add todo serialization

engine/todo.c

@@ -0,0 +1,56 @@
+#include "todo.h"
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+// Memory management
+void todo_free_item(TodoItem *item) {
+  free(item->title);
+}
+
+// Item operations
+TodoItem todo_create_item(char *title) {
+  TodoItem item;
+  item.title_length = strlen(title);
+  item.title = malloc(item.title_length);
+  strcpy(item.title, title);
+  item.completed = false;
+
+  return item;
+}
+
+void todo_mark_item(TodoItem *item, bool_t completed) {
+  item->completed = completed;
+}
+
+void todo_print_item(TodoItem *item) {
+  printf("%s - ", item->title);
+  if (item->completed) {
+    printf("Completed\n");
+  } else {
+    printf("Not Completed\n");
+  }
+}
+
+// Serialization
+char *todo_item_serialize(TodoItem *item, int *buffer_size_out) {
+  // Layout of the serialized item:
+  // title_length - 1 byte
+  // title - title_length bytes
+  // completed - 1 byte
+  unsigned char title_length = item->title_length;  unsigned char completed_length = sizeof(item->completed);
+  int buffer_size = sizeof(unsigned char) + title_length + completed_length;
+
+  char *buffer = malloc(buffer_size);
+
+  // copy title length
+  memcpy(buffer, &title_length, sizeof(unsigned char));
+  // copy title
+  memcpy(buffer + sizeof(unsigned char), item->title, title_length);
+  // copy completed
+  memcpy(buffer + sizeof(unsigned char) + title_length, &item->completed, completed_length);
+
+  *buffer_size_out = buffer_size;
+
+  return buffer;
+}

engine/todo.h

@@ -0,0 +1,25 @@
+#ifndef TODO_H
+#define TODO_H
+#define TODO_MAX_TITLE_LENGTH 255
+
+#define true 1
+#define false 0
+typedef unsigned char bool_t;
+
+typedef struct {
+  unsigned char title_length;
+  char *title;
+  bool_t completed;
+} TodoItem;
+
+// Memory management
+void todo_free_item(TodoItem *item);
+
+// Item operations
+TodoItem todo_create_item(char *title);
+void todo_mark_item(TodoItem *item, bool_t completed);
+void todo_print_item(TodoItem *item);
+
+// Serialization
+char *todo_item_serialize(TodoItem *item, int *buffer_size_out);
+#endif