Add dequeue prototype

Author: Cuda-Chen

virtio-snd.c

@@ -712,6 +712,14 @@ static void __virtio_snd_frame_dequeue(short *out,
 
     props->ring.cons.tail = cons_next;
 
+    if (list_empty(&props->buf_queue_head))
+        goto finally;
+    vsnd_buf_queue_node_t *node =
+        list_first_entry(&props->buf_queue_head, vsnd_buf_queue_node_t, q);
+    list_del(&node->q);
+    // memcpy(out, node->addr, node->len);
+
+finally:
     props->ring.buf_ev_notity--;
     pthread_cond_signal(&props->ring.writable);
     pthread_mutex_unlock(&props->ring.lock);