CLHEP/Random/DRand48Engine.h

// $Id: DRand48Engine.h,v 1.12 2000/04/17 22:59:31 mf Exp $
// -*- C++ -*-
//
// -----------------------------------------------------------------------
//                             HEP Random
//                        --- DRand48Engine ---
//                          class header file
// -----------------------------------------------------------------------
// This file is part of Geant4 (simulation toolkit for HEP).
//
// Random engine using drand48() and srand48() functions from C standard
// library to implement the flat() basic distribution and for setting
// seeds.
// For Windows/NT platforms (WIN32), the code for drand48 has been
// extracted from the GNU C Library 2.0.1 and adapted for the native
// types.
// Copy constructor and operator= are private for objects of this class.

// =======================================================================
// G.Cosmo        - Created: 5th September 1995
//                - Minor corrections: 31st October 1996
//                - Added methods for engine status: 19th November 1996
//                - Added srand48(), seed48(), drand48() implementations
//                  for Windows/NT: 6th March 1997
//                - setSeed(), setSeeds() now have default dummy argument
//                  set to zero: 11th July 1997
// E.Tcherniaev   - Porting on KCC compiler: 2nd Feb 1998
// G.Cosmo        - Private copy constructor and operator=: 26th Feb 1998
// J.Marraffino   - Added stream operators and related constructor.
//                  Added automatic seed selection from seed table and
//                  engine counter: 16th Feb 1998
// =======================================================================

#ifndef DRand48Engine_h
#define DRand48Engine_h 1

#include "CLHEP/Random/RandomEngine.h"

#if defined(__KCC)

// Those function are available on all unix platform but their
// prototypes are not included in stdlib when KCC strict flag is
// set

extern "C" {
  extern double	drand48(void);
  extern void	srand48(long);
  extern unsigned short * seed48(unsigned short int [3]);
}

#endif  /* KCC */

#ifdef WIN32
   // ********************************************************************
   // Code extracted from GNU C Library 2.0.1

   /* Data structure for communication with thread safe versions.  */
   struct drand48_data
     {
       unsigned short int X[3];     /* Current state.  */
       unsigned short int a[3];     /* Factor in congruential formula.  */
       unsigned short int c;        /* Additive const. in congruential formula.  */
       unsigned short int old_X[3]; /* Old state.  */
       int init;                                /* Flag for initializing.  */
     };

   /* Internal function to compute next state of the generator.  */
   extern "C" { int drand48_iterate (unsigned short int xsubi[3],
                                                        struct drand48_data *buffer); }

   /* Return non-negative, double-precision floating-point value in [0.0,1.0).  */
   extern "C" { int drand48_r (struct drand48_data *buffer, double *result); }
   extern "C" { int erand48_r (unsigned short int xsubi[3],
                                            struct drand48_data *buffer, double *result); }

   /* Seed random number generator.  */
   extern "C" { int srand48_r (long seedval, struct drand48_data *buffer); }
   extern "C" { int seed48_r  (unsigned short int seed16v[3],
                                            struct drand48_data *buffer); }

   /* Return non-negative, double-precision floating-point value in [0.0,1.0).  */
   extern "C" { double drand48 (void); }
   extern "C" { double erand48 (unsigned short int xsubi[3]); }

   /* Seed random number generator.  */
   extern "C" { void srand48 (long seedval); }
   extern "C" { unsigned short int *seed48 (unsigned short int seed16v[3]);     }

   // End Code extracted from GNU C Library 2.0.1
   // ********************************************************************
#endif  /* WIN32 */

class DRand48Engine : public HepRandomEngine {

public:

  DRand48Engine(HepStd::istream& is);
  DRand48Engine();
  DRand48Engine(long seed);
  DRand48Engine(HepInt rowIndex, HepInt colIndex);
  virtual ~DRand48Engine();
  // Constructors and destructor

  HepDouble flat();
  // It returns a pseudo random number between 0 and 1,
  // according to the standard stdlib random function drand48()
  // but excluding the end points.

  void flatArray (const HepInt size, HepDouble* vect);
  // Fills the array "vect" of specified size with flat random values.

  void setSeed(long seed, HepInt dum=0);
  // Sets the state of the algorithm according to seed.

  void setSeeds(const long * seeds, HepInt dum=0);
  // Sets the state of the algorithm according to the zero terminated
  // array of seeds. Only the first seed is used.

  void saveStatus( const char filename[] = "DRand48.conf" ) const;
  // Saves on file DRand48.conf the current engine status.

  void restoreStatus( const char filename[] = "DRand48.conf" );
  // Reads from file DRand48.conf the last saved engine status
  // and restores it.

  void showStatus() const;
  // Dumps the engine status on the screen.

  friend HepStd::ostream& operator<< (HepStd::ostream& os, const DRand48Engine& e);
  friend HepStd::istream& operator>> (HepStd::istream& is,       DRand48Engine& e);

private:

  static HepInt  numEngines;
  static HepInt  maxIndex;

  DRand48Engine(const DRand48Engine &p);
  DRand48Engine & operator = (const DRand48Engine &p);
  // Private copy constructor and assignment operator.

};

#endif