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diff --git a/src/dsp/film_grain_common.h b/src/dsp/film_grain_common.h
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+/*
+ * Copyright 2020 The libgav1 Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef LIBGAV1_SRC_DSP_FILM_GRAIN_COMMON_H_
+#define LIBGAV1_SRC_DSP_FILM_GRAIN_COMMON_H_
+
+#include <cstddef>
+#include <cstdint>
+#include <memory>
+#include <type_traits>
+
+#include "src/dsp/common.h"
+#include "src/utils/array_2d.h"
+#include "src/utils/constants.h"
+#include "src/utils/cpu.h"
+
+namespace libgav1 {
+
+template <int bitdepth>
+int GetGrainMax() {
+  return (1 << (bitdepth - 1)) - 1;
+}
+
+template <int bitdepth>
+int GetGrainMin() {
+  return -(1 << (bitdepth - 1));
+}
+
+inline int GetFilmGrainRandomNumber(int bits, uint16_t* seed) {
+  uint16_t s = *seed;
+  uint16_t bit = (s ^ (s >> 1) ^ (s >> 3) ^ (s >> 12)) & 1;
+  s = (s >> 1) | (bit << 15);
+  *seed = s;
+  return s >> (16 - bits);
+}
+
+enum {
+  kAutoRegressionBorder = 3,
+  // The width of the luma noise array.
+  kLumaWidth = 82,
+  // The height of the luma noise array.
+  kLumaHeight = 73,
+  // The two possible widths of the chroma noise array.
+  kMinChromaWidth = 44,
+  kMaxChromaWidth = 82,
+  // The two possible heights of the chroma noise array.
+  kMinChromaHeight = 38,
+  kMaxChromaHeight = 73,
+  // The scaling lookup table maps bytes to bytes, so only uses 256 elements,
+  // plus one for overflow in 10bit lookups.
+  kScalingLookupTableSize = 257,
+  // Padding is added to the scaling lookup table to permit overwrites by
+  // InitializeScalingLookupTable_NEON.
+  kScalingLookupTablePadding = 6,
+  // Padding is added to each row of the noise image to permit overreads by
+  // BlendNoiseWithImageLuma_NEON and overwrites by WriteOverlapLine8bpp_NEON.
+  kNoiseImagePadding = 7,
+  // Padding is added to the end of the |noise_stripes_| buffer to permit
+  // overreads by WriteOverlapLine8bpp_NEON.
+  kNoiseStripePadding = 7,
+};  // anonymous enum
+
+}  // namespace libgav1
+
+#endif  // LIBGAV1_SRC_DSP_FILM_GRAIN_COMMON_H_