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/*
* Copyright (C) 2018 The Android Open Source Project
*
* 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 ANDROID_FRAMEWORKS_ML_NN_COMMON_INDEXED_SHAPE_WRAPPER_H
#define ANDROID_FRAMEWORKS_ML_NN_COMMON_INDEXED_SHAPE_WRAPPER_H
#include "OperationsUtils.h"
namespace android {
namespace nn {
// A wrapper over a Shape class implementing some indexing logic for a wrapped
// shape.
// To get an offset for an element in a tensor from vector index, one needs to
// calculate strides first. This class removes the need to recalculate strides
// for every indexing and also provides some utility functions.
class IndexedShapeWrapper {
public:
IndexedShapeWrapper(const Shape& wrapped_shape);
// Calculates the next index in a lexicograpical order for a wrapped shape
// inplace. Only accepts valid index for a given shape as an input.
// Sets lastIndex to true if the received index was the last in a
// lexicographical order for a given shape. In this case, index stays the
// same.
bool nextIndexInplace(std::vector<uint32_t>* index, bool* lastIndex) const;
// Given an index as a vector with per-dimension indices, calculates an
// offset of the element in a flattened tensor.
bool indexToFlatIndex(const std::vector<uint32_t>& index, uint32_t* flatIndex) const;
// Same as indexToFlatIndex, only ignores first dimensions of an index if
// they are not present in the shape. Also ignores dimensions of a shape of
// size 1.
// For example:
// for shape: [3, 1, 2]
// and index: [4, 2, 5, 1]
// the function will ignore dimensions with indices 4 and 5 and set
// flatIndex to 5 as a result.
bool broadcastedIndexToFlatIndex(const std::vector<uint32_t>& index, uint32_t* flatIndex) const;
private:
const Shape* const shape;
std::vector<uint32_t> strides;
bool isValid(const std::vector<uint32_t>& index) const;
};
} // namespace nn
} // namespace android
#endif // ANDROID_FRAMEWORKS_ML_NN_COMMON_INDEXED_SHAPE_WRAPPER_H
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