MTD_NUM_TXD
size = (MTD_NUM_RXD + MTD_NUM_TXD) * sizeof(struct mtd_desc);
size = MTD_NUM_RXD * MTD_RXBUF_SIZE + MTD_NUM_TXD * MTD_TXBUF_SIZE;
for (/* i = MTD_NUM_RXD */; i < (MTD_NUM_TXD + MTD_NUM_RXD); ++i) {
if (i == (MTD_NUM_RXD + MTD_NUM_TXD - 1)) { /* Last descr */
if (++sc->cur_tx >= MTD_NUM_TXD)
sc->desc[MTD_NUM_RXD + MTD_NUM_TXD - 1].conf