The Model of Design Representation

Other researchers have similar models of design representation Gajski and Kuhn s Y-chart [GajskiSS], and Knapp and Parker s Design Data Structure (DDS) [Knapp84] are two other examples. The three models are compared in a later section of this chapter. 

The Behavioral Domain describes the behavior, or functionality, of the design, either as a complete, program-like description, or as set of behavioral descriptions. For example, at the Algorithmic level, the Behavioral Domain might be represented by a description of the algorithm to be implemented. Variables and the operations on them 

The Structural Domain describes the hierarchical logical implementation of the design in an abstract, technology independent fashion. For example, at the Register-Transfer Level the Structural Domain describes the design in terms of an abstract set of functional units, multiplexors, and registers needed to implement the register transfers required by the Behavioral Domain, plus a controller and control ROM. 

Description and Constraint Components. Each of the three domains may also contain both a description component and a constraint component. The description is a representation of the design as it exists at that point in the design process. This description may be provided by the user (e.g., as the input description for a synthesis system) or it may be built under program control as an intermediate or final representation of the design and linked to the user-supplied information. The second component of each domain, the set of constraints restrains the design process. These constraints may be represented separately from the description, or they may be combined with the description, possibly as attributes. Timing constraints, area constraints, and power consumption constraints are typical examples. 

In this model of design representation, there are many levels of abstraction, each containing a Behavioral, Structural, and Physical Domain component. Only the levels of abstraction pertinent to the Workbench will be presented in detail. 

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