Norman Scaife

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Model-based design is advocated as the method of choice when dealing with critical systems as well as high quality systems. However, it often abstracts implementation details such as execution times. This can be a problem when dealing with urgent events whose implementation requires preemptive scheduling. In this paper, we propose an inter-task(More)
In previous work, we have proposed a method of preserving the functional semantics of model-based designs by the use of static checks and a double-buffer protocol [12]. However, this is restricted to static, fixed-priority scheduling and for high-priority to low-priority communications requires a double buffer to be stored for each pair of communicating(More)
The Simulink/Stateflow toolset is an integrated suite enabling model-based design and has become popular in the automotive and aeronautics industries. We have previously developed a translator called Simtolus from Simulink to the synchronous language Lustre and we build upon that work by encompassing Stateflow as well. Stateflow is problematical for(More)
Bounding resource usage is important for a number of areas, notably real-time embedded systems and safety-critical systems. In this paper, we present a fully automatic static type-based analysis for inferring upper bounds on resource usage for programs involving general algebraic datatypes and full recursion. Our method can easily be used to bound any(More)
The construction of a parallel vision system from Standard ML prototypes is presented. The system recognises 3D objects from 2D scenes through edge detection, grouping of edges into straight lines and line junction based model matching. Functional prototyping for parallelism is illustrated through the development of the straight line detection component.(More)
We study the implementation of a synchronous program as a set of multiple tasks running on the same computer, and scheduled by a real-time operating system using some preemptive scheduling policy, such as fixed priority or earliest-deadline first. Multitask implementations are necessary, for instance, in multiperiodic applications, when the worst-case(More)
This paper describes ongoing work aimed at the construction of formal cost models and analyses to yield verifiable guarantees of resource usage in the context of real-time embedded systems. Our work is conducted in terms of the domain-specific language Hume, a language that combines functional programming for computations with finitestate automata for(More)
We have been developing techniques for deriving parallel implementations of vision algorithms from prototypes written in a functional language (SML). Initially, we analysed simple, well understood algorithms to allow the prototyping methodology to be investigated in a predictable environment. Subsequently, we have extended our approach to more difficult(More)