[Ffmpeg-devel] alsa input / output
Sun Mar 25 15:10:57 CEST 2007
On Sun, Mar 25, 2007 at 01:29:56PM +0100, M?ns Rullg?rd wrote:
> Michael Niedermayer <michaelni at gmx.at> writes:
> > Hi
> > On Sun, Mar 25, 2007 at 11:48:19AM +0200, Reimar D?ffinger wrote:
> >> Hello,
> >> On Sun, Mar 25, 2007 at 05:26:16AM +0200, Michael Niedermayer wrote:
> >> > > I should also note that such a lock-free implementation depends
> >> > > on volatile keyword working "well enough" and pointer reads and
> >> > > writes being atomic on the architecture...
> >> >
> >> > could you show one example where volatile makes a difference in practice?
> >> In practice maybe not, but in theory you could do
> >> while (av_fifo_size(f) <= 0) sleep();
> >> and the compiler might inline av_fifo_size (not gcc though unless we
> > NO!!!
> > no compiler can do this, it breaks the seperation of implementation and API
> > no way to relink with a lavu with different fifo implementation ...
> > any inlining must be limited to within lavu ...
> That's not a problem if the library is linked statically. I'm not
> aware of linker that can do such inlining, but I'm pretty sure it's
the linker would have to disassemble the code ...
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
The educated differ from the uneducated as much as the living from the
dead. -- Aristotle
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