[PATCH v1 08/24] media: v4l2: Reorder field reflist

[Nicolas Dufresne <nicolas.dufresne@collabora.com>]

As per spec, the field refslist requires interleaving top and bottom
field in a specific way that does not fit inside the sort operation.
Reorder in-place the references so that their parity sart with the same
parity as the current picture and do that for both short and longterm
references separately.

Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
---
 drivers/media/v4l2-core/v4l2-h264.c | 45 +++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-h264.c b/drivers/media/v4l2-core/v4l2-h264.c
index c3fad382882d..2f7ee8d5479f 100644
--- a/drivers/media/v4l2-core/v4l2-h264.c
+++ b/drivers/media/v4l2-core/v4l2-h264.c
@@ -243,6 +243,43 @@ static int v4l2_h264_b1_ref_list_cmp(const void *ptra, const void *ptrb,
 	return poca < pocb ? -1 : 1;
 }
 
+/*
+ * The references need to be reorder so that reference are alternating between
+ * top and bottom ref starting with the current picture parity. This have to be
+ * done for short term and long term references separately.
+ */
+static void reorder_field_reflist(const struct v4l2_h264_reflist_builder *b,
+				  struct v4l2_h264_reference *reflist)
+{
+	struct v4l2_h264_reference tmplist[V4L2_H264_REF_LIST_LEN];
+	u8 lt, i = 0, j = 0, k = 0;
+
+	memcpy(tmplist, reflist, sizeof(tmplist[0]) * b->num_valid);
+
+	for (lt = 0; lt <= 1; lt++) {
+		do {
+			for (; i < b->num_valid && b->refs[tmplist[i].index].longterm == lt; i++) {
+				if (tmplist[i].fields == b->cur_pic_fields) {
+					reflist[k] = tmplist[i];
+					k++;
+					i++;
+					break;
+				}
+			}
+
+			for (; j < b->num_valid && b->refs[tmplist[j].index].longterm == lt; j++) {
+				if (tmplist[j].fields != b->cur_pic_fields) {
+					reflist[k] = tmplist[j];
+					k++;
+					j++;
+					break;
+				}
+			}
+		} while ((i < b->num_valid && b->refs[tmplist[i].index].longterm == lt) ||
+			 (j < b->num_valid && b->refs[tmplist[j].index].longterm == lt));
+	}
+}
+
 static char ref_type_to_char (u8 ref_type)
 {
 	switch (ref_type) {
@@ -345,6 +382,9 @@ v4l2_h264_build_p_ref_list(const struct v4l2_h264_reflist_builder *builder,
 	sort_r(reflist, builder->num_valid, sizeof(*reflist),
 	       v4l2_h264_p_ref_list_cmp, NULL, builder);
 
+	if (builder->cur_pic_fields != V4L2_H264_FRAME_REF)
+		reorder_field_reflist(builder, reflist);
+
 	print_ref_list_p(builder, reflist);
 }
 EXPORT_SYMBOL_GPL(v4l2_h264_build_p_ref_list);
@@ -378,6 +418,11 @@ v4l2_h264_build_b_ref_lists(const struct v4l2_h264_reflist_builder *builder,
 	sort_r(b1_reflist, builder->num_valid, sizeof(*b1_reflist),
 	       v4l2_h264_b1_ref_list_cmp, NULL, builder);
 
+	if (builder->cur_pic_fields != V4L2_H264_FRAME_REF) {
+		reorder_field_reflist(builder, b0_reflist);
+		reorder_field_reflist(builder, b1_reflist);
+	}
+
 	if (builder->num_valid > 1 &&
 	    !memcmp(b1_reflist, b0_reflist, builder->num_valid))
 		swap(b1_reflist[0], b1_reflist[1]);
-- 
2.34.1