review smart card writing of short and long value.

[eventualbuddha]

i.e. do we want to separate writing of short and long values?

[eventualbuddha]

My initial read of this is that we are probably okay to simply leave things as they are now. Writing a new short value by itself still only requires writing one chunk–let's call it chunks[0]–which contains the header, short & long lengths, and the short value itself. Writing a new long value requires writing chunks[0] again to update the long value length, plus updating however many subsequent chunks are needed to write the long value.

If we really wanted to separate them, we need to move the long value length from chunks[0] to chunks[1] and replace it with a boolean indicating whether there is a long value. Then we only have to re-write chunks[0] when writing a long value if we change whether there is a long value at all.

@benadida thoughts?

[benadida]

I was thinking we might have a fixed offset for the long value, even if the short value was shorter than that offset. I also worry a bit about extracting the card midway through writing the short value which would corrupt it. But I do agree that this might require more time and care to do right.