append uninitialized elements to array

[realhet]

Hello,

I've already found out how to create an array with uninitialized 
elements, but what I'm looking for is a way to append 16 
uninitialized ushorts to it and after I will it directly from 2 
SSE registers.

The approximate array length is known at the start so I could be 
able to do this by making an uninitializedArray and then doing 
the appending manually, but I wonder if there is a way to do this 
with array.reserve().

Basically it would be a thing that when this special 
uninitialized append is happening and when the reserved array 
size is big enough, it only increments the internal array length 
effectively.

Thanks