Legacy Document

Inside Macintosh: Devices /

Chapter 2 - Slot Manager / Slot Manager Reference

Slot Manager Routines / Getting Information From sResources

SGetBlock

You can use the SGetBlock function to obtain a copy of an sBlock data structure pointed to by the offset field of an sResource entry.

FUNCTION SGetBlock (spBlkPtr: SpBlockPtr): OSErr;

spBlkPtr

A pointer to a Slot Manager parameter block.

<--	spResult	Ptr	A pointer to a copy of an sBlock data structure (described on page 2-9).
-->	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
X	spFlags	SignedByte

DESCRIPTION

The SGetBlock function returns a copy of the sBlock data structure pointed to by the offset field of an sResource entry.

In the 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 SGetBlock function allocates a memory buffer, copies the contents of the sBlock data structure into it, and returns a pointer to it in the spResult field. You should dispose of this pointer by using the Memory Manager procedure DisposePtr.

SPECIAL CONSIDERATIONS

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

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

ASSEMBLY-LANGUAGE INFORMATION

The trap macro and routine selector for the SGetBlock function are

Trap macro	Selector
_SlotManager	$0005

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	$0005

Registers on exit
D0	Result code

RESULT CODES

noErr	0	No error
smNoMoresRsrcs	-344	Requested sResource not found