Pigs from sausages?  Reengineering from assembler to C via fermaT transformations

Software reengineering has been described as being "about as easy as reconstructing a pig from a sausage". But the development of program transformation theory, as embodied in the FermaT Transformation System, has made this miraculous feat into a practical possibility. This paper describes the theory behind the FermaT system and describes a recent migration project in which over 544,000 lines of assembler were transformed into efficient and maintainable structured C code. The FermaT Transformation System is now being used by Software Migrations Ltd to carry out major international software migration projects. This was a result of an EPSRC-funded project (GR/R56099)