Hi you all !
"CLAUDIO MASSAO KAWATA" [EMAIL PROTECTED] wrote:
(...)
Unfortunately, nothing, and that's why I'm mentioning it: there is
no EXE-packer for MSX! Or is there and I never realized that?
There is: POPCOM.COM: easy to use, not so great compression
(compressed .COM file usually some 60-65 % of original)
Also restoring compressed files doesn't always work perfectly
(although unpacking on execution goes fine).
But PMarc can also (in conjuction with some other file) produce
self-extracting COM-files. But works difficult, and reeeaaalllyyy
**ZZzzz** slow
POPCOM de-compresses really quickly, about as fast as when loading it
from a slow drive.
Yes, right, MSX would run out of memory and the program would be too
slow to start executing.
Need not be so. If the file is compressed, that means space is saved,
that can be used for the unpacking code.
Also when the compressed file is smaller, this saves on disk load
time. The net result is just a matter of compression efficiency,
speed, and code size required to use it.
Maybe MSX shouldn't have an EXE-packer...
Could someone find a use to an EXE-packer for MSX...?
(no use, there are no EXE's to pack on MSX...;-)
Use is limited, because...most MSX program files simply aren't that
big..(what's 20 kB., even for a Z80?).
Disadvantages:
-sometimes difficult to see IF a file is compressed (or what method)
-difficult to modify with a simple disk-editor
-might interfere with programs that store settings in the COM-file
itself (like with TED editor)
Advantages:
-less disk space needed
-difficult to modify with a simple disk-editor
(more difficult for hackers)
On PC's (sorry..) that's just a different calculation, with far
bigger EXEs, more memory disk space, faster CPU's etc.
BTW: PC's LHA can also produce self-extracting .LZH files (eh, well,
EXE's). Does anyone know if MSX's LHPACK can do that as well?
The docs don't and, for a long time, won't contain
the "important" data, that is, the compression algorithms. It
happens that most of them are copyrighted (yes, we live in a world
where ideas can be labelled and hidden in a safe). If someone
really wants to make a PKZip compatible compressor/decompressor,
get QUICK the Info-ZIP's freewares "zip" and "unzip" sources,
they still contain the implementation of all PKZip methods.
The only ones that are really annoying are "shrink" and "unshrink",
the copyright owners* are trying to force the group to keep the
implementations out of the package (they are currently part of the
source files, but they are not compiled "normally", you must make
custom versions if you want to have your "zip" and "unzip" to use
the methods - I tried but couldn't, too much for the poor Boreland
C compiler, and not enough patience/time to set-up DJGPP). The
other methods ("stone", "melt" and so on) work fine in PC (DOS),
Unix (Sun Sparcs, Digital Alphas) and Linux. Only once I got a
file that was "crunched" and had to dig out my PKUnzip (ugh!)
Check "http://ftp.unicamp.br/pub/pc/archivers/" (the address
is correct, it is HTTP to access an old FTP site - FTP is also
available), files "unzip540.zip" (PLEASE, DON'T LAUGH! - yes, the
sources are packed!) and "zip22.zip/zip23k.zip" (the second is
new beta). If you have access to a PC clone, download also the
"self-extractor", so you can extract, later, the sources (look
out for a ".EXE").
These sources can also be found on a more well known source: SimTel
(in the DOS collection, I think).
It does contain *all* sources for PKZIP 2.04-compatible crunching
uncrunching. Sources are in C though...
*And now, my spamming against the copyright (claimers) owners
of the shrink algorithm. Since 1987, Compuserve has spread a new
image file format, the very well known GIF. It uses an algorithm
named Lempel-Ziv-Huffman (LZH).
Errata: GIF uses LZW (Lempel, ZivWelch) method.
I suspect similar to LZH ( ARC, ZIP etc.), but still something
different.
And I agree, GIF copyright policy sucks bigtime
(if possible, better use PNG for instance).
(choose your favourite "I HATE YOU" word). Of course, other programs
also used LZH (LHA, PKZip and so on) and they also have to pay for
the use of the algorithm (that is not all that good - there are better
around - but files that use it saturate the world).
Nonsense...these are really different methods (although maybe having
some common origin).
LZH = freeware by some Japanese dude, and nobody's gonna change
that(sources available too)
And ZIP is *really* a free format. There have been many companies and
interested parties who investigated ZIP's copyrights, and common view
is that it's FREE (and should be).
And so was written...
Alwin Henseler ([EMAIL PROTECTED])
http://huizen.dds.nl/~alwinh/msx MSX Tech Doc page
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