GLSL big-endian/little-endian compatibility

In my pixel format, I have the following union (c++ end):

union
{
    int mInteger;
    struct
    {
        short mData1;
        short mData2;
    };
};

in GLSL I want to access whatever's in mData1... so I do this:

layout (location=4) in uint input_mInteger;
...
uint access_mData1=(input_mInteger&uint(0x0000FFFF));
// Do something with access_mData1...

My question is... will that work on both BigEndian and LittleEndian systems? Or will I have to switch my and mask to 0xFFFF0000 (and will it otherwise be the same code, or will I need to do even more work to access the value in the low word of mInteger?)