Legacy Document

Inside Macintosh: Devices /

Chapter 4 - SCSI Manager 4.3 / SCSI Manager 4.3 Reference

SCSI Manager 4.3 Functions / Client Functions

SCSIAction

You use the SCSIAction function to initiate a SCSI transaction or request a service from the XPT or SIM.

OSErr SCSIAction(SCSI_PB *scsiPB);

scsiPB

A pointer to a SCSI Manager parameter block.

-->	scsiPBLength	UInt16	The size of the parameter block.
-->	scsiFunctionCode	UInt8	The function selector code.
<--	scsiResult	OSErr	The returned result code.
-->	scsiDevice	DeviceIdent	A 4-byte value that uniquely identifies the target device.
-->	scsiCompletion	CallbackProc	A pointer to a completion routine. If this field is set to nil, the function is executed synchronously.
-->	scsiFlags	UInt32	Flags indicating the transfer direction and any special handling required for the request. See page 4-22 for descriptions of these flags.
-->	scsiDriverStorage	UInt8 *	Optional pointer to the device driver's private storage.

DESCRIPTION

The SCSIAction function initiates the request specified by the scsiFunctionCode field of the parameter block. Certain types of requests are handled by the XPT, but most are handled by the SIM. Table 4-2 lists the function selector codes. See the following sections for descriptions of the functions you access through SCSIAction.

When called asynchronously, SCSIAction normally returns the NoErr result code, indicating that the request was queued successfully. The result of the SCSI transaction is returned in the scsiResult field upon completion. If the SCSIAction function returns an error code, the request was not queued and the completion routine will not be called.

When the completion routine is called, it receives the A5 world that existed when the SCSIAction request was received. If A5 was invalid when the request was made, it is also invalid in the completion routine.

Your completion routine should use the following function prototype:

pascal void (*CallbackProc) (void * scsiPB);

There is no implied ordering of asynchronous requests made to different devices. An earlier request may be started later, and a later request may complete earlier. However, a series of requests to the same device is issued to that device in the order received, except when the scsiSIMQHead flag is set in the scsiFlags field of the parameter block.

When called synchronously, the SCSIAction function returns the actual result of the operation. It also places this result in the scsiResult field.

Table 4-2 SCSIAction function selector codes

Code	Function	Operation
00	SCSINop	No operation.
01	SCSIExecIO	Execute a SCSI I/O transaction.
02	Reserved
03	SCSIBusInquiry	Bus inquiry.
04	SCSIReleaseQ	Release a frozen SIM queue.
05-0F	Reserved
10	SCSIAbortCommand	Abort a SCSI command.
11	SCSIResetBus	Reset the SCSI bus.
12	SCSIResetDevice	Reset a SCSI device.
13	SCSITerminateIO	Terminate I/O transaction.
14-7F	Reserved
80	SCSIGetVirtualIDInfo	Return DeviceIdent of a virtual SCSI ID.
81	Reserved
82	SCSILoadDriver	Load a driver from a SCSI device.
83	Reserved
84	SCSIOldCall	SIM support function for original SCSI Manager emulation.
85	SCSICreateRefNumXref	Register a device driver.
86	SCSILookupRefNumXref	Find a driver reference number.
87	SCSIRemoveRefNumXref	Deregister a device driver.
88	SCSIRegisterWthNewXPT	XPT was replaced; SIM needs to reregister.
89-BF	Reserved
C0-FF	Vendor unique	Requests in this range are passed directly to the SIM without evaluation by the XPT.

RESULT CODES

noErr

0

Asynchronous request successfully queued, or synchronous request successfully completed

Note

Result codes for specific SCSIAction function requests are listed
in the following sections. See page 4-90 for a list of all result codes.