Re: [cc65] Zero page, C stack, and interrupts

On Mittwoch 28 April 2010, you wrote:
> Well good sir, why aren't we all using Groenix by now?  I'd like to
> give it a whirl myself.  

hehe well, as i wrote in an earlier mail, i keep my cc65 install bleeding edge 
(as in, i use a recent svn version) usually, and somehow it broke my stuff  
recently, no idea why. its also not quite finished or even useful at all, it 
"boots", loads a shell, and then you can barely do more than "ls" and "cat" 
and "ps" =) the largest "app" that exists right now is the texteditor "ned" 
(which i ported from JOS/Wings), and that one is almost unuseable because of 
too little memory =P (infact, memory is the one big problem. its even worse 
than with contiki)

> Are your libraries re-entrant?

most stuff is i guess, but the code is kinda ugly... for some functions (like 
xyprintf stuff) i just rewrote them in C, which makes them really large and 
slow, and some others i made work by wrapping critical parts into critical 
sections using semaphores (and that makes them specific to my kernel). that 
said, its maybe about 20 functions that need such fixes, not *that* much.

> A fully capable paged memory extension cartridge would REALLY
> come in handy for keeping re-entrant libraries fast.  But I
> haven't built that quite yet, have I?

hehe well, that would kill all the fun for me though :) if it doesnt work on a 
stock c64, then i dont care =)
 
> But then there's the careful use of CS and other semaphores.
> If the O/S has good cooperative support, how much would you
> REALLY need re-entrant code?  Most non-reentrant calls are
> short enough that other processes can block w/o causing
> problems.  Those that tie up shared memory for a long time
> perhaps wouldn't gain much from all the shortcuts.

well, for cooperative multitasking you dont really need reentrant libraries at 
all (look at contiki for an example). my goal was a relativly simple and 
straightforward preemptive kernel, that allows to write apps more or less "the 
usual way" without dealing with special OS related stuff too much (there still 
is some ofcourse, for creating new tasks, pipes, semaphores etc). the only 
thing i have that could be called "cooperative" is the "sleep" systemcall.
 
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