如何以编程方式确定（Windows）操作系统的最大用户模式空间？

I'm writing a diagnostic app which needs to log what the user has set as his user-mode space a.k.a. user-mode virtual address space a.k.a. the /3GB switch in WinXP or the increaseuserva switch in bcdedit on Vista/Win7.I'm writing a diagnostic app which needs to log