7.2 Opening the AG Driver

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This section describes how to access AG boards. The following functions are discussed in this section.

Function

Description

adiOpenDriver

Gains access to AG boards.

adiCloseDriver

Closes an open driver.

adiFetchAndProcess

Retrieves event from AG driver and processes it.

adiGetBoardInfo

Retrieves information about an AG board.

adiGetBoardSlots

Retrieves the board's MVIP configuration.
In order to communicate with an AG board, the application must first open the AG driver. The AG driver provides physical access to all AG boards in the host computer. The function adiOpenDriver invokes the AG driver open procedure and is prototyped below.

#include <adi.h> EXTRET adiOpenDriver ( unsigned *drvid, /* ADI Drv Handle */ MUX_HANDLE *muxid ); /* OS MUX Handle */
AG Access returns a drvid (driver handle) which is used when communicating with AG boards. The application supplies the driver handle to AG Access when invoking the following functions:

adiOpenPort: Associates the port with an open driver.

adiFetchAndProcess: Reads and processes events from an AG board.
The muxid (mux handle) is an operating system (OS) specific object used by the application process to wait for events, as described below:

UNIX - The mux handle is the file descriptor returned from the system open() call and is used by the application when invoking poll().

OS/2 - The mux handle is an event semaphore that is signaled when data is ready to be read from the AG board.

Windows NT: The mux handle is a Win32 event-object posted by an AG Access I/O thread. The application can use any Win32 event-object wait function, such as WaitForSingleObject or WaitForMultipleObjects.
The application passes the muxid to an OS wait routine, e.g., UNIX poll(), when it is ready to wait for and process AG Access events. The AG driver awakens the application when an event arrives from the AG board.
To promote portability, AG Access typecasts the mux handle to a MUX_HANDLE.
After the driver is open, the application can read the hardware configuration for each board in the system. The adiGetBoardInfo function returns information about the board such as its product name. The adiGetBoardSlots function returns the current MVIP address configuration.

Function	Description
adiOpenDriver	Gains access to AG boards.
adiCloseDriver	Closes an open driver.
adiFetchAndProcess	Retrieves event from AG driver and processes it.
adiGetBoardInfo	Retrieves information about an AG board.
adiGetBoardSlots	Retrieves the board's MVIP configuration.

(Page 3 of 11 in this chapter)