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Inside Macintosh: Memory /

Chapter 1 - Introduction to Memory Management / Memory Management Reference

Memory Management Routines / Setting the Properties of Relocatable Blocks

HGetState

You can use the HGetState function to get the current properties of a relocatable block (perhaps so that you can change and then later restore those properties).

FUNCTION HGetState (h: Handle): SignedByte;

h

A handle to a relocatable block.

DESCRIPTION

The HGetState function returns a signed byte containing the flags of the master pointer for the given handle. You can save this byte, change the state of any of the flags, and
then restore their original states by passing the byte to the HSetState procedure, described next.

You can use bit-manipulation functions on the returned signed byte to determine the value of a given attribute. Currently the following bits are used:

Bit	Meaning
0-4	Reserved
5	Set if relocatable block is a resource
6	Set if relocatable block is purgeable
7	Set if relocatable block is locked

If an error occurs during an attempt to get the state flags of the specified relocatable block, HGetState returns the low-order byte of the result code as its function result. For example, if the handle h points to a master pointer whose value is NIL, then the signed byte returned by HGetState will contain the value -109.

ASSEMBLY-LANGUAGE INFORMATION

The registers on entry and exit for HGetState are

Registers on entry
A0	Handle whose properties you want to get

Registers on exit
D0	Byte containing flags

RESULT CODES

noErr	0	No error
nilHandleErr	-109	NIL master pointer
memWZErr	-111	Attempt to operate on a free block