Inside Macintosh: Devices /

Chapter 5 - ADB Manager / ADB Manager Reference

Application-Defined Routines / ADB Command Completion Routines

MyCompletionRoutine

When you use the ADBOp function to send a command to an ADB device, the ADB Manager calls your completion routine when the ADB device has completed the command.

PROCEDURE MyCompletionRoutine;   {parameters passed in registers}

DESCRIPTION

The ADB Manager passes parameters to a completion routine in registers A0, A1, A2, and D0, as described next.

ASSEMBLY-LANGUAGE INFORMATION

On entry to your completion routine, the ADB Manager sets the following registers:

Register	Value
A0	A pointer to the data area specified by the buffer parameter to the ADBOp function. This area contains data stored as a Pascal string (maximum 8 bytes of data preceded by one length byte). For example, data returned by an ADB device in response to a Talk command issued by a call to the ADBOp function can be accessed through this pointer.
A1	A pointer to the completion routine.
A2	A pointer to the data area that was specified by the data parameter to the ADBOp function. Your completion routine can use this area to store information; for example, to set a flag indicating that the command has completed.
D0	The ADB command number (byte) that resulted in the completion routine being called.

SEE ALSO

See Listing 5-2 on page 5-25 for an example of a completion routine.