ov_index
op->ov_index = bucket;
size = op->ov_index;
i = op->ov_index;
op->ov_index = bucket;
ov->ov_index = x - (uintptr_t)mem + sizeof(union overhead);
op = opx->ov_magic == AMAGIC ? (void *)((caddr_t)cp - opx->ov_index) :
size = op->ov_index;
i = op->ov_index;