[alsa-devel] [PATCH] test: fix comment about first two fields of TLV data payload

[Clemens Ladisch]

Takashi Sakamoto wrote:
> On Aug 30 2016 14:32, Takashi Iwai wrote:
>> Takashi Sakamoto wrote:
>>> -    orig[0] = snd_ctl_elem_id_get_numid(trial->id);
>>> +    orig[0] = SNDRV_CTL_TLVT_CONTAINER;
>>>      orig[1] = 6 * sizeof(orig[0]);
>>>      orig[2] = 'a';
>>>      orig[3] = 'b';
>>
>> The container TLV type expects other TLVs as its content.  So the
>> above looks buggy to me...
>
> This is a test program just to serve to myself. So I hope this degree of roughness is allowed...
>
> Or could you please construct valid TLV array here?

In the kernel, you could use the macros from include/sound/tlv.h.

Either copy them into your test program, and use them directly:

	/* 4 words: */
	DECLARE_TLV_DB_MINMAX(orig, -60, +60);
	/* container with only one subitem; 8 words: */
	DECLARE_TLV_CONTAINER(orig_container,
		TLV_ITEM(SNDRV_CTL_TLVT_CHMAP_FIXED,
			 SNDRV_CHMAP_FL, SNDRV_CHMAP_FR, SNDRV_CHMAP_FC, SNDRV_CHMAP_LFE)
	);

or create the values by hand:

	orig[0] = SNDRV_CTL_TLVT_DB_MINMAX;
	orig[1] = 2 * sizeof(*orig);
	orig[2] = -60;
	orig[3] = +60;

	orig_container[0] = SNDRV_CTL_TLVT_CONTAINER;
	orig_container[1] = 6 * sizeof(*orig_container);
		orig_container[2] = SNDRV_CTL_TLVT_CHMAP_FIXED;
		orig_container[3] = 4 * sizeof(*orig_container);
		orig_container[4] = SNDRV_CHMAP_FL
		orig_container[5] = SNDRV_CHMAP_FR;
		orig_container[6] = SNDRV_CHMAP_FC;
		orig_container[7] = SNDRV_CHMAP_LFE;


Regards,
Clemens