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+/*
+ * Copyright 2019 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_UTILS_BLOCK_PARAMETERS_HOLDER_H_
+#define LIBGAV1_SRC_UTILS_BLOCK_PARAMETERS_HOLDER_H_
+
+#include <memory>
+
+#include "src/utils/array_2d.h"
+#include "src/utils/compiler_attributes.h"
+#include "src/utils/constants.h"
+#include "src/utils/parameter_tree.h"
+#include "src/utils/types.h"
+
+namespace libgav1 {
+
+// Holds a 2D array of |ParameterTree| objects. Each tree stores the parameters
+// corresponding to a superblock.
+class BlockParametersHolder {
+ public:
+  BlockParametersHolder() = default;
+
+  // Not copyable or movable.
+  BlockParametersHolder(const BlockParametersHolder&) = delete;
+  BlockParametersHolder& operator=(const BlockParametersHolder&) = delete;
+
+  // If |use_128x128_superblock| is true, 128x128 superblocks will be used,
+  // otherwise 64x64 superblocks will be used.
+  LIBGAV1_MUST_USE_RESULT bool Reset(int rows4x4, int columns4x4,
+                                     bool use_128x128_superblock);
+
+  // Finds the BlockParameters corresponding to |row4x4| and |column4x4|. This
+  // is done as a simple look up of the |block_parameters_cache_| matrix.
+  // Returns nullptr if the BlockParameters cannot be found.
+  BlockParameters* Find(int row4x4, int column4x4) const {
+    return block_parameters_cache_[row4x4][column4x4];
+  }
+
+  BlockParameters** Address(int row4x4, int column4x4) {
+    return block_parameters_cache_.data() + row4x4 * columns4x4_ + column4x4;
+  }
+
+  BlockParameters* const* Address(int row4x4, int column4x4) const {
+    return block_parameters_cache_.data() + row4x4 * columns4x4_ + column4x4;
+  }
+
+  int columns4x4() const { return columns4x4_; }
+
+  // Returns the ParameterTree corresponding to superblock starting at (|row|,
+  // |column|).
+  ParameterTree* Tree(int row, int column) { return trees_[row][column].get(); }
+
+  // Fills the cache matrix for the block starting at |row4x4|, |column4x4| of
+  // size |block_size| with the pointer |bp|.
+  void FillCache(int row4x4, int column4x4, BlockSize block_size,
+                 BlockParameters* bp);
+
+ private:
+  int rows4x4_ = 0;
+  int columns4x4_ = 0;
+  bool use_128x128_superblock_ = false;
+  Array2D<std::unique_ptr<ParameterTree>> trees_;
+
+  // This is a 2d array of size |rows4x4_| * |columns4x4_|. This is filled in by
+  // FillCache() and used by Find() to perform look ups using exactly one look
+  // up (instead of traversing the entire tree).
+  Array2D<BlockParameters*> block_parameters_cache_;
+};
+
+}  // namespace libgav1
+
+#endif  // LIBGAV1_SRC_UTILS_BLOCK_PARAMETERS_HOLDER_H_