[CDG5] Random questions

Elliot Nunn elliotnunn at fastmail.com
Mon Dec 10 23:10:06 AWST 2018


Grepping through System 9.2.2 reveals several compressed resources:

$ SimpleDeRez ~/System/..namedfork/rsrc -compcmt -ascii | grep -A3 _compressed | head -n9
data 'CDEF' (62, $61 /*sysheap, purgeable, _compressed*/) {
	$"A89F 6572 0012 0901 0000 0454 0003 03FF"            /* ..er.......T.... */
	$"0000 3F04 E56F FF44 8E70 7082 A2E0 0083"            /* ..?..o.D.pp..... */
	$"E2E0 0122 86E0 00E7 C0A2 0544 3EEF FF85"            /* ...".......D>... */
--
data 'DRVR' (2, ".Print", $71 /*sysheap, purgeable, locked, _compressed*/) {
	$"A89F 6572 0012 0901 0000 019A 0003 03FF"            /* ..er............ */
	$"0000 2278 058F FC90 00A0 00B0 00C0 00D0"            /* .."x............ */
	$"18B9 41C9 A5B9 D080 0001 1149 5948 0008"            /* ..A........IYH.. */

Could you have used a search method that extracted the resources
automatically?

Here are some Donn resources, both compressed and extracted (manual
operation... ugh!). How will I identify the mysterious Mac OS 9 format?

https://github.com/elliotnunn/donn-examples

Good for Greg!

> On 10 Dec 2018, at 9:24 pm, Max Poliakovski <maximumspatium at googlemail.com> wrote:
> 
> MacOS 9 doesn't apparently use compressed resources. I looked into the resource map of the System file from MacOS 9.2.2 and couldn't find any resource starting with 0xA89F6572.
> 
> Moreover, dcmp 3 does exist as 68k code only while Donn&Gregg decompression methods have PPC equivalents in 'ncmp' resources.
> 
> I therefore need more compressed resources for testing purpose. It would be great I you could locate Donn-compressed resources as well. They usually start with 0xA89F6572 00XX 0801...
> 
> Regarding re-compression, I think it should be easy to build a compressor for GreggyBits controlled by the decompression params. I'm not sure if the original compressor (whose source isn't publicly available) had an automatic way of determining best-fit compression params...
> 
> BTW, the author of GreggyBits compression - Greg Marriott - still does software development. According to his blog http://www.greggybits.com/about.html, he works for Apple again. He'd be surely pleased to see his ol' stuff reimplemented in Python. I'd do in his place...
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