git.distorted.org.uk Git - u/mdw/catacomb/blob - prim.c

   1 /* -*-c-*-
   2  *
   3  * $Id: prim.c,v 1.4 2004/04/08 01:36:15 mdw Exp $
   4  *
   5  * Finding primitive elements
   6  *
   7  * (c) 1999 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of Catacomb.
  13  *
  14  * Catacomb is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU Library General Public License as
  16  * published by the Free Software Foundation; either version 2 of the
  17  * License, or (at your option) any later version.
  18  *
  19  * Catacomb is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU Library General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU Library General Public
  25  * License along with Catacomb; if not, write to the Free
  26  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  27  * MA 02111-1307, USA.
  28  */
  29
  30 /*----- Header files ------------------------------------------------------*/
  31
  32 #include "mp.h"
  33 #include "mpint.h"
  34 #include "mpmont.h"
  35 #include "mprand.h"
  36 #include "pgen.h"
  37 #include "prim.h"
  38
  39 /*----- Main code ---------------------------------------------------------*/
  40
  41 /* --- @prim_test@ --- */
  42
  43 int prim_test(int rq, pgen_event *ev, void *p)
  44 {
  45   prim_ctx *c = p;
  46   int rc = rq;
  47
  48   switch (rq) {
  49     case PGEN_BEGIN:
  50       return (PGEN_TRY);
  51     case PGEN_TRY: {
  52       mp *x;
  53       rc = PGEN_FAIL;
  54
  55       if (!c->exp)
  56         x = mp_copy(ev->m);
  57       else {
  58         x = mpmont_exp(&c->mm, MP_NEW, ev->m, c->exp);
  59         if (MP_EQ(x, MP_ONE))
  60           goto done;
  61       }
  62       if (c->n == 0)
  63         goto ok;
  64       else {
  65         size_t n = c->n;
  66         mp **f = c->f;
  67         mp *y = MP_NEW;
  68         while (n) {
  69           y = mpmont_exp(&c->mm, y, x, *f);
  70           if (MP_EQ(y, MP_ONE)) {
  71             mp_drop(y);
  72             goto done;
  73           }
  74           n--; f++;
  75         }
  76         mp_drop(y);
  77       }
  78     ok:
  79       rc = PGEN_DONE;
  80       mp_drop(ev->m);
  81       ev->m = x;
  82       break;
  83     done:
  84       mp_drop(x);
  85     } break;
  86   }
  87
  88   return (rc);
  89 }
  90
  91 /* --- Trivial stepping functions -----------------------------------------*/
  92
  93 /* --- @prim_step@ --- */
  94
  95 int prim_step(int rq, pgen_event *ev, void *p)
  96 {
  97   unsigned *i = p;
  98   switch (rq) {
  99     case PGEN_BEGIN:
 100     case PGEN_TRY:
 101       if (*i >= NPRIME)
 102         return PGEN_FAIL;
 103       ev->m = mp_fromint(ev->m, primetab[(*i)++]);
 104       return (PGEN_TRY);
 105   }
 106   return (0);
 107 }
 108
 109 /*----- That's all, folks -------------------------------------------------*/