[linux-audio-dev] Plugin APIs (again)

[David Olofson]

On Wednesday 11 December 2002 00.05, Steve Harris wrote:
> On Tue, Dec 10, 2002 at 10:28:29 +0100, David Olofson wrote:
> > > it'd still be interesting to know how the sync problems this
> > > method poses are solved: you cannot rely on executable code
> > > modifications to be atomic. an indirect jump instruction is
> > > not guaranteed to work ok: a pointer on x86 is 32 bits, and
> > > atomic is 24 bits (besides, indirect jumps have ill influence
> > > on the cache). could do this with branching though -- but you
> > > don't want your dsp code interspersed with volatile if()s.
> >
> > There's no problem if you just wait until no processing is going
> > on (this is when you'd normally block on the audio deice), and
> > then switch in the new version.
>
> The solution in SyncModular is much simpler, theres a big "Compile"
> button and when you press it the sound goes away for a second or so
> :)

Well, yeah - but I was under the impression that the idea was to 
*avoid* that. :-)


> > Obiously, you'll have to remake connections and all that stuff as
> > well, but that's no different from non-compiling approaches.
>
> Well, you dont because the connections are part of the code (at the
> lower levels at least).

Yeah. I was rather thinking about connections to the host or "outside 
world" - and then there's state data, of course.


> I think this is one of the things that makes it efficient.

Indeed. You can't beat passing data through registers without 
copying, and flow control by placement rather than jumping. :-)


//David Olofson - Programmer, Composer, Open Source Advocate

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