X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/8b021c3f89a78c3006ffc5d480feca6ef86d544e..2b645fb792c62ae0d38fcde4c39e1bd0889b0e06:/pgen.c

diff --git a/pgen.c b/pgen.c
index 0e67c76..dca61d9 100644
--- a/pgen.c
+++ b/pgen.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: pgen.c,v 1.5 2000/06/17 11:52:36 mdw Exp $
+ * $Id: pgen.c,v 1.8 2002/01/13 13:42:53 mdw Exp $
  *
  * Prime generation glue
  *
@@ -30,6 +30,17 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: pgen.c,v $
+ * Revision 1.8  2002/01/13 13:42:53  mdw
+ * More efficient Rabin-Miller test: with random witnesses, skip redundant
+ * Montgomerization.  (Being bijective, it can't affect the distribution.)
+ *
+ * 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.
  *
@@ -138,11 +149,15 @@ 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;
@@ -190,8 +205,8 @@ 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 --- */
@@ -267,17 +282,17 @@ 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;
       }
@@ -314,8 +329,7 @@ mp *pgen(const char *name, mp *d, mp *m, pgen_proc *event, void *ectx,
     ev.m = 0;
   }
   ev.r->ops->destroy(ev.r);
-  if (d != MP_NEW)
-    mp_drop(d);
+  mp_drop(d);
 
   return (ev.m);
 }
@@ -339,7 +353,7 @@ static int verify(dstr *v)
   pf.step = 2;
   p = pgen("p", MP_NEW, m, pgen_evspin, 0, 0, pgen_filter, &pf,
 	   rabin_iters(mp_bits(m)), pgen_test, &r);
-  if (!p || MP_CMP(p, !=, q)) {
+  if (!p || !MP_EQ(p, q)) {
     fputs("\n*** pgen failed", stderr);
     fputs("\nm = ", stderr); mp_writefile(m, stderr, 10);
     fputs("\np = ", stderr); mp_writefile(p, stderr, 10);
@@ -350,8 +364,7 @@ static int verify(dstr *v)
 
   mp_drop(m);
   mp_drop(q);
-  if (p)
-    mp_drop(p);
+  mp_drop(p);
   assert(mparena_count(MPARENA_GLOBAL) == 0);
   return (ok);
 }