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138 lines
5.5 KiB
C++
138 lines
5.5 KiB
C++
///////////////////////////////////////////////////////////////////////
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// File: stridemap.h
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// Description: Indexing into a 4-d tensor held in a 2-d Array.
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// Author: Ray Smith
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// Created: Fri Sep 20 16:00:31 PST 2016
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//
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// (C) Copyright 2016, Google Inc.
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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///////////////////////////////////////////////////////////////////////
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#ifndef TESSERACT_LSTM_STRIDEMAP_H_
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#define TESSERACT_LSTM_STRIDEMAP_H_
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#include <string.h>
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#include <vector>
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#include "tprintf.h"
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namespace tesseract {
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// Enum describing the dimensions of the 'Tensor' in a NetworkIO.
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// A NetworkIO is analogous to a TF Tensor, except that the number of dimensions
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// is fixed (4), and they always have the same meaning. The underlying
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// representation is a 2-D array, for which the product batch*height*width
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// is always dim1 and depth is always dim2. FlexDimensions is used only for
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// batch, height, width with the StrideMap, and therefore represents the runtime
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// shape. The build-time shape is defined by StaticShape.
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enum FlexDimensions {
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FD_BATCH, // Index of multiple images.
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FD_HEIGHT, // y-coordinate in image.
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FD_WIDTH, // x-coordinate in image.
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FD_DIMSIZE, // Number of flexible non-depth dimensions.
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};
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// Encapsulation of information relating to the mapping from [batch][y][x] to
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// the first index into the 2-d array underlying a NetworkIO.
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class StrideMap {
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public:
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// Class holding the non-depth indices.
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class Index {
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public:
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explicit Index(const StrideMap& stride_map) : stride_map_(&stride_map) {
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InitToFirst();
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}
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Index(const StrideMap& stride_map, int batch, int y, int x)
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: stride_map_(&stride_map) {
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indices_[FD_BATCH] = batch;
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indices_[FD_HEIGHT] = y;
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indices_[FD_WIDTH] = x;
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SetTFromIndices();
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}
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// Accesses the index to the underlying array.
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int t() const { return t_; }
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int index(FlexDimensions dimension) const { return indices_[dimension]; }
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// Initializes the indices to the first valid location.
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void InitToFirst() {
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memset(indices_, 0, sizeof(indices_));
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t_ = 0;
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}
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// Initializes the indices to the last valid location.
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void InitToLast() { InitToLastOfBatch(MaxIndexOfDim(FD_BATCH)); }
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// Returns true if *this is a valid index.
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bool IsValid() const;
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// Returns true if the index of the given dimension is the last.
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bool IsLast(FlexDimensions dimension) const;
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// Given that the dimensions up to and including dim-1 are valid, returns
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// the maximum index for dimension dim.
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int MaxIndexOfDim(FlexDimensions dim) const;
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// Adds the given offset to the given dimension. Returns true if the result
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// makes a valid index.
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bool AddOffset(int offset, FlexDimensions dimension);
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// Increments the index in some encapsulated way that guarantees to remain
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// valid until it returns false, meaning that the iteration is complete.
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bool Increment();
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// Decrements the index in some encapsulated way that guarantees to remain
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// valid until it returns false, meaning that the iteration (that started
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// with InitToLast()) is complete.
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bool Decrement();
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private:
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// Initializes the indices to the last valid location in the given batch
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// index.
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void InitToLastOfBatch(int batch);
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// Computes and sets t_ from the current indices_.
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void SetTFromIndices();
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// Map into which *this is an index.
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const StrideMap* stride_map_;
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// Index to the first dimension of the underlying array.
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int t_;
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// Indices into the individual dimensions.
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int indices_[FD_DIMSIZE];
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};
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StrideMap() {
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memset(shape_, 0, sizeof(shape_));
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memset(t_increments_, 0, sizeof(t_increments_));
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}
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// Default copy constructor and operator= are OK to use here!
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// Sets up the stride for the given array of height, width pairs.
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void SetStride(const std::vector<std::pair<int, int>>& h_w_pairs);
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// Scales width and height dimensions by the given factors.
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void ScaleXY(int x_factor, int y_factor);
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// Reduces width to 1, across the batch, whatever the input size.
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void ReduceWidthTo1();
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// Transposes the width and height dimensions.
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void TransposeXY();
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// Returns the size of the given dimension.
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int Size(FlexDimensions dimension) const { return shape_[dimension]; }
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// Returns the total width required.
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int Width() const { return t_increments_[FD_BATCH] * shape_[FD_BATCH]; }
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private:
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// Computes t_increments_ from shape_.
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void ComputeTIncrements();
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// The size of each non-depth dimension.
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int shape_[FD_DIMSIZE];
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// Precomputed 't' increments for each dimension. This is the value of
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// the given dimension in the packed 3-d array that the shape_ represents.
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int t_increments_[FD_DIMSIZE];
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// Vector of size shape_[FD_BATCH] holds the height of each image in a batch.
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std::vector<int> heights_;
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// Vector of size shape_[FD_BATCH] holds the width of each image in a batch.
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std::vector<int> widths_;
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};
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} // namespace tesseract
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#endif // TESSERACT_LSTM_STRIDEMAP_H_
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