Polling; Callbacks; Memory Stream Callbacks - Analog Devices VisualDSP++ 5.0 Service Manual

Theory of Operation

Polling

Clients can use the
channel to determine whether a transfer is in progress by using the
ADI_DMA_CMD_GET_TRANSFER_STATUS
When given this command, the DMA manager examines the status of the
individual DMA channel. The function provides a response of
transfer is in progress, and a response of
in progress.
Note that memory streams can also be interrogated for transfer status.
Instead of passing the channel handle (
ter to the
adi_dma_Control()
(
ADI_DMA_STREAM_HANDLE
ADI_DMA_CHANNEL_HANDLE

Callbacks

Callbacks are the more commonly used mechanism that clients use to
determine when a transfer has completed. Callbacks are either live (mean-
ing they are made at interrupt time) or deferred (meaning they are made
after the hardware interrupt has completed processing using a callback
service).

Memory Stream Callbacks

When using memory streams, if the client provided a callback function as
a parameter to the
functions, the callback function is invoked by the DMA manager when
the transfer is complete.
6-22
adi_dma_Control()
command.
function, the client passes the stream handle
) parameter (casted to the
data type) to the
adi_dma_MemoryCopy()
VisualDSP++ 5.0 Device Drivers and System
Services Manual for Blackfin Processors
function to interrogate a specific
, if no transfer is currently
FALSE
ADI_DMA_CHANNEL_HANDLE
adi_dma_Control()
or
adi_dma_MemoryCopy2D()
, if a
TRUE
) parame-
function.