Antenna check: tests added, 'catchall' diode protection

src/db/db/dbLayoutToNetlist.cc

@@ -896,25 +896,36 @@ db::Region LayoutToNetlist::antenna_check (const db::Region &gate, const db::Reg
       double ametal = rmetal.area () * dbu * dbu;
 
       double r = ratio;
+      bool skip = false;
 
-      for (std::vector<std::pair<db::Region *, double> >::const_iterator d = diodes.begin (); d != diodes.end (); ++d) {
+      for (std::vector<std::pair<db::Region *, double> >::const_iterator d = diodes.begin (); d != diodes.end () && ! skip; ++d) {
 
         db::Region rdiode;
         deliver_shapes_of_net_recursive (0, m_net_clusters, *cid, *c, layer_of (*d->first), db::ICplxTrans (), rdiode);
 
-        r += rdiode.area () * dbu * dbu / d->second;
-
-      }
-
-      if (tl::verbosity () >= 0 /*50*/) {
-        tl::info << "cell [" << ly.cell_name (*cid) << "]: agate=" << tl::to_string (agate) << ", ametal=" << tl::to_string (ametal) << ", r=" << tl::sprintf ("%.12g", r);
-      }
-
-      if (agate > dbu * dbu && ametal / agate > r + db::epsilon) {
-        db::Shapes &shapes = ly.cell (*cid).shapes (dl.layer ());
-        for (db::Region::const_iterator r = rmetal.begin_merged (); ! r.at_end (); ++r) {
-          shapes.insert (*r);
+        if (fabs (d->second) < db::epsilon) {
+          if (rdiode.area () > 0) {
+            skip = true;
+          }
+        } else {
+          r += rdiode.area () * dbu * dbu * d->second;
         }
+
+      }
+
+      if (! skip) {
+
+        if (tl::verbosity () >= 50) {
+          tl::info << "cell [" << ly.cell_name (*cid) << "]: agate=" << tl::to_string (agate) << ", ametal=" << tl::to_string (ametal) << ", r=" << tl::sprintf ("%.12g", r);
+        }
+
+        if (agate > dbu * dbu && ametal / agate > r + db::epsilon) {
+          db::Shapes &shapes = ly.cell (*cid).shapes (dl.layer ());
+          for (db::Region::const_iterator r = rmetal.begin_merged (); ! r.at_end (); ++r) {
+            shapes.insert (*r);
+          }
+        }
+
       }
 
     }

src/db/db/dbLayoutToNetlist.h

@@ -517,6 +517,11 @@ public:
    *  A(diode) / Ared[um^2] to the ratio. A(diode) is the area of the
    *  diode layer per cluster. Both the diode layer and the Ared value
    *  are specified as pairs in "diodes".
+   *
+   *  A special case is Ared = 0: in this case, the presence of any shapes
+   *  on the diode layer will entirely disable the check on a cluster,
+   *  regardless of the diode's area.
+   *  In other words: any diode will make the net safe against antenna discharge.
    */
   db::Region antenna_check (const db::Region &gate, const db::Region &metal, double ratio, const std::vector<std::pair<db::Region *, double> > &diodes = std::vector<std::pair<db::Region *, double> > ());
 

src/db/unit_tests/dbLayoutToNetlistTests.cc

@@ -2263,6 +2263,7 @@ TEST(10_Antenna)
   unsigned int metal1     = define_layer (ly, lmap, 9);
   unsigned int via1       = define_layer (ly, lmap, 11);
   unsigned int metal2     = define_layer (ly, lmap, 12);
+  unsigned int diode      = define_layer (ly, lmap, 1);
 
   {
     db::LoadLayoutOptions options;
@@ -2283,6 +2284,7 @@ TEST(10_Antenna)
 
   db::DeepShapeStore dss;
 
+  std::auto_ptr<db::Region> rdiode (new db::Region (db::RecursiveShapeIterator (ly, tc, diode), dss));
   std::auto_ptr<db::Region> rpoly (new db::Region (db::RecursiveShapeIterator (ly, tc, poly), dss));
   std::auto_ptr<db::Region> rcont (new db::Region (db::RecursiveShapeIterator (ly, tc, cont), dss));
   std::auto_ptr<db::Region> rmetal1 (new db::Region (db::RecursiveShapeIterator (ly, tc, metal1), dss));
@@ -2293,6 +2295,7 @@ TEST(10_Antenna)
   ly2.dbu (ly.dbu ());
   db::Cell &top2 = ly2.cell (ly2.add_cell ("TOPTOP"));
 
+  rdiode->insert_into (&ly2, top2.cell_index (), ly2.insert_layer (db::LayerProperties (1, 0)));
   rpoly->insert_into (&ly2, top2.cell_index (), ly2.insert_layer (db::LayerProperties (6, 0)));
   rcont->insert_into (&ly2, top2.cell_index (), ly2.insert_layer (db::LayerProperties (8, 0)));
   rmetal1->insert_into (&ly2, top2.cell_index (), ly2.insert_layer (db::LayerProperties (9, 0)));
@@ -2367,6 +2370,72 @@ TEST(10_Antenna)
     a2_17.insert_into (&ly2, top2.cell_index (), ly2.insert_layer (db::LayerProperties (202, 0)));
   }
 
+  {
+    db::LayoutToNetlist l2n (&dss);
+
+    l2n.register_layer (*rdiode, "diode");
+    l2n.register_layer (*rpoly, "poly");
+    l2n.register_layer (*rcont, "cont");
+    l2n.register_layer (*rmetal1, "metal1");
+
+    //  Intra-layer
+    l2n.connect (*rdiode);
+    l2n.connect (*rpoly);
+    l2n.connect (*rcont);
+    l2n.connect (*rmetal1);
+    //  Inter-layer
+    l2n.connect (*rdiode,     *rcont);
+    l2n.connect (*rpoly,      *rcont);
+    l2n.connect (*rcont,      *rmetal1);
+
+    l2n.extract_netlist ();
+
+    std::vector<std::pair<db::Region *, double> > diodes;
+    //  8.0 means: increase r by 8.0 for each um^2 of diode attached to a net
+    diodes.push_back (std::make_pair (rdiode.get (), 8.0));
+
+    db::Region a3_3 = l2n.antenna_check (*rpoly, *rmetal1, 3, diodes);
+    db::Region a3_10 = l2n.antenna_check (*rpoly, *rmetal1, 10, diodes);
+    db::Region a3_30 = l2n.antenna_check (*rpoly, *rmetal1, 30, diodes);
+
+    a3_3.insert_into (&ly2, top2.cell_index (), ly2.insert_layer (db::LayerProperties (300, 0)));
+    a3_10.insert_into (&ly2, top2.cell_index (), ly2.insert_layer (db::LayerProperties (301, 0)));
+    a3_30.insert_into (&ly2, top2.cell_index (), ly2.insert_layer (db::LayerProperties (302, 0)));
+  }
+
+  {
+    db::LayoutToNetlist l2n (&dss);
+
+    l2n.register_layer (*rdiode, "diode");
+    l2n.register_layer (*rpoly, "poly");
+    l2n.register_layer (*rcont, "cont");
+    l2n.register_layer (*rmetal1, "metal1");
+
+    //  Intra-layer
+    l2n.connect (*rdiode);
+    l2n.connect (*rpoly);
+    l2n.connect (*rcont);
+    l2n.connect (*rmetal1);
+    //  Inter-layer
+    l2n.connect (*rdiode,     *rcont);
+    l2n.connect (*rpoly,      *rcont);
+    l2n.connect (*rcont,      *rmetal1);
+
+    l2n.extract_netlist ();
+
+    std::vector<std::pair<db::Region *, double> > diodes;
+    //  0.0 means: skip all nets where there is a rdiode attached
+    diodes.push_back (std::make_pair (rdiode.get (), 0.0));
+
+    db::Region a4_3 = l2n.antenna_check (*rpoly, *rmetal1, 3, diodes);
+    db::Region a4_10 = l2n.antenna_check (*rpoly, *rmetal1, 10, diodes);
+    db::Region a4_30 = l2n.antenna_check (*rpoly, *rmetal1, 30, diodes);
+
+    a4_3.insert_into (&ly2, top2.cell_index (), ly2.insert_layer (db::LayerProperties (400, 0)));
+    a4_10.insert_into (&ly2, top2.cell_index (), ly2.insert_layer (db::LayerProperties (401, 0)));
+    a4_30.insert_into (&ly2, top2.cell_index (), ly2.insert_layer (db::LayerProperties (402, 0)));
+  }
+
   std::string au = tl::testsrc ();
   au = tl::combine_path (au, "testdata");
   au = tl::combine_path (au, "algo");