Design Flow Management (DFM) in Ptolemy II Framework

Researchers: Bicheng William Wu
Advisor:Edward A. Lee
Sponsor:
Design flow is usually specified using block diagrams with pen and paper. Thus the Ptolemy project, a good framework for block diagram based design, is well suited for specifying and executing the design flow. Kalavade et al. [1] used Ptolemy 0 to implement a framework, the Design Methodology Management (DMM) domain, for systematically managing the design process. In that framework, tools are encapsulated in functional blocks, and the design data is enclosed in the tokens that flow on the arcs between blocks. Design flow execution become the execution of the graph of blocks.

The goal of this project is to design a similiar domain, but in the Ptolemy II framework. The emphasis is on choosing a deterministic semantics, and developing an interface standard for external tools.

The selected model of computation (MoC) for DFM is the timed-Process Network (PN) model, where processes in a network communicate through a set of single-input single-output FIFO channels. Writes to the channels are non blocking, while reads are blocking. This model ensures determinacy while allowing for parallel execution. Time is used as an additional control.

DFM will uses the PN semantics to support the following tasks, all of which are common in a design flow:

* Efficient flow execution. Run a tool only if the inputs and/or parameters have changed.

* Flow control. Some part of design flow is only run when a condition is met, for example, an if statement.

* Convergence. Some part of design flow need to be run repeatedly for some number of iterations or until a condition is met, like "for" and "while" loop.

These tasks can be handled by adding message tags onto tokens. These messages are additional conditions, processed by a tool block, along with input data and parameters to determine whether the tool can be executed.

Another part of this project is devoted to defining common interfaces for tools. There will be three classes of tools: internal Ptolemy tools, tools exist on the same file system, and distributed tool objects on the internet. Design data, files, and directory management will also be addressed in this project.

[1]
A. Kalavade, J. L. Pino, and E. A. Lee, ``Managing Complexity in Heterogeneous Specification, Simulation, and Synthesis,'' Invited Paper, Proc. of IEEE Int. Conf. on Acoustics, Speech, and Signal Processing, May 8-12, 1995, Detroit, MI, pp. 2833-2836 8.A

Last updated 03/22/99