push:NXM_OF_ETH_SRC[],push:NXM_OF_ETH_DST[],pop:NXM_OF_ETH_SRC[],pop:NXM_OF_ETH_DST[]
1：把src mac推到栈顶
push:NXM_OF_ETH_SRC[]
2：把dst mac推到栈顶
push:NXM_OF_ETH_DST[]
3：从栈顶读取mac存到NXM_OF_ETH_SRC[]
pop:NXM_OF_ETH_SRC[]
4：从栈顶读取mac存到NXM_OF_ETH_DST[]
pop:NXM_OF_ETH_DST[]