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Conference hydra::amiga_v1

Title:AMIGA NOTES
Notice:Join us in the *NEW* conference - HYDRA::AMIGA_V2
Moderator:HYDRA::MOORE
Created:Sat Apr 26 1986
Last Modified:Wed Feb 05 1992
Last Successful Update:Fri Jun 06 1997
Number of topics:5378
Total number of notes:38326

5247.0. "Powerpacker and similar compress/decompressors." by ULTRA::BURGESS (Mad Man across the water) Thu Dec 05 1991 11:37

	I have been browsing recent fish disks lately and found the 
powerpacker utilities interesting.  I would like to save some disk 
space anyway, but would like to do it by installing something  
"transparent"  that will just flip into file compress mode as soon as 
it realizes that the compress/decompress overhead is worth the time 
saved by accessing fewer blocks.  My guess (assumption) is that 3
blocks can normally be compressed to 2 and the time required to 
compress/decompress it is less than the time required to (not) access
the (saved) third block.  OK, maybe these numbers are off, but a few
studied experiments with disk-speed and powerpacker could soon come up
with the right break even point and my intuit sez its probably at a
fairly small number of blocks, i.e. less than the size of the buffer
space, so writing could be delayed until it is known that the file 
will be big enough to be worth compressing.  My question is how
transparent is powerpacker ?, or how transparent could it or a similar
utility be made ? 

	Reg

PS  I havn't seen many notes on it, maybe that should tell me 
    something ?


T.RTitleUserPersonal
Name
DateLines
5247.1thumbs up for PowerPackerWHAMMY::spodarykFor three strange days...Thu Dec 05 1991 12:2314
I generally PowerPack as much as many executables as I can - particularly
the large apps.  I don't notice any real delay due to decompression, but
the 020 probably helps that.

It might be worth doing some rough timings on starting up compressed -vs-
uncompressed applications.  M68000 vs 020 vs 030 might be useful.

Depending on the degree of compression you choose, I think it's generally
a 50-60% reduction.  There are somethings that won't compress, but I've
never had any problems with the stuff that is.  You compress the file
one time, and it attaches a small decompress header onto the file.
Very transparent.  

Steve
5247.21 thumb up, 1 questionTFH::KIRKa simple songThu Dec 05 1991 14:5433
I finally got PowerPacker, and it seems to do a good job.  I spent an evening 
going through files to compress, but I believe you can set up a script to do 
that as well.

I saved about 2 Meg out of 25 Meg used, and while the executables are 40 to 
60% smaller, it turns out that the scads of other files applications use 
aren't compressable.  (Like ProWrite is smaller, but the thesaurus and 
dictionary are the same size...)  So it's not like everything you own can be 
condensed.

I've got a 33 Mhz '030 GVP exhilarator, and it takes maybe 2 tenths of a 
second to unpack a 300K application.

It takes a minute or so to do the compression, and I've never seen more than a 
few per cent difference between the 5 or so levels of compression available.

Graphic and text files can be compressed, but then you can't just call them up 
into your paint program or editor and let them decompress themselves before 
use.  Mainly, once you've completed them, you can compress them, and then use 
the PowerPacker utilities to view them.  Maybe that means I have too many 
unfinished projects on my disks!  .-)

Question:  I've generated several multi-Meg animations, and when I try to 
PPack them, I'm told that there's not enough memory available (for instance a 
3 Meg anim file, and I've got 6 Meg Fast RAM, 2 Meg Chip)  (I think  that's
what the error window says, my memory gets more volatile every day.)  Any
clews? 

Overall, I think it's worth the $23 I spent for it.  

Thanks,

Jim
5247.3CSEXP1::ANDREWSI'm the NRAThu Dec 05 1991 15:2813
    There is a program out that will do kinda what you are looking for.  It
    intercepts the read from a file, and decompresses it on the fly for
    data.  So, you could use it to decompress the thesaurus, and any other
    static data.
    
    It does not do the compress on a save, you have to do that manually.
    So, it is only good for static datafiles.
    
    It think it is called pppatch or something similar.  I would imagine it
    is on a fish disk, or I found it on a local bbs.  I'll see if I can
    still find the original lzh file I got it from.
    
    Rob
5247.4with knobs onUPROAR::JARRETTPInspired Madman or Complete Jackass?Sun Dec 08 1991 09:487
    You should know that the PP patch program intercepts all reads so that
    you can even compress fonts, device drivers and maybe even icons.
    
    As an aside Power Packer 3.0 is not public domain and it really
    shouldn't be on EOT::UPLOAD. If you want to buy it (~8 pounds) you'll
    have to get it from amiganuts PD in the uk.