SH_CIRCLEQ_LASTP
((head)->scqh_last == -1 ? (void *)head : SH_CIRCLEQ_LASTP(head, type))
SH_CIRCLEQ_LASTP(head, type)->field.scqe_next = \
SH_PTR_TO_OFF(SH_CIRCLEQ_LASTP(head, type), elm); \