getInt16 abstract method
Returns the (possibly negative) integer represented by the two bytes at
byteOffset in this object, in two's complement binary
The return value will be between -215 and 215 - 1, inclusive.
byteOffset must be non-negative, and
byteOffset + 2 must be less than or equal to the length of this object.
int getInt16(int byteOffset, [Endian endian = Endian.big]);