Re: how to define a 2-index control element?

[Takashi Iwai <tiwai@suse.de>]

At Tue, 7 May 2002 11:55:51 +0200 (CEST),
Jaroslav wrote:
> 
> On Tue, 7 May 2002, Takashi Iwai wrote:
> 
> > > Card specific code may solve all that easily.
> >  
> > that's true.
> > but user may start alsamixer (or what else) and get huge amount of
> > bars (i thought), which should be avoided.
> 
> We can avoid this in alsa-lib.
 
yes.  i meant, anyway we need to implement a kind of workaround in the
general code of alsa-lib, not only as a card-specific plugin.


> > > We need to separate in our minds the _basic_ hardware access and
> > > layout/display consideration. Kernel is for the former, libraries and
> > > applications for the latter.
> > 
> > i reconsidered this issue yesterday.
> > in this case, we need to take also the number of controls in the
> > kernel space into accout.  if we have an instance for each of 1400+
> > controls, there are really 1400+ mallocs, and we'll look for a control
> > by a linear search from them.
> > and most likely the hardware doesn't need them.
> > it will be a big drawback.
> 
> If someone has hardware with 1400+ controls, than memory allocation issue 
> is out of question. I wrote that we can optimize current code - add some 
> hash tables for faster lookups for example.

well, about 200kB is not so big nowadays :)

i thought the hardware doesn't need allocate 1400 controls - the
controls are identical but have different indices.
in such a case, the indexed-access would be most straightforward.
no hash, no list.


> > otoh, the indexed access as Paul's suggestion needs only one control.
> > the drawback of this method is, as Jaroslav pointed, the lack of
> > notification.  the notification can be done but we cannot know which
> > element is affected.
> 
> I think that it's much bigger drawback than allocation of some more 
> kilobytes of memory.

hmm...


Takashi

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