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-rw-r--r--examples/plugins/sample_mixer_plugin.c319
1 files changed, 319 insertions, 0 deletions
diff --git a/examples/plugins/sample_mixer_plugin.c b/examples/plugins/sample_mixer_plugin.c
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index 0000000..e1a7567
--- /dev/null
+++ b/examples/plugins/sample_mixer_plugin.c
@@ -0,0 +1,319 @@
+/*
+** Copyright (c) 2021, The Linux Foundation. All rights reserved.
+**
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+** * Redistributions of source code must retain the above copyright
+** notice, this list of conditions and the following disclaimer.
+** * Redistributions in binary form must reproduce the above
+** copyright notice, this list of conditions and the following
+** disclaimer in the documentation and/or other materials provided
+** with the distribution.
+** * Neither the name of The Linux Foundation nor the names of its
+** contributors may be used to endorse or promote products derived
+** from this software without specific prior written permission.
+**
+** THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
+** WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+** MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT
+** ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
+** BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+** CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+** SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+** BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+** WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+** OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
+** IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+**/
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <sound/asound.h>
+#include <tinyalsa/plugin.h>
+#include <tinyalsa/asoundlib.h>
+
+#define SAMPLE_MIXER_PRIV_GET_CTL_PTR(p, idx) (p->ctls + idx)
+#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
+
+static const char *const sample_enum_text[] = {"One", "Two", "Three"};
+
+struct sample_mixer_priv {
+ struct snd_control *ctls;
+ int ctl_count;
+
+ struct snd_value_enum sample_enum;
+
+ mixer_event_callback event_cb;
+};
+
+static int sample_mixer_int_ctl_get(struct mixer_plugin *plugin,
+ struct snd_control *ctl, struct snd_ctl_elem_value *ev)
+{
+ return 0;
+}
+
+static int sample_mixer_int_ctl_put(struct mixer_plugin *plugin,
+ struct snd_control *ctl, struct snd_ctl_elem_value *ev)
+{
+/*
+ * Integer values can be retrieved using:
+ * uint32_t val1 = (uint32_t)ev->value.integer.value[0];
+ * uint32_t val2 = (uint32_t)ev->value.integer.value[1];
+ * uint32_t val3 = (uint32_t)ev->value.integer.value[2];
+ */
+ return 0;
+}
+
+static int sample_mixer_byte_array_ctl_get(struct mixer_plugin *plugin,
+ struct snd_control *ctl, struct snd_ctl_elem_value *ev)
+{
+ return 0;
+}
+
+static int sample_mixer_byte_array_ctl_put(struct mixer_plugin *plugin,
+ struct snd_control *ctl, struct snd_ctl_elem_value *ev)
+{
+/*
+ * Byte array payload can be retrieved using:
+ * void *payload = ev->value.bytes.data;
+ */
+
+ return 0;
+}
+
+static int sample_mixer_tlv_ctl_get(struct mixer_plugin *plugin,
+ struct snd_control *ctl, struct snd_ctl_tlv *ev)
+{
+ return 0;
+}
+
+static int sample_mixer_tlv_ctl_put(struct mixer_plugin *plugin,
+ struct snd_control *ctl, struct snd_ctl_tlv *tlv)
+{
+/*
+ * TLV payload and len can be retrieved using:
+ * void *payload = &tlv->tlv[0];
+ * size_t tlv_size = tlv->length;
+ */
+
+ return 0;
+}
+
+static int sample_mixer_enum_ctl_get(struct mixer_plugin *plugin,
+ struct snd_control *ctl, struct snd_ctl_elem_value *ev)
+{
+ return 0;
+}
+
+static int sample_mixer_enum_ctl_put(struct mixer_plugin *plugin,
+ struct snd_control *ctl, struct snd_ctl_elem_value *ev)
+{
+/*
+ * Enum value can be retrieved using:
+ * unsigned int val = ev->value.enumerated.item[0];
+ */
+ return 0;
+}
+
+static struct snd_value_int sample_mixer_ctl_value_int =
+ SND_VALUE_INTEGER(3, 0, 1000, 100);
+
+/* 512 max bytes for non-tlv byte controls */
+static struct snd_value_bytes byte_array_ctl_bytes =
+ SND_VALUE_BYTES(512);
+
+static struct snd_value_tlv_bytes sample_mixer_tlv_ctl_bytes =
+ SND_VALUE_TLV_BYTES(1024, sample_mixer_tlv_ctl_get, sample_mixer_tlv_ctl_put);
+
+static void create_integer_ctl(struct sample_mixer_priv *priv,
+ int ctl_idx, int pval, void *pdata)
+{
+ struct snd_control *ctl = SAMPLE_MIXER_PRIV_GET_CTL_PTR(priv, ctl_idx);
+ char *ctl_name = strdup("Sample integer control");
+
+ /* pval and pdata can be retrieved using snd_control during get()/put() */
+ INIT_SND_CONTROL_INTEGER(ctl, ctl_name, sample_mixer_int_ctl_get,
+ sample_mixer_int_ctl_put, sample_mixer_ctl_value_int, pval, pdata);
+}
+
+static void create_byte_array_ctl(struct sample_mixer_priv *priv,
+ int ctl_idx, int pval, void *pdata)
+{
+ struct snd_control *ctl = SAMPLE_MIXER_PRIV_GET_CTL_PTR(priv, ctl_idx);
+ char *ctl_name = strdup("Sample byte array control");
+
+ INIT_SND_CONTROL_BYTES(ctl, ctl_name, sample_mixer_byte_array_ctl_get,
+ sample_mixer_byte_array_ctl_put, byte_array_ctl_bytes,
+ pval, pdata);
+}
+
+static void create_tlv_ctl(struct sample_mixer_priv *priv,
+ int ctl_idx, int pval, void *pdata)
+{
+ struct snd_control *ctl = SAMPLE_MIXER_PRIV_GET_CTL_PTR(priv, ctl_idx);
+ char *ctl_name = strdup("Sample tlv control");
+
+ INIT_SND_CONTROL_TLV_BYTES(ctl, ctl_name, sample_mixer_tlv_ctl_bytes,
+ pval, pdata);
+}
+
+static void create_enum_ctl(struct sample_mixer_priv *priv,
+ int ctl_idx, struct snd_value_enum *e,
+ int pval, void *pdata)
+{
+ struct snd_control *ctl = SAMPLE_MIXER_PRIV_GET_CTL_PTR(priv, ctl_idx);
+ char *ctl_name = strdup("Sample enum control");
+
+ INIT_SND_CONTROL_ENUM(ctl, ctl_name, sample_mixer_enum_ctl_get,
+ sample_mixer_enum_ctl_put, e, pval, pdata);
+}
+
+static int sample_mixer_form_ctls(struct sample_mixer_priv *priv, int ctl_idx)
+{
+ create_integer_ctl(priv, ctl_idx, 0, NULL);
+ ctl_idx++;
+ create_byte_array_ctl(priv, ctl_idx, 0, NULL);
+ ctl_idx++;
+ create_tlv_ctl(priv, ctl_idx, 0, NULL);
+ ctl_idx++;
+ create_enum_ctl(priv, ctl_idx, &priv->sample_enum, 0, NULL);
+ ctl_idx++;
+
+ return 0;
+}
+
+static ssize_t sample_mixer_read_event(struct mixer_plugin *plugin,
+ struct snd_ctl_event *ev, size_t size)
+{
+ /* Fill snd_ctl_event *ev before sending.
+ * Return : sizeof(struct snd_ctl_event),
+ * 0 in case no event present.
+ */
+
+ return 0;
+}
+
+static int sample_mixer_subscribe_events(struct mixer_plugin *plugin,
+ mixer_event_callback event_cb)
+{
+ struct sample_mixer_priv *priv = plugin->priv;
+
+ priv->event_cb = event_cb;
+ /* event_cb is the callback function which needs to be called
+ * when an event occurs. This will unblock poll() on mixer fd
+ * which is called from mixer_wait_event().
+ * Once poll is unblocked, clients can call mixer_read_event()
+ * During unsubscribe(), event_cb is NULL.
+ */
+ return 0;
+}
+
+static int sample_mixer_alloc_ctls(struct sample_mixer_priv *priv)
+{
+ int ret = 0, i;
+
+ priv->ctls = calloc(priv->ctl_count, sizeof(*priv->ctls));
+ if (!priv->ctls) {
+ return -ENOMEM;
+ }
+
+ priv->sample_enum.items = ARRAY_SIZE(sample_enum_text);
+ priv->sample_enum.texts = calloc(priv->sample_enum.items, sizeof(*priv->sample_enum.texts));
+
+ for (i = 0; i < ARRAY_SIZE(sample_enum_text); i++)
+ priv->sample_enum.texts[i] = strdup(sample_enum_text[i]);
+
+ return sample_mixer_form_ctls(priv, 0);
+}
+
+static void sample_mixer_free_ctls(struct sample_mixer_priv *priv)
+{
+ int num_enums, i;
+ struct snd_control *ctl = NULL;
+
+ for (i = 0; i < priv->ctl_count; i++) {
+ ctl = SAMPLE_MIXER_PRIV_GET_CTL_PTR(priv, i);
+ if (ctl->name)
+ free((void *)ctl->name);
+ }
+
+ num_enums = priv->sample_enum.items;
+
+ for (i = 0; i < num_enums; i++)
+ free(priv->sample_enum.texts[i]);
+
+ free(priv->sample_enum.texts);
+ priv->ctl_count = 0;
+
+ if (priv->ctls) {
+ free(priv->ctls);
+ priv->ctls = NULL;
+ }
+}
+
+static void sample_mixer_close(struct mixer_plugin **plugin)
+{
+ struct mixer_plugin *mp = *plugin;
+ struct sample_mixer_priv *priv = mp->priv;
+
+ /* unblock mixer event during close */
+ if (priv->event_cb)
+ priv->event_cb(mp);
+ sample_mixer_subscribe_events(mp, NULL);
+ sample_mixer_free_ctls(priv);
+ free(priv);
+ free(*plugin);
+ *plugin = NULL;
+}
+
+int sample_mixer_open(struct mixer_plugin **plugin, unsigned int card)
+{
+ struct mixer_plugin *mp;
+ struct sample_mixer_priv *priv;
+ int i, ret = 0;
+ int ctl_cnt = 4;
+
+ mp = calloc(1, sizeof(*mp));
+ if (!mp) {
+ return -ENOMEM;
+ }
+
+ priv = calloc(1, sizeof(*priv));
+ if (!priv) {
+ ret = -ENOMEM;
+ goto err_priv_alloc;
+ }
+
+ priv->ctl_count = ctl_cnt;
+ ret = sample_mixer_alloc_ctls(priv);
+ if (ret)
+ goto err_ctls_alloc;
+
+ /* Register the controls */
+ mp->controls = priv->ctls;
+ mp->num_controls = priv->ctl_count;
+ mp->priv = priv;
+ *plugin = mp;
+
+ return 0;
+
+err_ctls_alloc:
+ sample_mixer_free_ctls(priv);
+ free(priv);
+
+err_priv_alloc:
+ free(mp);
+ return ret;
+}
+
+struct mixer_plugin_ops mixer_plugin_ops = {
+ .open = sample_mixer_open,
+ .close = sample_mixer_close,
+ .subscribe_events = sample_mixer_subscribe_events,
+ .read_event = sample_mixer_read_event,
+};