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NdisAdjustBufferLength

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This function modifies the length specified in a buffer descriptor allocated or copied by the caller.

VOID NdisAdjustBufferLength(
IN PNDIS_BUFFER Buffer, 
IN UINT Length );

Parameters

  • Buffer
    Pointer to the buffer descriptor previously allocated with the NdisAllocateBuffer function.
  • Length
    Specifies the new length, in bytes, to be set in the buffer descriptor.

Remarks

The caller of this function can pass only a buffer descriptor that was allocated by the caller. It cannot pass a buffer descriptor that was allocated by another driver.

For example, the driver of a busmaster DMA NIC calls this function with buffer descriptors that it allocated to specify receive buffers in its shared memory block. Before such a driver indicates received data, it calls this function to make the buffer descriptor that it includes in the receive indication match the size of the received data if it is less than the size of the NIC's receive buffer. When a receive packet with such an adjusted buffer descriptor has been consumed and returned to the miniport, the driver again calls this function to make the buffer descriptor match the actual size of its receive buffer again.

The Length parameter passed to this function cannot be larger than the Length that was passed to the NdisAllocateBuffer function when the buffer descriptor was allocated.

The caller of this function must restore the length to its original value before it frees the buffer descriptor with the NdisFreeBuffer function.

The driver must release any spin lock that it is currently holding before calling this function.

A driver calling this function can run at any IRQL, but usually runs at IRQL <=DISPATCH_LEVEL.

Requirements

Runs on Versions Defined in Include Link to
Windows CE OS 2.0 and later Ndis.h    

Note   This API is part of the complete Windows CE OS package as provided by Microsoft. The functionality of a particular platform is determined by the original equipment manufacturer (OEM) and some devices may not support this API.

See Also

NdisAllocateBuffer, NdisFreeBuffer, NdisReleaseSpinLock

 Last updated on Tuesday, July 13, 2004

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