[9fans] Porting XaoS (saga continues)

[Jan Hubicka hubicka@horac.ta.jcu.cz]

On Tue, Sep 09, 1997 at 07:39:39AM +0000, forsyth@caldo.demon.co.uk wrote:
> see /sys/src/cmd/disk/kfs/libp/port/qlock.c and related
> files for a user-level QLock and RWLockimplementation.  you should
Opps. I have just demo installation so I can't read sources :(
I really want to see them, but I am poor student and $120 is too much
for me :(
> be able to implementat what you need with that.  note too that
> sleep(0) will relinquish the CPU.  see /sys/src/cmd/exportfs
> and /sys/src/cmd/telco for other examples of multi-process
> servers and different approaches to synchronisation.
> you'll also find a concurrency-safe version of
> malloc.c in at least one of those directories.
> 
> most new concurrent programs in Plan 9 are (best)
> written in Alef, so not much effort has gone into providing
I am sorry, but I don't plan to rewrite XaoS into alef, since I want
to keep portability with other OSes too.
> a complete programming package for the venerable C.
> 
> one point that's easy to overlook is that fork(2) notes that rfork(RFPROC|RFMEM)
> causes ALL subsequent forks to share data.  consequently, you need to ensure that
> einit(...) is called to initialise the graphics event code before you do
> the first RFMEM rfork, otherwise things can get a little bit confused.
Ok. Need I do that in case other tasks don't access graphics too?
(Linux requires the opposite so it would require one extra ifdef, wich
is always ugly... :( )
> 
> as to the second question, i'm afraid that Plan 9 graphics supports only
> up to 8 bits (0 <= Bitmap.ldepth <= 3).  it's not just 8½; it would require
> a fair amount of effort to change.
OK no problem :) So XaoS now supports all modes supported by 8 1/2 - 1boo
and 8 bpp :)
Yesterday I implemented dithering, so XaoS should emulate truecolor..

Honza

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