Creates a handle for an area of memory in the process' virtual address space. You can use the handle in conjunction with MapRtSharedMemory to share memory among RT processes and between RT and Windows processes.

RTHANDLE CreateRtMemoryHandle(
    PVOID pOffset,   // location of memory to be shared within calling thread's virtual address space
    DWORD cbSize     // size in bytes of contiguous memory to be shared
);

Parameters

pOffset

Offset of the memory area within the calling thread's virtual address space to be shared.

cbSize

Number of bytes to include in the shared memory area.

Remarks

Before the microprocessor can access an area of memory in Protected Mode, an RT handle for the memory area must exist in one of the descriptor tables: the GDT or LDT. CreateRtMemoryHandle lets you add an RT handle to the GDT which allows global access to physical memory within the thread's virtual address space.

A segment created with this system call can be deleted by calling DeleteRtMemoryHandle. The memory associated with these handles does not return to the memory pool of the calling thread's process for reallocation when the RT handles are deleted. When the segment is deleted, the GDT slot is returned to the memory manager for reassignment.

Return Values

An RTHANDLE for the shared memory area

Success.

BAD_RTHANDLE

Failure. To determine the status, call GetLastRtError.

Status

E_OK 0x0000

No exceptional conditions occurred.

E_MEM 0x0002

Creating an RT handle requires more available physical memory than currently exists.

E_LIMIT 0x0004

Creating the requested RT handle exceeds the process's object limit.

E_SLOT 0x000C

You cannot create more RT objects because the GDT's slots are full.

Requirements

See Also

Memory management system calls, DeleteRtMemoryHandle