protected override string ReadStringAt(uint index)
{
int start = (int) index;
uint length = (uint) (data.ReadCompressedUInt32 (ref start) & ~1);
if (length < 1)
return string.Empty;
var chars = new char [length / 2];
for (int i = start, j = 0; i < start + length; i += 2)
chars [j++] = (char) (data [i] | (data [i + 1] << 8));
return new string (chars);
}