jdk-sandbox: comparison src/java.base/share/classes/java/util/random/Xoroshiro128StarStar.java

equal deleted inserted replaced

-:b0c958c0e6c6
+:f02ffcb61dce
 *
 * 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;
+package java.util.random;
 import java.math.BigInteger;
 import java.util.concurrent.atomic.AtomicLong;
 /**
 * A generator of uniform pseudorandom values applicable for use in
 * (among other contexts) isolated parallel computations that may
-* generate subtasks.  Class {@code Xoroshiro128StarStar} implements
+* generate subtasks.  Class {@link Xoroshiro128StarStar} implements
-* interfaces {@link java.util.Rng} and {@link java.util.LeapableRng},
+* interfaces {@link RandomNumberGenerator} and {@link LeapableRNG},
 * 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 {@code Xoroshiro128StarStar} objects
+* as well as creating new {@link Xoroshiro128StarStar} objects
 * by "jumping" or "leaping".
-*
+* <p>
-* <p>Series of generated values pass the TestU01 BigCrush and PractRand test suites
+* Series of generated values pass the TestU01 BigCrush and PractRand test suites
 * that measure independence and uniformity properties of random number generators.
-*
+* <p>
-* <p>The class {@code Xoroshiro128StarStar} uses the {@code xoroshiro128} algorithm,
+* The class {@link Xoroshiro128StarStar} uses the {@code xoroshiro128} algorithm,
 * version 1.0 (parameters 24, 16, 37), with the "**" scrambler (a mixing function).
 * 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>
-* <p>The 64-bit values produced by the {@code nextLong()} method are equidistributed.
+* 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>
-* <p>In fact, the 64-bit values produced by the {@code nextLong()} method are 2-equidistributed.
+* In fact, the 64-bit values produced by the {@code nextLong()} method are 2-equidistributed.
 * To be precise: consider the (overlapping) length-2 subsequences of the cycle of 64-bit
 * values produced by {@code nextLong()} (assuming no other methods are called that would
 * affect the state).  There are 2<sup>128</sup>-1 such subsequences, and each subsequence,
 * which consists of 2 64-bit values, can have one of 2<sup>128</sup> values.  Of those
 * 2<sup>128</sup> subsequence values, each one is generated exactly once over the course
 * of the entire cycle, except that the subsequence (0, 0) never appears.
 * The values produced by the {@code nextInt()}, {@code nextFloat()}, and {@code nextDouble()}
 * methods are likewise 2-equidistributed, but note that that the subsequence (0, 0)
 * can also appear (but occurring somewhat less frequently than all other subsequences),
 * because the values produced by those methods have fewer than 64 randomly chosen bits.
-*
+* <p>
-* <p>Instances {@code Xoroshiro128StarStar} are <em>not</em> thread-safe.
+* Instances {@link Xoroshiro128StarStar} 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 {@code Xoroshiro128StarStar} that traverse
+* can be used to construct new instances of {@link Xoroshiro128StarStar} that traverse
 * other parts of the state cycle.
-*
+* <p>
-* <p>Instances of {@code Xoroshiro128StarStar} are not cryptographically
+* Instances of {@link Xoroshiro128StarStar} 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}.
 *
-* @author  Guy Steele
+* @since 14
-* @author  Doug Lea
-* @since   1.8
 */
-public final class Xoroshiro128StarStar implements LeapableRng {
+public final class Xoroshiro128StarStar implements LeapableRNG {
 /*
 * Implementation Overview.
 *
 * This is an implementation of the xoroshiro128** algorithm written
 * 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 {@code AbstractJumpableRng} and {@code AbstractRng}.
+* defined by classes {@link AbstractJumpableRNG} and {@link AbstractRNG}.
 */
 /* ---------------- static fields ---------------- */
 /**
 * The seed generator for default constructors.
 */
-private static final AtomicLong defaultGen = new AtomicLong(RngSupport.initialSeed());
+private static final AtomicLong DEFAULT_GEN = new AtomicLong(RNGSupport.initialSeed());
 /*
 * The period of this generator, which is 2**128 - 1.
 */
-private static final BigInteger thePeriod =
+private static final BigInteger PERIOD =
-	BigInteger.ONE.shiftLeft(128).subtract(BigInteger.ONE);
+BigInteger.ONE.shiftLeft(128).subtract(BigInteger.ONE);
 /* ---------------- instance fields ---------------- */
 /**
 * The per-instance state.
 *
 * @param x0 first word of the initial state
 * @param x1 second word of the initial state
 */
 public Xoroshiro128StarStar(long x0, long x1) {
-	this.x0 = x0;
+this.x0 = x0;
 this.x1 = x1;
-	// If x0 and x1 are both zero, we must choose nonzero values.
+// 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.
+// At least one of the two values generated here will be nonzero.
-	    this.x0 = RngSupport.mixStafford13(x0 += RngSupport.GOLDEN_RATIO_64);
+this.x0 = RNGSupport.mixStafford13(x0 += RNGSupport.GOLDEN_RATIO_64);
-	    this.x1 = (x0 += RngSupport.GOLDEN_RATIO_64);
+this.x1 = (x0 += RNGSupport.GOLDEN_RATIO_64);
-	}
+}
 }
 /**
-* Creates a new instance of {@code Xoroshiro128StarStar} using the
+* Creates a new instance of {@link Xoroshiro128StarStar} using the
 * specified {@code long} value as the initial seed. Instances of
-* {@code Xoroshiro128StarStar} created with the same seed in the same
+* {@link Xoroshiro128StarStar} created with the same seed in the same
 * program generate identical sequences of values.
 *
 * @param seed the initial seed
 */
 public Xoroshiro128StarStar(long seed) {
-	// Using a value with irregularly spaced 1-bits to xor the seed
+// Using a value with irregularly spaced 1-bits to xor the seed
-	// argument tends to improve "pedestrian" seeds such as 0 or
+// argument tends to improve "pedestrian" seeds such as 0 or
-	// other small integers.  We may as well use SILVER_RATIO_64.
+// 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
+// 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.
+// GOLDEN_RATIO_64 as the gamma value and Stafford13 as the mixer.
-this(RngSupport.mixStafford13(seed ^= RngSupport.SILVER_RATIO_64),
+this(RNGSupport.mixStafford13(seed ^= RNGSupport.SILVER_RATIO_64),
-	     RngSupport.mixStafford13(seed + RngSupport.GOLDEN_RATIO_64));
+RNGSupport.mixStafford13(seed + RNGSupport.GOLDEN_RATIO_64));
 }
 /**
-* Creates a new instance of {@code Xoroshiro128StarStar} that is likely to
+* Creates a new instance of {@link Xoroshiro128StarStar} 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 Xoroshiro128StarStar() {
-	// Using GOLDEN_RATIO_64 here gives us a good Weyl sequence of values.
+// Using GOLDEN_RATIO_64 here gives us a good Weyl sequence of values.
-this(defaultGen.getAndAdd(RngSupport.GOLDEN_RATIO_64));
+this(DEFAULT_GEN.getAndAdd(RNGSupport.GOLDEN_RATIO_64));
 }
 /**
-* Creates a new instance of {@code Xoroshiro128StarStar} using the specified array of
+* Creates a new instance of {@link Xoroshiro128StarStar} using the specified array of
-* initial seed bytes. Instances of {@code Xoroshiro128StarStar} created with the same
+* initial seed bytes. Instances of {@link Xoroshiro128StarStar} created with the same
 * seed array in the same program execution generate identical sequences of values.
 *
 * @param seed the initial seed
 */
 public Xoroshiro128StarStar(byte[] seed) {
-	// Convert the seed to 2 long values, which are not both zero.
+// Convert the seed to 2 long values, which are not both zero.
-	long[] data = RngSupport.convertSeedBytesToLongs(seed, 2, 2);
+long[] data = RNGSupport.convertSeedBytesToLongs(seed, 2, 2);
-	long x0 = data[0], x1 = data[1];
+long x0 = data[0], x1 = data[1];
 this.x0 = x0;
 this.x1 = x1;
 }
 /* ---------------- public methods ---------------- */
 public Xoroshiro128StarStar copy() { return new Xoroshiro128StarStar(x0, x1); }
 /*
+* To the extent possible under law, the author has dedicated all copyright and related and
-To the extent possible under law, the author has dedicated all copyright
+* neighboring rights to this software to the public domain worldwide. This software is
-and related and neighboring rights to this software to the public domain
+* distributed without any warranty.
-worldwide. This software is distributed without any warranty.
+* <p>
+* See <http://creativecommons.org/publicdomain/zero/1.0/>.
-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
+* This is the successor to xorshift128+. It is the fastest full-period generator passing
-relatively short period it is acceptable only for applications with a
+* BigCrush without systematic failures, but due to the relatively short period it is acceptable
-mild amount of parallelism; otherwise, use a xorshift1024* generator.
+* only for applications with a mild amount of parallelism; otherwise, use a xorshift1024*
+* generator.
-Beside passing BigCrush, this generator passes the PractRand test suite
+* <p>
-up to (and included) 16TB, with the exception of binary rank tests,
+* Beside passing BigCrush, this generator passes the PractRand test suite up to (and included)
-which fail due to the lowest bit being an LFSR; all other bits pass all
+* 16TB, with the exception of binary rank tests, which fail due to the lowest bit being an
-tests. We suggest to use a sign test to extract a random Boolean value.
+* LFSR; all other bits pass all tests. We suggest to use a sign test to extract a random
+* Boolean value.
-Note that the generator uses a simulated rotate operation, which most C
+* <p>
-compilers will turn into a single instruction. In Java, you can use
+* Note that the generator uses a simulated rotate operation, which most C compilers will turn
-Long.rotateLeft(). In languages that do not make low-level rotation
+* into a single instruction. In Java, you can use Long.rotateLeft(). In languages that do not
-instructions accessible xorshift128+ could be faster.
+* 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
+* The state must be seeded so that it is not everywhere zero. If you have a 64-bit seed, we
-a 64-bit seed, we suggest to seed a splitmix64 generator and use its
+* suggest to seed a splitmix64 generator and use its output to fill s.
-output to fill s. */
+*/
 /**
 * Returns a pseudorandom {@code long} value.
 *
 * @return a pseudorandom {@code long} value
 */
 public long nextLong() {
-	final long s0 = x0;
+final long s0 = x0;
-	long s1 = x1;
+long s1 = x1;
-	final long z = s0;
+final long z = s0;
-	s1 ^= s0;
+s1 ^= s0;
-	x0 = Long.rotateLeft(s0, 24) ^ s1 ^ (s1 << 16); // a, b
+x0 = Long.rotateLeft(s0, 24) ^ s1 ^ (s1 << 16); // a, b
-	x1 = Long.rotateLeft(s1, 37); // c
+x1 = Long.rotateLeft(s1, 37); // c
-	return Long.rotateLeft(z * 5, 7) * 9;  // "starstar" mixing function
+return Long.rotateLeft(z * 5, 7) * 9;  // "starstar" mixing function
 }
-public BigInteger period() { return thePeriod; }
+public BigInteger period() {
+return PERIOD;
-public double defaultJumpDistance() { return 0x1.0p64; }
+}
-public double defaultLeapDistance() { return 0x1.0p96; }
+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
+* This is the jump function for the generator. It is equivalent to 2**64 calls to nextLong();
-non-overlapping subsequences for parallel computations. */
+* it can be used to generate 2**64 non-overlapping subsequences for parallel computations.
+*/
-public void jump() { jumpAlgorithm(JUMP_TABLE); }
+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. */
+* 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
-public void leap() { jumpAlgorithm(LEAP_TABLE); }
+* 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;
+long s0 = 0, s1 = 0;
-	for (int i = 0; i < table.length; i++) {
+for (int i = 0; i < table.length; i++) {
-	    for (int b = 0; b < 64; b++) {
+for (int b = 0; b < 64; b++) {
-		if ((table[i] & (1L << b)) != 0) {
+if ((table[i] & (1L << b)) != 0) {
-		    s0 ^= x0;
+s0 ^= x0;
-		    s1 ^= x1;
+s1 ^= x1;
-		}
+}
-		nextLong();
+nextLong();
-	    }
+}
-	    x0 = s0;
+x0 = s0;
-	    x1 = s1;
+x1 = s1;
-	}
+}
 }
 }

branch	JDK-8193209-branch
changeset 57437	f02ffcb61dce
parent 57436	b0c958c0e6c6
child 57547	56cbdc3ea079