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/********************* */
/*! \file random.cpp
** \verbatim
** Top contributors (to current version):
** Aina Niemetz
** This file is part of the CVC4 project.
** Copyright (c) 2009-2020 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 "util/random.h"
#include <cfloat>
#include "base/check.h"
namespace CVC4 {
Random::Random(uint64_t seed) { setSeed(seed); }
void Random::setSeed(uint64_t seed)
{
d_seed = seed == 0 ? ~seed : seed;
d_state = d_seed;
}
uint64_t Random::operator()() { return rand(); }
uint64_t Random::rand()
{
/* 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). */
d_state ^= d_state >> 12;
d_state ^= d_state << 25;
d_state ^= d_state >> 27;
return d_state * uint64_t{2685821657736338717};
}
uint64_t Random::pick(uint64_t from, uint64_t to)
{
Assert(from <= to);
Assert(to < UINT64_MAX);
return (Random::rand() % (to - from + 1)) + from;
}
double Random::pickDouble(double from, double to)
{
Assert(from <= to);
Assert(to <= DBL_MAX);
return Random::rand() * (to - from) + from;
}
bool Random::pickWithProb(double probability)
{
Assert(probability <= 1);
uint64_t p = (uint64_t) (probability * 1000);
uint64_t r = pick(0, 999);
return r < p;
}
}
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