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Chapter 4 - SCSI Manager 4.3 / SCSI Manager 4.3 Reference

SCSI Manager 4.3 Functions / Client Functions

SCSITerminateIO

You can use the SCSITerminateIO function to cancel an I/O request.

OSErr SCSIAction(SCSITerminateIOPB *scsiPB);

scsiPB

A pointer to a SCSI terminate I/O parameter block, which is described on page 4-33.

-->	scsiPBLength	UInt16	The size of the parameter block.
-->	scsiFunctionCode	UInt8	The SCSITerminateIO function selector code (0x13).
<--	scsiResult	OSErr	The returned result code.
-->	scsiDevice	DeviceIdent	The device identification record.
-->	scsiCompletion	CallbackProc	A pointer to a completion routine. If this field is set to nil, the function is executed synchronously.
-->	scsiDriverStorage	UInt8 *	Optional pointer to the device driver's private storage.
-->	scsiIOptr	SCSI_IO *	A pointer to the SCSI I/O parameter block to be canceled.

DESCRIPTION

The SCSITerminateIO function cancels the SCSIExecIO request identified by the scsiIOptr field. If the request has not yet been delivered to the device, it is removed from the queue and its completion routine is called with a result code of scsiTerminated. If the request has already been started, the SIM attempts to send a TERMINATE IO PROCESS message to the device, either by asserting the /ATN signal or by reselecting the device. The function returns the scsiUnableToTerminate result code if the specified request has already been completed.

The SCSITerminateIO function differs from the SCSIAbortCommand function (described on page 4-45) only in the message it sends over the SCSI bus. TERMINATE IO PROCESS is an optional SCSI-2 message that instructs the device to complete a request normally although prematurely, while attempting to maintain media integrity.

SPECIAL CONSIDERATIONS

Because the interrupt that calls the completion routine can pre-empt the SCSITerminateIO request, this function can produce unexpected results if the completion routine for the canceled request reuses the parameter block.

RESULT CODES

noErr	0	No error
scsiBusInvalid	-7869	The bus ID is invalid
scsiRequestInvalid	-7870	The parameter block request is invalid
scsiPBLengthError	-7872	The parameter block is too small for this SIM
scsiQLinkInvalid	-7881	The qLink field was not 0
scsiUnableToTerminate	-7927	Unable to terminate I/O parameter block request