Object-Oriented Modeling for System Level Design

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Object-Oriented Modeling for System Level Design

• Abdallah Tabbara
• Bassam Tabbara
• A. Richard Newton
• UC Berkeley

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Project Goals

• Model all aspects
• Behavior
• Communication
• Structure
• of a design block starting at the system level
• Support specification, verification, and synthesis

3
Description

• Use an Object-Oriented methodology for modeling
  designs at the system level
• Object Modeling Technique (OMT) (Rumbaugh 91)
• Graphical design entry
• object model
• dynamic model
• functional model
• Visual debugging environment
• Specification can be verified, and synthesized

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Technology

• Objects
• Instantiation
• Encapsulation
• Methods for Communication
• Object-Oriented Input Specification
• OOP, simple, compact, intuitive
• implementation independent
• no side-effects
• Java define subset and policy

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Modeling Issues

• Hierarchy
• Communication
• Inputs
• Outputs
• Timing
• Blocks
• Combinational
• Sequential

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Object as the Building Block

• Basic unit of the hierarchy
• Methods
• Interface
• Communication
• Private Variables
• State
• Instances of other Objects

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Design Entry An Illustrative Example

• Handshake protocol between two processes
• Object Model
• Object Producer
• Object Consumer
• Object HandShake

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Design Specification An Illustrative Example (1)

• Dynamic Model
• describes the control aspects of a system
• Functional Model
• describes data value transformations

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Design Specification An Illustrative Example (2)
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Modeling in Java (1)

• class Producer extends Block
• private boolean Ready
• // Constructor
• public Producer(boolean i)
• Ready i
• // Methods
• public void ComputeReady(boolean Ack)
• Ready !Ack
• return(!Ack)
• public boolean ReadyStatus()
• return Ready

• class Consumer extends Block
• private boolean Ack
• // Constructor
• public Consumer(boolean i)
• Ack i
• // Methods
• public void ComputeAck(boolean Ready)
• Ack Ready
• return(Ready)
• public boolean AckStatus()
• return(Ack)

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Modeling in Java (2)

• class HandShake extends Block
• // State
• private int dataA, dataB
• // Internal Objects
• private Producer P
• private Consumer C
• // Constructor
• public HandShake()
• P new Producer(true)
• C new Consumer(false)

• // Methods
• public int Output(int data_in)
• if (P.ReadyStatus())
• dataA data
• if (C.AckStatus())
• dataB dataA
• // Latch
• P.ComputeReady(C.AckStatus())
• C.ComputeAck(P.ReadyStatus())
• return dataB

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Intermediate Design Representation

• Class File Intermediate Format (CFIF)
• Extracted from the Java Virtual Machine class
  file format.
• Each class file contains one Java type either a
  class, or an interface.
• CFIF output for the Producer in our example
  follows

methods2.access_flags ACC_PUBLIC
methods2.name_index ReadyStatus methods2.des
criptor_index ()Z methods2.attributes_count
1 methods2.attributes0.name_index
Code methods2.attributes0.max_stack
1 methods2.attributes0.max_locals
1 methods2.attributes0.code_length
5 methods2.attributes0.code0
aload_0 methods2.attributes0.code1
getfield -gt A Ready Z methods2.attributes0.cod
e4 ireturn ...
access_flags this_class Producer super_class
Block interfaces_count 0 fields_count
1 fields0.access_flags ACC_PRIVATE
fields0.name_index Ready fields0.descriptor_
index Z fields0.attributes_count
0 methods_count 3
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Advantages of This Approach

• Increased Productivity
• HDL Lines per week
• Intuitive Specification
• Ease of Design Space Exploration
• Block Level Methodology
• better design reuse
• Validation at the High Level
• Potential for Formal Verification

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Future Work

• Incorporate Design
• Validation (simulation)
• Verification (formal)
• Synthesis from CFIF
• Hardware
• Software

FOR MORE INFO...
Abdallah Tabbara atabbara_at_eecs.berkeley.edu Bassa
m Tabbara tbassam_at_eecs.berkeley.edu