Virtual Memory: 3.1 Using Virtual Memory: How to Use VM

There are five basic steps to using VM files. The steps are outlined below, and described in greater detail in the following sections.

Open (or create) the VM file
Before you perform any actions on a VM file, you must open it with VMOpen() . This routine can be used to open an existing VM file or create a new one. If you use the document control objects, they will open and create files automatically. Once you have created a VM file, you may want to change its attributes with VMSetAttributes() .
Bring a VM block into the global memory heap
After you open a VM file, you can bring blocks from the file into memory with VMLock() . You can also create new blocks with VMAlloc() and VMAttach() .
Access the data
Once a VM block has been brought into memory, you can access it the way you would any other memory block. When you are done with the data, you should unlock it with VMUnlock() . If you change the memory, you should mark it dirty with VMDirty() before unlocking it. This ensures that the new version of the block will be written to the disk.
Update the VM file
Use one of the several VM updating routines to copy the dirty blocks back to the disk. (If asynchronous update is allowed, the VM file manager will try to update blocks whenever they are unlocked.)
Close the VM file
Use VMClose() when you are done with the file. It will update the file and close it.