MiniportTransferData

MiniportTransferData

NDIS_STATUS
   MiniportTransferData(
       OUT PNDIS_PACKET Packet,
       OUT PUINT BytesTransferred,
       IN NDIS_HANDLE MiniportAdapterContext,
       IN NDIS_HANDLE MiniportReceiveContext,
       IN UINT ByteOffset,
       IN UINT BytesToTransfer
       );

MiniportTransferData is a required function in NIC drivers that do not indicate multipacket receives and/or media-specific information with NdisMIndicateReceivePacket and in those that do not support WAN media.

Parameters

Packet

Points to a packet descriptor with chained buffers into which MiniportTransferData should copy the received data.

BytesTransferred

Points to a variable that MiniportTransferData sets to the number of bytes it copied into the packet. This value is meaningless if MiniportTransferData returns NDIS_STATUS_PENDING.

MiniportAdapterContext

Specifies the handle to a miniport-allocated context area in which the driver maintains per-NIC state, set up by MiniportInitialize.

MiniportReceiveContext

Specifies the context handle previously passed to NdisM..IndicateReceive. The miniport can examine this value to determine which receive to copy.

ByteOffset

Specifies the offset within the received packet at which MiniportTransferData should begin the copy. If the entire packet is be copied, ByteOffset is zero.

BytesToTransfer

Specifies how many bytes to copy. The sum of ByteOffset and BytesToTransfer should be less than or equal to the packet size that was specified in the miniport’s receive indication. This value can be zero.

Return Value

MiniportTransferData can return one of the the following:

NDIS_STATUS_SUCCESS

MiniportTransferData copied the requested data into the protocol-supplied packet, and it set BytesTransferred to the number of bytes copied.

NDIS_STATUS_PENDING

The driver will complete the transfer asynchronously with a call to NdisMTransferDataComplete.

NDIS_STATUS_FAILURE

Either the data could not be copied or the input transfer range was invalid.

Comments

MiniportTransferData copies the contents of the received packet to a given protocol-allocated packet.

NDIS calls MiniportTransferData when a ProtocolReceive function calls NdisTransferData. The media header associated with a packet cannot be copied; only the data portion of a packet can be copied. The range passed to NdisTransferData never includes the media header. Usually, the ByteOffset input to MiniportTransferData excludes data that the miniport already indicated in the lookahead buffer.

A miniport must be prepared to copy a given packet more than once. If its NIC supports reading a given packet only once, the miniport must copy each received network packet to a staging buffer.

MiniportTransferData can call NdisQueryPacket to determine how many buffer descriptors the allocating protocol has provided. The protocol is responsible for supplying a packet descriptor that accommodates the transfer it requested. MiniportTransferData can call NdisQueryBuffer to determine how much data to copy into each protocol-supplied buffer.

MiniportTransferData can fail a request if the given ByteOffset and BytesToTransfer exceed the packet size originally indicated. Alternatively, MiniportTransferData can simply transfer all available data starting at any valid ByteOffset.

Because MiniportTransferData is asynchronous, a miniport that has this function cannot deliver receive indications while a transfer is pending. If MiniportTransferData returns NDIS_STATUS_PENDING, the miniport must call NdisMTransferDataComplete when the transfer is complete.

A driver that indicates packets with NdisMIndicateReceivePacket does not need a MiniportTransferData function because such a driver always indicates full packets to bound protocols.

Interrupts are still disabled when MiniportTransferData is called.

By default, MiniportTransferData runs at IRQL DISPATCH_LEVEL.