CORNER STITCHING FOR SIMPLE RECTILINEAR SHAPES

This paper extends the corner-stitching data structure proposed by Ous terhout [1] for manipulating rectangular objects in very large scale i ntegration (VLSI) layouts to L-shaped objects. This provides additiona l flexibility in the design of very large scale integration (VLSI) cir cuits [2], [3]. Our technique is fundamentally different from [1] and other extensions to the corner stitching data structure [4], [5] in th at it modifies the underlying topology of the data structure. This giv es rise to differences in the implementation of operations on the data structure, Our data structure is guaranteed to require less memory th an the original data structure. Experiments show that our data structu re required about 15%-17% less memory than the original data structure on VLSI layouts but was slower by a factor of two to eight. Extension s of corner stitching to T- and Z-shaped tiles ape also described.