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looking for file compresser


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#26 flashjazzcat ONLINE  

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Posted Tue Feb 13, 2018 8:10 AM

Also packing stuff into limited ROM space (for data which is unpacked into RAM, I should add), where one is constantly searching for an extra dozen bytes. :)

Edited by flashjazzcat, Tue Feb 13, 2018 8:11 AM.


#27 Heaven/TQA OFFLINE  

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Posted Tue Feb 13, 2018 8:25 AM

Or loading time savings even via Sio2sd highspeed....

#28 jmccorm OFFLINE  

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Posted Wed Feb 14, 2018 10:46 PM

Wisely used compression can make a difference between a game that needs to read levels from a floppy and a game that is distributed as a single binary load file (with all its advantages).
Or a difference between a program that needs 128 KB RAM or 64 KB RAM.


Thank you for making a strong argument!

#29 baktra OFFLINE  

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Posted Thu Feb 15, 2018 1:45 PM

As a cassette freak, I couldn't resist conducting an experiment with loading of the Curse of the Lost Miner game from cassette.

Compressed (with Super packer) 03:45 (including decompression). Not compressed: 06:41. Not so subtle difference. Of course, cassettes are no longer a concern.

With disk drive, the difference is not that big. 19 s and 15 s.



#30 Mr Robot OFFLINE  

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Posted Thu Jul 26, 2018 11:50 AM

Is it possible to detect the packer used on an XEX? Is it possible to unpack them?

 

I only have experience of Amiga packers but most of them were detectable and unpackable. 



#31 tebe OFFLINE  

tebe

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Posted Thu Jul 26, 2018 12:49 PM

https://github.com/epi/xebin

 

FlashPack pack/unpack

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#32 Fox-1 / mnx OFFLINE  

Fox-1 / mnx

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Posted Thu Jul 26, 2018 3:46 PM

Every packer has it's own characteristics so it's possible to detect which one is used.  Since the depacker routines are in the executable file it's technically possible to load it and save it back as an unpacked version.

 

For most files that are done with SuperPacker 1.0 from BeWe Soft it's not that difficult.  It's shows where all blocks of unpacked data are saved so you can save the memory locations block by block after loading and append them to create a working, non-packed, file again.  If the initial file worked with DOS it's very easy.  If not you need a memory monitor to alter some registers to enable DOS.  It's a bit harder when the file overwrites DOS-memory but not impossible, especially when using a custom O.S.



#33 CharlieChaplin OFFLINE  

CharlieChaplin

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Posted Fri Jul 27, 2018 8:05 AM

https://github.com/epi/xebin

 

FlashPack pack/unpack

 

Think I have a similar tool made by HiasSoft for me...  (works under WIN XP command processor for me).

 

Still it would be nice to get unpackers for DJ Packer (both versions), Superpacker 1.0 (Bewe), Powerpacker, Magnus Cruncher or Code3 Cruncher packed files to unpack them to their uncompressed form again (either for the PC or for the A8)...   ;-)

 

For very old packers and archivers there exist several A8 programs that can detect what packer or archiver (e.g. scrunch, squish, alf, etc.) had been used - but almost no-one ever used these old packers (that required extra depackers) or archivers (besides ARC and DCM)...

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#34 Fox-1 / mnx OFFLINE  

Fox-1 / mnx

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Posted Fri Jul 27, 2018 8:53 AM

The situation for archivers is a bit different as these are made to re-create non-compressed data.  A multi-depacker/de-cruncher that runs on bigger systems is certainly possible but it requires lot's of work to replicate and implement all depacker routines.

 

Older packers aren't a real problem as they mostly only used Run Lenght Encoding.

 

None-the-less, a tool like SuperPacker (the PC tool) to re-create de-crunched files would be a nice thing.

 

Also, when talking about Discommunicator and ARC... A PC tool to create (and restore) Atari 8-bit compatible archives would be welcome.  LZH, LZW and ZIP can be unpacked on A8 when archived with the right, limited, parameters but a tool to make them doesn't exist (not counting the CMD versions where you need to figure out what works and what doesn't for A8 usage).  Modern Win tools already dropped ARC support and LZH support is rare too.  Not to mention ALF and ZOO archives.






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