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Inside Macintosh: Devices /

Chapter 2 - Slot Manager / Slot Manager Reference

Slot Manager Routines / Getting Information From sResources

SReadStruct

You can use the SReadStruct function to obtain a copy of any data structure pointed to by an sResource entry. You might want to use this function, for example, when the data structure type is defined by the card designer.

FUNCTION SReadStruct (spBlkPtr: SpBlockPtr): OSErr;

spBlkPtr

A pointer to a Slot Manager parameter block.

-->	spResult	Ptr	A pointer to a memory block.
-->	spsPointer	Ptr	A pointer to the structure.
-->	spSize	LongInt	The length in bytes of the structure.
X	spByteLanes	SignedByte

DESCRIPTION

The SReadStruct function copies any arbitrary data structure from the declaration ROM of an expansion card into memory.

You provide a pointer to the structure in the spsPointer field and specify the size of the structure in the spSize field. You must also allocate a memory block for the result and send a pointer to it in the spResult field.

The SReadStruct function copies the data structure into the memory block pointed to by the spResult field.

SPECIAL CONSIDERATIONS

This function may alter the value of the spByteLanes field of the parameter block. Your application should not depend on the value returned in this field.

ASSEMBLY-LANGUAGE INFORMATION

The trap macro and routine selector for the SReadStruct function are

Trap macro	Selector
_SlotManager	$0007

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 D0 contains the result code.

Registers on entry
A0	Address of the parameter block
D0	$0007

Registers on exit
D0	Result code

RESULT CODES

noErr	0	No error
smNoMoresRsrcs	-344	Requested sResource not found

SEE ALSO

For information about obtaining a pointer to a data structure pointed to by the offset field of an sResource entry, rather than a copy of the data structure, see the description of the SFindStruct function on page 2-48.