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Inside Macintosh: Memory /

Chapter 3 - Virtual Memory Manager / Virtual Memory Manager Reference

Routines / Virtual Memory Management

HoldMemory

To make a portion of the address space resident in physical memory and ineligible for paging, use the HoldMemory function.

FUNCTION HoldMemory (address: UNIV Ptr; count: LongInt): OSErr;

address

The starting address of the range of memory to be held in RAM.

count

The size, in bytes, of the range of memory to be held in RAM.

DESCRIPTION

The HoldMemory function makes the portion of the address space beginning at address and having a size of count bytes resident in physical memory and ineligible for paging.

If the address parameter supplied to the HoldMemory function is not on a page boundary, then it is rounded down to the nearest page boundary. Similarly, if the specified range does not end on a page boundary, the count parameter is rounded up so that the entire range of memory is held.

SPECIAL CONSIDERATIONS

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

ASSEMBLY-LANGUAGE INFORMATION

The trap macro and routine selector for the HoldMemory function are

Trap macro	Selector
_MemoryDispatch	$0000

The registers on entry and exit for this routine are

Registers on entry
D0	Selector code
A0	Starting address
A1	Number of bytes to hold

Registers on exit
D0	Result code

RESULT CODES

noErr	0	No error
paramErr	-50	Error in parameter list
notEnoughMemoryErr	-620	Insufficient physical memory
interruptsMaskedErr	-624	Called with interrupts masked