Re: A82: Checksums and modules
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Re: A82: Checksums and modules
>Sorry I didn't make myself clear the first time. What I'm asking is how to
>figure the checksum the calc uses to determine if a PRGM is okay to accept
>through the link cable. Also, how would you go about reserving and
>removing space in the RAM for modules such as these? I want to be able to
>create levels on the 82, compress them, and then use my link cable to
>transfer them between computer and calc.
To create,delete,resize variables you need to use the biuld in function
(like on the ti85). I have not tested them with Ash, but they might work
(try it), they will not work with OS82.
>
>BTW, can anyone give me a list of compression algorithms that have been
>used for the 82 (and how well they do it)? My best algorithm can currently
>compress 50 bytes (SQRXZ world) down to 11 bytes (78% compression) using
>PCX bitmap style compression.
When this was discussed on list-zshell awhile ago, two algorithmes where
tried (bith intended to be used with BW pictures).
The simpel one (which I suggested) is
in each byte the first bit is the state of the following bit, and the rest
is the count.
So FF 82 7F = 128 black pixels, 2 black pixels, 128 white pixels.
The other one (which Stephan Jantzen? sugested) is a bit more complex, but
you can find info and code on ticalc.org. (It is called ZCP)
Both algorithmes where tested in games with bw pictures and gave a good
compression. ZCP is probably the best, the algorithme was optimezed to give
the best compression rates.
Dines
>
>
> Thomas J. Hruska -- thruska@tir.com
>Shining Light Productions -- "Meeting the needs of fellow programmers"
> http://www.geocities.com/SiliconValley/Heights/8504
> http://shinelight.home.ml.org
>
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