X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/ba6e6b64033b1f9de49feccb5c9cd438354481f7..0f00dc4c8eb47e67bc0f148c2dd109f73a451e0a:/math/prim.c

diff --git a/math/prim.c b/math/prim.c
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+/* -*-c-*-
+ *
+ * Finding primitive elements
+ *
+ * (c) 1999 Straylight/Edgeware
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of Catacomb.
+ *
+ * Catacomb is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Library General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * Catacomb is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with Catacomb; if not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include "mp.h"
+#include "mpint.h"
+#include "mpmont.h"
+#include "mprand.h"
+#include "pgen.h"
+#include "prim.h"
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @prim_test@ --- */
+
+int prim_test(int rq, pgen_event *ev, void *p)
+{
+  prim_ctx *c = p;
+  int rc = rq;
+
+  switch (rq) {
+    case PGEN_BEGIN:
+      return (PGEN_TRY);
+    case PGEN_TRY: {
+      mp *x;
+      rc = PGEN_FAIL;
+
+      if (!c->exp)
+	x = mp_copy(ev->m);
+      else {
+	x = mpmont_exp(&c->mm, MP_NEW, ev->m, c->exp);
+	if (MP_EQ(x, MP_ONE))
+	  goto done;
+      }
+      if (c->n == 0)
+	goto ok;
+      else {
+	size_t n = c->n;
+	mp **f = c->f;
+	mp *y = MP_NEW;
+	while (n) {
+	  y = mpmont_exp(&c->mm, y, x, *f);
+	  if (MP_EQ(y, MP_ONE)) {
+	    mp_drop(y);
+	    goto done;
+	  }
+	  n--; f++;
+	}
+	mp_drop(y);
+      }
+    ok:
+      rc = PGEN_DONE;
+      mp_drop(ev->m);
+      ev->m = x;
+      break;
+    done:
+      mp_drop(x);
+    } break;
+  }
+
+  return (rc);
+}
+
+/* --- Trivial stepping functions -----------------------------------------*/
+
+/* --- @prim_step@ --- */
+
+int prim_step(int rq, pgen_event *ev, void *p)
+{
+  unsigned *i = p;
+  switch (rq) {
+    case PGEN_BEGIN:
+    case PGEN_TRY:
+      if (*i >= NPRIME)
+	return PGEN_FAIL;
+      ev->m = mp_fromint(ev->m, primetab[(*i)++]);
+      return (PGEN_TRY);
+  }
+  return (0);
+}
+
+/*----- That's all, folks -------------------------------------------------*/