## Abstract

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 0(n!2 ^{2n-2}/n ^{1.5}). This is very concise compared to a sequence pair representation that has O((n!) ^{2}) combina-tions. The approximate ratio of sequence pair and O-tree combinations is O(n ^{2}(n/4e) ^{n}). The complexity of an O-tree is even smaller than a binary tree structure for a slicing floorplan that has O(n!2 ^{5n-3}/n ^{1.5}) 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 the previous central processing unit (CPU) intensive cluster refinement method.

Original language | English |
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Pages (from-to) | 26-29 |

Number of pages | 4 |

Journal | IEEE Circuits and Systems Magazine |

Volume | 3 |

Issue number | 2 |

DOIs | |

Publication status | Published - 2003 Jun |

## ASJC Scopus subject areas

- Engineering(all)
- Hardware and Architecture