From: deleveld AT noord DOT bart DOT nl (Douglas Eleveld)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Multitasking - some questions
Date: Sat, 21 Sep 96 16:09:57 GMT
Organization: bART Groningen
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Message-ID: <52140l$37c_002@gn2.noord.bART.nl>
References: <3B7A2E0B15 AT spy DOT isp DOT nsc DOT ru>
NNTP-Posting-Host: asyn02.gn2.noord.bart.nl
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

I modified a simple multitasking unit for DOS and added suppourt for the FPU.
I wrote some simple functions in Assembler so save and restore the FPU.  This 
is necessary because if you have a task switch during a FPU calculation and 
the new task is also in the middle of a FPU calc you'll get the stacks mixed 
up and everything will be wrong and (at least I always got) floating point 
errors.  I wrote the routines in TASM for Borland C++ 3.1 (uugghh) and I'm 
also trying to port that thing over to DJGPP.  I expect that there won't be 
any trouble withe the FPU, only I dont know enough about protected mode 
switches and the transfer buffer to say if that will be screwed up during a 
task switch. 

If you want my routines for the comprcessor just ask and I'll mail them or 
post them.

BTW. If your multitasking thing is NOT preemptive then you should't have to 
worry about the FPU because you'll be calling the task switch routine yourself 
and you won't break into the middle of an FPU calculation.

P.S. Please send the this multi-tasking thing when you're done of post where 
we can get it, it's (almost) the last thing that is stopping me from porting 
EVERYTHING I have to DJGPP.

In article <3B7A2E0B15 AT spy DOT isp DOT nsc DOT ru>,
   "Ilya P. Ryzhenkov" <ILYA AT spy DOT isp DOT nsc DOT ru> wrote:
>
> Hi!
> 
> So the question is : %subj%
> I mean what I must keep in mind while developing 
> multitasking environment ?
> I've already developed "integer" one for Watcom and
> now porting it to djgpp. That's it, I've queued DOS 

--- LARGE SNIP ---

> To do :
> Port to djgpp, add FPU support, add run_thread_on_event feature 
> (this may be extremly usable in GUI) and much more.
> 
> Availability :
> Soon it'll be available ! ;)) hehe, just after i'll do those to-do's
> 
> Next Global Step : 
> Add Loadable Modules Support !!!
> 
> -- Give peace a chance ! --
> 
> 
> 
>
>======================================================================
>Institute of Semiconductors Physics                Ilya P. Ryzhenkov 
>Russian Academy of Sciencies             e-mail: ilya AT spy DOT isp DOT nsc DOT ru
>Siberian Branch                          http://spy.isp.nsc.ru