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       1             : /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
       2             : /*
       3             :  * This file is part of the LibreOffice project.
       4             :  *
       5             :  * This Source Code Form is subject to the terms of the Mozilla Public
       6             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       7             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
       8             :  *
       9             :  * Contributor(s):
      10             :  *   Copyright (C) 2012 Tino Kluge <tino.kluge@hrz.tu-chemnitz.de>
      11             :  */
      12             : 
      13             : #include <boost/random.hpp>
      14             : #include <comphelper/random.hxx>
      15             : #include <rtl/instance.hxx>
      16             : 
      17             : // this is nothing but a simple wrapper around
      18             : // the boost random generators
      19             : 
      20             : namespace comphelper
      21             : {
      22             : namespace rng
      23             : {
      24             : 
      25             : // underlying random number generator
      26             : // boost::mt19937 implements the Mersenne twister algorithm which
      27             : // is fast and has good statistical properties, it produces integers
      28             : // in the range of [0, 2^32-1] internally
      29             : // memory requirement: 625*sizeof(uint32_t)
      30             : // http://en.wikipedia.org/wiki/Mersenne_twister
      31             : #define BOOST_RNG_ALGO  boost::mt19937
      32             : 
      33             : struct RandomNumberGenerator
      34             : {
      35             :     BOOST_RNG_ALGO global_rng;
      36         200 :     RandomNumberGenerator()
      37         200 :     {
      38             :         // initialises the state of the global random number generator
      39             :         // should only be called once.
      40             :         // (note, a few boost::variate_generator<> (like normal) have their
      41             :         // own state which would need a reset as well to guarantee identical
      42             :         // sequence of numbers, e.g. via myrand.distribution().reset())
      43         200 :         global_rng.seed(time(NULL));
      44         200 :     }
      45             : };
      46             : 
      47             : class theRandomNumberGenerator : public rtl::Static<RandomNumberGenerator, theRandomNumberGenerator> {};
      48             : 
      49             : // re-initialises the state of the global random number generator
      50           0 : void reseed(int i)
      51             : {
      52           0 :     return theRandomNumberGenerator::get().global_rng.seed(i);
      53             : }
      54             : 
      55             : // uniform ints [a,b] distribution
      56       76339 : int uniform_int_distribution(int a, int b)
      57             : {
      58       76339 :     boost::random::uniform_int_distribution<int> dist(a, b);
      59       76339 :     return dist(theRandomNumberGenerator::get().global_rng);
      60             : }
      61             : 
      62             : // uniform ints [a,b] distribution
      63           0 : unsigned int uniform_uint_distribution(unsigned int a, unsigned int b)
      64             : {
      65           0 :     boost::random::uniform_int_distribution<unsigned int> dist(a, b);
      66           0 :     return dist(theRandomNumberGenerator::get().global_rng);
      67             : }
      68             : 
      69             : // uniform size_t [a,b] distribution
      70       40764 : size_t uniform_size_distribution(size_t a, size_t b)
      71             : {
      72       40764 :     boost::random::uniform_int_distribution<size_t> dist(a, b);
      73       40764 :     return dist(theRandomNumberGenerator::get().global_rng);
      74             : }
      75             : 
      76             : // uniform size_t [a,b) distribution
      77           0 : double uniform_real_distribution(double a, double b)
      78             : {
      79             :     assert(a < b);
      80           0 :     boost::random::uniform_real_distribution<double> dist(a, b);
      81           0 :     return dist(theRandomNumberGenerator::get().global_rng);
      82             : }
      83             : 
      84             : } // namespace
      85        3315 : } // namespace
      86             : 
      87             : /* vim:set shiftwidth=4 softtabstop=4 expandtab: */