Hi Robin, On Tue, 2008-01-08 at 22:58 -0500, Robin Getz wrote: > OK - I see in: > > http://www.alsa-project.org/~tiwai/writing-an-alsa-driver/x1405.htm > > I assume that is what you mean? Exactly, yes. > If so, I'm still confused - since the pcmcia/vx (vxpocket driver) doesn't seem > to do that... ?? Hmmm, I never looked at the vxpocket driver .... > I do see the driver in pci/rme32.c - it is using pcm-indirect.h and the > snd_pcm_indirect_xxx functions - if that is the one we should be looking at? Yes. rme32.c is a good example. > My only question is - if you allow a mmaped intermediate buffer, how does the > driver notice when ALSA writes into this buffer? It's the ack() callback. ALSA writes/reads something into/from the intermediate buffer and calls the driver's ack() callback - if there is any. In the ack() callback the driver should call one of the snd_pcm_indirect_*_transfer() functions. There, the difference between current and last seen appl_ptr gives the "new position" of the PCM Layer in your intermediate buffer (where it will write/read next time). Joachim _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
