Re: LZ: Compression program
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Alan Bailey wrote:
>
>That's a good idea, there's the ZShell header the first two bytes, and
> then the desription of the program next, so it might be 15 or so. But
> maybe the first byte after the description could tell the unzipper and
> zipper how many bytes to skip, like this:
>
> $02, $FF,$FF <this is the high score, and then comes the acrtual code
> ^
> skip two bytes
> This could take some refining, but it's a start
I like the idea of just a datafile somewhere... On Macintosh every app
is assigned a four character creator code, and each creator has a four
char type code. for example: TI-Graphlink 85 for mac has a creator code
of TI85. It recognizes "85S ", "85P ", "85G ", "85B ", "85M ", "85C ",
"85L ", "85V ", "85I ", "ASC " and a couple others. My point is this,
though. Assign each ZShell app a 2 character creator code ((2^8)^2)=
2^16=65536 possible) and it doesn't matter what letters each one gets.
Then all hiscores, prefs, passwords, whatever get put into a prefs
file. Way in the future, when we all use ZShell 5 or 6, apps can be
modified to read from the datafile. Datareader already does that from a
program, so the trick would be to use it.
Second, runtime decompression is a good idea if we can make it happen.
PKLite for DOS and LZWRes or AutoDoubler internal compressor for Mac do
that: compress the app once, and expand code as it's needed. Question
is, when we compress our apps, do we squish the whole thing, or maybe 32
byte chunks or what?
Third, someone posted something about I2C ram chips (EEPROMs,
actually). The idea expressed was to build an external ram drive,
effectively, including compression. That sounds almost OK, because we
have plans and code at ticalc.org for talking to an I2C eeprom. so what
is required is a data format. everything on the external is compressed,
and it is accessed as a virtual drive. you'd need a special "driver" to
do that, but it could be done. sounds kinda like flash memory card
disks. dr dobbs journal had some interesting stuff to say about that a
while ago.
yikes... well, 'nuff said for now.
Chris.
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