private static final BigInteger PERIOD =
- BigInteger.ONE.shiftLeft(128).subtract(BigInteger.ONE);
-
- /* ---------------- 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 Xoroshiro128Plus(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) {
- // At least one of the two values generated here will be nonzero.
- this.x0 = RandomSupport.mixStafford13(x0 += RandomSupport.GOLDEN_RATIO_64);
- this.x1 = (x0 += RandomSupport.GOLDEN_RATIO_64);
- }
- }
-
- /**
- * Creates a new instance of {@link Xoroshiro128Plus} using the
- * specified {@code long} value as the initial seed. Instances of
- * {@link Xoroshiro128Plus} created with the same seed in the same
- * program generate identical sequences of values.
- *
- * @param seed the initial seed
- */
- public Xoroshiro128Plus(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 Xoroshiro128Plus} 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 Xoroshiro128Plus() {
- // 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 Xoroshiro128Plus} using the specified array of
- * initial seed bytes. Instances of {@link Xoroshiro128Plus} created with the same
- * seed array in the same program execution generate identical sequences of values.
- *
- * @param seed the initial seed
- */
- public Xoroshiro128Plus(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 Xoroshiro128Plus copy() { return new Xoroshiro128Plus(x0, x1); }
-
-
- /*
- * 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 the successor to xorshift128+. It is the fastest full-period generator passing
- * BigCrush without systematic failures, but due to the relatively short period it is acceptable
- * only for applications with a mild amount of parallelism; otherwise, use a xorshift1024*
- * generator.
- * <p>
- * Beside passing BigCrush, this generator passes the PractRand test suite up to (and included)
- * 16TB, with the exception of binary rank tests, which fail due to the lowest bit being an
- * LFSR; all other bits pass all tests. We suggest to use a sign test to extract a random
- * Boolean value.
- * <p>
- * Note that the generator uses a simulated rotate operation, which most C compilers will turn
- * into a single instruction. In Java, you can use Long.rotateLeft(). In languages that do not
- * make low-level rotation instructions accessible xorshift128+ could be faster.
- * <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.
- */
-
- /**
- * Returns a pseudorandom {@code long} value.
- *
- * @return a pseudorandom {@code long} value
- */
- public long nextLong() {
- final long s0 = x0;
- long s1 = x1;
- final long z = s0 + s1;
-
- s1 ^= s0;
- x0 = Long.rotateLeft(s0, 24) ^ s1 ^ (s1 << 16); // a, b
- x1 = Long.rotateLeft(s1, 37); // c
-
- return z;
- }
-
- public BigInteger period() {
- return PERIOD;
- }
-
- public double defaultJumpDistance() {
- return 0x1.0p64;
- }
-
- public double defaultLeapDistance() {
- return 0x1.0p96;
- }
-
- private static final long[] JUMP_TABLE = { 0xdf900294d8f554a5L, 0x170865df4b3201fcL };
-
- private static final long[] LEAP_TABLE = { 0xd2a98b26625eee7bL, 0xdddf9b1090aa7ac1L };
-
- /*
- * This is the jump function for the generator. It is equivalent
- * to 2**64 calls to nextLong(); it can be used to generate 2**64
- * non-overlapping subsequences for parallel computations.
- */
- public void jump() {
- jumpAlgorithm(JUMP_TABLE);
- }
-
- /**
- * This is the long-jump function for the generator. It is equivalent to 2**96 calls to next();
- * it can be used to generate 2**32 starting points, from each of which jump() will generate
- * 2**32 non-overlapping subsequences for parallel distributed computations.
- */
- 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;
- }
- }
-}