snd_mixer_groups()

Fill a structure with the number of groups in the mixer

Synopsis:

#include <sys/asoundlib.h>

int snd_mixer_groups( snd_mixer_t * handle, 
                      snd_mixer_groups_t * groups );

Library:

libasound.so

Description:

The snd_mixer_groups() function fills the following structure with the number of groups in the mixer that the handle was opened on. It also fills in the array of group IDs pointed to by pgroups to a limit of groups_size.

The structure is:

typedef struct snd_mixer_groups_s
{
    int32_t     groups, groups_size, groups_over;
    uint8_t     zero[4];                    /* alignment -- zero fill */
    snd_mixer_gid_t *pgroups;
    void        *pzero;                     /* align pointers on 64-bits --> point to NULL */
    uint8_t     reserved[128];      /* must be filled with zero */
}       snd_mixer_groups_t;

This call requires that the pgroups pointer is NULL, or points to a valid storage location for the groups. Additionally, groups_size reflects the size of this storage location in sizeof(snd_mixer_gid_t) units. On a successful return, the groups member contains the total groups in the mixer, and groups_over the number of groups that couldn't be copied to the storage location.

Returns:

Zero on success, or a negative value on error.

Errors:

-EINVAL

Invalid handle.

Classification:

ALSA

See also:

snd_mixer_group_read(), snd_mixer_group_write()