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HDAUDIO_BUFFER_DESCRIPTOR structure

The HDAUDIO_BUFFER_DESCRIPTOR structure specifies a buffer descriptor, which is an entry in a buffer descriptor list (BDL).

Syntax


typedef struct _HDAUDIO_BUFFER_DESCRIPTOR {
  PHYSICAL_ADDRESS Address;
  ULONG            Length;
  ULONG            InterruptOnCompletion;
} HDAUDIO_BUFFER_DESCRIPTOR, *PHDAUDIO_BUFFER_DESCRIPTOR;

Members

Address

Specifies the start address of a physically contiguous fragment of the buffer. In the case of a 32-bit address, the address should be right-justified and the 32 most significant bits (MSBs) of the member should be zero.

Length

Specifies the size in bytes of the buffer fragment.

InterruptOnCompletion

Specifies whether the DMA engine should generate an interrupt on completing the transfer of the buffer fragment. A value of 1 enables the interrupt. A value of 0 disables it.

Remarks

A BDL is an array of HDAUDIO_BUFFER_DESCRIPTOR structures. Each structure specifies a physically contiguous fragment of the buffer. A BDL specifies all the fragments that make up the buffer.

The Address member contains the physical memory address of the start of the buffer fragment. The Length member specifies the number of bytes of physically contiguous memory that the fragment contains.

If the InterruptOnCompletion bit is set during a DMA transfer to or from the buffer fragment, the DMA engine generates an interrupt on completion of the transfer.

This structure is used by the AllocateContiguousDmaBuffer and SetupDmaEngineWithBdl routines.

For more information about BDLs, see the Intel High Definition Audio Specification at the Intel HD Audio website.

Requirements

Header

Hdaudio.h (include Hdaudio.h)

See also

AllocateContiguousDmaBuffer
SetupDmaEngineWithBdl

 

 

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