From: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Date: Mon, 8 Jun 2020 14:10:10 +0000 (+0900)
Subject: seq: event_cntr: add an API to calculate the number of events
X-Git-Tag: v0.1.0~133
X-Git-Url: https://git.alsa-project.org/?a=commitdiff_plain;h=bdd9af6a209a01c310fad2d74021ba9a83d133d0;p=alsa-gobject.git

seq: event_cntr: add an API to calculate the number of events

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
---

diff --git a/src/seq/alsaseq.map b/src/seq/alsaseq.map
index d03af9b..745ecd0 100644
--- a/src/seq/alsaseq.map
+++ b/src/seq/alsaseq.map
@@ -172,6 +172,7 @@ ALSA_GOBJECT_0_0_0 {
 
     "alsaseq_event_cntr_get_type";
     "alsaseq_event_cntr_new";
+    "alsaseq_event_cntr_count_events";
   local:
     *;
 };
diff --git a/src/seq/event-cntr.c b/src/seq/event-cntr.c
index cc935c2..598dbf7 100644
--- a/src/seq/event-cntr.c
+++ b/src/seq/event-cntr.c
@@ -74,3 +74,82 @@ ALSASeqEventCntr *alsaseq_event_cntr_new(guint count, GError **error)
 
     return self;
 }
+
+static gsize calculate_event_size(struct snd_seq_event *ev, gboolean aligned)
+{
+    gsize size = sizeof(*ev);
+
+    switch (ev->flags & SNDRV_SEQ_EVENT_LENGTH_MASK) {
+    case SNDRV_SEQ_EVENT_LENGTH_VARIABLE:
+    {
+        const struct snd_seq_ev_ext *ext = &ev->data.ext;
+        if (aligned)
+            size += ext->len;
+        else
+            size += (ext->len + sizeof(*ev) - 1) / sizeof(*ev) * sizeof(*ev);
+        break;
+    }
+    default:
+        break;
+    }
+
+    return size;
+}
+
+struct event_iterator {
+    guint8 *buf;
+    gsize length;
+    gboolean aligned;
+
+    gsize offset;
+};
+
+static void event_iterator_init(struct event_iterator *iter, guint8 *buf,
+                                gsize length, gboolean aligned)
+{
+    iter->buf = buf;
+    iter->length = length;
+    iter->aligned = aligned;
+
+    iter->offset = 0;
+}
+
+static struct snd_seq_event *event_iterator_next(struct event_iterator *iter)
+{
+    struct snd_seq_event *ev;
+    gsize ev_size;
+
+    if (iter->offset + sizeof(*ev) > iter->length)
+        return NULL;
+    ev = (struct snd_seq_event *)(iter->buf + iter->offset);
+
+    ev_size = calculate_event_size(ev, iter->aligned);
+    if (iter->offset + ev_size > iter->length)
+        return NULL;
+    iter->offset += ev_size;
+
+    return ev;
+}
+
+/**
+ * alsaseq_event_cntr_count_events:
+ * @self: A #ALSASeqEventCntr.
+ * @count: (out): The count of stored events.
+ *
+ * count stored events.
+ */
+void alsaseq_event_cntr_count_events(ALSASeqEventCntr *self, gsize *count)
+{
+    ALSASeqEventCntrPrivate *priv;
+    struct event_iterator iter;
+    struct snd_seq_event *ev;
+
+    g_return_if_fail(ALSASEQ_IS_EVENT_CNTR(self));
+    priv = alsaseq_event_cntr_get_instance_private(self);
+
+    event_iterator_init(&iter, priv->buf, priv->length, priv->allocated);
+
+    *count = 0;
+    while ((ev = event_iterator_next(&iter)))
+        ++(*count);
+}
diff --git a/src/seq/event-cntr.h b/src/seq/event-cntr.h
index c737606..ac7caaa 100644
--- a/src/seq/event-cntr.h
+++ b/src/seq/event-cntr.h
@@ -47,6 +47,8 @@ GType alsaseq_event_cntr_get_type() G_GNUC_CONST;
 
 ALSASeqEventCntr *alsaseq_event_cntr_new(guint count, GError **error);
 
+void alsaseq_event_cntr_count_events(ALSASeqEventCntr *self, gsize *count);
+
 G_END_DECLS
 
 #endif
diff --git a/tests/alsaseq-event-cntr b/tests/alsaseq-event-cntr
index 9623190..8727bf5 100644
--- a/tests/alsaseq-event-cntr
+++ b/tests/alsaseq-event-cntr
@@ -13,6 +13,7 @@ target = ALSASeq.EventCntr()
 props = ()
 methods = (
     'new',
+    'count_events',
 )
 signals = ()