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Object Oriented Generators in Java

Michael Chu & Nicholas Weaver

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Roadmap

• OO generators

• Automatic services

• Component libraries

• Future goals

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Why Java?

• 100% Pure Buzzword Compliant

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Why Java?

• Reasonably nice

• Politically acceptable

• Object Oriented

• Good metadata interface

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What are OO Generators?

• A component:– Contains subcomponents which represent the

pieces of a design– Has a constructor which creates the

subcomponents and attaches them together– Has connections for interfacing with other

components– Any additional routines for additional

functionality

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What are OO Generators?

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Why Object Oriented?

• Allows smart components– Partial evaluation and simulation– Components can change once created

• Different instances of the same class can behave differently

• Convenient abstractions for automatic services– Can treat the design as a hierarchical tree or a

graph of components

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A Hierarchical Tree

• Each component is made up of subcomponents

• Tree structure captures the design hierarchy and programmer intuition

• Routine provides access to all child components and the parent component

• Used for automatic placement and evaluation ordering

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A Hierarchical Tree

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A Graph of Components

• Each component has a set of inputs and outputs

• Can follow all inputs and outputs, backwards and forwards

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A Graph of Components

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Examining objects

• java.lang.reflect package allows inspection of objects

• Can access all slots and methods and determine type

• Used to allow iteration over all subcomponents, inputs, and outputs

• Automated creation of backpointers

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Automatic Services

• Logic Trimming– Traces the graph from the array inputs and

outputs

• Partial Evaluation– Constant propagation– Structural changes based on inputs

• Simulation

• Netlist generation

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Partial Evaluation

• Library components can examine their inputs, and if possible, assign outputs or rearrange internal structure

• Changes are then propagated to dependant components in an iterative process– Connection values are never changed, only set,

guaranteeing convergence

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Partial Evaluation Example

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Partial Evaluation Example

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Partial Evaluation Example

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Simulation

• Library leaf nodes implement simulation routines.

• Changes are propagated similar to the partial evaluation system

• Assumes synchronous design

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Simulation for testing

• Larger components can implement a behavioral simulation routine

• Both routines automatically run concurrently– Differences produce warning messages

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Component Libraries

• Use the framework to build a series of libraries– Platform independent API– Include specialization and simulation routines– Perform netlist generation and similar services

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Target Platforms

• Targets:– Xilinx 4000E– Garp– Hierarchical Array

• All targets should have identical high-level primitives available– But implementations may use different details

• Low-level primitives can be target specific

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Current Status

• Basic structure completed

• Some automatic services– Logic trimming, simulation, partial evaluation

• Basic components of XC4000 library

• Simple designs completed– Counters, DNA sequence matching

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Future Development

• Simple control logic synthesis

• More components for Xilinx library

• Automatic and semi-automatic placement routines

• More supported platforms

• Real designs– Compare designs with those produced by HDL

and schematic capture