/**
* \brief Get TLV value for an HCTL element
* \param elem HCTL element
* \param tlv TLV array for value
* \param tlv_size size of TLV array in bytes
* \return 0 otherwise a negative error code on failure
*/
int snd_hctl_elem_tlv_read(snd_hctl_elem_t *elem, unsigned int *tlv, unsigned int tlv_size)
{
assert(elem);
assert(tlv);
assert(tlv_size >= 12);
return snd_ctl_elem_tlv_read(elem->hctl->ctl, &elem->id, tlv, tlv_size);
}
static int check_tlv(struct elem_set_trial *trial)
{
unsigned int orig[8], curr[8];
int err;
/*
* See a layout of 'struct snd_ctl_tlv'. I don't know the reason to
* construct this buffer with the same layout. It should be abstracted
* inner userspace library...
*/
orig[0] = snd_ctl_elem_id_get_numid(trial->id);
orig[1] = 6 * sizeof(orig[0]);
orig[2] = 'a';
orig[3] = 'b';
orig[4] = 'c';
orig[5] = 'd';
orig[6] = 'e';
orig[7] = 'f';
/*
* In in-kernel implementation, write and command operations are the
* same for an element set added by userspace applications. Here, I
* use write.
*/
err = snd_ctl_elem_tlv_write(trial->handle, trial->id,
(const unsigned int *)orig);
if (err < 0)
return err;
err = snd_ctl_elem_tlv_read(trial->handle, trial->id, curr,
sizeof(curr));
if (err < 0)
return err;
if (memcmp(curr, orig, sizeof(orig)) != 0)
return -EIO;
return 0;
}
/*
* add the TLV string and dB ranges to comment fields
*/
static int add_tlv_comments(snd_ctl_t *handle, snd_ctl_elem_id_t *id,
snd_ctl_elem_info_t *info, snd_config_t *comment)
{
unsigned int tlv[MAX_USER_TLV_SIZE];
unsigned int *db;
long dbmin, dbmax;
int err;
if (snd_ctl_elem_tlv_read(handle, id, tlv, sizeof(tlv)) < 0)
return 0; /* ignore error */
if (snd_ctl_elem_info_is_tlv_writable(info)) {
char *s = tlv_to_str(tlv);
if (s) {
err = snd_config_string_add(comment, "tlv", s);
if (err < 0) {
error("snd_config_string_add: %s", snd_strerror(err));
return err;
}
free(s);
}
}
err = snd_tlv_parse_dB_info(tlv, sizeof(tlv), &db);
if (err <= 0)
return 0;
snd_tlv_get_dB_range(db, snd_ctl_elem_info_get_min(info),
snd_ctl_elem_info_get_max(info),
&dbmin, &dbmax);
if (err < 0)
return err;
snd_config_integer_add(comment, "dbmin", dbmin);
snd_config_integer_add(comment, "dbmax", dbmax);
return 0;
}
