Wanted:Compaction Algorithm

Guy Harris guy at sun.uucp
Fri Feb 21 05:59:35 AEST 1986


> I am in need of a packing algorithm which works better than the
> PACK Utility of UNIX.  I have also looked at COMPRESS ( developed
> at University of Utah ).  COMPRESS works great if distinct number
> of input bytes is small.  But if the distinct input bytes reach
> 256 ( binary data ), PACK works better than COMPRESS.  With PACK
> I am getting a saving of 20-25%.  If anybody has an algorithm
> that would do better in packing "load modules", I would like to
> know about it.

Are you sure you have the latest version of "compress"?  I tried "pack"ing
and "compress"ing "/usr/bin/suntools" (which is a BMF executable image) and
"compress" did significantly better than "pack" did (it took significantly
more time doing it, but that's life).  Remember, Lempel-Ziv compression will
discover frequently-occurring sequences of bytes, and unless your machine
has all one-byte instructions you're likely to get some multi-byte sequences
occurring frequently.
-- 
	Guy Harris
	{ihnp4, decvax, seismo, decwrl, ...}!sun!guy
	guy at sun.arpa	(yes, really)



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