SM_INVALID
if (shiftmasks[shift].sm_type != SM_INVALID) {
shiftmasks[shift].sm_type = SM_INVALID;
shiftmasks[shift].sm_type = SM_INVALID;
case SM_INVALID:
if (shiftmasks[shift].sm_type != SM_INVALID) {
if (shiftmasks[shift].sm_type != SM_INVALID) {