source: trunk/c++_tools/random/random.cc @ 575

// $Id: random.cc 562 2006-03-15 09:19:51Z jari $

/*
  Copyright (C) 2005, 2006 Jari Häkkinen, Peter Johansson

  This file is part of the thep c++ tools library,
                                http://lev.thep.lu.se/trac/c++_tools

  The c++ tools library is free software; you can redistribute it
  and/or modify it under the terms of the GNU General Public License
  as published by the Free Software Foundation; either version 2 of
  the License, or (at your option) any later version.

  The c++ tools library is distributed in the hope that it will be
  useful, but WITHOUT ANY WARRANTY; without even the implied warranty
  of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  02111-1307, USA.
*/

#include <c++_tools/random/random.h>
#include <c++_tools/statistics/Histogram.h>

#include <fstream>
#include <iostream>


namespace theplu {
namespace random {


  RNG* RNG::instance_ = NULL;


  RNG::RNG(void)
  {
    gsl_rng_env_setup();  // support rng/seed changes through environment vars
    rng_ = gsl_rng_alloc(gsl_rng_default);  // Memory is allocated here!
  }



  RNG::~RNG(void)
  {
    gsl_rng_free(rng_);
    rng_=NULL;
    delete instance_;
  }



  u_long RNG::seed_from_devurandom(void)
  {
    u_char ulongsize=sizeof(u_long);
    char* buffer=new char[ulongsize];
    std::ifstream is("/dev/urandom");
    is.read(buffer,ulongsize);
    is.close();
    u_long s=0;
    for (u_int i=0; i<ulongsize; i++) {
      u_char ch=buffer[i];
      s+=ch<<((ulongsize-1-i)*8);
    }
    seed(s);
    return s;
  }



  DiscreteGeneral::DiscreteGeneral(const statistics::Histogram& hist)
  {
    double* p = new double[ hist.nof_bins() ];
    for (size_t i=0; i<hist.nof_bins(); i++) 
      p[ i ] = hist[i];
    gen_ = gsl_ran_discrete_preproc( hist.nof_bins(), p );
    delete p;
  }



  DiscreteGeneral::~DiscreteGeneral(void)
  {
    if (gen_)
      gsl_ran_discrete_free( gen_ );
    gen_ = NULL;
  }


}} // of namespace random and namespace theplu