Add random number generator. (#1370)

This adds a deterministic (seeded) random number generator (RNG). It implements the xorshift* generator (see S. Vigna, An experimental exploration of Marsaglia's xorshift generators, scrambled. ACM Trans. Math. Softw. 42(4): 30:1-30:23, 2016).

1 files changed, 64 insertions, 0 deletions

diff --git a/src/util/random.h b/src/util/random.h
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+++ b/src/util/random.h
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+/*********************                                                        */
+/*! \file random.h
+ ** \verbatim
+ ** Top contributors (to current version):
+ **   Aina Niemetz
+ ** This file is part of the CVC4 project.
+ ** Copyright (c) 2009-2017 by the authors listed in the file AUTHORS
+ ** in the top-level source directory) and their institutional affiliations.
+ ** All rights reserved.  See the file COPYING in the top-level source
+ ** directory for licensing information.\endverbatim
+ **
+ ** \brief A Random Number Generator.
+ **
+ ** A random number generator, implements the xorshift* generator
+ ** (see S. Vigna, An experimental exploration of Marsaglia's xorshift
+ ** generators, scrambled. ACM Trans. Math. Softw. 42(4): 30:1-30:23, 2016).
+ **/
+
+#include "cvc4_private.h"
+
+#ifndef __CVC4__UTIL__RANDOM_H
+#define __CVC4__UTIL__RANDOM_H
+
+#include "base/tls.h"
+
+namespace CVC4 {
+
+class Random
+{
+ public:
+  Random(uint64_t seed) : d_seed(seed), d_state(seed) {}
+
+  /* Get current RNG (singleton).  */
+  static Random& getRandom()
+  {
+    static CVC4_THREAD_LOCAL Random s_current(0);
+    return s_current;
+  }
+
+  /* Set seed of Random.  */
+  void setSeed(uint64_t seed)
+  {
+    d_seed = seed;
+    d_state = seed;
+  }
+
+  /* Next random uint64_t number. */
+  uint64_t rand();
+  /* Pick random uint64_t number between from and to (inclusive). */
+  uint64_t pick(uint64_t from, uint64_t to);
+  /* Pick random double number between from and to (inclusive). */
+  double pickDouble(double from, double to);
+  /* Pick with given probability (yes / no). */
+  bool pickWithProb(double probability);
+
+ private:
+  /* The seed of the RNG. */
+  uint64_t d_seed;
+  /* The current state of the RNG. */
+  uint64_t d_state;
+};
+
+}  // namespace CVC4
+#endif