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/**
* \file control/eld.c
* \brief ELD decoder
* \author Jaroslav Kysela <perex@perex>
* \date 2022
*/
/*
* Control Interface - Decode ELD
*
* Copyright (c) 2022 Jaroslav Kysela <perex@perex.cz>
*
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>
#include "control_local.h"
static void __fill_eld_ctl_id(snd_ctl_elem_id_t *id, int dev, int subdev)
{
snd_ctl_elem_id_set_interface(id, SND_CTL_ELEM_IFACE_PCM);
snd_ctl_elem_id_set_name(id, "ELD");
snd_ctl_elem_id_set_device(id, dev);
snd_ctl_elem_id_set_index(id, subdev);
}
int __snd_pcm_info_eld_fixup(snd_pcm_info_t * info)
{
snd_ctl_t *ctl;
snd_ctl_elem_info_t cinfo = {0};
snd_ctl_elem_value_t value = {0};
unsigned char *eld;
unsigned int l;
char *s, c;
int ret, valid;
ret = snd_ctl_hw_open(&ctl, NULL, info->card, 0);
if (ret < 0) {
SYSMSG("Cannot open the associated CTL\n");
return ret;
}
__fill_eld_ctl_id(&cinfo.id, info->device, info->subdevice);
value.id = cinfo.id;
ret = snd_ctl_elem_info(ctl, &cinfo);
if (ret >= 0 && cinfo.type == SND_CTL_ELEM_TYPE_BYTES)
ret = snd_ctl_elem_read(ctl, &value);
snd_ctl_close(ctl);
if (ret == -ENOENT || cinfo.type != SND_CTL_ELEM_TYPE_BYTES || cinfo.count == 0)
return 0;
if (ret < 0) {
SYSMSG("Cannot read ELD\n");
return ret;
}
/* decode connected HDMI device name */
eld = value.value.bytes.data;
if (cinfo.count < 20 || cinfo.count > 256)
return -EIO;
l = eld[4] & 0x1f;
if (l == 0 || l > 16 || 20 + l > cinfo.count)
return -EIO;
s = alloca(l + 1);
s[l] = '\0';
/* sanitize */
valid = 0;
while (l > 0) {
l--;
c = eld[20 + l];
if (c < ' ' || c >= 0x7f) {
s[l] = ' ';
} else {
valid += !!isalnum(c);
s[l] = c;
}
}
if (valid > 3)
snd_strlcpy((char *)info->name, s, sizeof(info->name));
return 0;
}
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