No, if you want to be able to switch from working with large units to bytes, then you would need to change the organization of the bits between big-endian and little-endian, so that the bit-fields lie in sequence in memory. Thinking about it, unless adding an 8-bit field is very common, I am not sure that switching from bigger words to bytes is actually going to save you work on many machines. If you are inserting a 5 or 10 bit wide field, you are going to need to shift all the bits in all the bytes, and it will likely be quicker to do that work on full words, rather than individual bytes. Only in the special case of adding an exact multiple of 8 bits (that isn't also a multiple of the natural word size) would moving bytes make sense.