Gather up another utility.

[u/mdw/catacomb] / pgen.c

diff --git a/pgen.c b/pgen.c
index 74a10bc..ac8db38 100644 (file)
--- a/pgen.c
+++ b/pgen.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: pgen.c,v 1.7 2001/02/03 16:05:32 mdw Exp $
+ * $Id: pgen.c,v 1.10 2004/04/08 01:36:15 mdw Exp $
  *
  * Prime generation glue
  *
@@ -27,25 +27,6 @@
  * MA 02111-1307, USA.
  */
 
-/*----- Revision history --------------------------------------------------* 
- *
- * $Log: pgen.c,v $
- * Revision 1.7  2001/02/03 16:05:32  mdw
- * Now @mp_drop@ checks its argument is non-NULL before attempting to free
- * it.  Note that the macro version @MP_DROP@ doesn't do this.
- *
- * Revision 1.6  2000/10/08 12:11:22  mdw
- * Use @MP_EQ@ instead of @MP_CMP@.
- *
- * Revision 1.5  2000/06/17 11:52:36  mdw
- * Signal a pgen abort if the jump and base share a common factor.
- *
- * Revision 1.4  1999/12/22 16:01:11  mdw
- * Same file, completely different code.  Main interface for new prime-
- * search system.
- *
- */
-
 /*----- Header files ------------------------------------------------------*/
 
 #include <assert.h>
@@ -145,11 +126,15 @@ int pgen_test(int rq, pgen_event *ev, void *p)
       rabin_create(r, ev->m);
       rc = PGEN_TRY;
       break;
-    case PGEN_TRY: {
-      mp *a = mprand_range(MP_NEW, ev->m, ev->r, 0);
-      rc = rabin_test(r, a);
-      mp_drop(a);
-    } break;
+    case PGEN_TRY:
+      if (!ev->tests)
+       rc = rabin_rtest(r, MP_TWO);
+      else {
+       mp *a = mprand_range(MP_NEW, ev->m, ev->r, 0);
+       rc = rabin_rtest(r, a);
+       mp_drop(a);
+      }
+      break;
     case PGEN_DONE:
       rabin_destroy(r);
       rc = PGEN_DONE;
@@ -197,8 +182,8 @@ mp *pgen(const char *name, mp *d, mp *m, pgen_proc *event, void *ectx,
     ev.m = MP_COPY(m);
   else
     ev.m = 0;
-  ev.steps = steps;
-  ev.tests = tests;
+  ev.steps = 0;
+  ev.tests = 0;
   ev.r = fibrand_create(0);
 
   /* --- Tell the event handler we're under way --- */
@@ -274,17 +259,17 @@ mp *pgen(const char *name, mp *d, mp *m, pgen_proc *event, void *ectx,
     /* --- If decrementing counters is requested, do that --- */
 
     if ((act & A_STEP) && steps) {
-      ev.steps--;
-      if (!ev.steps) {
+      ev.steps++;
+      if (ev.steps == steps) {
        act |= A_EVENT | A_ENDSTEP | A_DONE;
        rc = PGEN_ABORT;
       }
-      ev.tests = tests;
+      ev.tests = 0;
     }
 
     if ((act & A_TEST) && tests) {
-      ev.tests--;
-      if (!ev.tests) {
+      ev.tests++;
+      if (ev.tests == tests) {
        act |= A_ENDTEST | A_ENDSTEP | A_DONE;
        rc = PGEN_DONE;
       }
@@ -326,6 +311,37 @@ mp *pgen(const char *name, mp *d, mp *m, pgen_proc *event, void *ectx,
   return (ev.m);
 }
 
+/* --- @pgen_primep@ --- *
+ *
+ * Arguments:  @mp *p@ = a number to check
+ *             @grand *gr@ = a random number source
+ *
+ * Returns:    Nonzero if @p@ is really prime.
+ */
+
+int pgen_primep(mp *p, grand *gr)
+{
+  int i = rabin_iters(mp_bits(p));
+  rabin r;
+  mp *x = MP_NEW;
+
+  if (MP_ISNEG(p)) return (0);
+  switch (pfilt_smallfactor(p)) {
+    case PGEN_DONE: return (1);
+    case PGEN_FAIL: return (0);
+  }
+  rabin_create(&r, p);
+  while (i) {
+    x = mprand_range(x, p, gr, 0);
+    if (rabin_rtest(&r, x) == PGEN_FAIL)
+      break;
+    i--;
+  }
+  MP_DROP(x);
+  rabin_destroy(&r);
+  return (!i);
+}
+
 /*----- Test rig ----------------------------------------------------------*/
 
 #ifdef TEST_RIG