image.c

@@ -6,34 +6,58 @@
 #include "image.h"
 #include "matrix.h"
 
+int endian_swap(int input) {
+    return ((input >> 24) & 0xff) |      // move byte 3 to byte 0
+           ((input << 8) & 0xff0000) |   // move byte 1 to byte 2
+           ((input >> 8) & 0xff00) |     // move byte 2 to byte 1
+           ((input << 24) & 0xff000000); // byte 0 to byte 3
+}
+
+int validate_files(FILE* image_file, FILE* label_file) {
+
+    // read magic number from files
+    int magic_number_label, magic_number_images;
+    fread(&magic_number_label, 4, 1, label_file);
+    fread(&magic_number_images, 4, 1, image_file);
+
+    // compare magic numbers with pre-defined value
+    if(endian_swap(magic_number_label) != 2049 || endian_swap(magic_number_images) != 2051) {
+        return 0;
+    }
+
+    return 1;
+}
+
 Image** import_images(char* image_file_string, char* label_file_string, int number_of_images) {
 
     // create file pointer for the image and label data
-    FILE* image_file = fopen(image_file_string, 'r');
+    FILE* image_file = fopen(image_file_string, "r");
-    FILE* label_file = fopen(label_file_string, 'r');
+    FILE* label_file = fopen(label_file_string, "r");
 
     // check if the file could be opened
     if(image_file == NULL || label_file == NULL) {
         printf("ERROR: File could not be opened! (import_images)");
+        exit(1);
     }
 
-    do {
+    // check magic number of the files
-        ch = fgetc(label_file);
+    if(validate_files(image_file, label_file)) {
-        printf("%c", ch);
+        printf("ERROR: File validation failed! (validate_files)");
+        exit(1);
+    }
 
-        // Checking if character is not EOF.
+
-        // If it is EOF stop reading.
+    // Jakob Section
-    } while (ch != EOF);
 
 
     // allocate memory for the storage of images
-//    Image** images = malloc(sizeof(Image) * number_of_images);
+    Image** images = malloc(sizeof(Image) * number_of_images);
 
     fclose(image_file);
     fclose(label_file);
 }
 
-void img_print (Img* img) {
+void img_print (Image* img) {
 
     //print the image
     matrix_print(img->pixel_values);
@@ -42,6 +66,6 @@ void img_print (Img* img) {
     printf("%d", img->image_label);
 }
 
-void img_free (Img* img) {
+void img_free (Image* img) {
 
 }

image.h

@@ -1,5 +1,7 @@
 #pragma once
 
+#include "matrix.h"
+
 typedef struct {
     Matrix* pixel_values;
     int image_label;

main.c

@@ -5,6 +5,6 @@
 #include "image.h"
 
 int main() {
-    Image** images = import_images("train-images.idx3-ubyte", "train-labels.idx3-ubyte", 20);
+    Image** images = import_images("../data/train-images.idx3-ubyte", "../data/train-labels.idx1-ubyte", 20);
 
 }

matrix.c

@@ -265,5 +265,5 @@ Matrix* matrix_flatten(Matrix* matrix, int axis) {
             else if (axis == 1) result_matrix->numbers[0][i * matrix->columns + j] = matrix->numbers[i][j];
         }
     }
-    return mat;
+    return result_matrix;
 }