Re-engeneering a Safety-Critical Application Using SPARK 95 and GNORT

This paper describes a new development of the GNAT Ada95 compilation system (GNORT) that is appropriate for the development of high integrity embedded systems. We describe GNORT, the motivation for its development, and give some technical detail of its implementation. The latter part of the paper goes on to describe SHOLIS—an existing safety-critical application written in SPARK 83 that has been re-engineered to take advantage of SPARK 95 and GNORT. We assess the benefits of this approach through metrics on the SHOLIS application source and object code. These data may be of interest to engineers who are considering Ada95 for a new project or converting an existing Ada83 application to Ada95.