Limitations on the portability of real time Ada programs
This paper describes areas of the Ada language where transportability is restricted by the fact that implementation choices are allowed. Transportability guidelines have been developed previously for Ada [2,3,10], but have taken the approach that only features of the language which are guaranteed to be supported by all implementations should be used. The “common intersection” approach rules out use of many features that were included in Ada because they are required for real-time applications. This paper addresses the transportability of real-time Ada programs from a realistic point of view. Specifically, time-critical applications are of little use being transportable if they execute too slowly on all available implementations; and reasonable people will not wish to transport an application to architectures and/or compilation systems that do not support the requirements of the application.
A practical approach to managing these difficulties is presented as a set of transportability guidelines. These guidelines are intended to improve the transportability of programs which must rely on language features that are implementation dependent.