1 /* JNI interface to C RngStream code */
3 /* Copyright (c) 2006-2014. The SimGrid Team.
4 * All rights reserved. */
6 /* This program is free software; you can redistribute it and/or modify it
7 * under the terms of the license (GNU LGPL) which comes with this package. */
9 package org.simgrid.msg;
11 * Export of RngStreams for Java
13 public class RngStream {
15 * Represents the bind between the RngStream java object and the C object.
19 * Creates and returns a new stream without identifier.
20 * This procedure reserves space to keep the information relative to
21 * the RngStream, initializes its seed Ig , sets Bg and Cg equal to Ig , sets its antithetic and
22 * precision switches to 0. The seed Ig is equal to the initial seed of the package given by
23 * setPackageSeed if this is the first stream created, otherwise it is Z steps ahead
24 * of that of the most recently created stream.
30 * Creates and returns a new stream with identifier "name".
31 * This procedure reserves space to keep the information relative to
32 * the RngStream, initializes its seed Ig , sets Bg and Cg equal to Ig , sets its antithetic and
33 * precision switches to 0. The seed Ig is equal to the initial seed of the package given by
34 * setPackageSeed if this is the first stream created, otherwise it is Z steps ahead
35 * of that of the most recently created stream.
37 public RngStream(String name) {
41 * The natively implemented method to create a C RngStream object.
43 private native void create(String name);
47 protected void finalize() {
51 * Release the C RngStream object
53 private native void destroy();
56 * Sets the initial seed of the package RngStreams to the six integers in the vector seed. This will
57 * be the seed (initial state) of the first stream. If this procedure is not called, the default initial
58 * seed is (12345, 12345, 12345, 12345, 12345, 12345). If it is called, the first 3 values of the seed
59 * must all be less than m1 = 4294967087, and not all 0; and the last 3 values must all be less
60 * than m2 = 4294944443, and not all 0. Returns false for invalid seeds, and true otherwise.
62 public static native boolean setPackageSeed(int seed[]);
64 * Reinitializes the stream g to its initial state: Cg and Bg are set to Ig .
66 public native void resetStart();
68 * Reinitializes the stream g to the beginning of its current substream: Cg is set to Bg .
70 public native void restartStartSubstream();
72 * Reinitializes the stream g to the beginning of its next substream: Ng is computed, and Cg and
75 public native void resetNextSubstream();
77 * If a = true the stream g will start generating antithetic variates, i.e., 1 - U instead of U , until
78 * this method is called again with a = false.
80 public native void setAntithetic(boolean a);
82 * Sets the initial seed Ig of stream g to the vector seed. This vector must satisfy the same
83 * conditions as in setPackageSeed. The stream is then reset to this initial seed. The
84 * states and seeds of the other streams are not modified. As a result, after calling this procedure,
85 * the initial seeds of the streams are no longer spaced Z values apart. We discourage the use of
86 * this procedure. Returns false for invalid seeds, and true otherwise.
88 public native boolean setSeed(int seed[]);
90 * Advances the state of the stream by k values, without modifying the states of other streams (as
91 * in RngStream_SetSeed), nor the values of Bg and Ig associated with this stream. If e > 0, then
92 * k = 2e + c; if e < 0, then k = -2-e + c; and if e = 0, then k = c. Note: c is allowed to take
93 * negative values. We discourage the use of this procedure.
95 public native void advanceState(int e, int g);
98 * Returns a (pseudo)random number from the uniform distribution over the interval (0, 1), after advancing the state by one step. The returned number has 32 bits of precision
99 * in the sense that it is always a multiple of 1/(232 - 208), unless RngStream_IncreasedPrecis
100 * has been called for this stream.
102 public native double randU01();
104 * Returns a (pseudo)random number from the discrete uniform distribution over the integers
105 * {i, i + 1, . . . , j}
107 public native int randInt(int i, int j);
110 * Class initializer, to initialize various JNI stuff
112 public static native void nativeInit();