Merge pull request #1851 from KLayout/bugfix/issue-1832

Bugfix/issue 1832

src/db/db/dbCircuit.cc

@@ -825,6 +825,41 @@ void Circuit::do_purge_nets (bool keep_pins)
   }
 }
 
+static bool can_purge_device (const db::Device &device)
+{
+  if (! device.device_class ()) {
+    return false;
+  }
+
+  const std::vector<db::DeviceTerminalDefinition> &tdefs = device.device_class ()->terminal_definitions ();
+  if (tdefs.size () <= 1) {
+    return false;
+  }
+
+  const db::Net *net = device.net_for_terminal (tdefs.front ().id ());
+  for (auto t = tdefs.begin () + 1; t != tdefs.end (); ++t) {
+    if (net != device.net_for_terminal (t->id ())) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+void Circuit::purge_devices ()
+{
+  std::vector<db::Device *> devices_to_be_purged;
+  for (device_iterator d = begin_devices (); d != end_devices (); ++d) {
+    if (can_purge_device (*d)) {
+      devices_to_be_purged.push_back (d.operator-> ());
+    }
+  }
+
+  for (auto d = devices_to_be_purged.begin (); d != devices_to_be_purged.end (); ++d) {
+    remove_device (*d);
+  }
+}
+
 /**
  *  @brief Sanity check for device to be removed
  */

src/db/db/dbCircuit.h

@@ -732,6 +732,14 @@ class DB_PUBLIC Circuit
    */
   void purge_nets_keep_pins ();
 
+  /**
+   *  @brief Purges invalid devices
+   *
+   *  This method will purge all invalid devices, i.e. those
+   *  whose terminals are all connected to the same net.
+   */
+  void purge_devices ();
+
   /**
    *  @brief Combine devices
    *

src/db/db/dbNetlist.cc

@@ -619,6 +619,13 @@ void Netlist::purge_nets ()
   }
 }
 
+void Netlist::purge_devices ()
+{
+  for (bottom_up_circuit_iterator c = begin_bottom_up (); c != end_bottom_up (); ++c) {
+    c->purge_devices ();
+  }
+}
+
 void Netlist::make_top_level_pins ()
 {
   size_t ntop = top_circuit_count ();
@@ -684,6 +691,8 @@ void Netlist::simplify ()
 {
   make_top_level_pins ();
   purge ();
+
+  //  combine devices are purge nets that are created in that step
   combine_devices ();
   purge_nets ();
 }

src/db/db/dbNetlist.h

@@ -508,6 +508,14 @@ class DB_PUBLIC Netlist
    */
   void purge_nets ();
 
+  /**
+   *  @brief Purges invalid devices
+   *
+   *  This method will purge all invalid devices, i.e. those
+   *  whose terminals are all connected to the same net.
+   */
+  void purge_devices ();
+
   /**
    *  @brief Creates pins for top-level circuits
    *

src/db/db/dbNetlistDeviceClasses.cc

@@ -116,7 +116,7 @@ class ResistorDeviceCombiner
   {
     double va = a->parameter_value (0);
     double vb = b->parameter_value (0);
-    a->set_parameter_value (0, va + vb < 1e-10 ? 0.0 : va * vb / (va + vb));
+    a->set_parameter_value (0, va + vb < 1e-30 ? 0.0 : va * vb / (va + vb));
 
     //  parallel width is sum of both, length is the one that gives the same value of resistance
     //    R = 1/(1/R1 + 1/R2)
@@ -204,7 +204,7 @@ class CapacitorDeviceCombiner
   {
     double va = a->parameter_value (0);
     double vb = b->parameter_value (0);
-    a->set_parameter_value (0, va + vb < 1e-10 ? 0.0 : va * vb / (va + vb));
+    a->set_parameter_value (0, va + vb < 1e-30 ? 0.0 : va * vb / (va + vb));
 
     //  TODO: does this implementation make sense?
     double aa = a->parameter_value (1);
@@ -259,7 +259,7 @@ class InductorDeviceCombiner
   {
     double va = a->parameter_value (0);
     double vb = b->parameter_value (0);
-    a->set_parameter_value (0, va + vb < 1e-10 ? 0.0 : va * vb / (va + vb));
+    a->set_parameter_value (0, va + vb < 1e-30 ? 0.0 : va * vb / (va + vb));
   }
 
   void serial (Device *a, Device *b) const

src/db/db/gsiDeclDbNetlist.cc

@@ -1809,6 +1809,12 @@ Class<db::Circuit> decl_dbCircuit (decl_dbNetlistObject, "db", "Circuit",
     "For example, serial or parallel resistors can be combined into "
     "a single resistor.\n"
   ) +
+  gsi::method ("purge_devices", &db::Circuit::purge_devices,
+    "@brief Purges invalid devices.\n"
+    "Purges devices which are considered invalid. Such devices are for example those whose terminals are all connected to a single net.\n"
+    "\n"
+    "This method has been added in version 0.29.7."
+  ) +
   gsi::method ("purge_nets", &db::Circuit::purge_nets,
     "@brief Purges floating nets.\n"
     "Floating nets are nets with no device or subcircuit attached to. Such floating "
@@ -2176,6 +2182,12 @@ Class<db::Netlist> decl_dbNetlist ("db", "Netlist",
     "Floating nets can be created as effect of reconnections of devices or pins. "
     "This method will eliminate all nets that make less than two connections."
   ) +
+  gsi::method ("purge_devices", &db::Netlist::purge_devices,
+    "@brief Purges invalid devices.\n"
+    "Purges devices which are considered invalid. Such devices are for example those whose terminals are all connected to a single net.\n"
+    "\n"
+    "This method has been added in version 0.29.7."
+  ) +
   gsi::method ("simplify", &db::Netlist::simplify,
     "@brief Convenience method that combines the simplification.\n"
     "This method is a convenience method that runs \\make_top_level_pins, \\purge, \\combine_devices and \\purge_nets."