什么数据类型是32位操作系统中的16位和64位操作系统中的32位？

I'm looking for a datatype (which will be used as an Index), it should be 16 bits in 32-bit os and 32-bits in 64-bit OS. I use VS2010, and I'm aware that HALF_PTR can be used but it doesn't sound good when used for index and I can still typedef it to a more meaningful name, but before that is there any defined datatype that I can use for this purpose?I'm looking for a datatype (which will be used