1 files changed, 61 insertions, 0 deletions
diff --git a/third_party/aom/aom_dsp/recenter.h b/third_party/aom/aom_dsp/recenter.h
new file mode 100644
index 0000000000..b3fd412907
--- /dev/null
+++ b/third_party/aom/aom_dsp/recenter.h
@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2018, Alliance for Open Media. All rights reserved
+ *
+ * This source code is subject to the terms of the BSD 2 Clause License and
+ * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
+ * was not distributed with this source code in the LICENSE file, you can
+ * obtain it at www.aomedia.org/license/software. If the Alliance for Open
+ * Media Patent License 1.0 was not distributed with this source code in the
+ * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
+ */
+
+#ifndef AOM_AOM_DSP_RECENTER_H_
+#define AOM_AOM_DSP_RECENTER_H_
+
+#include "config/aom_config.h"
+
+#include "aom/aom_integer.h"
+
+// Inverse recenters a non-negative literal v around a reference r
+static INLINE uint16_t inv_recenter_nonneg(uint16_t r, uint16_t v) {
+  if (v > (r << 1))
+    return v;
+  else if ((v & 1) == 0)
+    return (v >> 1) + r;
+  else
+    return r - ((v + 1) >> 1);
+}
+
+// Inverse recenters a non-negative literal v in [0, n-1] around a
+// reference r also in [0, n-1]
+static INLINE uint16_t inv_recenter_finite_nonneg(uint16_t n, uint16_t r,
+                                                  uint16_t v) {
+  if ((r << 1) <= n) {
+    return inv_recenter_nonneg(r, v);
+  } else {
+    return n - 1 - inv_recenter_nonneg(n - 1 - r, v);
+  }
+}
+
+// Recenters a non-negative literal v around a reference r
+static INLINE uint16_t recenter_nonneg(uint16_t r, uint16_t v) {
+  if (v > (r << 1))
+    return v;
+  else if (v >= r)
+    return ((v - r) << 1);
+  else
+    return ((r - v) << 1) - 1;
+}
+
+// Recenters a non-negative literal v in [0, n-1] around a
+// reference r also in [0, n-1]
+static INLINE uint16_t recenter_finite_nonneg(uint16_t n, uint16_t r,
+                                              uint16_t v) {
+  if ((r << 1) <= n) {
+    return recenter_nonneg(r, v);
+  } else {
+    return recenter_nonneg(n - 1 - r, n - 1 - v);
+  }
+}
+
+#endif  // AOM_AOM_DSP_RECENTER_H_