网卡adapter结构定义的问题

各位大虾,小弟现在做8139芯片网卡驱动.前些时候下载\"源代码及分析\"之\"nic driver(rtl8139&sis900 for win2k)\"程序,读到rtl8139中有如下一个定义:
typedef struct tagADAPTER{

NDIS_HANDLE MiniportAdapterHandle;
NDIS_HANDLE WrapperConfigurationContext;

UCHAR NetworkAddress[6];
UCHAR mc_filter[8];
ULONG PacketFilter;

PUCHAR ioaddr;
//i/o
ULONG BaseIO;
NDIS_MINIPORT_INTERRUPT IntObj;

//irq
ULONG IRQLevel;
ULONG IRQVector;
ULONG IRQAffinity;
USHORT IRQMode;

PUCHAR tx_bufs; // TX_BUF_SIZE * NUM_OF_DESC
NDIS_PHYSICAL_ADDRESS tx_bufs_dma;

//2.接收:
PUCHAR rx_ring;
NDIS_PHYSICAL_ADDRESS rx_ring_dma;
USHORT read_ptr;

PUCHAR rx_bufs;
NDIS_PHYSICAL_ADDRESS rx_bufs_dma;

//packet,buffer & pool
NDIS_HANDLE pkt_pool;
NDIS_HANDLE buf_pool;

PNDIS_PACKET pkt_desc[NUM_OF_PACKETS];
PNDIS_BUFFER buf_desc[NUM_OF_PACKETS];

UINT FreeRxPkt, FreeTxDesc;
UINT cur_rx, cur_tx, dirty_tx, dirty_rx;

//isr status
USHORT curISR;

//
ULONG ERR_COUNT;
ULONG XMIT_OK, XMIT_ERR;
ULONG RCV_OK, RCV_ERR;
ULONG RCV_NO_BUFFER;

ULONG rev_byte, xmit_byte;

char twistie, twist_row, twist_col; /* Twister tune state. */
}ADAPTER, *PADAPTER;
这是一个适配器结构的定义,可是我却不知道它是依据什么来定义的,我查阅了它的芯片资料和编程手册,但发现根本找不到.望高手指点迷津,让迷途人早日回归正路!!!谢谢