7、nsfer—setbasedonyourknowledgeofdevice(androunduptoamultipleofPAGE_SIZE)AllDmaPortMicrochannel-typebusportnumber—initializefromPortattributeofresourcedescriptorSlavetypedef struct _DEVICE_EXTENSION { PADAPTER_OBJECT AdapterObject; // device's adapter o
8、bject ULONG nMapRegisters; // max # map registers ULONG nMapRegistersAllocated; // # allocated for this xfer ULONG numxfer; // # bytes transferred so far ULONG xfer; // # bytes to transfer during this stage UL