libvpx: Add VP9 decoder.

source/libvpx/vp9/common/vp9_sadmxn.h

+/*
+ *  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.
+ */
+
+#ifndef VP9_COMMON_VP9_SADMXN_H_
+#define VP9_COMMON_VP9_SADMXN_H_
+
+static __inline
+unsigned int sad_mx_n_c(
+  const unsigned char *src_ptr,
+  int  src_stride,
+  const unsigned char *ref_ptr,
+  int  ref_stride,
+  int m,
+  int n) {
+  int r, c;
+  unsigned int sad = 0;
+
+  for (r = 0; r < n; r++) {
+    for (c = 0; c < m; c++) {
+      sad += abs(src_ptr[c] - ref_ptr[c]);
+    }
+
+    src_ptr += src_stride;
+    ref_ptr += ref_stride;
+  }
+
+  return sad;
+}
+
+#endif