1 /********************* */
2 /*! \file random.cpp
3 ** \verbatim
4 ** Top contributors (to current version):
5 ** Aina Niemetz
6 ** This file is part of the CVC4 project.
7 ** Copyright (c) 2009-2019 by the authors listed in the file AUTHORS
8 ** in the top-level source directory) and their institutional affiliations.
9 ** All rights reserved. See the file COPYING in the top-level source
10 ** directory for licensing information.\endverbatim
11 **
12 ** \brief A Random Number Generator.
13 **
14 ** A random number generator, implements the xorshift* generator
15 ** (see S. Vigna, An experimental exploration of Marsaglia's xorshift
16 ** generators, scrambled. ACM Trans. Math. Softw. 42(4): 30:1-30:23, 2016).
17 **/
18
19 #include "util/random.h"
20
21 #include <cfloat>
22 #include "base/cvc4_assert.h"
23
24 namespace CVC4 {
25
Random(uint64_t seed)26 Random::Random(uint64_t seed) { setSeed(seed); }
27
setSeed(uint64_t seed)28 void Random::setSeed(uint64_t seed)
29 {
30 d_seed = seed == 0 ? ~seed : seed;
31 d_state = d_seed;
32 }
33
operator ()()34 uint64_t Random::operator()() { return rand(); }
35
rand()36 uint64_t Random::rand()
37 {
38 /* xorshift* generator (see S. Vigna, An experimental exploration of
39 * Marsaglia's xorshift generators, scrambled. ACM Trans. Math. Softw.
40 * 42(4): 30:1-30:23, 2016). */
41 d_state ^= d_state >> 12;
42 d_state ^= d_state << 25;
43 d_state ^= d_state >> 27;
44 return d_state * uint64_t{2685821657736338717};
45 }
46
pick(uint64_t from,uint64_t to)47 uint64_t Random::pick(uint64_t from, uint64_t to)
48 {
49 Assert(from <= to);
50 Assert(to < UINT64_MAX);
51 return (Random::rand() % (to - from + 1)) + from;
52 }
53
pickDouble(double from,double to)54 double Random::pickDouble(double from, double to)
55 {
56 Assert(from <= to);
57 Assert(to <= DBL_MAX);
58 return Random::rand() * (to - from) + from;
59 }
60
pickWithProb(double probability)61 bool Random::pickWithProb(double probability)
62 {
63 Assert(probability <= 1);
64 uint64_t p = (uint64_t) (probability * 1000);
65 uint64_t r = pick(0, 999);
66 return r < p;
67 }
68
69 }
70