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Inside Macintosh: Devices /

Chapter 1 - Device Manager / Device Manager Reference

Device Manager Functions / Controlling and Monitoring Device Drivers

PBKillIO

You can use the PBKillIO function to terminate all current and pending I/O requests for a device driver.

pascal OSErr PBKillIO(ParmBlkPtr paramBlock, Boolean async); 

paramBlock

A pointer to a CntrlParam structure of the Device Manager parameter block.

async

A Boolean value that indicates whether the request is asynchronous. You must set this field to false because the PBKillIO function does not support asynchronous requests.

-->	ioCompletion	ProcPtr	A pointer to a completion routine.
<--	ioResult	OSErr	The device driver's result code.
-->	ioCRefNum	short	The driver reference number.

DESCRIPTION

The PBKillIO function stops any current I/O request being processed by the driver specified by the ioCRefNum field, and removes all pending requests from the I/O queue for that driver. The Device Manager calls the completion routine, if any, for each pending request, and sets the ioResult field of each request equal to the result code abortErr.

The Device Manager passes PBKillIO requests to a device driver only if the driver is open and enabled for control calls. If the driver returns an error, the I/O queue is left unchanged and no completion routines are called.

WARNING

The PBKillIO function terminates all pending I/O requests for a driver, including requests initiated by other applications.

SPECIAL CONSIDERATIONS

The Device Manager always executes the PBKillIO function immediately; that is, it never places a PBKillIO request in the I/O queue. However, you should not call this function immediately--always call the PBKillIO function synchronously.

Although the Device Manager imposes no restrictions on calling PBKillIO at interrupt time, you should consult a device driver's documentation to determine if it supports this.

ASSEMBLY-LANGUAGE INFORMATION

The trap macro for the PBKillIO function is _KillIO (0xA006). You must set up register A0 with the address of the parameter block. When _KillIO returns, register D0 contains the result code. Register D0 is the only register affected by this function.

Registers on entry
A0	Address of the parameter block

Registers on exit
D0	Result code

RESULT CODES

noErr	0	No error
controlErr	-17	Driver does not respond to this control request
badUnitErr	-21	Driver reference number does not match unit table
unitEmptyErr	-22	Driver reference number specifies a nil handle in unit table
notOpenErr	-28	Driver not open

SEE ALSO

For information about the high-level function for terminating current and pending I/O requests for a driver, see the description of the KillIO function on page 1-80.