Evaluation of HAL/S Language Compilability Using SAMSO's Compiler Writing System (CWS).

NASALangley is engaged in a program to develop an adaptable guidance and control software concept for spacecraft such as shuttle-launched payloads. It is envisioned that this flight software be written in a higher-order language, such as HALS, to facilitate changes or additions. To make this adaptable software transferable to various onboard computers, a compiler writing system capability is necessary. A joint program with the Air Force Space and Missile Systems Organization was initaiated to determine if the Compiler Writing System CWS owned by the Air Force could be utilized for this purpose. The present study explores the feasibility of including the HALS language constructs in CWS and the effort required to implement these constructs. This will determine the compilability of HALS using CWS and permit NASALangley to identify the HALS constructs desired for their applications. The study consisted of comparing the implementation of the Space Programming Language using CWS with the requirements for the implementation of HALS. It is the conclusion of the study that CWS already contains many of the language features of HALS and that it can be expanded for compiling part or all of HALS. It is assumed that persons reading and evaluating this report have a basic familiarity with 1 the principles of compiler construction and operation, and 2 the logical structure and applications characteristics of HALS and SPL. Author