ZPic83

Post by **qarnos** » Fri 07 Jul, 2006 6:36 am

Hi guys,

Just poking through my old projects and I found zpic83 - an image compressor with an on-calc decompressor.

I never developed it to the point I would have liked but I thought, why keep it to myself?

The file can be downloaded here.

zpic83.exe can also be used to generate uncompressed images and is more forgiving than pic83 with regards to the image format (IIRC: pic83 required 1-bit PCX file... zpic83 doesn't care about colour depth).

It can take images of any size, but the decompressor will just output a flat stream of data, so it's only really useful for full-screen pics.

I actually wrote an on-calc compressor, which I still have, but it still needed a bit of work. Maybe once I've got the 3D engine out of the way I will take another look at it.

Post by **tr1p1ea** » Fri 07 Jul, 2006 7:18 am

Looks pretty cool, makes me wonder what else you have just 'lying around'

.

What method for compression did you use? Or did you create your own technique?

Post by **qarnos** » Fri 07 Jul, 2006 7:27 am

tr1p1ea wrote:Looks pretty cool, makes me wonder what else you have just 'lying around' .

What method for compression did you use? Or did you create your own technique?

It was either LZSS or LZ77... I can't remember but they are almost identical. I originally wanted to use LZW but it's patented.

Post by **tr1p1ea** » Fri 07 Jul, 2006 7:37 am

Nice, i believe coelurus used LZ77 compression for his maps in Gemini.

Had you planned on making a game or something that would make use of this? Or did you just intend on releasing it as a util?

Post by **qarnos** » Fri 07 Jul, 2006 7:41 am

tr1p1ea wrote:Nice, i believe coelurus used LZ77 compression for his maps in Gemini.

Had you planned on making a game or something that would make use of this? Or did you just intend on releasing it as a util?

I originally wanted to write a compression program for the calc. I actually made some "concept graphics" outlining how the screen would look, etc.

Another option I had considered was making self-extracting programs. It would be great for archive memory - store the program compressed, then decompress to RAM to run it. Although it screws program write-back if you want to use it.

Post by **tr1p1ea** » Fri 07 Jul, 2006 7:48 am

I believe Crunchy OS uses a similar tactic, of decompressing programs to RAM for execution. It solves the writeback problem by creating AppVars and patching programs i believe.

CompWiz · Post by **CompWiz** » Fri 07 Jul, 2006 3:27 pm

yeah, the compression is nice with crunchyOS for people with 83+ calcs, as you can fit more programs in. Plus, when a program crashes, it is safe in the archive, so it isn't corrupted or lost.
And yes, it does use AppVars and patching to do writeback.