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Inside Macintosh: Memory /

Chapter 2 - Memory Manager / Memory Manager Reference

Memory Manager Routines / Changing the Sizes of Relocatable and Nonrelocatable Blocks

SetPtrSize

You can use the SetPtrSize procedure to change the logical size of the nonrelocatable block corresponding to a pointer.

PROCEDURE SetPtrSize (p: Ptr; newSize: Size);

p

A pointer to a nonrelocatable block.

newSize

The desired new logical size, in bytes, of the nonrelocatable block.

DESCRIPTION

The SetPtrSize procedure attempts to change the logical size of the nonrelocatable block pointed to by p. The new logical size is specified by newSize.

An attempt to increase the size of a nonrelocatable block might fail because of a block above it that is either nonrelocatable or locked. You should be prepared for this possibility.

SPECIAL CONSIDERATIONS

Because SetPtrSize allocates memory, you should not call it at interrupt time.

ASSEMBLY-LANGUAGE INFORMATION

The registers on entry and exit for SetPtrSize are

Registers on entry
A0	Pointer to the nonrelocatable block
D0	Desired new size of nonrelocatable block

Registers on exit
D0	Result code

RESULT CODES

noErr	0	No error
memFullErr	-108	Not enough memory
memWZErr	-111	Attempt to operate on a free block