[alsa-devel] sw parameter boundary
is the boundary sw parameter still used ? where is it for ?
in the PCM kernel core (e.g. snd_pcm_playback_avail) it clearly serves as a pointers wrap point, but which one ? The one at the end of the DMA buffer or the one at the end of a process (virtual) address range (4 GB) ?
At Wed, 25 Jun 2008 10:44:19 +0200, Norbert van Bolhuis wrote:
is the boundary sw parameter still used ?
Yes.
where is it for ?
It defines the wrap point to the position 0.
in the PCM kernel core (e.g. snd_pcm_playback_avail) it clearly serves as a pointers wrap point, but which one ?
It's for the absolute position handled internally. This isn't exported outside, so you don't care much about it, normally.
The one at the end of the DMA buffer or the one at the end of a process (virtual) address range (4 GB) ?
No.
Takashi
At Thu, 26 Jun 2008 10:43:08 +0200, Norbert van Bolhuis wrote:
It's for the absolute position handled internally. This isn't exported outside, so you don't care much about it, normally.
OK, but what does an ALSA driver need to do with boundary, nothing ?
The boundary is aligned to buffer_size so that the offset can be calculated properly even after the overwrap.
Takashi
OK, but what does an ALSA driver need to do with boundary, nothing ?
The boundary is aligned to buffer_size so that the offset can be calculated properly even after the overwrap.
OK, so I assume that's a yes. I don't see any driver maniplating boundary though.
participants (2)
-
Norbert van Bolhuis -
Takashi Iwai