getLayerId
if (getLayerId(buffer) == GARMIN_LAYERID_APPL) {
getLayerId(garmin_data_p->privpkt) ==
getLayerId(data) == GARMIN_LAYERID_APPL)) {
if (getLayerId(garmin_data_p->outbuffer) != GARMIN_LAYERID_APPL) {
getLayerId(garmin_data_p->outbuffer));
if (getLayerId(urb->transfer_buffer) == GARMIN_LAYERID_APPL) {