The Speech Sciences

Much of the work on developing program transformation systems has concentrated on sys-tems to assist in program development. However, the four separate surveys carried out between 1977 and 1990 [18,20,22,24], summarised in [17], show that between 40 % and 60 % of all com-mercial software eort is devoted to software maintenance rather than the development of new systems. In this paper we describe a joint project between the University of Durham and CSM Ltd to develop a method and tool for reverse engineering and software maintenance based on program transformation theory. We present an example which illustrates how such a tool can extract a high-level abstract specication from the low-level source code of a program by a process of formal program transformation based on a theory of program equivalence [27]. All the code-level reverse engineering of the example program was carried out on the prototype tool with the resulting code pasted directly into the paper.