* sw parameter boundary
@ 2008-06-25 8:44 Norbert van Bolhuis
2008-06-25 15:45 ` Takashi Iwai
0 siblings, 1 reply; 5+ messages in thread
From: Norbert van Bolhuis @ 2008-06-25 8:44 UTC (permalink / raw)
To: alsa-devel
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) ?
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* Re: sw parameter boundary
2008-06-25 8:44 sw parameter boundary Norbert van Bolhuis
@ 2008-06-25 15:45 ` Takashi Iwai
2008-06-26 8:43 ` Norbert van Bolhuis
0 siblings, 1 reply; 5+ messages in thread
From: Takashi Iwai @ 2008-06-25 15:45 UTC (permalink / raw)
To: Norbert van Bolhuis; +Cc: alsa-devel
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
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: sw parameter boundary
2008-06-25 15:45 ` Takashi Iwai
@ 2008-06-26 8:43 ` Norbert van Bolhuis
2008-06-26 10:19 ` Takashi Iwai
0 siblings, 1 reply; 5+ messages in thread
From: Norbert van Bolhuis @ 2008-06-26 8:43 UTC (permalink / raw)
Cc: alsa-devel
> 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 ?
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* Re: sw parameter boundary
2008-06-26 8:43 ` Norbert van Bolhuis
@ 2008-06-26 10:19 ` Takashi Iwai
2008-06-26 14:36 ` Norbert van Bolhuis
0 siblings, 1 reply; 5+ messages in thread
From: Takashi Iwai @ 2008-06-26 10:19 UTC (permalink / raw)
To: Norbert van Bolhuis; +Cc: alsa-devel
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
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: sw parameter boundary
2008-06-26 10:19 ` Takashi Iwai
@ 2008-06-26 14:36 ` Norbert van Bolhuis
0 siblings, 0 replies; 5+ messages in thread
From: Norbert van Bolhuis @ 2008-06-26 14:36 UTC (permalink / raw)
To: alsa-devel
>> 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.
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end of thread, other threads:[~2008-06-26 14:36 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
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2008-06-25 8:44 sw parameter boundary Norbert van Bolhuis
2008-06-25 15:45 ` Takashi Iwai
2008-06-26 8:43 ` Norbert van Bolhuis
2008-06-26 10:19 ` Takashi Iwai
2008-06-26 14:36 ` Norbert van Bolhuis
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