v4l2src: add a function pointer for get_frame function and optimize a bit

Use a function-pointer for mmap/read, as this can't change during capture. Also
sprinkle a few G_LIKELY/UNLIKELY to improve the error-less code path.

2 files changed, 18 insertions, 8 deletions

diff --git a/sys/v4l2/gstv4l2src.c b/sys/v4l2/gstv4l2src.c
index 783a6bd1..1178f5a8 100644
--- a/sys/v4l2/gstv4l2src.c
+++ b/sys/v4l2/gstv4l2src.c
@@ -202,6 +202,12 @@ static void gst_v4l2src_set_property (GObject * object, guint prop_id,
 static void gst_v4l2src_get_property (GObject * object, guint prop_id,
     GValue * value, GParamSpec * pspec);
 
+/* get_frame io methods */
+static GstFlowReturn
+gst_v4l2src_get_read (GstV4l2Src * v4l2src, GstBuffer ** buf);
+static GstFlowReturn
+gst_v4l2src_get_mmap (GstV4l2Src * v4l2src, GstBuffer ** buf);
+
 static void
 gst_v4l2src_base_init (gpointer g_class)
 {
@@ -616,6 +622,12 @@ gst_v4l2src_set_caps (GstBaseSrc * src, GstCaps * caps)
   if (!gst_v4l2src_capture_init (v4l2src, caps))
     return FALSE;
 
+  if (v4l2src->use_mmap) {
+    v4l2src->get_frame = gst_v4l2src_get_mmap;
+  } else {
+    v4l2src->get_frame = gst_v4l2src_get_read;
+  }
+
   if (!gst_v4l2src_capture_start (v4l2src))
     return FALSE;
 
@@ -850,7 +862,7 @@ gst_v4l2src_get_mmap (GstV4l2Src * v4l2src, GstBuffer ** buf)
 
 again:
   ret = gst_v4l2src_grab_frame (v4l2src, &temp);
-  if (ret != GST_FLOW_OK)
+  if (G_UNLIKELY (ret != GST_FLOW_OK))
     goto done;
 
   if (v4l2src->frame_byte_size > 0) {
@@ -889,13 +901,9 @@ gst_v4l2src_create (GstPushSrc * src, GstBuffer ** buf)
   GstV4l2Src *v4l2src = GST_V4L2SRC (src);
   GstFlowReturn ret;
 
-  if (v4l2src->use_mmap) {
-    ret = gst_v4l2src_get_mmap (v4l2src, buf);
-  } else {
-    ret = gst_v4l2src_get_read (v4l2src, buf);
-  }
+  ret = v4l2src->get_frame (v4l2src, buf);
   /* set buffer metadata */
-  if (ret == GST_FLOW_OK && *buf) {
+  if (G_LIKELY (ret == GST_FLOW_OK && *buf)) {
     GstClock *clock;
     GstClockTime timestamp;
 
diff --git a/sys/v4l2/gstv4l2src.h b/sys/v4l2/gstv4l2src.h
index fef3f108..68f45d97 100644
--- a/sys/v4l2/gstv4l2src.h
+++ b/sys/v4l2/gstv4l2src.h
@@ -45,7 +45,7 @@ G_BEGIN_DECLS
 typedef struct _GstV4l2Src GstV4l2Src;
 typedef struct _GstV4l2SrcClass GstV4l2SrcClass;
 
-
+typedef GstFlowReturn (*GstV4l2SrcGetFunc)(GstV4l2Src * v4l2src, GstBuffer ** buf);
 
 /**
  * GstV4l2Src:
@@ -80,6 +80,8 @@ struct _GstV4l2Src
   guint64 offset;
 
   gint     fps_d, fps_n;       /* framerate if device is open */
+  
+  GstV4l2SrcGetFunc get_frame;
 };
 
 struct _GstV4l2SrcClass