Adi_Pdd_Write Functional Description - Analog Devices VisualDSP++ 5.0 Service Manual

adi_pdd_Write Functional Description

The
adi_pdd_Write
to the application calling the
transmit the data within the buffers out through the device. For all API
functions, if error checking is enabled, the routine validates the physical
driver handle upon entry into the function. For detailed reference infor-
mation, see "adi_pdd_Write Functional Description" on page
As in the case for
peripheral DMA, the device manager manages all buffer queueing and
transmission. As a result, if the device is supported by peripheral DMA,
the
adi_pdd_Write
functionality need be provided by this routine. This greatly simplifies
device drivers for devices that are supported by processor DMA. Physical
drivers that are supported by peripheral DMA must provide this function,
but should simply return
never get called.
For devices that are not supported by peripheral DMA, the
function is passed one or more buffers that the application has provided
for transmission out through the device. The physical driver can choose to
process the buffers immediately, or provide the logic and functionality to
queue or stage these buffers for transmission at a later time. The physical
driver is required, however, to process the buffers in the order in which
they were received.
Each buffer has a processed flag and processed size flag that the physical
driver sets based on when it considers a buffer processed and how much
data was transmitted out through the device. Unlike the
case, the entire contents of the buffer is expected to be transmitted.
Also, any buffer can be flagged by the application for notification when
the buffer has completed processing. If a buffer is not flagged for a call-
back, the physical driver does not notify the device manager when the
buffer is processed. However, if the buffer is flagged for a callback, once
VisualDSP++ 5.0 Device Drivers and System
Services Manual for Blackfin Processors
function is called by the device manager in response
adi_dev_Write
, for devices that are supported by
adi_pdd_Read
function is never called by the device manager and no
ADI_DEV_NOT_SUPPORTED
Device Driver Manager
function. Its purpose is to
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as this routine should
adi_pdd_Write
adi_pdd_Read
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