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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* This file is part of the LibreOffice project.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* Contributor(s):
* Copyright (C) 2012 Tino Kluge <tino.kluge@hrz.tu-chemnitz.de>
*/
#include <comphelper/random.hxx>
#include <rtl/instance.hxx>
#include <assert.h>
#include <time.h>
#include <random>
// this is nothing but a simple wrapper around
// the std::random generators
namespace comphelper
{
namespace rng
{
// underlying random number generator
// std::mt19937 implements the Mersenne twister algorithm which
// is fast and has good statistical properties, it produces integers
// in the range of [0, 2^32-1] internally
// memory requirement: 625*sizeof(uint32_t)
// http://en.wikipedia.org/wiki/Mersenne_twister
#define STD_RNG_ALGO std::mt19937
struct RandomNumberGenerator
{
STD_RNG_ALGO global_rng;
RandomNumberGenerator()
{
// initialises the state of the global random number generator
// should only be called once.
// (note, a few std::variate_generator<> (like normal) have their
// own state which would need a reset as well to guarantee identical
// sequence of numbers, e.g. via myrand.distribution().reset())
global_rng.seed(time(NULL));
}
};
class theRandomNumberGenerator : public rtl::Static<RandomNumberGenerator, theRandomNumberGenerator> {};
// re-initialises the state of the global random number generator
void reseed(int i)
{
return theRandomNumberGenerator::get().global_rng.seed(i);
}
// uniform ints [a,b] distribution
int uniform_int_distribution(int a, int b)
{
std::uniform_int_distribution<int> dist(a, b);
return dist(theRandomNumberGenerator::get().global_rng);
}
// uniform ints [a,b] distribution
unsigned int uniform_uint_distribution(unsigned int a, unsigned int b)
{
std::uniform_int_distribution<unsigned int> dist(a, b);
return dist(theRandomNumberGenerator::get().global_rng);
}
// uniform size_t [a,b] distribution
size_t uniform_size_distribution(size_t a, size_t b)
{
std::uniform_int_distribution<size_t> dist(a, b);
return dist(theRandomNumberGenerator::get().global_rng);
}
// uniform size_t [a,b) distribution
double uniform_real_distribution(double a, double b)
{
assert(a < b);
std::uniform_real_distribution<double> dist(a, b);
return dist(theRandomNumberGenerator::get().global_rng);
}
} // namespace
} // namespace
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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