1 // Copyright (C) 2018-2019 Intel Corporation
2 // SPDX-License-Identifier: Apache-2.0
8 #include <MnistUbyte.h>
10 using namespace FormatReader;
12 int MnistUbyte::reverseInt(int i) {
13 unsigned char ch1, ch2, ch3, ch4;
14 ch1 = (unsigned char) (i & 255);
15 ch2 = (unsigned char) ((i >> 8) & 255);
16 ch3 = (unsigned char) ((i >> 16) & 255);
17 ch4 = (unsigned char) ((i >> 24) & 255);
18 return (static_cast<int>(ch1) << 24) + (static_cast<int>(ch2) << 16) + (static_cast<int>(ch3) << 8) + ch4;
21 MnistUbyte::MnistUbyte(const std::string &filename) {
22 std::ifstream file(filename, std::ios::binary);
23 if (!file.is_open()) {
27 int number_of_images = 0;
30 file.read(reinterpret_cast<char *>(&magic_number), sizeof(magic_number));
31 magic_number = reverseInt(magic_number);
32 if (magic_number != 2051) {
35 file.read(reinterpret_cast<char *>(&number_of_images), sizeof(number_of_images));
36 number_of_images = reverseInt(number_of_images);
37 file.read(reinterpret_cast<char *>(&n_rows), sizeof(n_rows));
38 n_rows = reverseInt(n_rows);
39 _height = (size_t) n_rows;
40 file.read(reinterpret_cast<char *>(&n_cols), sizeof(n_cols));
41 n_cols = reverseInt(n_cols);
42 _width = (size_t) n_cols;
43 if (number_of_images > 1) {
44 std::cout << "[MNIST] Warning: number_of_images in mnist file equals " << number_of_images
45 << ". Only a first image will be read." << std::endl;
48 size_t size = _width * _height * 1;
50 _data.reset(new unsigned char[size], std::default_delete<unsigned char[]>());
52 if (0 < number_of_images) {
53 for (int r = 0; r < n_rows; ++r) {
54 for (int c = 0; c < n_cols; ++c) {
55 unsigned char temp = 0;
56 file.read(reinterpret_cast<char *>(&temp), sizeof(temp));
57 _data.get()[count++] = temp;