Re: matrix mixer control (Re: Complex mixer questio

[Abramo Bagnara <abramo.bagnara@libero.it>]

Jaroslav Kysela ha scritto:
> On Tue, 1 Apr 2003, Abramo Bagnara wrote:
> 
> 
>>I agree with Jaroslav fully:
>>- have one ALSA control for each primitive hw control (1536 different 
>>controls)
>>- add a field to struct sndrv_ctl_elem_info explaining how index field 
>>of sndvr_ctl_elem_id should be interpreted (32,16+16,10+11+11, ecc.)
>>
>>This permit to have native support for N dimensional control.
>>
>>About kernel memory issues, this concerns easily solvable implementation 
>>detail to not worry about when designing sane API.
> 
> 
> Ok, I've added the dimension description to the info structure. Although 
> it is completely irrelevant to data transfers.
> 
> Also, I've implemented multi element in the kernel space to save memory 
> and it makes the searching faster. The reference code is in the trident 
> driver. I'll recode other drivers containing many "same" controls to use 
> this method later.

The lack of sparse matrix support I see in your implementation is a very 
unfortunate design choice.

I suggest you to use an hash table pointing to a pair { kcontrol_index, 
kcontrol_volatile_index } (16+16 should be enough) for control id 
searching and to move index info into snd_kcontrol_volatile_t.

Note also that allocating snd_kcontrol_volatile's at end of struct 
_snd_kcontrol (i.e. adding

         snd_kcontrol_volatile_t vd[0];    /* volatile data */

at end of struct), you'd avoid an extra indirection and separate 
allocation (not had time to double check if this conflicts with 
something other, however).

-- 
Abramo Bagnara                       mailto:abramo.bagnara@libero.it

Opera Unica                          Phone: +39.546.656023
Via Emilia Interna, 140
48014 Castel Bolognese (RA) - Italy



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