Legacy Document

Inside Macintosh: Devices /

Chapter 2 - Slot Manager / Slot Manager Reference

Slot Manager Routines / Loading Drivers and Executing Code From sResources

SGetDriver

You can use the SGetDriver function to load an sResource's device driver.

FUNCTION SGetDriver (spBlkPtr: SpBlockPtr): OSErr;

spBlkPtr

A pointer to a Slot Manager parameter block.

<--	spResult	Handle	A handle to the device driver.
-->	spsExecPBlk	Ptr	A pointer to the SEBlock.
-->	spSlot	SignedByte	The slot number.
-->	spID	SignedByte	The sResource ID.
-->	spExtDev	SignedByte	The external device ID.
X	spSize	SignedByte
X	spFlags	SignedByte

DESCRIPTION

The SGetDriver function loads a device driver from an sResource into a relocatable block in the system heap.

You specify an sResource with the spSlot, spID, and spExtDev fields of the Slot Manager parameter block you point to in the spBlkPtr parameter, and provide a pointer to a slot execution parameter block in the spsExecPBlk field.

The SGetDriver function searches the sResource for an sRsrcLoadRec entry. If it finds one, it loads the sLoadDriver record and executes it. If no sRsrcLoadRec entry exists, the SGetDriver function looks for an sRsrcDrvrDir entry. If it finds one, it loads the driver into memory.

The SGetDriver function returns a handle to the driver in the spResult field of the parameter block.

SPECIAL CONSIDERATIONS

The SGetDriver function allocates memory; your application should not call this function at interrupt time.

ASSEMBLY-LANGUAGE INFORMATION

The trap macro and routine selector for the SGetDriver function are

Trap macro	Selector
_SlotManager	$002D

You must set up register D0 with the routine selector and register A0 with the address of the Slot Manager parameter block. When _SlotManager returns, register A0 contains a handle to the loaded driver, and register D0 contains the result code.

Registers on entry
A0	Address of the parameter block
D0	$002D

Registers on exit
A0	Handle to loaded driver
D0	Result code

RESULT CODES

noErr	0	No error
smNoMoresRsrcs	-344	Requested sResource not found

SEE ALSO

For more information about sResources, including the sRsrcDrvrDir and sRsrcLoadRec entry types, see Designing Cards and Drivers for the Macintosh Family, third edition.