Floorplanning using a tree representation

Pei Ning Guo*, Toshihiko Takahashi, Chung Kuan Cheng, Takeshi Yoshimura

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

77 Citations (Scopus)


We present an ordered tree (O tree) structure to represent nonslicing floorplans. The O tree uses only n(2 + [lg n]) bits for a floorplan of n rectangular blocks. We define an admissible placement as a compacted placement in both x and y directions. For each admissible placement, we can find an O-tree representation. We show that the number of possible O-tree combinations is O(n!22n-2/n1.5). This is very concise compared to a sequence pair representation that has O((n!)2) combinations. The approximate ratio of sequence pair and O-tree combinations is O(n2(n/4e)n). The complexity of O tree is even smaller than a binary tree structure for slicing floorplan that has O(n!25n-3/n1.5) combinations. Given an O tree, it takes only linear time to construct the placement and its constraint graph. We have developed a deterministic floorplanning algorithm utilizing the structure of O tree. Empirical results on MCNC (www.mcnc.org) benchmarks show promising performance with average 16% improvement in wire length and 1% less dead space over previous central processing unit (CPU) intensive cluster refinement method.

Original languageEnglish
Pages (from-to)281-289
Number of pages9
JournalIEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems
Issue number2
Publication statusPublished - 2001 Feb
Externally publishedYes


  • Building block placement
  • Floorplan
  • Rooted ordered tree

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Hardware and Architecture
  • Computer Science Applications
  • Computational Theory and Mathematics


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