Analog Devices VisualDSP++ 5.0 Service Manual page 257

DESCRIPTOR
Figure 6-2. Descriptor Chain
Descriptors can be submitted at any time, regardless of the dataflow state.
The DMA manager maintains independent queues of descriptors for each
channel, keeping the DMA controller busy with transfers until all queued
descriptors are processed.
Both one-dimensional and two-dimensional transfers can be intermixed
on the same channel. Each transfer can define a different transfer type,
length, and so on. Additionally, callbacks to the client's callback function
can be made upon completion of every descriptor, any individual descrip-
tor, or configured to never call back.
When the large descriptor chaining mode is used, descriptor chains are
submitted to the channel using the
following parameters:
• The channel handle. This is the value provided to the client during
the
adi_dma_Open()
• A handle of the type
Because the same
descriptor-based operating modes (including large descriptors,
small descriptors, and arrays of descriptors), the
ADI_DMA_DESCRIPTOR_HANDLE
conveniently represents each of the descriptor types.
For the large descriptor chaining mode, descriptors are of the type
ADI_DMA_DESCRIPTOR_LARGE
model descriptor. When calling the
VisualDSP++ 5.0 Device Drivers and System
Services Manual for Blackfin Processors
DESCRIPTOR
0 1
function.
ADI_DMA_DESCRIPTOR_HANDLE
adi_dma_Queue()
, which is a data type that defines a large
. . .
function with the
adi_dma_Queue()
function is used for all
data type acts as a container that
adi_dma_Queue()
DMA Manager
DESCRIPTOR
N
to a descriptor.
function, the client
6-17