diff --git a/PDelays.cc b/PDelays.cc
index 0f72a3a51..5e5862567 100644
--- a/PDelays.cc
+++ b/PDelays.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: PDelays.cc,v 1.11 2003/06/21 01:21:42 steve Exp $"
+#ident "$Id: PDelays.cc,v 1.12 2006/01/02 05:33:19 steve Exp $"
 #endif
 
 # include "config.h"
@@ -62,8 +62,7 @@ void PDelays::set_delays(const svector<PExpr*>*del, bool df)
       delete_flag_ = df;
 }
 
-static unsigned long calculate_val(Design*des, NetScope*scope,
-				   const PExpr*expr)
+static NetExpr*calculate_val(Design*des, NetScope*scope, const PExpr*expr)
 {
 
       NetExpr*dex = expr->elaborate_expr(des, scope);
@@ -85,7 +84,9 @@ static unsigned long calculate_val(Design*des, NetScope*scope,
 		  delay = 0;
 
 	    delete tmp;
-	    return delay;
+	    NetEConst*tmp2 = new NetEConst(verinum(delay));
+	    tmp2->set_line(*expr);
+	    return tmp2;
       }
 
 
@@ -96,23 +97,19 @@ static unsigned long calculate_val(Design*des, NetScope*scope,
 		  des->scale_to_precision(fn.as_ulong(), scope);
 
 	    delete tmp;
-	    return delay;
+	    NetEConst*tmp2 = new NetEConst(verinum(delay));
+	    tmp2->set_line(*expr);
+	    return tmp2;
       }
 
-	/* Oops, cannot evaluate down to a constant. Error message. */
-      delete dex;
-
-      cerr << expr->get_line() << ": sorry: non-constant "
-	   << "delays not supported here: " << *expr << endl;
-      des->errors += 1;
-      return 0;
-
+	/* Oops, cannot evaluate down to a constant. */
+      return dex;
 }
 
 void PDelays::eval_delays(Design*des, NetScope*scope,
-			  unsigned long&rise_time,
-			  unsigned long&fall_time,
-			  unsigned long&decay_time) const
+			  NetExpr*&rise_time,
+			  NetExpr*&fall_time,
+			  NetExpr*&decay_time) const
 {
       assert(scope);
 
@@ -146,6 +143,9 @@ void PDelays::eval_delays(Design*des, NetScope*scope,
 
 /*
  * $Log: PDelays.cc,v $
+ * Revision 1.12  2006/01/02 05:33:19  steve
+ *  Node delays can be more general expressions in structural contexts.
+ *
  * Revision 1.11  2003/06/21 01:21:42  steve
  *  Harmless fixup of warnings.
  *
diff --git a/PDelays.h b/PDelays.h
index d62efa189..3c9349869 100644
--- a/PDelays.h
+++ b/PDelays.h
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: PDelays.h,v 1.7 2002/08/12 01:34:58 steve Exp $"
+#ident "$Id: PDelays.h,v 1.8 2006/01/02 05:33:19 steve Exp $"
 #endif
 
 # include  "svector.h"
@@ -34,6 +34,7 @@ using namespace std;
 
 class Design;
 class NetScope;
+class NetExpr;
 class PExpr;
 
 /*
@@ -53,9 +54,9 @@ class PDelays {
       void set_delays(const svector<PExpr*>*del, bool delete_flag=true);
 
       void eval_delays(Design*des, NetScope*scope,
-		       unsigned long&rise_time,
-		       unsigned long&fall_time,
-		       unsigned long&decay_time) const;
+		       NetExpr*&rise_time,
+		       NetExpr*&fall_time,
+		       NetExpr*&decay_time) const;
 
       void dump_delays(ostream&out) const;
 
@@ -72,6 +73,9 @@ ostream& operator << (ostream&o, const PDelays&);
 
 /*
  * $Log: PDelays.h,v $
+ * Revision 1.8  2006/01/02 05:33:19  steve
+ *  Node delays can be more general expressions in structural contexts.
+ *
  * Revision 1.7  2002/08/12 01:34:58  steve
  *  conditional ident string using autoconfig.
  *
diff --git a/PExpr.h b/PExpr.h
index a9387ca17..17491d304 100644
--- a/PExpr.h
+++ b/PExpr.h
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: PExpr.h,v 1.75 2005/12/07 04:04:23 steve Exp $"
+#ident "$Id: PExpr.h,v 1.76 2006/01/02 05:33:19 steve Exp $"
 #endif
 
 # include  <string>
@@ -66,9 +66,9 @@ class PExpr : public LineInfo {
 	// continuous assign or other wholly structural context.
       virtual NetNet* elaborate_net(Design*des, NetScope*scope,
 				    unsigned lwidth,
-				    unsigned long rise,
-				    unsigned long fall,
-				    unsigned long decay,
+				    const NetExpr* rise,
+				    const NetExpr* fall,
+				    const NetExpr* decay,
 				    Link::strength_t drive0 =Link::STRONG,
 				    Link::strength_t drive1 =Link::STRONG)
 	    const;
@@ -129,9 +129,9 @@ class PEConcat : public PExpr {
 				     bool implicit_net_ok =false) const;
       virtual NetNet* elaborate_net(Design*des, NetScope*scope,
 				    unsigned width,
-				    unsigned long rise,
-				    unsigned long fall,
-				    unsigned long decay,
+				    const NetExpr* rise,
+				    const NetExpr* fall,
+				    const NetExpr* decay,
 				    Link::strength_t drive0,
 				    Link::strength_t drive1) const;
       virtual NetExpr*elaborate_expr(Design*des, NetScope*,
@@ -199,9 +199,9 @@ class PEFNumber : public PExpr {
 
       virtual NetNet* elaborate_net(Design*des, NetScope*scope,
 				    unsigned lwidth,
-				    unsigned long rise,
-				    unsigned long fall,
-				    unsigned long decay,
+				    const NetExpr* rise,
+				    const NetExpr* fall,
+				    const NetExpr* decay,
 				    Link::strength_t drive0,
 				    Link::strength_t drive1) const;
 
@@ -233,9 +233,9 @@ class PEIdent : public PExpr {
 	// Structural r-values are OK.
       virtual NetNet* elaborate_net(Design*des, NetScope*scope,
 				    unsigned lwidth,
-				    unsigned long rise,
-				    unsigned long fall,
-				    unsigned long decay,
+				    const NetExpr* rise,
+				    const NetExpr* fall,
+				    const NetExpr* decay,
 				    Link::strength_t drive0,
 				    Link::strength_t drive1) const;
 
@@ -294,15 +294,15 @@ class PEIdent : public PExpr {
 
       NetNet* elaborate_net_ram_(Design*des, NetScope*scope,
 				 NetMemory*mem, unsigned lwidth,
-				 unsigned long rise,
-				 unsigned long fall,
-				 unsigned long decay) const;
+				 const NetExpr* rise,
+				 const NetExpr* fall,
+				 const NetExpr* decay) const;
 
       NetNet* elaborate_net_bitmux_(Design*des, NetScope*scope,
 				    NetNet*sig,
-				    unsigned long rise,
-				    unsigned long fall,
-				    unsigned long decay,
+				    const NetExpr* rise,
+				    const NetExpr* fall,
+				    const NetExpr* decay,
 				    Link::strength_t drive0,
 				    Link::strength_t drive1) const;
 
@@ -332,9 +332,9 @@ class PENumber : public PExpr {
       virtual void dump(ostream&) const;
       virtual NetNet* elaborate_net(Design*des, NetScope*scope,
 				    unsigned lwidth,
-				    unsigned long rise,
-				    unsigned long fall,
-				    unsigned long decay,
+				    const NetExpr* rise,
+				    const NetExpr* fall,
+				    const NetExpr* decay,
 				    Link::strength_t drive0,
 				    Link::strength_t drive1) const;
       virtual NetEConst*elaborate_expr(Design*des, NetScope*,
@@ -370,9 +370,9 @@ class PEString : public PExpr {
       virtual void dump(ostream&) const;
       virtual NetNet* elaborate_net(Design*des, NetScope*scope,
 				    unsigned width,
-				    unsigned long rise,
-				    unsigned long fall,
-				    unsigned long decay,
+				    const NetExpr* rise,
+				    const NetExpr* fall,
+				    const NetExpr* decay,
 				    Link::strength_t drive0,
 				    Link::strength_t drive1) const;
       virtual NetEConst*elaborate_expr(Design*des, NetScope*,
@@ -395,9 +395,9 @@ class PEUnary : public PExpr {
       virtual void dump(ostream&out) const;
       virtual NetNet* elaborate_net(Design*des, NetScope*scope,
 				    unsigned width,
-				    unsigned long rise,
-				    unsigned long fall,
-				    unsigned long decay,
+				    const NetExpr* rise,
+				    const NetExpr* fall,
+				    const NetExpr* decay,
 				    Link::strength_t drive0,
 				    Link::strength_t drive1) const;
       virtual NetExpr*elaborate_expr(Design*des, NetScope*,
@@ -423,9 +423,9 @@ class PEBinary : public PExpr {
       virtual void dump(ostream&out) const;
       virtual NetNet* elaborate_net(Design*des, NetScope*scope,
 				    unsigned width,
-				    unsigned long rise,
-				    unsigned long fall,
-				    unsigned long decay,
+				    const NetExpr* rise,
+				    const NetExpr* fall,
+				    const NetExpr* decay,
 				    Link::strength_t drive0,
 				    Link::strength_t drive1) const;
       virtual NetEBinary*elaborate_expr(Design*des, NetScope*,
@@ -442,44 +442,44 @@ class PEBinary : public PExpr {
 
       NetNet* elaborate_net_add_(Design*des, NetScope*scope,
 				 unsigned lwidth,
-				 unsigned long rise,
-				 unsigned long fall,
-				 unsigned long decay) const;
+				 const NetExpr* rise,
+				 const NetExpr* fall,
+				 const NetExpr* decay) const;
       NetNet* elaborate_net_bit_(Design*des, NetScope*scope,
 				 unsigned lwidth,
-				 unsigned long rise,
-				 unsigned long fall,
-				 unsigned long decay) const;
+				 const NetExpr* rise,
+				 const NetExpr* fall,
+				 const NetExpr* decay) const;
       NetNet* elaborate_net_cmp_(Design*des, NetScope*scope,
 				 unsigned lwidth,
-				 unsigned long rise,
-				 unsigned long fall,
-				 unsigned long decay) const;
+				 const NetExpr* rise,
+				 const NetExpr* fall,
+				 const NetExpr* decay) const;
       NetNet* elaborate_net_div_(Design*des, NetScope*scope,
 				 unsigned lwidth,
-				 unsigned long rise,
-				 unsigned long fall,
-				 unsigned long decay) const;
+				 const NetExpr* rise,
+				 const NetExpr* fall,
+				 const NetExpr* decay) const;
       NetNet* elaborate_net_mod_(Design*des, NetScope*scope,
 				 unsigned lwidth,
-				 unsigned long rise,
-				 unsigned long fall,
-				 unsigned long decay) const;
+				 const NetExpr* rise,
+				 const NetExpr* fall,
+				 const NetExpr* decay) const;
       NetNet* elaborate_net_log_(Design*des, NetScope*scope,
 				 unsigned lwidth,
-				 unsigned long rise,
-				 unsigned long fall,
-				 unsigned long decay) const;
+				 const NetExpr* rise,
+				 const NetExpr* fall,
+				 const NetExpr* decay) const;
       NetNet* elaborate_net_mul_(Design*des, NetScope*scope,
 				 unsigned lwidth,
-				 unsigned long rise,
-				 unsigned long fall,
-				 unsigned long decay) const;
+				 const NetExpr* rise,
+				 const NetExpr* fall,
+				 const NetExpr* decay) const;
       NetNet* elaborate_net_shift_(Design*des, NetScope*scope,
 				   unsigned lwidth,
-				   unsigned long rise,
-				   unsigned long fall,
-				   unsigned long decay) const;
+				   const NetExpr* rise,
+				   const NetExpr* fall,
+				   const NetExpr* decay) const;
 };
 
 /*
@@ -497,9 +497,9 @@ class PETernary : public PExpr {
       virtual void dump(ostream&out) const;
       virtual NetNet* elaborate_net(Design*des, NetScope*scope,
 				    unsigned width,
-				    unsigned long rise,
-				    unsigned long fall,
-				    unsigned long decay,
+				    const NetExpr* rise,
+				    const NetExpr* fall,
+				    const NetExpr* decay,
 				    Link::strength_t drive0,
 				    Link::strength_t drive1) const;
       virtual NetETernary*elaborate_expr(Design*des, NetScope*,
@@ -527,9 +527,9 @@ class PECallFunction : public PExpr {
       virtual void dump(ostream &) const;
       virtual NetNet* elaborate_net(Design*des, NetScope*scope,
 				    unsigned width,
-				    unsigned long rise,
-				    unsigned long fall,
-				    unsigned long decay,
+				    const NetExpr* rise,
+				    const NetExpr* fall,
+				    const NetExpr* decay,
 				    Link::strength_t drive0,
 				    Link::strength_t drive1) const;
       virtual NetExpr*elaborate_expr(Design*des, NetScope*scope,
@@ -546,6 +546,9 @@ class PECallFunction : public PExpr {
 
 /*
  * $Log: PExpr.h,v $
+ * Revision 1.76  2006/01/02 05:33:19  steve
+ *  Node delays can be more general expressions in structural contexts.
+ *
  * Revision 1.75  2005/12/07 04:04:23  steve
  *  Allow constant concat expressions.
  *
diff --git a/PGate.cc b/PGate.cc
index 070f5d4f7..f96242d30 100644
--- a/PGate.cc
+++ b/PGate.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: PGate.cc,v 1.16 2004/02/18 17:11:54 steve Exp $"
+#ident "$Id: PGate.cc,v 1.17 2006/01/02 05:33:19 steve Exp $"
 #endif
 
 # include "config.h"
@@ -90,12 +90,66 @@ void PGate::elaborate_scope(Design*, NetScope*) const
  * parameters. This method understands how to handle the different
  * numbers of expressions.
  */
+
+void PGate::eval_delays(Design*des, NetScope*scope,
+			NetExpr*&rise_expr,
+			NetExpr*&fall_expr,
+			NetExpr*&decay_expr) const
+{
+      delay_.eval_delays(des, scope, rise_expr, fall_expr, decay_expr);
+}
+
 void PGate::eval_delays(Design*des, NetScope*scope,
 			unsigned long&rise_time,
 			unsigned long&fall_time,
 			unsigned long&decay_time) const
 {
-      delay_.eval_delays(des, scope, rise_time, fall_time, decay_time);
+      NetExpr*rise_expr, *fall_expr, *decay_expr;
+      delay_.eval_delays(des, scope, rise_expr, fall_expr, decay_expr);
+
+      if (rise_expr == 0) {
+	    rise_time = 0;
+	    fall_time = 0;
+	    decay_time = 0;
+      }
+
+      if (NetEConst*tmp = dynamic_cast<NetEConst*> (rise_expr)) {
+	    rise_time = tmp->value().as_ulong();
+
+      } else {
+	    cerr << get_line() << ": error: Delay expressions must be "
+		 << "constant here." << endl;
+	    cerr << get_line() << ":      : Cannot calculate "
+		 << *rise_expr << endl;
+	    des->errors += 1;
+	    rise_time = 0;
+      }
+
+      if (NetEConst*tmp = dynamic_cast<NetEConst*> (fall_expr)) {
+	    fall_time = tmp->value().as_ulong();
+
+      } else {
+	    if (fall_expr != rise_expr) {
+		  cerr << get_line() << ": error: Delay expressions must be "
+		       << "constant here." << endl;
+		  cerr << get_line() << ":      : Cannot calculate "
+		       << *rise_expr << endl;
+	    }
+	    des->errors += 1;
+	    fall_time = 0;
+      }
+
+      if (NetEConst*tmp = dynamic_cast<NetEConst*> (decay_expr)) {
+	    decay_time = tmp->value().as_ulong();
+
+      } else {
+	    cerr << get_line() << ": error: Delay expressions must be "
+		 << "constant here." << endl;
+	    cerr << get_line() << ":      : Cannot calculate "
+		 << *rise_expr << endl;
+	    des->errors += 1;
+	    decay_time = 0;
+      }
 }
 
 PGAssign::PGAssign(svector<PExpr*>*pins)
@@ -191,6 +245,9 @@ perm_string PGModule::get_type()
 
 /*
  * $Log: PGate.cc,v $
+ * Revision 1.17  2006/01/02 05:33:19  steve
+ *  Node delays can be more general expressions in structural contexts.
+ *
  * Revision 1.16  2004/02/18 17:11:54  steve
  *  Use perm_strings for named langiage items.
  *
diff --git a/PGate.h b/PGate.h
index 3d8aca025..2e84604dc 100644
--- a/PGate.h
+++ b/PGate.h
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: PGate.h,v 1.29 2004/10/04 01:10:52 steve Exp $"
+#ident "$Id: PGate.h,v 1.30 2006/01/02 05:33:19 steve Exp $"
 #endif
 
 # include  "svector.h"
@@ -66,11 +66,22 @@ class PGate : public LineInfo {
 
       perm_string get_name() const { return name_; }
 
+	// This method evaluates the delays all the way to an
+	// integer. If the delay is non-constant, then set the times
+	// to 0, print an error message and mark an error to the
+	// design.
       void eval_delays(Design*des, NetScope*scope,
 		       unsigned long&rise_time,
 		       unsigned long&fall_time,
 		       unsigned long&decay_time) const;
 
+	// This evaluates the delays as far as possible, but returns
+	// an expression, and do not signal errors.
+      void eval_delays(Design*des, NetScope*scope,
+		       NetExpr*&rise_time,
+		       NetExpr*&fall_time,
+		       NetExpr*&decay_time) const;
+
       unsigned pin_count() const { return pins_? pins_->count() : 0; }
       const PExpr*pin(unsigned idx) const { return (*pins_)[idx]; }
 
@@ -227,6 +238,9 @@ class PGModule  : public PGate {
 
 /*
  * $Log: PGate.h,v $
+ * Revision 1.30  2006/01/02 05:33:19  steve
+ *  Node delays can be more general expressions in structural contexts.
+ *
  * Revision 1.29  2004/10/04 01:10:52  steve
  *  Clean up spurious trailing white space.
  *
diff --git a/elab_net.cc b/elab_net.cc
index f39be3176..cc539b891 100644
--- a/elab_net.cc
+++ b/elab_net.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: elab_net.cc,v 1.176 2005/10/11 16:15:52 steve Exp $"
+#ident "$Id: elab_net.cc,v 1.177 2006/01/02 05:33:19 steve Exp $"
 #endif
 
 # include "config.h"
@@ -39,9 +39,9 @@
 static bool must_be_self_determined_flag = false;
 
 NetNet* PExpr::elaborate_net(Design*des, NetScope*scope, unsigned,
-			     unsigned long,
-			     unsigned long,
-			     unsigned long,
+			     const NetExpr*,
+			     const NetExpr*,
+			     const NetExpr*,
 			     Link::strength_t,
 			     Link::strength_t) const
 {
@@ -57,9 +57,9 @@ NetNet* PExpr::elaborate_net(Design*des, NetScope*scope, unsigned,
  */
 NetNet* PEBinary::elaborate_net(Design*des, NetScope*scope,
 				unsigned width,
-				unsigned long rise,
-				unsigned long fall,
-				unsigned long decay,
+				const NetExpr* rise,
+				const NetExpr* fall,
+				const NetExpr* decay,
 				Link::strength_t drive0,
 				Link::strength_t drive1) const
 {
@@ -161,9 +161,9 @@ NetNet* PEBinary::elaborate_net(Design*des, NetScope*scope,
  */
 NetNet* PEBinary::elaborate_net_add_(Design*des, NetScope*scope,
 				     unsigned lwidth,
-				     unsigned long rise,
-				     unsigned long fall,
-				     unsigned long decay) const
+				     const NetExpr* rise,
+				     const NetExpr* fall,
+				     const NetExpr* decay) const
 {
       NetNet*lsig = left_->elaborate_net(des, scope, lwidth, 0, 0, 0),
 	    *rsig = right_->elaborate_net(des, scope, lwidth, 0, 0, 0);
@@ -268,9 +268,9 @@ NetNet* PEBinary::elaborate_net_add_(Design*des, NetScope*scope,
  */
 NetNet* PEBinary::elaborate_net_bit_(Design*des, NetScope*scope,
 				     unsigned width,
-				     unsigned long rise,
-				     unsigned long fall,
-				     unsigned long decay) const
+				     const NetExpr* rise,
+				     const NetExpr* fall,
+				     const NetExpr* decay) const
 {
       NetNet*lsig = left_->elaborate_net(des, scope, width, 0, 0, 0),
 	    *rsig = right_->elaborate_net(des, scope, width, 0, 0, 0);
@@ -350,9 +350,9 @@ NetNet* PEBinary::elaborate_net_bit_(Design*des, NetScope*scope,
 static NetNet* compare_eq_constant(Design*des, NetScope*scope,
 				   NetNet*lsig, NetEConst*rexp,
 				   char op_code,
-				   unsigned long rise,
-				   unsigned long fall,
-				   unsigned long decay)
+				   const NetExpr* rise,
+				   const NetExpr* fall,
+				   const NetExpr* decay)
 {
       if (op_code != 'e' && op_code != 'n')
 	    return 0;
@@ -464,9 +464,9 @@ static NetNet* compare_eq_constant(Design*des, NetScope*scope,
  */
 NetNet* PEBinary::elaborate_net_cmp_(Design*des, NetScope*scope,
 				     unsigned lwidth,
-				     unsigned long rise,
-				     unsigned long fall,
-				     unsigned long decay) const
+				     const NetExpr* rise,
+				     const NetExpr* fall,
+				     const NetExpr* decay) const
 {
 
 	/* Elaborate the operands of the compare first as expressions
@@ -691,9 +691,9 @@ NetNet* PEBinary::elaborate_net_cmp_(Design*des, NetScope*scope,
  */
 NetNet* PEBinary::elaborate_net_div_(Design*des, NetScope*scope,
 				     unsigned lwidth,
-				     unsigned long rise,
-				     unsigned long fall,
-				     unsigned long decay) const
+				     const NetExpr* rise,
+				     const NetExpr* fall,
+				     const NetExpr* decay) const
 {
       NetNet*lsig = left_->elaborate_net(des, scope, lwidth, 0, 0, 0);
       if (lsig == 0) return 0;
@@ -771,9 +771,9 @@ NetNet* PEBinary::elaborate_net_div_(Design*des, NetScope*scope,
  */
 NetNet* PEBinary::elaborate_net_mod_(Design*des, NetScope*scope,
 				     unsigned lwidth,
-				     unsigned long rise,
-				     unsigned long fall,
-				     unsigned long decay) const
+				     const NetExpr* rise,
+				     const NetExpr* fall,
+				     const NetExpr* decay) const
 {
       NetNet*lsig = left_->elaborate_net(des, scope, 0, 0, 0, 0);
       if (lsig == 0) return 0;
@@ -824,9 +824,9 @@ NetNet* PEBinary::elaborate_net_mod_(Design*des, NetScope*scope,
 
 NetNet* PEBinary::elaborate_net_log_(Design*des, NetScope*scope,
 				     unsigned lwidth,
-				     unsigned long rise,
-				     unsigned long fall,
-				     unsigned long decay) const
+				     const NetExpr* rise,
+				     const NetExpr* fall,
+				     const NetExpr* decay) const
 {
       NetNet*lsig = left_->elaborate_net(des, scope, 0, 0, 0, 0);
       NetNet*rsig = right_->elaborate_net(des, scope, 0, 0, 0, 0);
@@ -913,9 +913,9 @@ NetNet* PEBinary::elaborate_net_log_(Design*des, NetScope*scope,
 
 NetNet* PEBinary::elaborate_net_mul_(Design*des, NetScope*scope,
 				       unsigned lwidth,
-				       unsigned long rise,
-				       unsigned long fall,
-				       unsigned long decay) const
+				       const NetExpr* rise,
+				       const NetExpr* fall,
+				       const NetExpr* decay) const
 {
       verinum*lnum = left_->eval_const(des, scope);
       verinum*rnum = right_->eval_const(des, scope);
@@ -1000,9 +1000,9 @@ NetNet* PEBinary::elaborate_net_mul_(Design*des, NetScope*scope,
 
 NetNet* PEBinary::elaborate_net_shift_(Design*des, NetScope*scope,
 				       unsigned lwidth,
-				       unsigned long rise,
-				       unsigned long fall,
-				       unsigned long decay) const
+				       const NetExpr* rise,
+				       const NetExpr* fall,
+				       const NetExpr* decay) const
 {
       NetNet*lsig = left_->elaborate_net(des, scope, lwidth, 0, 0, 0);
       if (lsig == 0) return 0;
@@ -1196,9 +1196,9 @@ NetNet* PEBinary::elaborate_net_shift_(Design*des, NetScope*scope,
  */
 NetNet* PECallFunction::elaborate_net(Design*des, NetScope*scope,
 				      unsigned width,
-				      unsigned long rise,
-				      unsigned long fall,
-				      unsigned long decay,
+				      const NetExpr* rise,
+				      const NetExpr* fall,
+				      const NetExpr* decay,
 				      Link::strength_t drive0,
 				      Link::strength_t drive1) const
 {
@@ -1321,9 +1321,9 @@ NetNet* PECallFunction::elaborate_net(Design*des, NetScope*scope,
  */
 NetNet* PEConcat::elaborate_net(Design*des, NetScope*scope,
 				unsigned,
-				unsigned long rise,
-				unsigned long fall,
-				unsigned long decay,
+				const NetExpr* rise,
+				const NetExpr* fall,
+				const NetExpr* decay,
 				Link::strength_t drive0,
 				Link::strength_t drive1) const
 {
@@ -1460,9 +1460,9 @@ NetNet* PEConcat::elaborate_net(Design*des, NetScope*scope,
  */
 NetNet* PEIdent::elaborate_net_bitmux_(Design*des, NetScope*scope,
 				       NetNet*sig,
-				       unsigned long rise,
-				       unsigned long fall,
-				       unsigned long decay,
+				       const NetExpr* rise,
+				       const NetExpr* fall,
+				       const NetExpr* decay,
 				       Link::strength_t drive0,
 				       Link::strength_t drive1) const
 {
@@ -1515,9 +1515,9 @@ NetNet* PEIdent::elaborate_net_bitmux_(Design*des, NetScope*scope,
 
 NetNet* PEIdent::elaborate_net(Design*des, NetScope*scope,
 			       unsigned lwidth,
-			       unsigned long rise,
-			       unsigned long fall,
-			       unsigned long decay,
+			       const NetExpr* rise,
+			       const NetExpr* fall,
+			       const NetExpr* decay,
 			       Link::strength_t drive0,
 			       Link::strength_t drive1) const
 {
@@ -1660,9 +1660,9 @@ NetNet* PEIdent::elaborate_net(Design*des, NetScope*scope,
  */
 NetNet* PEIdent::elaborate_net_ram_(Design*des, NetScope*scope,
 				    NetMemory*mem, unsigned lwidth,
-				    unsigned long rise,
-				    unsigned long fall,
-				    unsigned long decay) const
+				    const NetExpr* rise,
+				    const NetExpr* fall,
+				    const NetExpr* decay) const
 {
       assert(scope);
 
@@ -1809,9 +1809,9 @@ NetNet* PEConcat::elaborate_lnet(Design*des, NetScope*scope,
  */
 NetNet* PEFNumber::elaborate_net(Design*des, NetScope*scope,
 				 unsigned lwidth,
-				 unsigned long rise,
-				 unsigned long fall,
-				 unsigned long decay,
+				 const NetExpr* rise,
+				 const NetExpr* fall,
+				 const NetExpr* decay,
 				 Link::strength_t drive0,
 				 Link::strength_t drive1) const
 {
@@ -2143,9 +2143,9 @@ NetNet* PEIdent::elaborate_port(Design*des, NetScope*scope) const
  */
 NetNet* PENumber::elaborate_net(Design*des, NetScope*scope,
 				unsigned lwidth,
-				unsigned long rise,
-				unsigned long fall,
-				unsigned long decay,
+				const NetExpr* rise,
+				const NetExpr* fall,
+				const NetExpr* decay,
 				Link::strength_t drive0,
 				Link::strength_t drive1) const
 {
@@ -2259,9 +2259,9 @@ NetNet* PENumber::elaborate_net(Design*des, NetScope*scope,
  */
 NetNet* PEString::elaborate_net(Design*des, NetScope*scope,
 				unsigned lwidth,
-				unsigned long rise,
-				unsigned long fall,
-				unsigned long decay,
+				const NetExpr* rise,
+				const NetExpr* fall,
+				const NetExpr* decay,
 				Link::strength_t drive0,
 				Link::strength_t drive1) const
 {
@@ -2316,9 +2316,9 @@ NetNet* PEString::elaborate_net(Design*des, NetScope*scope,
  */
 NetNet* PETernary::elaborate_net(Design*des, NetScope*scope,
 				 unsigned width,
-				 unsigned long rise,
-				 unsigned long fall,
-				 unsigned long decay,
+				 const NetExpr* rise,
+				 const NetExpr* fall,
+				 const NetExpr* decay,
 				 Link::strength_t drive0,
 				 Link::strength_t drive1) const
 {
@@ -2458,9 +2458,9 @@ NetNet* PETernary::elaborate_net(Design*des, NetScope*scope,
 
 NetNet* PEUnary::elaborate_net(Design*des, NetScope*scope,
 			       unsigned width,
-			       unsigned long rise,
-			       unsigned long fall,
-			       unsigned long decay,
+			       const NetExpr* rise,
+			       const NetExpr* fall,
+			       const NetExpr* decay,
 			       Link::strength_t drive0,
 			       Link::strength_t drive1) const
 {
@@ -2645,6 +2645,9 @@ NetNet* PEUnary::elaborate_net(Design*des, NetScope*scope,
 
 /*
  * $Log: elab_net.cc,v $
+ * Revision 1.177  2006/01/02 05:33:19  steve
+ *  Node delays can be more general expressions in structural contexts.
+ *
  * Revision 1.176  2005/10/11 16:15:52  steve
  *  Logical or/and return VT_LOGIC type.
  *
diff --git a/elaborate.cc b/elaborate.cc
index 7a2e2f10c..b979a2f46 100644
--- a/elaborate.cc
+++ b/elaborate.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: elaborate.cc,v 1.332 2005/11/26 00:35:42 steve Exp $"
+#ident "$Id: elaborate.cc,v 1.333 2006/01/02 05:33:19 steve Exp $"
 #endif
 
 # include "config.h"
@@ -75,7 +75,7 @@ void PGAssign::elaborate(Design*des, NetScope*scope) const
 {
       assert(scope);
 
-      unsigned long rise_time, fall_time, decay_time;
+      NetExpr* rise_time, *fall_time, *decay_time;
       eval_delays(des, scope, rise_time, fall_time, decay_time);
 
       Link::strength_t drive0 = drive_type(strength0());
@@ -204,10 +204,20 @@ void PGAssign::elaborate(Design*des, NetScope*scope) const
 		  if (debug_elaborate) {
 			cerr << get_line() << ": debug: PGAssign: "
 			     << "Connect lval to " << id->path()
-			     << " through bufz. delay=("
-			     << rise_time << ":"
-			     << fall_time << ":"
-			     << decay_time << ")" << endl;
+			     << " through bufz. delay=(";
+			if (rise_time)
+			      cerr << *rise_time << ":";
+			else
+			      cerr << "<none>:";
+			if (fall_time)
+			      cerr << *fall_time << ":";
+			else
+			      cerr << "<none>:";
+			if (decay_time)
+			      cerr << *decay_time;
+			else
+			      cerr << "<none>";
+			cerr << ")" << endl;
 		  }
 
 		  NetBUFZ*dev = new NetBUFZ(scope, scope->local_symbol(),
@@ -332,7 +342,7 @@ void PGBuiltin::elaborate(Design*des, NetScope*scope) const
 	/* Detect the special case that the l-value width exactly
 	   matches the gate count. In this case, we will make a single
 	   gate that has the desired vector width. */
-      if (lval_sig->vector_width() == (long)count) {
+      if (lval_sig->vector_width() == count) {
 	    instance_width = count;
 	    count = 1;
 
@@ -359,7 +369,7 @@ void PGBuiltin::elaborate(Design*des, NetScope*scope) const
 	   of the rise and fall times. Finally, if all three
 	   values are given, they are taken as specified. */
 
-      unsigned long rise_time, fall_time, decay_time;
+      NetExpr* rise_time, *fall_time, *decay_time;
       eval_delays(des, scope, rise_time, fall_time, decay_time);
 
       struct attrib_list_t*attrib_list = 0;
@@ -522,7 +532,7 @@ void PGBuiltin::elaborate(Design*des, NetScope*scope) const
 		  for (unsigned gdx = 0 ;  gdx < count ;  gdx += 1)
 			connect(cur[gdx]->pin(idx), sig->pin(0));
 
-	    } else if (sig->vector_width() == (long)count) {
+	    } else if (sig->vector_width() == count) {
 
 		    /* Handle the general case that each bit of the
 		       value is connected to a different instance. In
@@ -1027,6 +1037,7 @@ void PGModule::elaborate_mod_(Design*des, Module*rmod, NetScope*scope) const
 
 void PGModule::elaborate_udp_(Design*des, PUdp*udp, NetScope*scope) const
 {
+      NetExpr*rise_expr =0, *fall_expr =0, *decay_expr =0;
 
       perm_string my_name = get_name();
       if (my_name == 0)
@@ -1035,19 +1046,49 @@ void PGModule::elaborate_udp_(Design*des, PUdp*udp, NetScope*scope) const
 	/* When the parser notices delay expressions in front of a
 	   module or primitive, it interprets them as parameter
 	   overrides. Correct that misconception here. */
-      unsigned long rise_time = 0, fall_time = 0, decay_time = 0;
       if (overrides_) {
 	    PDelays tmp_del;
 	    tmp_del.set_delays(overrides_, false);
-	    tmp_del.eval_delays(des, scope, rise_time, fall_time, decay_time);
+	    tmp_del.eval_delays(des, scope, rise_expr, fall_expr, decay_expr);
+
+	    if (dynamic_cast<NetEConst*> (rise_expr)) {
+
+	    } else {
+		  cerr << get_line() << ": error: Delay expressions must be "
+		       << "constant for primitives." << endl;
+		  cerr << get_line() << ":      : Cannot calculate "
+		       << *rise_expr << endl;
+		  des->errors += 1;
+	    }
+
+	    if (dynamic_cast<NetEConst*> (fall_expr)) {
+
+	    } else {
+		  cerr << get_line() << ": error: Delay expressions must be "
+		       << "constant for primitives." << endl;
+		  cerr << get_line() << ":      : Cannot calculate "
+		       << *rise_expr << endl;
+		  des->errors += 1;
+	    }
+
+	    if (dynamic_cast<NetEConst*> (decay_expr)) {
+
+	    } else {
+		  cerr << get_line() << ": error: Delay expressions must be "
+		       << "constant for primitives." << endl;
+		  cerr << get_line() << ":      : Cannot calculate "
+		       << *rise_expr << endl;
+		  des->errors += 1;
+	    }
+
       }
 
 
       assert(udp);
       NetUDP*net = new NetUDP(scope, my_name, udp->ports.count(), udp);
-      net->rise_time(rise_time);
-      net->fall_time(fall_time);
-      net->decay_time(decay_time);
+      net->rise_time(rise_expr);
+      net->fall_time(fall_expr);
+      net->decay_time(decay_expr);
 
       struct attrib_list_t*attrib_list = 0;
       unsigned attrib_list_n = 0;
@@ -3028,6 +3069,9 @@ Design* elaborate(list<perm_string>roots)
 
 /*
  * $Log: elaborate.cc,v $
+ * Revision 1.333  2006/01/02 05:33:19  steve
+ *  Node delays can be more general expressions in structural contexts.
+ *
  * Revision 1.332  2005/11/26 00:35:42  steve
  *  More precise about r-value width of constants.
  *
diff --git a/ivl_target.h b/ivl_target.h
index 37e4edaa3..a865abafd 100644
--- a/ivl_target.h
+++ b/ivl_target.h
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: ivl_target.h,v 1.163 2005/12/22 15:44:29 steve Exp $"
+#ident "$Id: ivl_target.h,v 1.164 2006/01/02 05:33:19 steve Exp $"
 #endif
 
 #ifdef __cplusplus
@@ -702,6 +702,22 @@ extern ivl_memory_t ivl_expr_memory(ivl_expr_t net);
  * drive strengths for the output pin-0, and match the drive values
  * stored in the ivl_nexus_ptr_t object for the pin.
  *
+ * Logic devices have a logic propagation delay. The delay can be any
+ * expression, although the most common expression is an IVL_EX_NUMBER
+ * for a number value. The expression already includes scaling for the
+ * containing module, so the delay value is always taken to be in
+ * simulation clock ticks.
+ *
+ * If the delay is present, then ivl_logic_delay returns a non-nil
+ * object. If any of the three delays is present, then all three are
+ * present, even if they are all the same. The compiler will translate
+ * shorthands into a complete set of delay expressions.
+ *
+ * The ivl_logic_delay expression will always be an IVL_EX_NUMBER, an
+ * IVL_EX_ULONG, or an IVL_EX_SIGNAL. These expressions can easily be
+ * used in structural contexts. The compiler will take care of
+ * elaborating more complex expressions to nets.
+ *
  * - IVL_LO_PULLUP/IVL_LO_PULLDOWN
  * These devices are grouped as logic devices with zero inputs because
  * the outputs have the same characteristics as other logic
@@ -725,7 +741,7 @@ extern ivl_logic_t ivl_logic_type(ivl_net_logic_t net);
 extern ivl_nexus_t ivl_logic_pin(ivl_net_logic_t net, unsigned pin);
 extern unsigned    ivl_logic_pins(ivl_net_logic_t net);
 extern ivl_udp_t   ivl_logic_udp(ivl_net_logic_t net);
-extern unsigned    ivl_logic_delay(ivl_net_logic_t net, unsigned transition);
+extern ivl_expr_t  ivl_logic_delay(ivl_net_logic_t net, unsigned transition);
 extern ivl_drive_t ivl_logic_drive0(ivl_net_logic_t net);
 extern ivl_drive_t ivl_logic_drive1(ivl_net_logic_t net);
 extern unsigned    ivl_logic_width(ivl_net_logic_t net);
@@ -1687,6 +1703,9 @@ _END_DECL
 
 /*
  * $Log: ivl_target.h,v $
+ * Revision 1.164  2006/01/02 05:33:19  steve
+ *  Node delays can be more general expressions in structural contexts.
+ *
  * Revision 1.163  2005/12/22 15:44:29  steve
  *  Document binary expression use.
  *
diff --git a/netlist.h b/netlist.h
index f0cd5119b..1bbb3b83a 100644
--- a/netlist.h
+++ b/netlist.h
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: netlist.h,v 1.353 2005/11/27 05:56:20 steve Exp $"
+#ident "$Id: netlist.h,v 1.354 2006/01/02 05:33:19 steve Exp $"
 #endif
 
 /*
@@ -105,13 +105,13 @@ class NetObj  : public Attrib, public virtual LineInfo {
 
       unsigned pin_count() const { return npins_; }
 
-      unsigned rise_time() const { return delay1_; }
-      unsigned fall_time() const { return delay2_; }
-      unsigned decay_time() const { return delay3_; }
+      const NetExpr* rise_time() const { return delay1_; }
+      const NetExpr* fall_time() const { return delay2_; }
+      const NetExpr* decay_time() const { return delay3_; }
 
-      void rise_time(unsigned d) { delay1_ = d; }
-      void fall_time(unsigned d) { delay2_ = d; }
-      void decay_time(unsigned d) { delay3_ = d; }
+      void rise_time(const NetExpr* d) { delay1_ = d; }
+      void fall_time(const NetExpr* d) { delay2_ = d; }
+      void decay_time(const NetExpr* d) { delay3_ = d; }
 
       Link&pin(unsigned idx);
       const Link&pin(unsigned idx) const;
@@ -124,9 +124,9 @@ class NetObj  : public Attrib, public virtual LineInfo {
       perm_string name_;
       Link*pins_;
       const unsigned npins_;
-      unsigned delay1_;
-      unsigned delay2_;
-      unsigned delay3_;
+      const NetExpr* delay1_;
+      const NetExpr* delay2_;
+      const NetExpr* delay3_;
 };
 
 class Link {
@@ -3451,6 +3451,9 @@ extern ostream& operator << (ostream&, NetNet::Type);
 
 /*
  * $Log: netlist.h,v $
+ * Revision 1.354  2006/01/02 05:33:19  steve
+ *  Node delays can be more general expressions in structural contexts.
+ *
  * Revision 1.353  2005/11/27 05:56:20  steve
  *  Handle bit select of parameter with ranges.
  *
diff --git a/t-dll-api.cc b/t-dll-api.cc
index 581939c71..f3db3bb1c 100644
--- a/t-dll-api.cc
+++ b/t-dll-api.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: t-dll-api.cc,v 1.131 2005/08/06 17:58:16 steve Exp $"
+#ident "$Id: t-dll-api.cc,v 1.132 2006/01/02 05:33:19 steve Exp $"
 #endif
 
 # include "config.h"
@@ -608,7 +608,7 @@ extern "C" ivl_udp_t ivl_logic_udp(ivl_net_logic_t net)
       return net->udp;
 }
 
-extern "C" unsigned  ivl_logic_delay(ivl_net_logic_t net, unsigned transition)
+extern "C" ivl_expr_t ivl_logic_delay(ivl_net_logic_t net, unsigned transition)
 {
       assert(transition < 3);
       return net->delay[transition];
@@ -2033,6 +2033,9 @@ extern "C" ivl_statement_t ivl_stmt_sub_stmt(ivl_statement_t net)
 
 /*
  * $Log: t-dll-api.cc,v $
+ * Revision 1.132  2006/01/02 05:33:19  steve
+ *  Node delays can be more general expressions in structural contexts.
+ *
  * Revision 1.131  2005/08/06 17:58:16  steve
  *  Implement bi-directional part selects.
  *
diff --git a/t-dll.cc b/t-dll.cc
index a3580724f..34fa463d8 100644
--- a/t-dll.cc
+++ b/t-dll.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: t-dll.cc,v 1.154 2005/08/06 17:58:16 steve Exp $"
+#ident "$Id: t-dll.cc,v 1.155 2006/01/02 05:33:19 steve Exp $"
 #endif
 
 # include "config.h"
@@ -602,6 +602,44 @@ void dll_target::logic_attributes(struct ivl_net_logic_s *obj,
       obj->attr  = fill_in_attributes(net);
 }
 
+void dll_target::make_logic_delays_(struct ivl_net_logic_s*obj,
+				    const NetObj*net)
+{
+      obj->delay[0] = 0;
+      obj->delay[1] = 0;
+      obj->delay[2] = 0;
+
+	/* Translate delay expressions to ivl_target form. Try to
+	   preserve pointer equality, not as a rule but to save on
+	   expression trees. */
+      if (net->rise_time()) {
+	    expr_ = 0;
+	    net->rise_time()->expr_scan(this);
+	    obj->delay[0] = expr_;
+	    expr_ = 0;
+      }
+      if (net->fall_time()) {
+	    if (net->fall_time() == net->rise_time()) {
+		  obj->delay[1] = obj->delay[0];
+	    } else {
+		  expr_ = 0;
+		  net->fall_time()->expr_scan(this);
+		  obj->delay[1] = expr_;
+		  expr_ = 0;
+	    }
+      }
+      if (net->decay_time()) {
+	    if (net->decay_time() == net->rise_time()) {
+		  obj->delay[2] = obj->delay[0];
+	    } else {
+		  expr_ = 0;
+		  net->decay_time()->expr_scan(this);
+		  obj->delay[2] = expr_;
+		  expr_ = 0;
+	    }
+      }
+}
+
 /*
  * Add a bufz object to the scope that contains it.
  *
@@ -682,10 +720,8 @@ bool dll_target::bufz(const NetBUFZ*net)
       obj->name_ = net->name();
       logic_attributes(obj, net);
 
-      obj->delay[0] = net->rise_time();
-      obj->delay[1] = net->fall_time();
-      obj->delay[2] = net->decay_time();
-
+      make_logic_delays_(obj, net);
+	    
       scope_add_logic(scope, obj);
 
       return true;
@@ -859,9 +895,7 @@ void dll_target::logic(const NetLogic*net)
 
       logic_attributes(obj, net);
 
-      obj->delay[0] = net->rise_time();
-      obj->delay[1] = net->fall_time();
-      obj->delay[2] = net->decay_time();
+      make_logic_delays_(obj, net);
 
       scope_add_logic(scope, obj);
 }
@@ -1104,9 +1138,7 @@ void dll_target::udp(const NetUDP*net)
       obj->scope_= scope;
       obj->name_ = net->name();
 
-      obj->delay[0] = net->rise_time();
-      obj->delay[1] = net->fall_time();
-      obj->delay[2] = net->decay_time();
+      make_logic_delays_(obj, net);
 
       obj->nattr = 0;
       obj->attr = 0;
@@ -2131,6 +2163,9 @@ extern const struct target tgt_dll = { "dll", &dll_target_obj };
 
 /*
  * $Log: t-dll.cc,v $
+ * Revision 1.155  2006/01/02 05:33:19  steve
+ *  Node delays can be more general expressions in structural contexts.
+ *
  * Revision 1.154  2005/08/06 17:58:16  steve
  *  Implement bi-directional part selects.
  *
diff --git a/t-dll.h b/t-dll.h
index c2bd3617d..e985c90fe 100644
--- a/t-dll.h
+++ b/t-dll.h
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: t-dll.h,v 1.128 2005/07/11 16:56:51 steve Exp $"
+#ident "$Id: t-dll.h,v 1.129 2006/01/02 05:33:19 steve Exp $"
 #endif
 
 # include  "target.h"
@@ -166,6 +166,7 @@ struct dll_target  : public target_t, public expr_scan_t {
       void sub_off_from_expr_(long);
       void mul_expr_by_const_(long);
 
+      void make_logic_delays_(struct ivl_net_logic_s*obj, const NetObj*net);
       void make_scope_parameters(ivl_scope_t scope, const NetScope*net);
 
       static ivl_expr_t expr_from_value_(const verinum&that);
@@ -424,7 +425,7 @@ struct ivl_net_logic_s {
       struct ivl_attribute_s*attr;
       unsigned nattr;
 
-      unsigned delay[3];
+      ivl_expr_t delay[3];
 };
 
 
@@ -670,6 +671,9 @@ struct ivl_statement_s {
 
 /*
  * $Log: t-dll.h,v $
+ * Revision 1.129  2006/01/02 05:33:19  steve
+ *  Node delays can be more general expressions in structural contexts.
+ *
  * Revision 1.128  2005/07/11 16:56:51  steve
  *  Remove NetVariable and ivl_variable_t structures.
  *
diff --git a/tgt-stub/stub.c b/tgt-stub/stub.c
index 2a0636c3a..4c9e520cf 100644
--- a/tgt-stub/stub.c
+++ b/tgt-stub/stub.c
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: stub.c,v 1.135 2005/12/22 15:38:33 steve Exp $"
+#ident "$Id: stub.c,v 1.136 2006/01/02 05:33:20 steve Exp $"
 #endif
 
 # include "config.h"
@@ -1282,6 +1282,23 @@ static void show_signal(ivl_signal_t net)
 
 }
 
+static void test_expr_is_delay(ivl_expr_t exp)
+{
+      switch (ivl_expr_type(exp)) {
+	  case IVL_EX_ULONG:
+	    return;
+	  case IVL_EX_NUMBER:
+	    return;
+	  case IVL_EX_SIGNAL:
+	    return;
+	  default:
+	    break;
+      }
+
+      fprintf(out, "      ERROR: Expression is not a suitable delay\n");
+      stub_errors += 1;
+}
+
 /*
  * All logic gates have inputs and outputs that match exactly in
  * width. For example, and AND gate with 4 bit inputs generates a 4
@@ -1308,10 +1325,10 @@ static void show_logic(ivl_net_logic_t net)
 	    fprintf(out, "  bufif1 %s", name);
 	    break;
 	  case IVL_LO_BUFZ:
-	    fprintf(out, "  bufz #(%u) %s", ivl_logic_delay(net, 0), name);
+	    fprintf(out, "  bufz %s", name);
 	    break;
 	  case IVL_LO_NOT:
-	    fprintf(out, "  not #(%u) %s", ivl_logic_delay(net, 0), name);
+	    fprintf(out, "  not %s", name);
 	    break;
 	  case IVL_LO_OR:
 	    fprintf(out, "  or %s", name);
@@ -1336,9 +1353,21 @@ static void show_logic(ivl_net_logic_t net)
 	    break;
       }
 
-      fprintf(out, " <width=%u, delay=%u/%u/%u>\n",
-	      ivl_logic_width(net), ivl_logic_delay(net,0),
-	      ivl_logic_delay(net,1), ivl_logic_delay(net,2));
+      fprintf(out, " <width=%u>\n", ivl_logic_width(net));
+
+      fprintf(out, "    <Delays...>\n");
+      if (ivl_logic_delay(net,0)) {
+	    test_expr_is_delay(ivl_logic_delay(net,0));
+	    show_expression(ivl_logic_delay(net,0), 6);
+      }
+      if (ivl_logic_delay(net,1)) {
+	    test_expr_is_delay(ivl_logic_delay(net,1));
+	    show_expression(ivl_logic_delay(net,1), 6);
+      }
+      if (ivl_logic_delay(net,2)) {
+	    test_expr_is_delay(ivl_logic_delay(net,2));
+	    show_expression(ivl_logic_delay(net,2), 6);
+      }
 
       npins = ivl_logic_pins(net);
 
@@ -1551,6 +1580,9 @@ int target_design(ivl_design_t des)
 
 /*
  * $Log: stub.c,v $
+ * Revision 1.136  2006/01/02 05:33:20  steve
+ *  Node delays can be more general expressions in structural contexts.
+ *
  * Revision 1.135  2005/12/22 15:38:33  steve
  *  More detailed check of binary expressions.
  *
diff --git a/tgt-vvp/eval_expr.c b/tgt-vvp/eval_expr.c
index 555339d74..e02628bc2 100644
--- a/tgt-vvp/eval_expr.c
+++ b/tgt-vvp/eval_expr.c
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: eval_expr.c,v 1.128 2005/12/22 15:42:22 steve Exp $"
+#ident "$Id: eval_expr.c,v 1.129 2006/01/02 05:33:20 steve Exp $"
 #endif
 
 # include  "vvp_priv.h"
@@ -57,7 +57,9 @@ int number_is_immediate(ivl_expr_t ex, unsigned lim_wid)
       const char*bits;
       unsigned idx;
 
-      assert(ivl_expr_type(ex) == IVL_EX_NUMBER);
+      if (ivl_expr_type(ex) != IVL_EX_NUMBER
+	  && ivl_expr_type(ex) != IVL_EX_ULONG)
+	    return 0;
 
       bits = ivl_expr_bits(ex);
       for (idx = lim_wid ;  idx < ivl_expr_width(ex) ;  idx += 1)
@@ -2175,6 +2177,9 @@ struct vector_info draw_eval_expr(ivl_expr_t exp, int stuff_ok_flag)
 
 /*
  * $Log: eval_expr.c,v $
+ * Revision 1.129  2006/01/02 05:33:20  steve
+ *  Node delays can be more general expressions in structural contexts.
+ *
  * Revision 1.128  2005/12/22 15:42:22  steve
  *  Pad part selects
  *
diff --git a/tgt-vvp/vvp_scope.c b/tgt-vvp/vvp_scope.c
index 04eaf5a2d..a0a8bd9ab 100644
--- a/tgt-vvp/vvp_scope.c
+++ b/tgt-vvp/vvp_scope.c
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: vvp_scope.c,v 1.138 2005/11/25 17:55:26 steve Exp $"
+#ident "$Id: vvp_scope.c,v 1.139 2006/01/02 05:33:20 steve Exp $"
 #endif
 
 # include  "vvp_priv.h"
@@ -945,17 +945,25 @@ static void draw_net_in_scope(ivl_signal_t sig)
 
 static void draw_delay(ivl_net_logic_t lptr)
 {
-      unsigned d0 = ivl_logic_delay(lptr, 0);
-      unsigned d1 = ivl_logic_delay(lptr, 1);
-      unsigned d2 = ivl_logic_delay(lptr, 2);
+      ivl_expr_t d0 = ivl_logic_delay(lptr, 0);
+      ivl_expr_t d1 = ivl_logic_delay(lptr, 1);
+      ivl_expr_t d2 = ivl_logic_delay(lptr, 2);
 
       if (d0 == 0 && d1 == 0 && d2 == 0)
 	    return;
 
+	/* FIXME: Assume that the expression is a constant */
+      assert(number_is_immediate(d0, 64));
+      assert(number_is_immediate(d1, 64));
+      assert(number_is_immediate(d2, 64));
+
       if (d0 == d1 && d1 == d2)
-	    fprintf(vvp_out, " (%d)", d0);
+	    fprintf(vvp_out, " (%lu)", get_number_immediate(d0));
       else
-	    fprintf(vvp_out, " (%d,%d,%d)", d0, d1, d2);
+	    fprintf(vvp_out, " (%lu,%lu,%lu)",
+		    get_number_immediate(d0),
+		    get_number_immediate(d1),
+		    get_number_immediate(d2));
 }
 
 static void draw_udp_def(ivl_udp_t udp)
@@ -1045,9 +1053,11 @@ static void draw_logic_in_scope(ivl_net_logic_t lptr)
 {
       unsigned pdx;
       const char*ltype = "?";
-      const char*lcasc = 0x0;
+      const char*lcasc = 0;
       char identity_val = '0';
 
+      int need_delay_flag = ivl_logic_delay(lptr,0)? 1 : 0;
+
       unsigned vector_width = width_of_nexus(ivl_logic_pin(lptr, 0));
 
       ivl_drive_t str0, str1;
@@ -1207,10 +1217,9 @@ static void draw_logic_in_scope(ivl_net_logic_t lptr)
 			fprintf(vvp_out, "L_%p/%d/%d .functor %s %u",
 				lptr, level, inst, lcasc, vector_width);
 		  else {
-			fprintf(vvp_out, "L_%p .functor %s %u",
-				lptr, ltype, vector_width);
-
-			draw_delay(lptr);
+			fprintf(vvp_out, "L_%p%s .functor %s %u",
+				lptr, need_delay_flag? "/d" : "",
+				ltype, vector_width);
 
 			if (str0 != IVL_DR_STRONG || str1 != IVL_DR_STRONG)
 			      fprintf(vvp_out, " [%u %u]", str0, str1);
@@ -1244,6 +1253,40 @@ static void draw_logic_in_scope(ivl_net_logic_t lptr)
 	/* Free the array of char*. The strings themselves are
 	   persistent, held by the ivl_nexus_t objects. */
       free(input_strings);
+
+	/* If there are delays, then draw the delay functor to carry
+	   that delay. This is the final output. */
+      if (need_delay_flag) {
+	    ivl_expr_t rise_exp  = ivl_logic_delay(lptr,0);
+	    ivl_expr_t fall_exp  = ivl_logic_delay(lptr,1);
+	    ivl_expr_t decay_exp = ivl_logic_delay(lptr,2);
+
+	    if (number_is_immediate(rise_exp,64)
+		&& number_is_immediate(fall_exp,64)
+		&& number_is_immediate(decay_exp,64)) {
+
+		  fprintf(vvp_out, "L_%p .delay (%lu,%lu,%lu) L_%p/d;\n",
+			  lptr, get_number_immediate(rise_exp),
+			  get_number_immediate(rise_exp),
+			  get_number_immediate(rise_exp), lptr);
+	    } else {
+		  ivl_signal_t sig;
+		  assert(ivl_expr_type(rise_exp) == IVL_EX_SIGNAL);
+		  assert(ivl_expr_type(fall_exp) == IVL_EX_SIGNAL);
+		  assert(ivl_expr_type(decay_exp) == IVL_EX_SIGNAL);
+
+		  fprintf(vvp_out, "L_%p .delay  L_%p/d", lptr, lptr);
+
+		  sig = ivl_expr_signal(rise_exp);
+		  fprintf(vvp_out, ", V_%p", sig);
+
+		  sig = ivl_expr_signal(fall_exp);
+		  fprintf(vvp_out, ", V_%p", sig);
+
+		  sig = ivl_expr_signal(decay_exp);
+		  fprintf(vvp_out, ", V_%p;\n", sig);
+	    }
+      }
 }
 
 static void draw_event_in_scope(ivl_event_t obj)
@@ -2110,6 +2153,9 @@ int draw_scope(ivl_scope_t net, ivl_scope_t parent)
 
 /*
  * $Log: vvp_scope.c,v $
+ * Revision 1.139  2006/01/02 05:33:20  steve
+ *  Node delays can be more general expressions in structural contexts.
+ *
  * Revision 1.138  2005/11/25 17:55:26  steve
  *  Put vec8 and vec4 nets into seperate net classes.
  *