The MACLOG family of layout generators creates parameterized custom layouts for many of the cells in the AT&T Cell Library. The authors describe not the MACLOG generators themselves, but the MACLOG framework that is the base of all the generators. The MACLOG generators are built on an object-oriented framework. Though object-oriented design techniques have been described in the literature, the MACLOG framework is one of the first such frameworks used to build an industrial-quality layout generator set. The attempt to build an object-oriented framework structure around the module types results in excessive code duplication and a hard-to-maintain structure. The authors found the service hierarchy-the types of information provided to the user by the generator-often to be a more effective axis for decomposition of functions in the framework. The authors describe the MACLOG framework and detail experiments with framework structure.>

The MACLOG layout generator set is built on an object-oriented framework. Most frameworks are built around the hierarchy of module types. We found the service hierarchy—the types of information provided to the user by the generator—made the framework and generators easier to design and modify. This paper describes the MACLOG framework and details our experience with framework structure.