libvpx: Add VP9 decoder.

source/libvpx/vp9/encoder/vp9_satd_c.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 <stdlib.h>
+#include "vpx_ports/mem.h"
+#include "./vp9_rtcd.h"
+unsigned int vp9_satd16x16_c(const unsigned char *src_ptr,
+                             int  src_stride,
+                             const unsigned char *ref_ptr,
+                             int  ref_stride,
+                             unsigned int *psatd) {
+  int r, c, i;
+  unsigned int satd = 0;
+  DECLARE_ALIGNED(16, short, diff_in[256]);
+  DECLARE_ALIGNED(16, short, diff_out[16]);
+  short *in;
+
+  for (r = 0; r < 16; r++) {
+    for (c = 0; c < 16; c++) {
+      diff_in[r * 16 + c] = src_ptr[c] - ref_ptr[c];
+    }
+    src_ptr += src_stride;
+    ref_ptr += ref_stride;
+  }
+
+  in = diff_in;
+  for (r = 0; r < 16; r += 4) {
+    for (c = 0; c < 16; c += 4) {
+      vp9_short_walsh4x4_c(in + c, diff_out, 32);
+      for (i = 0; i < 16; i++)
+        satd += abs(diff_out[i]);
+    }
+    in += 64;
+  }
+
+  if (psatd)
+    *psatd = satd;
+
+  return satd;
+}