--- a/src/java.base/share/classes/java/util/random/Xoshiro256StarStar.java Thu Jun 27 18:02:51 2019 -0300
+++ b/src/java.base/share/classes/java/util/random/Xoshiro256StarStar.java Thu Jun 27 18:30:27 2019 -0300
@@ -22,7 +22,8 @@
* 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;
@@ -30,14 +31,14 @@
/**
* A generator of uniform pseudorandom values applicable for use in
* (among other contexts) isolated parallel computations that may
- * generate subtasks. Class {@code Xoshiro256StarStar} implements
- * interfaces {@link java.util.Rng} and {@link java.util.LeapableRng},
+ * generate subtasks. Class {@link Xoshiro256StarStar} implements
+ * 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 Xoshiro256StarStar} objects
+ * as well as creating new {@link Xoshiro256StarStar} objects
* by "jumping" or "leaping".
- *
- * <p>Series of generated values pass the TestU01 BigCrush and PractRand test suites
+ * <p>
+ * Series of generated values pass the TestU01 BigCrush and PractRand test suites
* that measure independence and uniformity properties of random number generators.
* (Most recently validated with
* <a href="http://simul.iro.umontreal.ca/testu01/tu01.html">version 1.2.3 of TestU01</a>
@@ -47,21 +48,21 @@
* These tests validate only the methods for certain
* types and ranges, but similar properties are expected to hold, at
* least approximately, for others as well.
- *
- * <p>The class {@code Xoshiro256StarStar} uses the {@code xoshiro256} algorithm,
+ * <p>
+ * The class {@link Xoshiro256StarStar} uses the {@code xoshiro256} algorithm,
* version 1.0 (parameters 17, 45), with the "**" scrambler (a mixing function).
* Its state consists of four {@code long} fields {@code x0}, {@code x1}, {@code x2},
* and {@code x3}, which can take on any values provided that they are not all zero.
* The period of this generator is 2<sup>256</sup>-1.
- *
- * <p>The 64-bit values produced by the {@code nextLong()} method are equidistributed.
+ * <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>256</sup>-1,
* each nonzero {@code long} value is generated 2<sup>192</sup> times,
* but the value 0 is generated only 2<sup>192</sup>-1 times.
* The values produced by the {@code nextInt()}, {@code nextFloat()}, and {@code nextDouble()}
* methods are likewise equidistributed.
- *
- * <p>In fact, the 64-bit values produced by the {@code nextLong()} method are 4-equidistributed.
+ * <p>
+ * In fact, the 64-bit values produced by the {@code nextLong()} method are 4-equidistributed.
* To be precise: consider the (overlapping) length-4 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>256</sup>-1 such subsequences, and each subsequence,
@@ -72,24 +73,23 @@
* methods are likewise 4-equidistributed, but note that that the subsequence (0, 0, 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>Instances {@code Xoshiro256StarStar} are <em>not</em> thread-safe.
+ * <p>
+ * Instances {@link Xoshiro256StarStar} 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 Xoshiro256StarStar} that traverse
+ * can be used to construct new instances of {@link Xoshiro256StarStar} that traverse
* other parts of the state cycle.
- *
- * <p>Instances of {@code Xoshiro256StarStar} are not cryptographically
+ * <p>
+ * Instances of {@link Xoshiro256StarStar} 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 1.9
+ * @since 14
*/
-public final class Xoshiro256StarStar implements LeapableRng {
+public final class Xoshiro256StarStar implements LeapableRNG {
/*
* Implementation Overview.
@@ -128,13 +128,13 @@
/**
* 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**256 - 1.
*/
- private static final BigInteger thePeriod =
- BigInteger.ONE.shiftLeft(256).subtract(BigInteger.ONE);
+ private static final BigInteger PERIOD =
+ BigInteger.ONE.shiftLeft(256).subtract(BigInteger.ONE);
/* ---------------- instance fields ---------------- */
@@ -157,63 +157,63 @@
* @param x3 fourth word of the initial state
*/
public Xoshiro256StarStar(long x0, long x1, long x2, long x3) {
- this.x0 = x0;
+ this.x0 = x0;
this.x1 = x1;
this.x2 = x2;
this.x3 = x3;
- // If x0, x1, x2, and x3 are all zero, we must choose nonzero values.
+ // If x0, x1, x2, and x3 are all zero, we must choose nonzero values.
if ((x0 | x1 | x2 | x3) == 0) {
- // At least three of the four values generated here will be nonzero.
- this.x0 = RngSupport.mixStafford13(x0 += RngSupport.GOLDEN_RATIO_64);
- this.x1 = (x0 += RngSupport.GOLDEN_RATIO_64);
- this.x2 = (x0 += RngSupport.GOLDEN_RATIO_64);
- this.x3 = (x0 += RngSupport.GOLDEN_RATIO_64);
- }
+ // At least three of the four values generated here will be nonzero.
+ this.x0 = RNGSupport.mixStafford13(x0 += RNGSupport.GOLDEN_RATIO_64);
+ this.x1 = (x0 += RNGSupport.GOLDEN_RATIO_64);
+ this.x2 = (x0 += RNGSupport.GOLDEN_RATIO_64);
+ this.x3 = (x0 += RNGSupport.GOLDEN_RATIO_64);
+ }
}
/**
- * Creates a new instance of {@code Xoshiro256StarStar} using the
+ * Creates a new instance of {@link Xoshiro256StarStar} using the
* specified {@code long} value as the initial seed. Instances of
- * {@code Xoshiro256StarStar} created with the same seed in the same
+ * {@link Xoshiro256StarStar} created with the same seed in the same
* program generate identical sequences of values.
*
* @param seed the initial seed
*/
public Xoshiro256StarStar(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(RngSupport.mixStafford13(seed ^= RngSupport.SILVER_RATIO_64),
- RngSupport.mixStafford13(seed += RngSupport.GOLDEN_RATIO_64),
- RngSupport.mixStafford13(seed += RngSupport.GOLDEN_RATIO_64),
- RngSupport.mixStafford13(seed + RngSupport.GOLDEN_RATIO_64));
+ // 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(RNGSupport.mixStafford13(seed ^= RNGSupport.SILVER_RATIO_64),
+ RNGSupport.mixStafford13(seed += RNGSupport.GOLDEN_RATIO_64),
+ RNGSupport.mixStafford13(seed += RNGSupport.GOLDEN_RATIO_64),
+ RNGSupport.mixStafford13(seed + RNGSupport.GOLDEN_RATIO_64));
}
/**
- * Creates a new instance of {@code Xoshiro256StarStar} that is likely to
+ * Creates a new instance of {@link Xoshiro256StarStar} 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 Xoshiro256StarStar() {
- // Using GOLDEN_RATIO_64 here gives us a good Weyl sequence of values.
- this(defaultGen.getAndAdd(RngSupport.GOLDEN_RATIO_64));
+ // Using GOLDEN_RATIO_64 here gives us a good Weyl sequence of values.
+ this(DEFAULT_GEN.getAndAdd(RNGSupport.GOLDEN_RATIO_64));
}
/**
- * Creates a new instance of {@code Xoshiro256StarStar} using the specified array of
- * initial seed bytes. Instances of {@code Xoshiro256StarStar} created with the same
+ * Creates a new instance of {@link Xoshiro256StarStar} using the specified array of
+ * initial seed bytes. Instances of {@link Xoshiro256StarStar} created with the same
* seed array in the same program execution generate identical sequences of values.
*
* @param seed the initial seed
*/
public Xoshiro256StarStar(byte[] seed) {
- // Convert the seed to 4 long values, which are not all zero.
- long[] data = RngSupport.convertSeedBytesToLongs(seed, 4, 4);
- long x0 = data[0], x1 = data[1], x2 = data[2], x3 = data[3];
+ // Convert the seed to 4 long values, which are not all zero.
+ long[] data = RNGSupport.convertSeedBytesToLongs(seed, 4, 4);
+ long x0 = data[0], x1 = data[1], x2 = data[2], x3 = data[3];
this.x0 = x0;
this.x1 = x1;
this.x2 = x2;
@@ -222,64 +222,75 @@
/* ---------------- public methods ---------------- */
- public Xoshiro256StarStar copy() { return new Xoshiro256StarStar(x0, x1, x2, x3); }
+ public Xoshiro256StarStar copy() {
+ return new Xoshiro256StarStar(x0, x1, x2, x3);
+ }
/**
* Returns a pseudorandom {@code long} value.
*
* @return a pseudorandom {@code long} value
*/
-
- public long nextLong() {
- final long z = x0;
- long q0 = x0, q1 = x1, q2 = x2, q3 = x3;
- { long t = q1 << 17; q2 ^= q0; q3 ^= q1; q1 ^= q2; q0 ^= q3; q2 ^= t; q3 = Long.rotateLeft(q3, 45); } // xoshiro256 1.0
- x0 = q0; x1 = q1; x2 = q2; x3 = q3;
- return Long.rotateLeft(z * 5, 7) * 9; // "starstar" mixing function
+ public long nextLong() {
+ final long z = x0;
+ long q0 = x0, q1 = x1, q2 = x2, q3 = x3;
+ { long t = q1 << 17; q2 ^= q0; q3 ^= q1; q1 ^= q2; q0 ^= q3; q2 ^= t; q3 = Long.rotateLeft(q3, 45); } // xoshiro256 1.0
+ x0 = q0; x1 = q1; x2 = q2; x3 = q3;
+ 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 = {
- 0x180ec6d33cfd0abaL, 0xd5a61266f0c9392cL, 0xa9582618e03fc9aaL, 0x39abdc4529b1661cL };
-
+ 0x180ec6d33cfd0abaL, 0xd5a61266f0c9392cL, 0xa9582618e03fc9aaL, 0x39abdc4529b1661cL };
+
private static final long[] LEAP_TABLE = {
- 0x76e15d3efefdcbbfL, 0xc5004e441c522fb3L, 0x77710069854ee241L, 0x39109bb02acbe635L };
-
-/* This is the jump function for the generator. It is equivalent
- to 2**128 calls to next(); it can be used to generate 2**128
- non-overlapping subsequences for parallel computations. */
+ 0x76e15d3efefdcbbfL, 0xc5004e441c522fb3L, 0x77710069854ee241L, 0x39109bb02acbe635L };
- public void jump() { jumpAlgorithm(JUMP_TABLE); }
-
-/* This is the long-jump function for the generator. It is equivalent to
- 2**192 calls to next(); it can be used to generate 2**64 starting points,
- from each of which jump() will generate 2**64 non-overlapping
- subsequences for parallel distributed computations. */
+ /**
+ * This is the jump function for the generator. It is equivalent to 2**128 calls to next(); it
+ * can be used to generate 2**128 non-overlapping subsequences for parallel computations.
+ */
+ public void jump() {
+ jumpAlgorithm(JUMP_TABLE);
+ }
- public void leap() { jumpAlgorithm(LEAP_TABLE); }
+ /**
+ * This is the long-jump function for the generator. It is equivalent to 2**192 calls to next();
+ * it can be used to generate 2**64 starting points, from each of which jump() will generate
+ * 2**64 non-overlapping subsequences for parallel distributed computations.
+ */
+ public void leap() {
+ jumpAlgorithm(LEAP_TABLE);
+ }
private void jumpAlgorithm(long[] table) {
- long s0 = 0, s1 = 0, s2 = 0, s3 = 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;
- s2 ^= x2;
- s3 ^= x3;
- }
- nextLong();
- }
- x0 = s0;
- x1 = s1;
- x2 = s2;
- x3 = s3;
- }
+ long s0 = 0, s1 = 0, s2 = 0, s3 = 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;
+ s2 ^= x2;
+ s3 ^= x3;
+ }
+ nextLong();
+ }
+ x0 = s0;
+ x1 = s1;
+ x2 = s2;
+ x3 = s3;
+ }
}
}