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Inside Macintosh: Memory /

Chapter 2 - Memory Manager / Memory Manager Reference

Memory Manager Routines / Managing Relocatable Blocks

RecoverHandle

The Memory Manager does not allow you to change relocatable blocks into nonrelocatable blocks, or vice-versa. However, if you no longer have access to a handle but still have access to its master pointer, you can use the RecoverHandle function to recreate a handle to the relocatable block referenced by the master pointer.

FUNCTION RecoverHandle (p: Ptr): Handle;

p

The master pointer to a relocatable block.

DESCRIPTION

The RecoverHandle function returns a handle to the relocatable block pointed to by p. If p doesn't point to a valid block, the results of RecoverHandle are undefined.

SPECIAL CONSIDERATIONS

Even though RecoverHandle does not move or purge memory, you should not call it at interrupt time.

ASSEMBLY-LANGUAGE INFORMATION

The registers on entry and exit for RecoverHandle are

Registers on entry
A0	Master pointer

Registers on exit
A0	Handle to master pointer's relocatable block
D0	Unchanged

Unlike most other Memory Manager routines, RecoverHandle does not return a
result code in register D0; the previous contents of D0 are preserved unchanged.
The result code is, however, returned by MemError.

The RecoverHandle function looks only in the current heap zone for the relocatable block pointed to by the parameter p. If you want to use the RecoverHandle function to recover a handle for a relocatable block in the system heap, set bit 10 of the routine trap word. In most development systems, you can do this by supplying the word SYS as the second argument to the routine macro, as follows:

_RecoverHandle ,SYS

RESULT CODES

noErr	0	No error
memBCErr	-115	Block check failed