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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

NewOldCall

The XPT calls this function when a client calls any of the original SCSI Manager functions other than SCSISelect (which is handled by SCSIOldCall). The NewOldCall function must conform to the following type definition:

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.
<--	scsiResult	OSErr	The SCSIComplete 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.
<--	scsiCurrentPhase	UInt16	The current SCSI bus phase.
-->	scsiSelector	SInt16	The _SCSIDispatch trap selector.
<--	scsiOldCallResult	OSErr	The function result code.
<--	scsiSCSImessage	UInt8	The SCSIComplete message byte.

DESCRIPTION

After an original SCSI Manager transaction begins, the NewOldCall function receives all subsequent original SCSI Manager function requests until the transaction is completed. The XPT converts all original SCSI Manager function requests (except SCSIGet and SCSIStat) into SCSI Manager 4.3 parameter block requests and sends them to the appropriate SIM.

A SIM uses the scsiSelector field of the parameter block to determine which function to perform and should return the current bus phase and message byte in the appropriate fields after each request.

The XPT converts a SCSIReset request into a SCSIResetBus request and sends it to all SIMs that support original SCSI Manager emulation. The XPT handles SCSIStat requests itself, using the information returned in the scsiCurrentPhase field.

RESULT CODES

Result codes from all emulated functions except SCSIComplete are returned in the scsiOldCallResult field. The SCSIComplete result is returned in scsiResult. This indicates to the XPT that the transaction is complete and that the SIM is ready to start a new original SCSI Manager transaction. See the chapter "SCSI Manager" in this book for a list of original SCSI Manager result codes.