Module placement with boundary constraints using B*-trees

The module placement problem is to determine the co-ordinates of logic modules in a chip such that no two modules overlap and some cost (e.g. silicon area, interconnection length, etc.) is optimised. To shorten connections between inputs and outputs and/or make related modules adjacent, it is desired to place some modules along the specific boundaries of a chip. To deal with such boundary constraints, we explore the feasibility conditions of a B*-tree with boundary constraints and develop a simulated annealing-based algorithm using B*-trees. Unlike most previous work, the proposed algorithm guarantees a feasible B*-tree with boundary constraints for each perturbation. Experimental results show that the algorithm can obtain a smaller silicon area than the most recent work based on sequence pairs