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Inside Macintosh: Devices /

Chapter 4 - SCSI Manager 4.3 / SCSI Manager 4.3 Reference

SCSI Manager 4.3 Functions / SIM Internal Functions

SCSIOldCall

The XPT calls this function when a client calls the original SCSI Manager function SCSISelect.

typedef void (*SIMActionProc) (void * scsiPB, Ptr SIMGlobals);

scsiPB

A pointer to a SCSI I/O parameter block, which is described on page 4-23.

SIMGlobals

A pointer to the SIM's static data storage.

-->	scsiPBLength	UInt16	The size of the parameter block.
-->	scsiFunctionCode	UInt8	The SCSIOldCall function selector code (0x84).
-->	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.
<--	scsiCurrentPhase	UInt16	The current SCSI bus phase.
-->	scsiSelector	SInt16	The SCSISelect trap selector (0x02).
<--	scsiOldCallResult	OSErr	The result code from SCSISelect.

DESCRIPTION

This function indicates the beginning of an original SCSI Manager transaction. A SIM that supports original SCSI Manager emulation should attempt to select the device described in the scsiDevice field. Because the entire SCSI transaction is not completed by a call to SCSIOldCall, the result code for this function is returned in the scsiOldCallResult field rather than the scsiResult field, as with other functions. Subsequent original SCSI Manager function calls for this transaction are made through the NewOldCall function.

If the SIM successfully selects the device, it should queue the parameter block like any other SCSI I/O parameter block. The parameter block should not be removed until the NewOldCall function completes a SCSIComplete command.

To provide full compatibility with the original SCSI Manager, a SIM must be able to perform a SCSI arbitration and select process independent of a SCSI message-out or command phase. If the SIM requires the CDB or message-out bytes it will not be able to perform the select operation at the time of the SCSIOldCall request. The SIM should return noErr in the scsiOldCallResult field and wait for a subsequent I/O request before actually selecting the device.

RESULT CODES

The SCSIOldCall function returns an appropriate SCSISelect result code in the scsiOldCallResult field of the parameter block.