git.distorted.org.uk Git - u/mdw/catacomb/blob - math/pfilt.h

   1 /* -*-c-*-
   2  *
   3  * Finding and testing prime numbers
   4  *
   5  * (c) 1999 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Catacomb.
  11  *
  12  * Catacomb is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU Library General Public License as
  14  * published by the Free Software Foundation; either version 2 of the
  15  * License, or (at your option) any later version.
  16  *
  17  * Catacomb is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU Library General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU Library General Public
  23  * License along with Catacomb; if not, write to the Free
  24  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  25  * MA 02111-1307, USA.
  26  */
  27
  28 #ifndef CATACOMB_PFILT_H
  29 #define CATACOMB_PFILT_H
  30
  31 #ifdef __cplusplus
  32   extern "C" {
  33 #endif
  34
  35 /*----- Header files ------------------------------------------------------*/
  36
  37 #ifndef CATACOMB_MP_H
  38 #  include "mp.h"
  39 #endif
  40
  41 #ifndef CATACOMB_PRIMETAB_H
  42 #  include "primetab.h"
  43 #endif
  44
  45 /*----- Data structures ---------------------------------------------------*/
  46
  47 typedef struct pfilt {
  48   mp *m;
  49   smallprime r[NPRIME];
  50 } pfilt;
  51
  52 /*----- Functions provided ------------------------------------------------*/
  53
  54 /* --- @pfilt_smallfactor@ --- *
  55  *
  56  * Arguments:   @mp *m@ = integer to test
  57  *
  58  * Returns:     One of the @PGEN@ result codes.
  59  *
  60  * Use:         Tests a number by dividing by a number of small primes.  This
  61  *              is a useful first step if you're testing random primes; for
  62  *              sequential searches, @pfilt_create@ works better.
  63  */
  64
  65 extern int pfilt_smallfactor(mp */*m*/);
  66
  67 /* --- @pfilt_create@ --- *
  68  *
  69  * Arguments:   @pfilt *p@ = pointer to prime filtering context
  70  *              @mp *m@ = pointer to initial number to test
  71  *
  72  * Returns:     A @PGEN@ result code.
  73  *
  74  * Use:         Tests an initial number for primality by computing its
  75  *              residue modulo various small prime numbers.  This is fairly
  76  *              quick, but not particularly certain.  If a @PGEN_TRY@
  77  *              result is returned, perform Rabin-Miller tests to confirm.
  78  */
  79
  80 extern int pfilt_create(pfilt */*p*/, mp */*m*/);
  81
  82 /* --- @pfilt_destroy@ --- *
  83  *
  84  * Arguments:   @pfilt *p@ = pointer to prime filtering context
  85  *
  86  * Returns:     ---
  87  *
  88  * Use:         Discards a context and all the resources it holds.
  89  */
  90
  91 extern void pfilt_destroy(pfilt */*p*/);
  92
  93 /* --- @pfilt_step@ --- *
  94  *
  95  * Arguments:   @pfilt *p@ = pointer to prime filtering context
  96  *              @mpw step@ = how much to step the number
  97  *
  98  * Returns:     One of the @PGEN@ result codes.
  99  *
 100  * Use:         Steps a number by a small amount.  Stepping is much faster
 101  *              than initializing with a new number.  The test performed is
 102  *              the same simple one used by @primetab_create@, so @PGEN_TRY@
 103  *              results should be followed up by a Rabin-Miller test.
 104  */
 105
 106 extern int pfilt_step(pfilt */*p*/, mpw /*step*/);
 107
 108 /* --- @pfilt_muladd@ --- *
 109  *
 110  * Arguments:   @pfilt *p@ = destination prime filtering context
 111  *              @const pfilt *q@ = source prime filtering context
 112  *              @mpw m@ = number to multiply by
 113  *              @mpw a@ = number to add
 114  *
 115  * Returns:     One of the @PGEN@ result codes.
 116  *
 117  * Use:         Multiplies the number in a prime filtering context by a
 118  *              small value and then adds a small value.  The destination
 119  *              should either be uninitialized or the same as the source.
 120  *
 121  *              Common things to do include multiplying by 2 and adding 0 to
 122  *              turn a prime into a jump for finding other primes with @q@ as
 123  *              a factor of @p - 1@, or multiplying by 2 and adding 1.
 124  */
 125
 126 extern int pfilt_muladd(pfilt */*p*/, const pfilt */*q*/,
 127                         mpw /*m*/, mpw /*a*/);
 128
 129 /* --- @pfilt_jump@ --- *
 130  *
 131  * Arguments:   @pfilt *p@ = pointer to prime filtering context
 132  *              @const pfilt *j@ = pointer to another filtering context
 133  *
 134  * Returns:     One of the @PGEN@ result codes.
 135  *
 136  * Use:         Steps a number by a large amount.  Even so, jumping is much
 137  *              faster than initializing a new number.  The test peformed is
 138  *              the same simple one used by @primetab_create@, so @PGEN_TRY@
 139  *              results should be followed up by a Rabin-Miller test.
 140  *
 141  *              Note that the number stored in the @j@ context is probably
 142  *              better off being even than prime.  The important thing is
 143  *              that all of the residues for the number have already been
 144  *              computed.
 145  */
 146
 147 extern int pfilt_jump(pfilt */*p*/, const pfilt */*j*/);
 148
 149 /*----- That's all, folks -------------------------------------------------*/
 150
 151 #ifdef __cplusplus
 152   }
 153 #endif
 154
 155 #endif