ALLENDE: A Procedural Language for the Hierarchical Specification of VLSI Layouts

ALLENDE is a simple and powerful procedural language for VLSI layout. In ALLENDE the layout is described hierarchically as a composition of cells; absolute sizes or positions are never specified. The layout description is translated into linear constraints, which express design rules and relative position of the layout elements. By solving these constraints we obtain the absolute layout, which is guaranteed to be free of design rule violations. Errors in the layout description are immediately detected and easily located. ALLENDE consists of five procedures to be called from a Pascal or C program. A lot of parameterization is possible when specifying layout elements, besides the ability to make use of the full power of Pascal or C. The ALLENDE system has been implemented for the nMOS technology.