ACG.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 _ACG_h
#define _ACG_h 1 
 
#include <RNG.h>
#include <math.h>
#ifdef __GNUG__
//#pragma interface
#endif
 
//
//  Additive number generator. This method is presented in Volume II
//  of The Art of Computer Programming by Knuth. I've coded the algorithm
//  and have added the extensions by Andres Nowatzyk of CMU to randomize
//  the result of algorithm M a bit by using an LCG & a spatial
//  permutation table.
//
//  The version presented uses the same constants for the LCG that Andres
//  uses (chosen by trial & error). The spatial permutation table is
//  the same size (it's based on word size). This is for 32-bit words.
//
//  The ``auxillary table'' used by the LCG table varies in size, and
//  is chosen to be the the smallest power of two which is larger than
//  twice the size of the state table.
//
 
class ACG : public RNG {
 
    uint32_t initialSeed;   // used to reset generator
    int initialTableEntry;
 
    uint32_t *state;
    uint32_t *auxState;
    short stateSize;
    short auxSize;
    uint32_t lcgRecurr;
    short j;
    short k;
 
protected:
 
public:
    ACG(uint32_t seed = 0, int size = 55);
    virtual ~ACG();
    //
    // Return a long-words word of random bits
    //
    virtual uint32_t asLong();
    virtual void reset();
};
 
#endif