Code Generation

This code generator is patterned after the Ptolemy Classic code generator where actors have template files consisting of code blocks. The code blocks are stitched together to create the resulting file.

See Code Generation section of the Complete Demos page for more demos.

Simple Demo

  1. Generate HTML code that describes a model.
    If you are viewing this page from within vergil, open $PTII/ptolemy/cg/adapter/generic/html/demo/HierarchicalModel/HierarchicalModel.xml
    If you are viewing this page from a browser, start vergil with: $PTII/bin/vergil /Users/cxh/ptII/ptolemy/cg/adapter/generic/html/demo/HierarchicalModel/HierarchicalModel.xml
  2. Click on the HTMLCodeGenerator icon.
  3. A dialog box will appear, click on "Generate"
  4. An HTML description of the model will be generated and displayed.

Java Command Line Demo

To generate Java code for a simple model, run:
	$PTII/bin/ptcg -language java $PTII/ptolemy/cg/kernel/generic/program/procedural/java/test/auto/Display.xml 
	java -classpath $PTII -language java $PTII/ptolemy/cg/kernel/generic/program/procedural/java/test/auto/Display.xml

Package overview

The cg facility uses an adapter pattern where classes in a regular Ptolemy II model have corresponding classes in the cg facility.

The cg subpackages are structured so that language specific code is separate from generic code.

The main entry point is $PTII/ptolemy/cg/kernel/generic/ This file is invoked by $PTII/bin/ptcg. To get the complete list of options, run $PTII/bin/ptcg -help.

To invoke the cg code generator from the GUI, drag in a code generator attribute from More Libraries -> CodeGenerators ->CGCodegen.

The ptolemy/cg directory has these subdirectories:

Language specific adapters classes that correspond with regular Ptolemy II classes.
The classes for the procedural languages (C and Java)
The adapter definitions that are shared between the procedural languages. For example, the Display adapter is at ptolemy/cg/adapter/generic/program/procedural/adapters/ptolemy/actor/lib/gui/
The adapters for actors that generate C. In general, the Java class extends the shared adapter and contains only a constructor. There is an optional .c file that contains C-specific blocks of code used in code generation. For example, we have ptolemy/cg/adapter/generic/program/procedural/c/adapters/ptolemy/actor/lib/gui/ and ptolemy/cg/adapter/generic/program/procedural/c/adapters/ptolemy/actor/lib/gui/Display.c
The adapters for actors that generate Java. The layout is similar to the C version, except the .j file contains the Java template blocks. The file is named .j so that it does not get compiled.
Graphical User Interface (gui) code. If a model has a attribute in it, then double clicking on that attribute brings up the code generator gui.
Non-language specific code generation classes and language-specific type information.
Modular code generation work and syntactic code generation work

Hints about working with the tree

Because the tree is so deep, you may find it easier to use a few tools to quickly search files from the command line.

Search for files

To find all the files named Display use:
	cd $PTII/ptolemy/cg
	find . -name "Display"

Search all the files for a string

	find . -type f | xargs grep MyString

How to add an actor

Adding code generation support for an actor is fairly complex, but follows a pattern.

  1. First, check to see that there is no already a code generation version of the actor. It could be that there is one for a different language. Also, look for code generation versions of the actors that are similar to the actor in question.
  2. Read the style guide at $PTII/doc/coding/style.htm. In particular, pay attention to the parts about makefiles.
  3. The ptolemy/cg directory contains subdirectories that mimic the Ptolemy II tree. So, if we are adding a code generation version of an actor in ptolemy/actor/lib, then we will be working in similar subdirectories in ptolemy/cg.
  4. The code generation system reads blocks of code from a template file and does substitution. Most of the work occurs in a file that is shared between the procedural languages (C and Java). The directory is $PTII/ptolemy/cg/adapter/generic/program/procedural/adapters/ptolemy/actor/lib/
  5. The C or Java specific code is in
    $PTII/ptolemy/cg/adapter/generic/program/procedural/c/adapters/ptolemy/actor/lib/ or
    These directories contain corresponding .c or .j files that define the blocks used in the generated code.
    These directories also contain a test/auto/ directory that contains the test models.

Supporting different targets

A target is typically an architecture-specific platform. For example, the arduino target generates C-code meant to run on the Arduino platform.

To generate code for a target, use the -generatorPackageList command line argument to $PTII/bin/cg. The value of the -generatorPackageList parameter i a semicolon or * separated list of Java packages to be searched for adapters. For example

	  $PTII/bin/ptcg -generatorPackageList generic.program.procedural.c.arduino ptolemy/cg/adapter/generic/program/procedural/c/arduino/adapters/ptolemy/actor/lib/gui/test/auto/Display.xml