uint32 size = 4  + 2
uint32 size = 2  + 2
XPT_SizeOfInterfaceDescriptor(XPTInterfaceDescriptor *id){    uint32 size = 4 /* parent interface */ + 2 /* num_methods */        + 2 /* num_constants */, i;    for (i = 0; i < id->num_methods; i++)        size += XPT_SizeOfMethodDescriptor(&id->method_descriptors[i]);    for (i = 0; i < id->num_constants; i++)        size += XPT_SizeOfConstDescriptor(&id->const_descriptors[i]);    return size;}