64 lines
2.0 KiB
C++
64 lines
2.0 KiB
C++
// Copyright (C) 2018-2020 Intel Corporation
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// SPDX-License-Identifier: Apache-2.0
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//
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#include <fstream>
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#include <iostream>
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#include <string>
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#include <MnistUbyte.h>
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using namespace FormatReader;
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int MnistUbyte::reverseInt(int i) {
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unsigned char ch1, ch2, ch3, ch4;
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ch1 = (unsigned char) (i & 255);
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ch2 = (unsigned char) ((i >> 8) & 255);
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ch3 = (unsigned char) ((i >> 16) & 255);
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ch4 = (unsigned char) ((i >> 24) & 255);
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return (static_cast<int>(ch1) << 24) + (static_cast<int>(ch2) << 16) + (static_cast<int>(ch3) << 8) + ch4;
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}
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MnistUbyte::MnistUbyte(const std::string &filename) {
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std::ifstream file(filename, std::ios::binary);
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if (!file.is_open()) {
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return;
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}
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int magic_number = 0;
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int number_of_images = 0;
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int n_rows = 0;
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int n_cols = 0;
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file.read(reinterpret_cast<char *>(&magic_number), sizeof(magic_number));
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magic_number = reverseInt(magic_number);
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if (magic_number != 2051) {
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return;
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}
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file.read(reinterpret_cast<char *>(&number_of_images), sizeof(number_of_images));
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number_of_images = reverseInt(number_of_images);
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file.read(reinterpret_cast<char *>(&n_rows), sizeof(n_rows));
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n_rows = reverseInt(n_rows);
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_height = (size_t) n_rows;
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file.read(reinterpret_cast<char *>(&n_cols), sizeof(n_cols));
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n_cols = reverseInt(n_cols);
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_width = (size_t) n_cols;
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if (number_of_images > 1) {
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std::cout << "[MNIST] Warning: number_of_images in mnist file equals " << number_of_images
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<< ". Only a first image will be read." << std::endl;
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}
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size_t size = _width * _height * 1;
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_data.reset(new unsigned char[size], std::default_delete<unsigned char[]>());
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size_t count = 0;
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if (0 < number_of_images) {
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for (int r = 0; r < n_rows; ++r) {
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for (int c = 0; c < n_cols; ++c) {
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unsigned char temp = 0;
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file.read(reinterpret_cast<char *>(&temp), sizeof(temp));
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_data.get()[count++] = temp;
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}
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}
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}
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file.close();
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}
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