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