Application Interface - Analog Devices VisualDSP++ 5.0 Service Manual

Device Driver Overview
The system services overview covers the following topics:
• "Application Interface" on page 1-20
• "Device Driver Architecture" on page 1-21
• "Initialization" on page 1-23
• "Termination" on page 1-24
• "Device Driver Directory and File Structure" on page 1-24

Application Interface

The device driver model provides a consistent, simple, and familiar appli-
cation programming interface (API) for device drivers. All devices drivers
that conform to the model use the same simple interface into the driver.
Most devices receive and/or transmit data, sometimes transforming the
data in the process. This data is encapsulated in a buffer. The buffer may
contain small bits of data, such as for a UART-type device that processes
one character at a time, or large pieces of data, such as a video device that
processes NTSC frames of approximately 1 MB in size. Applications typi-
cally provide the buffers to the device, though it is possible for devices to
pass buffers from one device to another without any application
involvement.
The actual API is a model-compliant driver that consists of the following
basic functions:
•
adi_dev_Open()
•
adi_dev_Close()
•
adi_dev_Read()
1-20
– Opens a device for use.
– Closes down a device.
– Provides a device with buffers for inbound data.
VisualDSP++ 5.0 Device Drivers and System
Services Manual for Blackfin Processors