Jaroslav Kysela wrote: > > On Wed, 31 Oct 2001, Paul Davis wrote: > > > >there is something wrong with either the pcm.c example or with the > > >documentation in alsa-lib/src/pcm/pcm.c. > > > > > >the documentation says about snd_pcm_mmap_commit: > > > > > > 'To call this with offset/frames values different from that returned by > > > snd_pcm_mmap_begin has undefined effects and it has to be avoided.' > > > > IMHO. the documentation is wrong. it should say that you cannot call > > it with a value greater than the one returned by snd_pcm_mmap_begin(). > > > > all the commit does it to move forward the driver's notion of the "s/w > > pointer", used for tracking xruns etc. its fine to move it less than > > it could possibly be moved, but not OK to move it more. > > The documentation is correct, but the check in the pcm.c example is really > not necessary, because mmap_begin guarantees that the returned count of > frames is less or equal to the requested count. I corrected the > documentation. Using the same value as for mmap_begin is not necessary in > the current implementation, but we can rely on the same value in the > future, so please, follow the documentation to create "bug-free" > and clean applications.
I have to partially disagree, nothing inhibits to do: frames = buffer_size; snd_pcm_mmap_begin(pcm, areas, &offset, &frames); and then reduce the number of frames to call snd_pcm_mmap_commit with. Perhaps it's useless, but this is how I designed this API. -- Abramo Bagnara mailto:[EMAIL PROTECTED] Opera Unica Phone: +39.546.656023 Via Emilia Interna, 140 48014 Castel Bolognese (RA) - Italy ALSA project http://www.alsa-project.org It sounds good! _______________________________________________ Alsa-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/alsa-devel
