GetDmaAlignment routine

The GetDmaAlignment routine returns the alignment requirements of the DMA system.

Syntax


ULONG GetDmaAlignment(
  _In_  PDMA_ADAPTER DmaAdapter
);

Parameters

DmaAdapter [in]

A pointer to the DMA_ADAPTER structure returned by IoGetDmaAdapter that represents the bus-master adapter or DMA controller.

Return value

GetDmaAlignment returns the alignment requirements, in bytes, of the DMA system. The starting address and length of DMA buffers must be a multiple of this value.

Remarks

GetDmaAlignment is not a system routine that can be called directly by name. This routine is callable only by pointer from the address returned in a DMA_OPERATIONS structure. Drivers obtain the address of this routine by calling IoGetDmaAdapter.

A driver can call this routine to determine alignment requirements for DMA buffers it allocates. The returned value should be used to set the AlignmentRequirement field in the device object. A driver may need to increase this value because of additional hardware device restrictions. For more information, see Initializing a Device Object.

Requirements

Version

Available starting with Windows 2000.

Header

Wdm.h (include Wdm.h, Ntddk.h, or Ntifs.h)

IRQL

PASSIVE_LEVEL

DDI compliance rules

IrqlDispatch

See also

DEVICE_OBJECT
DMA_ADAPTER
DMA_OPERATIONS
IoGetDmaAdapter

 

 

Send comments about this topic to Microsoft

Show:
© 2014 Microsoft