1 // This may look like C code, but it is really -*- C++ -*- 2 /* 3 Copyright (C) 1988 Free Software Foundation 4 written by Dirk Grunwald (grunwald@cs.uiuc.edu) 5 6 This file is part of GNU CC. 7 8 GNU CC is distributed in the hope that it will be useful, 9 but WITHOUT ANY WARRANTY. No author or distributor 10 accepts responsibility to anyone for the consequences of using it 11 or for whether it serves any particular purpose or works at all, 12 unless he says so in writing. Refer to the GNU CC General Public 13 License for full details. 14 15 Everyone is granted permission to copy, modify and redistribute 16 GNU CC, but only under the conditions described in the 17 GNU CC General Public License. A copy of this license is 18 supposed to have been given to you along with GNU CC so you 19 can know your rights and responsibilities. It should be in a 20 file named COPYING. Among other things, the copyright notice 21 and this notice must be preserved on all copies. 22 */ 23 #ifndef _ACG_h 24 #define _ACG_h 1 25 26 #include <RNG.h> 27 #include <math.h> 28 #ifdef __GNUG__ 29 #pragma once 30 #pragma interface 31 #endif 32 33 // 34 // Additive number generator. This method is presented in Volume II 35 // of The Art of Computer Programming by Knuth. I've coded the algorithm 36 // and have added the extensions by Andres Nowatzyk of CMU to randomize 37 // the result of algorithm M a bit by using an LCG & a spatial 38 // permutation table. 39 // 40 // The version presented uses the same constants for the LCG that Andres 41 // uses (chosen by trial & error). The spatial permutation table is 42 // the same size (it's based on word size). This is for 32-bit words. 43 // 44 // The ``auxillary table'' used by the LCG table varies in size, and 45 // is chosen to be the the smallest power of two which is larger than 46 // twice the size of the state table. 47 // 48 49 class ACG : public RNG { 50 51 unsigned long initialSeed; // used to reset generator 52 int initialTableEntry; 53 54 unsigned long *state; 55 unsigned long *auxState; 56 short stateSize; 57 short auxSize; 58 unsigned long lcgRecurr; 59 short j; 60 short k; 61 62 protected: 63 64 public: 65 ACG(unsigned long seed = 0, int size = 55); 66 virtual ~ACG(); 67 // 68 // Return a long-words word of random bits 69 // 70 virtual unsigned long asLong(); 71 virtual void reset(); 72 }; 73 74 #endif 75