low_address
queue_start = low_address(cmd_q->qdma_tail);
tail = low_address(cmd_q->qdma_tail + cmd_q->qidx * Q_DESC_SIZE);
dma_addr_lo = low_address(cmd_q->qdma_tail);
uint8_t low_address = *((uint8_t *)&two_byte);
if (low_address == 0)