DPIMM-II 2003 DPIMM-II 2003 UCSD VLSI CAD LAB UCSD VLSI CAD LAB Compression Schemes for "Dummy Fill" VLSI Layout Data Robert Ellis, Andrew B. Kahng and Yuhong Zheng ( Texas A&M University and UCSD) ( Texas A&M University and UCSD) http://vlsicad.ucsd.edu http://vlsicad.ucsd.edu Supported by MARCO GSRC
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DPIMM-II 2003 UCSD VLSI CAD LAB Compression Schemes for "Dummy Fill" VLSI Layout Data Robert Ellis, Andrew B. Kahng and Yuhong Zheng ( Texas A&M University.
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A fill pattern can be expressed as a binary (0-1) matrix
Problem: Given a 0-1 matrix B [mn] digitized from a dummy fill layout, compress it with the objective of minimizing output data size h Compression ratio r = mn/h One-sided loss
• Limited loss can improve compressibility• Asymmetric loss:
JBIG (Joint Bi-level Image Experts Group) is an experts group of ISO, IEC and CCITT (JTC1/SC2/WG9 and SGVIII). Its goal is to define a compression standard for bi-level image coding• JBIG1: international standard for lossless compression
of bi-level images (ITU-T T.82) (1993)• JBIG2: the first International standard that provides for
both lossless and lossy compression of bi-level images (1999)
JBIG* methods are based on Arithmetic Coding and Context-based Statistical Modeling
We have implemented algorithms based on JBIG* methods in combination with the new concept of one-sided loss to compress binary data files of dummy fill features.
JBIG1 is quite effective. Our new heuristics A2-A3 and the fixed speckle loss heuristic offer better compression with slower runtime, especially as data files become larger
Ongoing research examines synergies between fill generation and compression, as well as compression techniques that exploit constructs in the GDSII standard (AREF and SREF) and the new OASIS format (8 repetitions) for layout data.
Experimental Results (Cont’d)Run time of fill compression heuristics
0100200300400500600700
1 2 3 4 5Test cases
Run
time
(s)
Bzip2
A1
A2.1
A2.2@20%loss
A2.2@40%loss
A3@20%loss
For lossless compression, A1 is the most cost-effective method, taking only 2.7 longer than Bzip2 on average. A2.1 is nearly as cost effective, but takes 5.9 longer than Bzip2 on average.
A3 is the most cost-effective proportional loss method, taking 3.7 longer than Bzip2 on average. The running time of A2.2 is 9.4 longer than Bzip2 on average with proportional loss ratio k=0.2 and 10.3 longer with k=0.4.