free_data
void free_data() const;
struct free_data* next;
free_data* first_free;
if (size < sizeof(free_data))
size = sizeof(free_data);
free_data* freeData = (free_data*)data;
if (size < sizeof(free_data))
size = sizeof(free_data);
free_data* freeData = header->first_free;
free_data* last = NULL;