/******************************

	交換高低字節(jié)

********************************/

int low2high(int i)
{
return ((i>>8)&0x00ff)+((i<<8)&0xff00);
}

/******************************

	將數(shù)據(jù)報讀取到packetRAM[]中

********************************/

static void readpacket(int i)
{
		packetRAM[i]=low2high(CS8900_RTDATA);
}

/******************************

	交換以太頭地址

********************************/

void EthResp()
{
	packetRAM[1]=packetRAM[4];//packetRAM[pktDest12]=packetRAM[pktSrc12];
	packetRAM[2]=packetRAM[5];//packetRAM[pktDest34]=packetRAM[pktSrc34];
	packetRAM[3]=packetRAM[6];//packetRAM[pktDest56]=packetRAM[pktSrc56];

	packetRAM[4]=0x0123;
	packetRAM[5]=0x4567;
	packetRAM[6]=0x89AB;

}
/******************************

	發(fā)送數(shù)據(jù)報文的函數(shù)

********************************/
void sendpacket()
{
	//寫發(fā)送命令字

	//CS8900_PP_TxCommand=0x00C0;
	io_write(IO_BASE+IO_TX_COMMAND, TxStart | TxCMD_LOW);//TxStart	=(3<<6),TxCMD_LOW=(0x09),command=c9h
	
	//寫入發(fā)送數(shù)據(jù)報文的長度

	//CS8900_PP_TxLength=packetRAM[pktLen];pktLen=0,讀取數(shù)組中首地址中的值
	io_write(IO_BASE+IO_TX_LENGTH, packetRAM[0]);
	//CS8900_TxLEN=packetRAM[pktLen];
	//等待線路空閑的時候發(fā)送while(!(get_reg(PP_BusSTAT)&PP_BusSTAT_TxRDY));

	while(!(reg_read(0x0138)&0x0100));//PP_BusSTAT_TxRDY=0x0100  // Ready for Tx data

	//寫入需要發(fā)送的數(shù)據(jù)

	for(i=1;i<=packetRAM[pktLen]/2;i++)
		//CS8900_(PP_TxBASE+2*i-2)=low2high(packetRAM[i]);
		CS8900_RTDATA=low2high(packetRAM[i]);
}
//
void receive()
{
for(;;)
{
	while( reg_read(0x0124)&0x0100)//pp_rer為接收幀狀態(tài)寄存器，此句為檢測數(shù)據(jù)無錯接收
	{
		packetRAM[0]=reg_read(0x0402);//rxlength為接收長，只讀寄存器，當RXOK置位時自動生成接收幀長度，但注意包不包括CRC的長度
		//收取前面的74個字節(jié)，如果是ICMP正好包括了最后一個字符 14+20+8+32

		for (i=1;i<=23; i++)//pktDest12=1,目的地址
		{
		     readpacket(i);
				//packetRAM[i]=low2high(CS8900_RTDATA);//交換CS8900_RTDATA即為PORT0口的高低字節(jié)，PORT0在16位模式下存放CPU和8900交換的數(shù)據(jù)幀	
		}//交換是因為大小斷不一樣
		
		//檢查幀的類型 如果是 0806 表示arp

		if (packetRAM[7]==0x0806)//pktType 	=7	幀類型	 0800 IP	0806 ARP
		{
			//*******************************
			
			//發(fā)現(xiàn)ARP數(shù)據(jù)報文就開始發(fā)送RARP

			//*********************************
			

			//判斷arp是否合法
			/*	
			if (packetRAM[arp_hwtype]!=0x0001)
			return;
			if (packetRAM[arp_prtype]!=0x0800)
			return;
			if (packetRAM[arp_hwlen]!=0x0604)
			return;
			if (packetRAM[arp_op]!=0x0001)
			return;
			if (packetRAM[arp_tpa]!=IP12)
			return;
			if (packetRAM[arp_tpa+1]!=IP34)
			return;
			*/
			//判斷結(jié)束 如果沒有返回說明需要發(fā)送RARP			
			//******************************

			//		發(fā)送arp request

			//********************************

			//修改arp操作碼為rarp

			packetRAM[11]=0x0002;	//arp_op=11	,arp 操作碼 00 01 表示Request 00 02 表示Reply
			
			//交換以太Mac
			
			EthResp();						
			
			//源mac 寫到目的mac

			packetRAM[17]=packetRAM[12];//packetRAM[arp_tha]=packetRAM[arp_sha];
			packetRAM[18]=packetRAM[12+1];//packetRAM[arp_tha+1]=packetRAM[arp_sha+1];
			packetRAM[19]=packetRAM[12+2];//packetRAM[arp_tha+2]=packetRAM[arp_sha+2];
			
			//源ip 寫到目的ip

			packetRAM[20]=packetRAM[15];//packetRAM[arp_tpa]=packetRAM[arp_spa];
			packetRAM[20+1]=packetRAM[15+1];//packetRAM[arp_tpa+1]=packetRAM[arp_spa+1];
			
			//重寫源mac

			packetRAM[12]=0x0123;//packetRAM[arp_sha]=MAC12;
			packetRAM[12+1]=0x4567;//packetRAM[arp_sha+1]=MAC34;
			packetRAM[12+2]=0x89AB;//packetRAM[arp_sha+2]=MAC56;
			
			//重寫源IP

			packetRAM[15]=0xCA71;
			packetRAM[15+1]=0x1824;
			
			//發(fā)送rarp報文

			sendpacket();
		
		}

		

	}
}
}