20 * |
20 * |
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
22 * or visit www.oracle.com if you need additional information or have any |
22 * or visit www.oracle.com if you need additional information or have any |
23 * questions. |
23 * questions. |
24 */ |
24 */ |
25 package java.util; |
25 |
|
26 package java.util.random; |
26 |
27 |
27 import java.math.BigInteger; |
28 import java.math.BigInteger; |
28 import java.util.concurrent.atomic.AtomicLong; |
29 import java.util.concurrent.atomic.AtomicLong; |
29 |
30 |
30 /** |
31 /** |
31 * A generator of uniform pseudorandom values applicable for use in |
32 * A generator of uniform pseudorandom values applicable for use in |
32 * (among other contexts) isolated parallel computations that may |
33 * (among other contexts) isolated parallel computations that may |
33 * generate subtasks. Class {@code L64X256Random} implements |
34 * generate subtasks. Class {@link L64X256Random} implements |
34 * interfaces {@link java.util.Rng} and {@link java.util.SplittableRng}, |
35 * interfaces {@link RandomNumberGenerator} and {@link SplittableRNG}, |
35 * and therefore supports methods for producing pseudorandomly chosen |
36 * and therefore supports methods for producing pseudorandomly chosen |
36 * numbers of type {@code int}, {@code long}, {@code float}, and {@code double} |
37 * numbers of type {@code int}, {@code long}, {@code float}, and {@code double} |
37 * as well as creating new split-off {@code L64X256Random} objects, |
38 * as well as creating new split-off {@link L64X256Random} objects, |
38 * with similar usages as for class {@link java.util.SplittableRandom}. |
39 * with similar usages as for class {@link java.util.SplittableRandom}. |
39 * |
40 * <p> |
40 * <p>Series of generated values pass the TestU01 BigCrush and PractRand test suites |
41 * Series of generated values pass the TestU01 BigCrush and PractRand test suites |
41 * that measure independence and uniformity properties of random number generators. |
42 * that measure independence and uniformity properties of random number generators. |
42 * (Most recently validated with |
43 * (Most recently validated with |
43 * <a href="http://simul.iro.umontreal.ca/testu01/tu01.html">version 1.2.3 of TestU01</a> |
44 * <a href="http://simul.iro.umontreal.ca/testu01/tu01.html">version 1.2.3 of TestU01</a> |
44 * and <a href="http://pracrand.sourceforge.net">version 0.90 of PractRand</a>. |
45 * and <a href="http://pracrand.sourceforge.net">version 0.90 of PractRand</a>. |
45 * Note that TestU01 BigCrush was used to test not only values produced by the {@code nextLong()} |
46 * Note that TestU01 BigCrush was used to test not only values produced by the {@code nextLong()} |
46 * method but also the result of bit-reversing each value produced by {@code nextLong()}.) |
47 * method but also the result of bit-reversing each value produced by {@code nextLong()}.) |
47 * These tests validate only the methods for certain |
48 * These tests validate only the methods for certain |
48 * types and ranges, but similar properties are expected to hold, at |
49 * types and ranges, but similar properties are expected to hold, at |
49 * least approximately, for others as well. |
50 * least approximately, for others as well. |
50 * |
51 * <p> |
51 * <p>{@code L64X256Random} is a specific member of the LXM family of algorithms |
52 * {@link L64X256Random} is a specific member of the LXM family of algorithms |
52 * for pseudorandom number generators. Every LXM generator consists of two |
53 * for pseudorandom number generators. Every LXM generator consists of two |
53 * subgenerators; one is an LCG (Linear Congruential Generator) and the other is |
54 * subgenerators; one is an LCG (Linear Congruential Generator) and the other is |
54 * an Xorshift generator. Each output of an LXM generator is the sum of one |
55 * an Xorshift generator. Each output of an LXM generator is the sum of one |
55 * output from each subgenerator, possibly processed by a final mixing function |
56 * output from each subgenerator, possibly processed by a final mixing function |
56 * (but {@code L64X256Random} does not use a mixing function). |
57 * (but {@link L64X256Random} does not use a mixing function). |
57 * |
58 * <p> |
58 * <p>The LCG subgenerator for {@code L64X256Random} has an update step of the |
59 * The LCG subgenerator for {@link L64X256Random} has an update step of the |
59 * form {@code s = m * s + a}, where {@code s}, {@code m}, and {@code a} are all |
60 * form {@code s = m * s + a}, where {@code s}, {@code m}, and {@code a} are all |
60 * of type {@code long}; {@code s} is the mutable state, the multiplier {@code m} |
61 * of type {@code long}; {@code s} is the mutable state, the multiplier {@code m} |
61 * is fixed (the same for all instances of {@code L64X256Random}}) and the addend |
62 * is fixed (the same for all instances of {@link L64X256Random}}) and the addend |
62 * {@code a} is a parameter (a final field of the instance). The parameter |
63 * {@code a} is a parameter (a final field of the instance). The parameter |
63 * {@code a} is required to be odd (this allows the LCG to have the maximal |
64 * {@code a} is required to be odd (this allows the LCG to have the maximal |
64 * period, namely 2<sup>64</sup>); therefore there are 2<sup>63</sup> distinct choices |
65 * period, namely 2<sup>64</sup>); therefore there are 2<sup>63</sup> distinct choices |
65 * of parameter. |
66 * of parameter. |
66 * |
67 * <p> |
67 * <p>The Xorshift subgenerator for {@code L64X256Random} is the {@code xoshiro256} algorithm, |
68 * The Xorshift subgenerator for {@link L64X256Random} is the {@code xoshiro256} algorithm, |
68 * version 1.0 (parameters 17, 45), without any final scrambler such as "+" or "**". |
69 * version 1.0 (parameters 17, 45), without any final scrambler such as "+" or "**". |
69 * Its state consists of four {@code long} fields {@code x0}, {@code x1}, {@code x2}, |
70 * Its state consists of four {@code long} fields {@code x0}, {@code x1}, {@code x2}, |
70 * and {@code x3}, which can take on any values provided that they are not all zero. |
71 * and {@code x3}, which can take on any values provided that they are not all zero. |
71 * The period of this subgenerator is 2<sup>256</sup>-1. |
72 * The period of this subgenerator is 2<sup>256</sup>-1. |
72 * |
73 * <p> |
73 * <p> Because the periods 2<sup>64</sup> and 2<sup>256</sup>-1 of the two subgenerators |
74 * Because the periods 2<sup>64</sup> and 2<sup>256</sup>-1 of the two subgenerators |
74 * are relatively prime, the <em>period</em> of any single {@code L64X256Random} object |
75 * are relatively prime, the <em>period</em> of any single {@link L64X256Random} object |
75 * (the length of the series of generated 64-bit values before it repeats) is the product |
76 * (the length of the series of generated 64-bit values before it repeats) is the product |
76 * of the periods of the subgenerators, that is, 2<sup>64</sup>(2<sup>256</sup>-1), |
77 * of the periods of the subgenerators, that is, 2<sup>64</sup>(2<sup>256</sup>-1), |
77 * which is just slightly smaller than 2<sup>320</sup>. Moreover, if two distinct |
78 * which is just slightly smaller than 2<sup>320</sup>. Moreover, if two distinct |
78 * {@code L64X256Random} objects have different {@code a} parameters, then their |
79 * {@link L64X256Random} objects have different {@code a} parameters, then their |
79 * cycles of produced values will be different. |
80 * cycles of produced values will be different. |
80 * |
81 * <p> |
81 * <p>The 64-bit values produced by the {@code nextLong()} method are exactly equidistributed. |
82 * The 64-bit values produced by the {@code nextLong()} method are exactly equidistributed. |
82 * For any specific instance of {@code L64X256Random}, over the course of its cycle each |
83 * For any specific instance of {@link L64X256Random}, over the course of its cycle each |
83 * of the 2<sup>64</sup> possible {@code long} values will be produced 2<sup>256</sup>-1 times. |
84 * of the 2<sup>64</sup> possible {@code long} values will be produced 2<sup>256</sup>-1 times. |
84 * The values produced by the {@code nextInt()}, {@code nextFloat()}, and {@code nextDouble()} |
85 * The values produced by the {@code nextInt()}, {@code nextFloat()}, and {@code nextDouble()} |
85 * methods are likewise exactly equidistributed. |
86 * methods are likewise exactly equidistributed. |
86 * |
87 * <p> |
87 * <p> In fact, the 64-bit values produced by the {@code nextLong()} method are 4-equidistributed. |
88 * In fact, the 64-bit values produced by the {@code nextLong()} method are 4-equidistributed. |
88 * To be precise: for any specific instance of {@code L64X256Random}, consider |
89 * To be precise: for any specific instance of {@link L64X256Random}, consider |
89 * the (overlapping) length-4 subsequences of the cycle of 64-bit values produced by |
90 * the (overlapping) length-4 subsequences of the cycle of 64-bit values produced by |
90 * {@code nextLong()} (assuming no other methods are called that would affect the state). |
91 * {@code nextLong()} (assuming no other methods are called that would affect the state). |
91 * There are 2<sup>64</sup>(2<sup>256</sup>-1) such subsequences, and each subsequence, |
92 * There are 2<sup>64</sup>(2<sup>256</sup>-1) such subsequences, and each subsequence, |
92 * which consists of 4 64-bit values, can have one of 2<sup>256</sup> values. Of those |
93 * which consists of 4 64-bit values, can have one of 2<sup>256</sup> values. Of those |
93 * 2<sup>256</sup> subsequence values, nearly all of them (2<sup>256</sup>-2<sup>64</sup>) |
94 * 2<sup>256</sup> subsequence values, nearly all of them (2<sup>256</sup>-2<sup>64</sup>) |
94 * occur 2<sup>64</sup> times over the course of the entire cycle, and the other |
95 * occur 2<sup>64</sup> times over the course of the entire cycle, and the other |
95 * 2<sup>64</sup> subsequence values occur only 2<sup>64</sup>-1 times. So the ratio |
96 * 2<sup>64</sup> subsequence values occur only 2<sup>64</sup>-1 times. So the ratio |
96 * of the probability of getting one of the less common subsequence values and the |
97 * of the probability of getting one of the less common subsequence values and the |
97 * probability of getting one of the more common subsequence values is 1-2<sup>-64</sup>. |
98 * probability of getting one of the more common subsequence values is 1-2<sup>-64</sup>. |
98 * (Note that the set of 2<sup>64</sup> less-common subsequence values will differ from |
99 * (Note that the set of 2<sup>64</sup> less-common subsequence values will differ from |
99 * one instance of {@code L64X256Random} to another, as a function of the additive |
100 * one instance of {@link L64X256Random} to another, as a function of the additive |
100 * parameter of the LCG.) The values produced by the {@code nextInt()}, {@code nextFloat()}, |
101 * parameter of the LCG.) The values produced by the {@code nextInt()}, {@code nextFloat()}, |
101 * and {@code nextDouble()} methods are likewise 4-equidistributed. |
102 * and {@code nextDouble()} methods are likewise 4-equidistributed. |
102 * |
103 * <p> |
103 * <p>Method {@link #split} constructs and returns a new {@code L64X256Random} |
104 * Method {@link #split} constructs and returns a new {@link L64X256Random} |
104 * instance that shares no mutable state with the current instance. However, with |
105 * instance that shares no mutable state with the current instance. However, with |
105 * very high probability, the values collectively generated by the two objects |
106 * very high probability, the values collectively generated by the two objects |
106 * have the same statistical properties as if the same quantity of values were |
107 * have the same statistical properties as if the same quantity of values were |
107 * generated by a single thread using a single {@code L64X256Random} object. |
108 * generated by a single thread using a single {@link L64X256Random} object. |
108 * This is because, with high probability, distinct {@code L64X256Random} objects |
109 * This is because, with high probability, distinct {@link L64X256Random} objects |
109 * have distinct {@code a} parameters and therefore use distinct members of the |
110 * have distinct {@code a} parameters and therefore use distinct members of the |
110 * algorithmic family; and even if their {@code a} parameters are the same, with |
111 * algorithmic family; and even if their {@code a} parameters are the same, with |
111 * very high probability they will traverse different parts of their common state |
112 * very high probability they will traverse different parts of their common state |
112 * cycle. |
113 * cycle. |
113 * |
114 * <p> |
114 * <p>As with {@link java.util.SplittableRandom}, instances of |
115 * As with {@link java.util.SplittableRandom}, instances of |
115 * {@code L64X256Random} are <em>not</em> thread-safe. |
116 * {@link L64X256Random} are <em>not</em> thread-safe. |
116 * They are designed to be split, not shared, across threads. For |
117 * They are designed to be split, not shared, across threads. For |
117 * example, a {@link java.util.concurrent.ForkJoinTask} fork/join-style |
118 * example, a {@link java.util.concurrent.ForkJoinTask} fork/join-style |
118 * computation using random numbers might include a construction |
119 * computation using random numbers might include a construction |
119 * of the form {@code new Subtask(someL64X256Random.split()).fork()}. |
120 * of the form {@code new Subtask(someL64X256Random.split()).fork()}. |
120 * |
121 * <p> |
121 * <p>This class provides additional methods for generating random |
122 * This class provides additional methods for generating random |
122 * streams, that employ the above techniques when used in |
123 * streams, that employ the above techniques when used in |
123 * {@code stream.parallel()} mode. |
124 * {@code stream.parallel()} mode. |
124 * |
125 * <p> |
125 * <p>Instances of {@code L64X256Random} are not cryptographically |
126 * Instances of {@link L64X256Random} are not cryptographically |
126 * secure. Consider instead using {@link java.security.SecureRandom} |
127 * secure. Consider instead using {@link java.security.SecureRandom} |
127 * in security-sensitive applications. Additionally, |
128 * in security-sensitive applications. Additionally, |
128 * default-constructed instances do not use a cryptographically random |
129 * default-constructed instances do not use a cryptographically random |
129 * seed unless the {@linkplain System#getProperty system property} |
130 * seed unless the {@linkplain System#getProperty system property} |
130 * {@code java.util.secureRandomSeed} is set to {@code true}. |
131 * {@code java.util.secureRandomSeed} is set to {@code true}. |
131 * |
132 * |
132 * @author Guy Steele |
133 * @since 14 |
133 * @since 1.9 |
|
134 */ |
134 */ |
135 public final class L64X256Random extends AbstractSplittableRng { |
135 public final class L64X256Random extends AbstractSplittableRNG { |
136 |
136 |
137 /* |
137 /* |
138 * Implementation Overview. |
138 * Implementation Overview. |
139 * |
139 * |
140 * The split() operation uses the current generator to choose six new 64-bit |
140 * The split() operation uses the current generator to choose six new 64-bit |
212 * @param x1 second word of the initial state for the xorshift generator |
212 * @param x1 second word of the initial state for the xorshift generator |
213 * @param x2 third word of the initial state for the xorshift generator |
213 * @param x2 third word of the initial state for the xorshift generator |
214 * @param x3 fourth word of the initial state for the xorshift generator |
214 * @param x3 fourth word of the initial state for the xorshift generator |
215 */ |
215 */ |
216 public L64X256Random(long a, long s, long x0, long x1, long x2, long x3) { |
216 public L64X256Random(long a, long s, long x0, long x1, long x2, long x3) { |
217 // Force a to be odd. |
217 // Force a to be odd. |
218 this.a = a | 1; |
218 this.a = a | 1; |
219 this.s = s; |
219 this.s = s; |
220 this.x0 = x0; |
220 this.x0 = x0; |
221 this.x1 = x1; |
221 this.x1 = x1; |
222 this.x2 = x2; |
222 this.x2 = x2; |
223 this.x3 = x3; |
223 this.x3 = x3; |
224 // If x0, x1, x2, and x3 are all zero, we must choose nonzero values. |
224 // If x0, x1, x2, and x3 are all zero, we must choose nonzero values. |
225 if ((x0 | x1 | x2 | x3) == 0) { |
225 if ((x0 | x1 | x2 | x3) == 0) { |
226 // At least three of the four values generated here will be nonzero. |
226 // At least three of the four values generated here will be nonzero. |
227 this.x0 = RngSupport.mixStafford13(s += RngSupport.GOLDEN_RATIO_64); |
227 this.x0 = RNGSupport.mixStafford13(s += RNGSupport.GOLDEN_RATIO_64); |
228 this.x1 = RngSupport.mixStafford13(s += RngSupport.GOLDEN_RATIO_64); |
228 this.x1 = RNGSupport.mixStafford13(s += RNGSupport.GOLDEN_RATIO_64); |
229 this.x2 = RngSupport.mixStafford13(s += RngSupport.GOLDEN_RATIO_64); |
229 this.x2 = RNGSupport.mixStafford13(s += RNGSupport.GOLDEN_RATIO_64); |
230 this.x3 = RngSupport.mixStafford13(s + RngSupport.GOLDEN_RATIO_64); |
230 this.x3 = RNGSupport.mixStafford13(s + RNGSupport.GOLDEN_RATIO_64); |
231 } |
231 } |
232 } |
232 } |
233 |
233 |
234 /** |
234 /** |
235 * Creates a new instance of {@code L64X256Random} using the |
235 * Creates a new instance of {@link L64X256Random} using the |
236 * specified {@code long} value as the initial seed. Instances of |
236 * specified {@code long} value as the initial seed. Instances of |
237 * {@code L64X256Random} created with the same seed in the same |
237 * {@link L64X256Random} created with the same seed in the same |
238 * program execution generate identical sequences of values. |
238 * program execution generate identical sequences of values. |
239 * |
239 * |
240 * @param seed the initial seed |
240 * @param seed the initial seed |
241 */ |
241 */ |
242 public L64X256Random(long seed) { |
242 public L64X256Random(long seed) { |
243 // Using a value with irregularly spaced 1-bit to xor the seed |
243 // Using a value with irregularly spaced 1-bit to xor the seed |
244 // argument tends to improve "pedestrian" seeds such as 0 or |
244 // argument tends to improve "pedestrian" seeds such as 0 or |
245 // other small integers. We may as well use SILVER_RATIO_64. |
245 // other small integers. We may as well use SILVER_RATIO_64. |
246 // |
246 // |
247 // The seed is hashed by mixMurmur64 to produce the `a` parameter. |
247 // The seed is hashed by mixMurmur64 to produce the `a` parameter. |
248 // The seed is hashed by mixStafford13 to produce the initial `x0`, |
248 // The seed is hashed by mixStafford13 to produce the initial `x0`, |
249 // which will then be used to produce the first generated value. |
249 // which will then be used to produce the first generated value. |
250 // The other x values are filled in as if by a SplitMix PRNG with |
250 // The other x values are filled in as if by a SplitMix PRNG with |
251 // GOLDEN_RATIO_64 as the gamma value and Stafford13 as the mixer. |
251 // GOLDEN_RATIO_64 as the gamma value and Stafford13 as the mixer. |
252 this(RngSupport.mixMurmur64(seed ^= RngSupport.SILVER_RATIO_64), |
252 this(RNGSupport.mixMurmur64(seed ^= RNGSupport.SILVER_RATIO_64), |
253 1, |
253 1, |
254 RngSupport.mixStafford13(seed), |
254 RNGSupport.mixStafford13(seed), |
255 RngSupport.mixStafford13(seed += RngSupport.GOLDEN_RATIO_64), |
255 RNGSupport.mixStafford13(seed += RNGSupport.GOLDEN_RATIO_64), |
256 RngSupport.mixStafford13(seed += RngSupport.GOLDEN_RATIO_64), |
256 RNGSupport.mixStafford13(seed += RNGSupport.GOLDEN_RATIO_64), |
257 RngSupport.mixStafford13(seed + RngSupport.GOLDEN_RATIO_64)); |
257 RNGSupport.mixStafford13(seed + RNGSupport.GOLDEN_RATIO_64)); |
258 } |
258 } |
259 |
259 |
260 /** |
260 /** |
261 * Creates a new instance of {@code L64X256Random} that is likely to |
261 * Creates a new instance of {@link L64X256Random} that is likely to |
262 * generate sequences of values that are statistically independent |
262 * generate sequences of values that are statistically independent |
263 * of those of any other instances in the current program execution, |
263 * of those of any other instances in the current program execution, |
264 * but may, and typically does, vary across program invocations. |
264 * but may, and typically does, vary across program invocations. |
265 */ |
265 */ |
266 public L64X256Random() { |
266 public L64X256Random() { |
267 // Using GOLDEN_RATIO_64 here gives us a good Weyl sequence of values. |
267 // Using GOLDEN_RATIO_64 here gives us a good Weyl sequence of values. |
268 this(defaultGen.getAndAdd(RngSupport.GOLDEN_RATIO_64)); |
268 this(defaultGen.getAndAdd(RNGSupport.GOLDEN_RATIO_64)); |
269 } |
269 } |
270 |
270 |
271 /** |
271 /** |
272 * Creates a new instance of {@code L64X256Random} using the specified array of |
272 * Creates a new instance of {@link L64X256Random} using the specified array of |
273 * initial seed bytes. Instances of {@code L64X256Random} created with the same |
273 * initial seed bytes. Instances of {@link L64X256Random} created with the same |
274 * seed array in the same program execution generate identical sequences of values. |
274 * seed array in the same program execution generate identical sequences of values. |
275 * |
275 * |
276 * @param seed the initial seed |
276 * @param seed the initial seed |
277 */ |
277 */ |
278 public L64X256Random(byte[] seed) { |
278 public L64X256Random(byte[] seed) { |
279 // Convert the seed to 6 long values, of which the last 4 are not all zero. |
279 // Convert the seed to 6 long values, of which the last 4 are not all zero. |
280 long[] data = RngSupport.convertSeedBytesToLongs(seed, 6, 4); |
280 long[] data = RNGSupport.convertSeedBytesToLongs(seed, 6, 4); |
281 long a = data[0], s = data[1], x0 = data[2], x1 = data[3], x2 = data[4], x3 = data[5]; |
281 long a = data[0], s = data[1], x0 = data[2], x1 = data[3], x2 = data[4], x3 = data[5]; |
282 // Force a to be odd. |
282 // Force a to be odd. |
283 this.a = a | 1; |
283 this.a = a | 1; |
284 this.s = s; |
284 this.s = s; |
285 this.x0 = x0; |
285 this.x0 = x0; |
286 this.x1 = x1; |
286 this.x1 = x1; |
287 this.x2 = x2; |
287 this.x2 = x2; |
289 } |
289 } |
290 |
290 |
291 /* ---------------- public methods ---------------- */ |
291 /* ---------------- public methods ---------------- */ |
292 |
292 |
293 /** |
293 /** |
294 * Constructs and returns a new instance of {@code L64X256Random} |
294 * Constructs and returns a new instance of {@link L64X256Random} |
295 * that shares no mutable state with this instance. |
295 * that shares no mutable state with this instance. |
296 * However, with very high probability, the set of values collectively |
296 * However, with very high probability, the set of values collectively |
297 * generated by the two objects has the same statistical properties as if |
297 * generated by the two objects has the same statistical properties as if |
298 * same the quantity of values were generated by a single thread using |
298 * same the quantity of values were generated by a single thread using |
299 * a single {@code L64X256Random} object. Either or both of the two |
299 * a single {@link L64X256Random} object. Either or both of the two |
300 * objects may be further split using the {@code split} method, |
300 * objects may be further split using the {@code split} method, |
301 * and the same expected statistical properties apply to the |
301 * and the same expected statistical properties apply to the |
302 * entire set of generators constructed by such recursive splitting. |
302 * entire set of generators constructed by such recursive splitting. |
303 * |
303 * |
304 * @param source a {@code SplittableRng} instance to be used instead |
304 * @param source a {@link SplittableRNG} instance to be used instead |
305 * of this one as a source of pseudorandom bits used to |
305 * of this one as a source of pseudorandom bits used to |
306 * initialize the state of the new ones. |
306 * initialize the state of the new ones. |
307 * @return a new instance of {@code L64X256Random} |
307 * |
308 */ |
308 * @return a new instance of {@link L64X256Random} |
309 public L64X256Random split(SplittableRng source) { |
309 */ |
310 // Literally pick a new instance "at random". |
310 public L64X256Random split(SplittableRNG source) { |
311 return new L64X256Random(source.nextLong(), source.nextLong(), |
311 // Literally pick a new instance "at random". |
312 source.nextLong(), source.nextLong(), |
312 return new L64X256Random(source.nextLong(), source.nextLong(), |
313 source.nextLong(), source.nextLong()); |
313 source.nextLong(), source.nextLong(), |
|
314 source.nextLong(), source.nextLong()); |
314 } |
315 } |
315 |
316 |
316 /** |
317 /** |
317 * Returns a pseudorandom {@code long} value. |
318 * Returns a pseudorandom {@code long} value. |
318 * |
319 * |
319 * @return a pseudorandom {@code long} value |
320 * @return a pseudorandom {@code long} value |
320 */ |
321 */ |
321 |
|
322 public long nextLong() { |
322 public long nextLong() { |
323 final long z = s + x0; |
323 final long z = s + x0; |
324 s = m * s + a; // LCG |
324 s = M * s + a; // LCG |
325 long q0 = x0, q1 = x1, q2 = x2, q3 = x3; |
325 long q0 = x0, q1 = x1, q2 = x2, q3 = x3; |
326 { long t = q1 << 17; q2 ^= q0; q3 ^= q1; q1 ^= q2; q0 ^= q3; q2 ^= t; q3 = Long.rotateLeft(q3, 45); } // xoshiro256 1.0 |
326 { long t = q1 << 17; q2 ^= q0; q3 ^= q1; q1 ^= q2; q0 ^= q3; q2 ^= t; q3 = Long.rotateLeft(q3, 45); } // xoshiro256 1.0 |
327 x0 = q0; x1 = q1; x2 = q2; x3 = q3; |
327 x0 = q0; x1 = q1; x2 = q2; x3 = q3; |
328 return z; |
328 return z; |
329 } |
329 } |
330 |
330 |
331 public BigInteger period() { return thePeriod; } |
331 public BigInteger period() { |
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332 return PERIOD; |
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333 } |
332 } |
334 } |