Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!uwm.edu!bionet!apple!shrinkit
From: shrinkit@Apple.COM (Andrew Nicholas)
Newsgroups: comp.sys.apple2
Subject: Re: IIgs Unzip thing
Message-ID: <50740@apple.Apple.COM>
Date: 25 Mar 91 10:48:48 GMT
References: <4388@orbit.cts.com>
Organization: Apple Computer Inc., Cupertino, CA
Lines: 47

In article <4388@orbit.cts.com> svetozar@pnet51.orb.mn.org (Eric C. Anderson) writes:

>The aforementioned "zip07src.zip" file is 110047 bytes in length.  After
>uncompressing it, I re-archived all the resulting files with GS-ShrinkIt.  The
>resulting file was 156303 bytes in length.  I hope everyone won't laugh at my
>ignorance, but if a .SHK archive is 42% larger than a .ZIP archive, would it
>not be a good idea for someone to write a program for the Apple II family
>incorporating PKZIP's superior compression algorithm?  On the other hand,
>programs such as ARJ and LZH in the PC world achieve even better compression
>than PKZIP, using something called "static LZW"; perhaps this would be a
>profitable route for some software author to investigate.

Hi, you've been trying to send me email, and I've been getting all of it, and
I've also been writing really long, long replies which evidently aren't getting
to you.  I just sent you email again, so let me know if you don't get it.

Now, about better compression methods -- I have had an "almost working"
assembly version of LZH for 2 years now.  I have never gotten the assembly code
to work correctly... then again, I've never gotten the chance lately to GET
it to work because I'm so busy (I am, really).

ARJ?  Did I miss something?  I knew of PKZIP, PAK, LZH, LZB, LZC, LZW, LZJ, and
a bunch of other LZ variants (LZFG, etc), but not ARJ.  Something to do with
arithmetic coding?

Btw, Orca/C 1.1 (and 1.2 I'm assuming, mine hasn't come yet) will correctly
compile the LZH source code and make it work.  It took something like 8 
minutes to compress Finder v1.3 on a stock GS.  It took GS-ShrinkIt something
like 23 seconds.  I remember doing this at KansasFest and came to the
conclusion that the C source was almost useless -- even with all of Orca/C's
optimizations >ON< (which isn't saying much, because the output which was
produced by the compressor didn't match the output produced when optimizations
were left off... hence my distrust of Orca/C 1.1's optimizer)... even with
the optimizations ON, it still took 7 some minutes to compress the
Finder.  The better the compression was going to be, the longer it took.
It wasn't uncommon to see compression times that took 1/2 hour or longer...
although I've never compressed something like the whole SYSTEM 504 disk.  That
would probably take hours to compress... and decompress.

andy

-- 
Andy Nicholas		  GEnie & America-Online: shrinkit
Apple Computer, Inc.  	 	      CompuServe: 70771,2615    
Apple IIGS System Software		InterNET: shrinkit@apple.com

I'm doing this on my own time, so I don't speak for Apple.