RNG.h

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// This may look like C code, but it is really -*- C++ -*-
/* 
Copyright (C) 1988 Free Software Foundation
    written by Dirk Grunwald (grunwald@cs.uiuc.edu)
 
This file is part of the GNU C++ Library.  This library is free
software; you can redistribute it and/or modify it under the terms of
the GNU Library General Public License as published by the Free
Software Foundation; either version 2 of the License, or (at your
option) any later version.  This 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 Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free Software
Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#ifndef _RNG_h
#define _RNG_h 1
#ifdef __GNUG__
//#pragma interface
#endif
 
 
/*
 * int32_t and uint32_t have been defined by the configure procedure.  Just
 * use these in place of the ones that libg++ used to provide. 
 */
#if defined(HAVE_INTTYPES_H)
#include <inttypes.h>
#elif defined(HAVE_SYS_TYPES_H)
#include <sys/types.h>
#elif defined(HAVE__G_CONFIG_H)
#include <_G_config.h>
typedef _G_int32_t int32_t;
typedef _G_uint32_t uint32_t;
#endif
 
#include <assert.h>
#include <math.h>
 
union PrivateRNGSingleType {            // used to access floats as unsigneds
    float s;
    uint32_t u;
};
 
union PrivateRNGDoubleType {            // used to access doubles as unsigneds
    double d;
    uint32_t u[2];
};
 
//
// Base class for Random Number Generators. See ACG and MLCG for instances.
//
class RNG {
    static PrivateRNGSingleType singleMantissa; // mantissa bit vector
    static PrivateRNGDoubleType doubleMantissa; // mantissa bit vector
public:
    RNG();
    virtual ~RNG();
    //
    // Return a long-words word of random bits
    //
    virtual uint32_t asLong() = 0;
    virtual void reset() = 0;
    //
    // Return random bits converted to either a float or a double
    //
    virtual float asFloat();
    virtual double asDouble();
};
 
#endif