libvpx: Add VP9 decoder.

source/libvpx/vp9/common/vp9_swapyv12buffer.c

+/*
+ *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "vp9/common/vp9_swapyv12buffer.h"
+
+void vp9_swap_yv12_buffer(YV12_BUFFER_CONFIG *new_frame,
+                          YV12_BUFFER_CONFIG *last_frame) {
+  unsigned char *temp;
+
+  temp = last_frame->buffer_alloc;
+  last_frame->buffer_alloc = new_frame->buffer_alloc;
+  new_frame->buffer_alloc = temp;
+
+  temp = last_frame->y_buffer;
+  last_frame->y_buffer = new_frame->y_buffer;
+  new_frame->y_buffer = temp;
+
+  temp = last_frame->u_buffer;
+  last_frame->u_buffer = new_frame->u_buffer;
+  new_frame->u_buffer = temp;
+
+  temp = last_frame->v_buffer;
+  last_frame->v_buffer = new_frame->v_buffer;
+  new_frame->v_buffer = temp;
+}