RxDesc
i = roundup2(sizeof(union RxDesc)*RE_RX_BUF_NUM, RE_DESC_ALIGN);
union RxDesc *rxptr;
memset(&rxptr[i], 0, sizeof(union RxDesc));
sizeof(union RxDesc)*RE_RX_BUF_NUM,
sizeof(union RxDesc) * RE_TX_BUF_NUM,
union RxDesc *rxptr = arg;
union RxDesc *rxptr;
union RxDesc *rx_desc; /* 8 bits alignment */