From c571535e556999b94d0faddc890683553873f746 Mon Sep 17 00:00:00 2001
From: Matthias Koefferlein <matthias@koefferlein.de>
Date: Sat, 29 Dec 2018 23:48:31 +0100
Subject: [PATCH] WIP: standard device classes, added GSI binding plus tests.

---
 src/db/db/db.pro                             |   4 +-
 src/db/db/gsiDeclDbNetlistDeviceClasses.cc   | 232 +++++++++++++
 src/db/db/gsiDeclDbNetlistDeviceExtractor.cc |   0
 src/rba/unit_tests/rba.cc                    |   1 +
 testdata/ruby/dbNetlistDeviceClasses.rb      | 331 +++++++++++++++++++
 5 files changed, 567 insertions(+), 1 deletion(-)
 create mode 100644 src/db/db/gsiDeclDbNetlistDeviceClasses.cc
 create mode 100644 src/db/db/gsiDeclDbNetlistDeviceExtractor.cc
 create mode 100644 testdata/ruby/dbNetlistDeviceClasses.rb

diff --git a/src/db/db/db.pro b/src/db/db/db.pro
index 65b36ade9..25cbb07b3 100644
--- a/src/db/db/db.pro
+++ b/src/db/db/db.pro
@@ -147,7 +147,9 @@ SOURCES = \
     gsiDeclDbNetlist.cc \
     dbNetlistDeviceClasses.cc \
     dbNetlistDeviceExtractor.cc \
-    dbNetlistExtractor.cc
+    dbNetlistExtractor.cc \
+    gsiDeclDbNetlistDeviceClasses.cc \
+    gsiDeclDbNetlistDeviceExtractor.cc
 
 HEADERS = \
   dbArray.h \
diff --git a/src/db/db/gsiDeclDbNetlistDeviceClasses.cc b/src/db/db/gsiDeclDbNetlistDeviceClasses.cc
new file mode 100644
index 000000000..8ce4a554c
--- /dev/null
+++ b/src/db/db/gsiDeclDbNetlistDeviceClasses.cc
@@ -0,0 +1,232 @@
+
+/*
+
+  KLayout Layout Viewer
+  Copyright (C) 2006-2018 Matthias Koefferlein
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  This program 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 General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+*/
+
+#include "gsiDecl.h"
+#include "dbNetlistDeviceClasses.h"
+
+namespace gsi
+{
+
+//  TODO: move this to gsiMethods.h
+
+template <class R>
+class ConstantValueGetter
+  : public StaticMethodBase
+{
+public:
+  ConstantValueGetter (const std::string &name, const R &v, const std::string &doc)
+    : StaticMethodBase (name, doc, true), m_v (v)
+  {
+  }
+
+  void initialize ()
+  {
+    this->clear ();
+    //  Note: a constant must not return a reference to an existing object, hence "set_return_new":
+    this->template set_return_new<R> ();
+  }
+
+  virtual MethodBase *clone () const
+  {
+    return new ConstantValueGetter (*this);
+  }
+
+  virtual void call (void *, SerialArgs &, SerialArgs &ret) const
+  {
+    mark_called ();
+    ret.write<R> (m_v);
+  }
+
+private:
+  R m_v;
+};
+
+template <class R>
+Methods
+constant (const std::string &name, const R &v, const std::string &doc = std::string ())
+{
+  return Methods (new ConstantValueGetter <R> (name, v, doc));
+}
+
+
+extern Class<db::DeviceClass> decl_dbDeviceClass;
+
+Class<db::DeviceClassResistor> decl_dbDeviceClassResistor (decl_dbDeviceClass, "db", "DeviceClassResistor",
+  gsi::constant ("TERMINAL_A", db::DeviceClassResistor::terminal_id_A,
+    "@brief A constant giving the terminal ID for terminal A"
+  ) +
+  gsi::constant ("TERMINAL_B", db::DeviceClassResistor::terminal_id_B,
+    "@brief A constant giving the terminal ID for terminal B"
+  ) +
+  gsi::constant ("PARAM_R", db::DeviceClassResistor::param_id_R,
+    "@brief A constant giving the parameter ID for parameter R"
+  ),
+  "@brief A device class for a resistor.\n"
+  "This class can be used to describe resistors. Resistors are defined by their combination behavior and "
+  "the basic parameter 'R' which is the resistance in Ohm.\n"
+  "\n"
+  "A resistor has two terminals, A and B.\n"
+  "\n"
+  "This class has been introduced in version 0.26."
+);
+
+Class<db::DeviceClassCapacitor> decl_dbDeviceClassCapacitor (decl_dbDeviceClass, "db", "DeviceClassCapacitor",
+  gsi::constant ("TERMINAL_A", db::DeviceClassCapacitor::terminal_id_A,
+    "@brief A constant giving the terminal ID for terminal A"
+  ) +
+  gsi::constant ("TERMINAL_B", db::DeviceClassCapacitor::terminal_id_B,
+    "@brief A constant giving the terminal ID for terminal B"
+  ) +
+  gsi::constant ("PARAM_C", db::DeviceClassCapacitor::param_id_C,
+    "@brief A constant giving the parameter ID for parameter C"
+  ),
+  "@brief A device class for a capacitor.\n"
+  "This class can be used to describe capacitors. Capacitors are defined by their combination behavior and "
+  "the basic parameter 'C' which is the capacitance in Farad.\n"
+  "\n"
+  "A capacitor has two terminals, A and B.\n"
+  "\n"
+  "This class has been introduced in version 0.26."
+);
+
+Class<db::DeviceClassInductor> decl_dbDeviceClassInductor (decl_dbDeviceClass, "db", "DeviceClassInductor",
+  gsi::constant ("TERMINAL_A", db::DeviceClassInductor::terminal_id_A,
+    "@brief A constant giving the terminal ID for terminal A"
+  ) +
+  gsi::constant ("TERMINAL_B", db::DeviceClassInductor::terminal_id_B,
+    "@brief A constant giving the terminal ID for terminal B"
+  ) +
+  gsi::constant ("PARAM_L", db::DeviceClassInductor::param_id_L,
+    "@brief A constant giving the parameter ID for parameter L"
+  ),
+  "@brief A device class for an inductor.\n"
+  "This class can be used to describe inductors. Inductors are defined by their combination behavior and "
+  "the basic parameter 'L' which is the inductance in Henry.\n"
+  "\n"
+  "An inductor has two terminals, A and B.\n"
+  "\n"
+  "This class has been introduced in version 0.26."
+);
+
+Class<db::DeviceClassDiode> decl_dbDeviceClassDiode (decl_dbDeviceClass, "db", "DeviceClassDiode",
+  gsi::constant ("TERMINAL_A", db::DeviceClassDiode::terminal_id_A,
+    "@brief A constant giving the terminal ID for terminal A"
+  ) +
+  gsi::constant ("TERMINAL_C", db::DeviceClassDiode::terminal_id_C,
+    "@brief A constant giving the terminal ID for terminal C"
+  ) +
+  gsi::constant ("PARAM_A", db::DeviceClassDiode::param_id_A,
+    "@brief A constant giving the parameter ID for parameter A"
+  ),
+  "@brief A device class for a diode.\n"
+  "This class can be used to describe diodes. Diodes are defined by their combination behavior and "
+  "the basic parameter 'A' which is their area in square micrometers.\n"
+  "\n"
+  "Diodes only combine when parallel and in the same direction. In this case, their areas are added."
+  "\n"
+  "An inductor has two terminals, A (anode) and C (cathode).\n"
+  "\n"
+  "This class has been introduced in version 0.26."
+);
+
+Class<db::DeviceClassMOS3Transistor> decl_dbDeviceClassMOS3Transistor (decl_dbDeviceClass, "db", "DeviceClassMOS3Transistor",
+  gsi::constant ("TERMINAL_S", db::DeviceClassMOS3Transistor::terminal_id_S,
+    "@brief A constant giving the terminal ID for terminal S"
+  ) +
+  gsi::constant ("TERMINAL_D", db::DeviceClassMOS3Transistor::terminal_id_D,
+    "@brief A constant giving the terminal ID for terminal D"
+  ) +
+  gsi::constant ("TERMINAL_G", db::DeviceClassMOS3Transistor::terminal_id_G,
+    "@brief A constant giving the terminal ID for terminal G"
+  ) +
+  gsi::constant ("PARAM_L", db::DeviceClassMOS3Transistor::param_id_L,
+    "@brief A constant giving the parameter ID for parameter L"
+  ) +
+  gsi::constant ("PARAM_W", db::DeviceClassMOS3Transistor::param_id_W,
+    "@brief A constant giving the parameter ID for parameter W"
+  ) +
+  gsi::constant ("PARAM_AS", db::DeviceClassMOS3Transistor::param_id_AS,
+    "@brief A constant giving the parameter ID for parameter AS"
+  ) +
+  gsi::constant ("PARAM_AD", db::DeviceClassMOS3Transistor::param_id_AD,
+    "@brief A constant giving the parameter ID for parameter AD"
+  ),
+  "@brief A device class for a 3-terminal MOS transistor.\n"
+  "This class can be used to describe MOS transistors without a bulk terminal. "
+  "A device class for a MOS transistor with a bulk terminal is \\DeviceClassMOS4Transistor. "
+  "MOS transistors are defined by their combination behavior and the basic parameters.\n"
+  "\n"
+  "The parameters are L, W, AS and AD for the gate length and width in micrometers and source and drain area "
+  "in square micrometers.\n"
+  "\n"
+  "The terminals are S, G and D for source, gate and drain.\n"
+  "\n"
+  "MOS transistors combine in parallel mode, when both gate lengths are identical and "
+  "their gates are connected (source and drain can be swapped). In this case, their widths and source and drain "
+  "areas are added.\n"
+  "\n"
+  "This class has been introduced in version 0.26."
+);
+
+Class<db::DeviceClassMOS4Transistor> decl_dbDeviceClassMOS4Transistor (decl_dbDeviceClass, "db", "DeviceClassMOS4Transistor",
+  gsi::constant ("TERMINAL_S", db::DeviceClassMOS4Transistor::terminal_id_S,
+    "@brief A constant giving the terminal ID for terminal S"
+  ) +
+  gsi::constant ("TERMINAL_D", db::DeviceClassMOS4Transistor::terminal_id_D,
+    "@brief A constant giving the terminal ID for terminal D"
+  ) +
+  gsi::constant ("TERMINAL_G", db::DeviceClassMOS4Transistor::terminal_id_G,
+    "@brief A constant giving the terminal ID for terminal G"
+  ) +
+  gsi::constant ("TERMINAL_B", db::DeviceClassMOS4Transistor::terminal_id_B,
+    "@brief A constant giving the terminal ID for terminal B"
+  ) +
+  gsi::constant ("PARAM_L", db::DeviceClassMOS4Transistor::param_id_L,
+    "@brief A constant giving the parameter ID for parameter L"
+  ) +
+  gsi::constant ("PARAM_W", db::DeviceClassMOS4Transistor::param_id_W,
+    "@brief A constant giving the parameter ID for parameter W"
+  ) +
+  gsi::constant ("PARAM_AS", db::DeviceClassMOS4Transistor::param_id_AS,
+    "@brief A constant giving the parameter ID for parameter AS"
+  ) +
+  gsi::constant ("PARAM_AD", db::DeviceClassMOS4Transistor::param_id_AD,
+    "@brief A constant giving the parameter ID for parameter AD"
+  ),
+  "@brief A device class for a 4-terminal MOS transistor.\n"
+  "This class can be used to describe MOS transistors with a bulk terminal. "
+  "A device class for a MOS transistor without a bulk terminal is \\DeviceClassMOS3Transistor. "
+  "MOS transistors are defined by their combination behavior and the basic parameters.\n"
+  "\n"
+  "The parameters are L, W, AS and AD for the gate length and width in micrometers and source and drain area "
+  "in square micrometers.\n"
+  "\n"
+  "The terminals are S, G, D and B for source, gate, drain and bulk.\n"
+  "\n"
+  "MOS transistors combine in parallel mode, when both gate lengths are identical and "
+  "their gates and bulk terminals are connected (source and drain can be swapped). In this case, their widths and source and drain "
+  "areas are added.\n"
+  "\n"
+  "This class has been introduced in version 0.26."
+);
+
+}
diff --git a/src/db/db/gsiDeclDbNetlistDeviceExtractor.cc b/src/db/db/gsiDeclDbNetlistDeviceExtractor.cc
new file mode 100644
index 000000000..e69de29bb
diff --git a/src/rba/unit_tests/rba.cc b/src/rba/unit_tests/rba.cc
index 51020ae1e..2df8e38bb 100644
--- a/src/rba/unit_tests/rba.cc
+++ b/src/rba/unit_tests/rba.cc
@@ -110,6 +110,7 @@ RUBYTEST (dbLayoutDiff, "dbLayoutDiff.rb")
 RUBYTEST (dbLayoutQuery, "dbLayoutQuery.rb")
 RUBYTEST (dbMatrix, "dbMatrix.rb")
 RUBYTEST (dbNetlist, "dbNetlist.rb")
+RUBYTEST (dbNetlistDeviceClasses, "dbNetlistDeviceClasses.rb")
 RUBYTEST (dbPathTest, "dbPathTest.rb")
 RUBYTEST (dbPCells, "dbPCells.rb")
 RUBYTEST (dbPointTest, "dbPointTest.rb")
diff --git a/testdata/ruby/dbNetlistDeviceClasses.rb b/testdata/ruby/dbNetlistDeviceClasses.rb
new file mode 100644
index 000000000..cfd51b421
--- /dev/null
+++ b/testdata/ruby/dbNetlistDeviceClasses.rb
@@ -0,0 +1,331 @@
+# encoding: UTF-8
+
+# KLayout Layout Viewer
+# Copyright (C) 2006-2018 Matthias Koefferlein
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+if !$:.member?(File::dirname($0))
+  $:.push(File::dirname($0))
+end
+
+load("test_prologue.rb")
+
+class DBNetlist_TestClass < TestBase
+
+  def test_1_Resistors
+  
+    cls = RBA::DeviceClassResistor::new
+
+    nl = RBA::Netlist::new
+    nl.add(cls)
+
+    circuit = RBA::Circuit::new
+    nl.add(circuit)
+
+    r1 = circuit.create_device(cls, "r1")
+    r1.set_parameter(RBA::DeviceClassResistor::PARAM_R, 1.0)
+    r2 = circuit.create_device(cls, "r2")
+    r2.set_parameter("R", 3.0)
+
+    pin_a = circuit.create_pin ("A")
+    pin_b = circuit.create_pin ("B")
+
+    n1 = circuit.create_net("n1")
+    circuit.connect_pin(pin_a, n1)
+    r1.connect_terminal(RBA::DeviceClassResistor::TERMINAL_A, n1)
+
+    n2 = circuit.create_net("n2")
+    r1.connect_terminal(RBA::DeviceClassResistor::TERMINAL_B, n2)
+    r2.connect_terminal(RBA::DeviceClassResistor::TERMINAL_A, n2)
+
+    n3 = circuit.create_net("n3")
+    r2.connect_terminal(RBA::DeviceClassResistor::TERMINAL_B, n3)
+    circuit.connect_pin(pin_b, n3)
+
+    assert_equal(nl.to_s, <<END)
+Circuit  (A=n1,B=n3):
+  D r1 (A=n1,B=n2) [R=1]
+  D r2 (A=n2,B=n3) [R=3]
+END
+
+    nl.combine_devices
+    nl.purge
+
+    assert_equal(nl.to_s, <<END)
+Circuit  (A=n1,B=n3):
+  D r1 (A=n1,B=n3) [R=4]
+END
+
+  end
+
+  def test_2_Capacitors
+  
+    cls = RBA::DeviceClassCapacitor::new
+
+    nl = RBA::Netlist::new
+    nl.add(cls)
+
+    circuit = RBA::Circuit::new
+    nl.add(circuit)
+
+    c1 = circuit.create_device(cls, "c1")
+    c1.set_parameter(RBA::DeviceClassCapacitor::PARAM_C, 2.0)
+    c2 = circuit.create_device(cls, "c2")
+    c2.set_parameter("C", 3.0)
+
+    pin_a = circuit.create_pin ("A")
+    pin_b = circuit.create_pin ("B")
+
+    n1 = circuit.create_net("n1")
+    circuit.connect_pin(pin_a, n1)
+    c1.connect_terminal(RBA::DeviceClassCapacitor::TERMINAL_A, n1)
+
+    n2 = circuit.create_net("n2")
+    c1.connect_terminal(RBA::DeviceClassCapacitor::TERMINAL_B, n2)
+    c2.connect_terminal(RBA::DeviceClassCapacitor::TERMINAL_A, n2)
+
+    n3 = circuit.create_net("n3")
+    c2.connect_terminal(RBA::DeviceClassCapacitor::TERMINAL_B, n3)
+    circuit.connect_pin(pin_b, n3)
+
+    assert_equal(nl.to_s, <<END)
+Circuit  (A=n1,B=n3):
+  D c1 (A=n1,B=n2) [C=2]
+  D c2 (A=n2,B=n3) [C=3]
+END
+
+    nl.combine_devices
+    nl.purge
+
+    assert_equal(nl.to_s, <<END)
+Circuit  (A=n1,B=n3):
+  D c1 (A=n1,B=n3) [C=1.2]
+END
+
+  end
+
+  def test_3_Inductors
+  
+    cls = RBA::DeviceClassInductor::new
+
+    nl = RBA::Netlist::new
+    nl.add(cls)
+
+    circuit = RBA::Circuit::new
+    nl.add(circuit)
+
+    l1 = circuit.create_device(cls, "l1")
+    l1.set_parameter(RBA::DeviceClassInductor::PARAM_L, 1.0)
+    l2 = circuit.create_device(cls, "l2")
+    l2.set_parameter("L", 3.0)
+
+    pin_a = circuit.create_pin ("A")
+    pin_b = circuit.create_pin ("B")
+
+    n1 = circuit.create_net("n1")
+    circuit.connect_pin(pin_a, n1)
+    l1.connect_terminal(RBA::DeviceClassInductor::TERMINAL_A, n1)
+
+    n2 = circuit.create_net("n2")
+    l1.connect_terminal(RBA::DeviceClassInductor::TERMINAL_B, n2)
+    l2.connect_terminal(RBA::DeviceClassInductor::TERMINAL_A, n2)
+
+    n3 = circuit.create_net("n3")
+    l2.connect_terminal(RBA::DeviceClassInductor::TERMINAL_B, n3)
+    circuit.connect_pin(pin_b, n3)
+
+    assert_equal(nl.to_s, <<END)
+Circuit  (A=n1,B=n3):
+  D l1 (A=n1,B=n2) [L=1]
+  D l2 (A=n2,B=n3) [L=3]
+END
+
+    nl.combine_devices
+    nl.purge
+
+    assert_equal(nl.to_s, <<END)
+Circuit  (A=n1,B=n3):
+  D l1 (A=n1,B=n3) [L=4]
+END
+
+  end
+
+  def test_4_Diodes
+  
+    cls = RBA::DeviceClassDiode::new
+
+    nl = RBA::Netlist::new
+    nl.add(cls)
+
+    circuit = RBA::Circuit::new
+    nl.add(circuit)
+
+    d1 = circuit.create_device(cls, "d1")
+    d1.set_parameter(RBA::DeviceClassDiode::PARAM_A, 1.0)
+    d2 = circuit.create_device(cls, "d2")
+    d2.set_parameter("A", 3.0)
+
+    pin_a = circuit.create_pin ("A")
+    pin_b = circuit.create_pin ("B")
+
+    n1 = circuit.create_net("n1")
+    circuit.connect_pin(pin_a, n1)
+    d1.connect_terminal(RBA::DeviceClassDiode::TERMINAL_A, n1)
+    d2.connect_terminal(RBA::DeviceClassDiode::TERMINAL_A, n1)
+
+    n2 = circuit.create_net("n2")
+    d1.connect_terminal(RBA::DeviceClassDiode::TERMINAL_C, n2)
+    d2.connect_terminal(RBA::DeviceClassDiode::TERMINAL_C, n2)
+    circuit.connect_pin(pin_b, n2)
+
+    assert_equal(nl.to_s, <<END)
+Circuit  (A=n1,B=n2):
+  D d1 (A=n1,C=n2) [A=1]
+  D d2 (A=n1,C=n2) [A=3]
+END
+
+    nl.combine_devices
+    nl.purge
+
+    assert_equal(nl.to_s, <<END)
+Circuit  (A=n1,B=n2):
+  D d1 (A=n1,C=n2) [A=4]
+END
+
+  end
+
+  def test_5_MOS3
+  
+    cls = RBA::DeviceClassMOS3Transistor::new
+
+    nl = RBA::Netlist::new
+    nl.add(cls)
+
+    circuit = RBA::Circuit::new
+    nl.add(circuit)
+
+    d1 = circuit.create_device(cls, "d1")
+    d1.set_parameter(RBA::DeviceClassMOS3Transistor::PARAM_L, 1.0)
+    d1.set_parameter(RBA::DeviceClassMOS3Transistor::PARAM_W, 2.0)
+    d1.set_parameter(RBA::DeviceClassMOS3Transistor::PARAM_AS, 3.0)
+    d1.set_parameter(RBA::DeviceClassMOS3Transistor::PARAM_AD, 4.0)
+    d2 = circuit.create_device(cls, "d2")
+    d2.set_parameter("L", 1.0)
+    d2.set_parameter("W", 3.0)
+    d2.set_parameter("AS", 4.0)
+    d2.set_parameter("AD", 5.0)
+
+    pin_a = circuit.create_pin ("A")
+    pin_b = circuit.create_pin ("B")
+    pin_c = circuit.create_pin ("C")
+
+    n1 = circuit.create_net("n1")
+    circuit.connect_pin(pin_a, n1)
+    d1.connect_terminal(RBA::DeviceClassMOS3Transistor::TERMINAL_S, n1)
+    d2.connect_terminal(RBA::DeviceClassMOS3Transistor::TERMINAL_S, n1)
+
+    n2 = circuit.create_net("n2")
+    circuit.connect_pin(pin_b, n2)
+    d1.connect_terminal(RBA::DeviceClassMOS3Transistor::TERMINAL_D, n2)
+    d2.connect_terminal(RBA::DeviceClassMOS3Transistor::TERMINAL_D, n2)
+
+    n3 = circuit.create_net("n3")
+    circuit.connect_pin(pin_c, n3)
+    d1.connect_terminal(RBA::DeviceClassMOS3Transistor::TERMINAL_G, n3)
+    d2.connect_terminal(RBA::DeviceClassMOS3Transistor::TERMINAL_G, n3)
+
+    assert_equal(nl.to_s, <<END)
+Circuit  (A=n1,B=n2,C=n3):
+  D d1 (S=n1,G=n3,D=n2) [L=1,W=2,AS=3,AD=4]
+  D d2 (S=n1,G=n3,D=n2) [L=1,W=3,AS=4,AD=5]
+END
+
+    nl.combine_devices
+    nl.purge
+
+    assert_equal(nl.to_s, <<END)
+Circuit  (A=n1,B=n2,C=n3):
+  D d1 (S=n1,G=n3,D=n2) [L=1,W=5,AS=7,AD=9]
+END
+
+  end
+
+  def test_6_MOS4
+  
+    cls = RBA::DeviceClassMOS4Transistor::new
+
+    nl = RBA::Netlist::new
+    nl.add(cls)
+
+    circuit = RBA::Circuit::new
+    nl.add(circuit)
+
+    d1 = circuit.create_device(cls, "d1")
+    d1.set_parameter(RBA::DeviceClassMOS4Transistor::PARAM_L, 1.0)
+    d1.set_parameter(RBA::DeviceClassMOS4Transistor::PARAM_W, 2.0)
+    d1.set_parameter(RBA::DeviceClassMOS4Transistor::PARAM_AS, 3.0)
+    d1.set_parameter(RBA::DeviceClassMOS4Transistor::PARAM_AD, 4.0)
+    d2 = circuit.create_device(cls, "d2")
+    d2.set_parameter("L", 1.0)
+    d2.set_parameter("W", 3.0)
+    d2.set_parameter("AS", 4.0)
+    d2.set_parameter("AD", 5.0)
+
+    pin_a = circuit.create_pin ("A")
+    pin_b = circuit.create_pin ("B")
+    pin_c = circuit.create_pin ("C")
+    pin_d = circuit.create_pin ("D")
+
+    n1 = circuit.create_net("n1")
+    circuit.connect_pin(pin_a, n1)
+    d1.connect_terminal(RBA::DeviceClassMOS4Transistor::TERMINAL_S, n1)
+    d2.connect_terminal(RBA::DeviceClassMOS4Transistor::TERMINAL_S, n1)
+
+    n2 = circuit.create_net("n2")
+    circuit.connect_pin(pin_b, n2)
+    d1.connect_terminal(RBA::DeviceClassMOS4Transistor::TERMINAL_D, n2)
+    d2.connect_terminal(RBA::DeviceClassMOS4Transistor::TERMINAL_D, n2)
+
+    n3 = circuit.create_net("n3")
+    circuit.connect_pin(pin_c, n3)
+    d1.connect_terminal(RBA::DeviceClassMOS4Transistor::TERMINAL_G, n3)
+    d2.connect_terminal(RBA::DeviceClassMOS4Transistor::TERMINAL_G, n3)
+
+    n4 = circuit.create_net("n4")
+    circuit.connect_pin(pin_d, n4)
+    d1.connect_terminal(RBA::DeviceClassMOS4Transistor::TERMINAL_B, n4)
+    d2.connect_terminal(RBA::DeviceClassMOS4Transistor::TERMINAL_B, n4)
+
+    assert_equal(nl.to_s, <<END)
+Circuit  (A=n1,B=n2,C=n3,D=n4):
+  D d1 (S=n1,G=n3,D=n2,B=n4) [L=1,W=2,AS=3,AD=4]
+  D d2 (S=n1,G=n3,D=n2,B=n4) [L=1,W=3,AS=4,AD=5]
+END
+
+    nl.combine_devices
+    nl.purge
+
+    assert_equal(nl.to_s, <<END)
+Circuit  (A=n1,B=n2,C=n3,D=n4):
+  D d1 (S=n1,G=n3,D=n2,B=n4) [L=1,W=5,AS=7,AD=9]
+END
+
+  end
+
+end
+
+load("test_epilogue.rb")
+