GDI Memory Services

GDI provides several memory-related services to driver writers, including the ability to allocate and deallocate system memory, user memory, private user memory, and video memory, as well as the ability to lock and unlock a range of memory. The following table lists the GDI memory services.

Function	Description
EngAllocMem	Allocates a block of memory, and inserts a caller-supplied tag before the allocation.
EngAllocPrivateUserMem	Allocates a block of private user memory from the address space of a specified process, and inserts a caller-supplied tag before the allocation.
EngAllocUserMem	Allocates a block of memory from the address space of the current process, and inserts a caller-supplied tag before the allocation.
EngFreeMem	Deallocates a block of system memory allocated by EngAllocMem.
EngFreePrivateUserMem	Deallocates a block of private user memory allocated by EngAllocPrivateUserMem.
EngFreeUserMem	Deallocates a block of user memory allocated by EngAllocUserMem.
EngSecureMem	Locks down the specified address range in memory.
EngUnsecureMem	Unlocks a memory address range that is locked down.
HeapVidMemAllocAligned	Allocates off-screen memory for a display driver by using the DirectDraw video memory heap manager.
VidMemFree	Frees off-screen memory allocated for a display driver by HeapVidMemAllocAligned.