Copyright © 2006, by the author(s).

We present a framework to extend the concept of type systems in programming languages to capture the dynamic interaction in component-based design, such as the communication protocols between components. In our system, the interaction types and the dynamic behavior of components are defined using interface automata - an automata-based formalism. Type checking, which checks the compatibility of a component with a certain interaction type, is conducted through automata composition. Our type system is polymorphic in that a component may be compatible with more than one interaction type. We show that a subtyping relation exists among various interaction types and this relation can be described using a partial order. This system-level type order can be used to facilitate the design of polymorphic components and simplify type checking.

Abstract not found

Rapid exploration of the design space with simulation models is essential for quality hardware systems research and development. Despite striking commonalities across hardware systems, designers routinely fail to achieve high levels of reuse across models constructed in existing general-purpose and domain-specific languages. This lack of reuse adversely impacts hardware system design by slowing the rate at which ideas are evaluated. This paper presents an examination of existing languages to reveal their fundamental limitations regarding reuse in hardware modeling. With this understanding, a solution is described in the context of the design and implementation of the Liberty Structural Specification Language (LSS), the input language for a publicly available high-level digital-hardware modeling tool called the Liberty Simulation Environment. LSS is the first language to enable low-overhead reuse by simultaneously supporting static inference based on hardware structure and flexibility via parameterizable structure. Through LSS, this paper also introduces a new type inference algorithm and a new programming language technique, called use-based specialization, which, in a manner analogous to type inference, customizes reusable components by statically inferring structural properties that otherwise would have had to have been specified manually.

Abstract. Developing a single embedded application involves a multitude of different development tools including several different simulators. Most tools use different abstractions, have their own formalisms to represent the system under development, utilize different input and output data formats and have their own semantics. A unified environment that allows capturing the system in one place and one that drives all necessary simulators and analysis tools from this shared representation needs a common representation technology that must support several different abstractions and formalisms seamlessly. Describing the individual formalisms by metamodels and carefully composing them is the underlying technology behind MILAN, a Model-based Integrated Simulation Framework. MILAN is an extensible framework that supports multi-granular simulation of embedded systems by seamlessly integrating existing simulators into a unified environment. Formal metamodels and explicit constraints define the domain-specific modeling language developed for MILAN that combines hierarchical, heterogeneous, parametric dataflow representation with strong data typing. Multiple modeling aspects separate orthogonal concepts. The language also allows the representation of the design space of the application, not just a point solution. Non-functional requirements are captured as formal, application-specific constraints. MILAN has integrated tool support for design-space exploration and pruning. The models are used to automatically configure the integrated functional simulators, high level performance and power estimators, cycle accurate performance simulators and power-aware simulators. Simulation results are used to automatically update the system models. The paper focuses on the modeling methodology and briefly describes how the integrated models are utilized in the framework. 1

Abstract not found

Version 4.0 2

In this paper, we consider concurrent models of computation where ”actors” (components that are in charge of their own actions) communicate by exchanging messages. The interfaces of actors principally consist of “ports,” which mediate the exchange of messages. Actor-oriented architectures contrast with and complement object-oriented models by emphasizing the exchange of data between concurrent components rather than transfer of control. Examples of such models of computation include the classical actor model, synchronous languages, dataflow models, and discrete-event models. Many of these models of computation benefit considerably from having access to causality information about the components. This paper augments the interfaces of such components to include such causality information. It shows how this causality information can be algebraically composed so that compositions of components acquire causality interfaces that are inferred from their components and the interconnections. We illustrate the use of these causality interfaces to statically analyze discrete-event models for uniqueness of behaviors, synchronous models for causality loops, and dataflow models for schedulability.

Copyright © 2006, by the author(s).

To identify the best processor designs, designers explore a vast design space. To assess the quality of candidate designs, designers construct and use simulators. Unfortunately, simulator construction is a bottleneck in this design-space exploration because existing simulator construction methodologies lead to long simulator development times. This bottleneck limits exploration to a small set of designs, potentially diminishing quality of the final design.