source: trunk/lib/random/random.cc @ 375

// $Id: random.cc 375 2005-08-07 21:51:58Z jari $

#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(u_long s)
  {
    gsl_rng_env_setup();  // support rng/seed changes through environment vars
    rng_ = gsl_rng_alloc(gsl_rng_default);  // Memory is allocated here!
    seed(s);
  }



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



  RNG* RNG::instance(u_long seed)
  {
    if (!instance_)
      instance_ = new RNG(seed);
    return 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