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Inside Macintosh: Devices /

Chapter 2 - Slot Manager / Slot Manager Reference

Slot Manager Routines / Getting Information From sResources

SReadLong

You can use the SReadLong function to determine the value of a long word pointed to by the offset field of an sResource entry.

FUNCTION SReadLong (spBlkPtr: SpBlockPtr): OSErr;

spBlkPtr

A pointer to a Slot Manager parameter block.

<--	spResult	LongInt	The contents of the long word.
-->	spsPointer	Ptr	A pointer to an sResource (described in "The sResource," beginning on page 2-7).
-->	spID	SignedByte	The ID of the sResource entry.
X	spSize	LongInt
X	spOffsetData	LongInt
X	spByteLanes	SignedByte

DESCRIPTION

The SReadLong function returns the 32-bit value pointed to by the offset field of an sResource entry. In the Slot Manager parameter block you point to in the spBlkPtr parameter, you provide a pointer to the sResource in the spsPointer field and specify the ID of the entry in the spID field. The SReadLong function returns the long word value in the spResult field.

SPECIAL CONSIDERATIONS

This function may alter the values of the spSize, spOffsetData, and spByteLanes fields of the parameter block. Your application should not depend on the values returned in these fields.

ASSEMBLY-LANGUAGE INFORMATION

The trap macro and routine selector for the SReadLong function are

Trap macro	Selector
_SlotManager	$0002

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	$0002

Registers on exit
D0	Result code

RESULT CODES

noErr	0	No error
smNoMoresRsrcs	-344	Requested sResource not found