getInt64 method
Returns the (possibly negative) integer represented by the eight bytes at
the specified byteOffset
in this object, in two's complement binary
form.
The return value will be between -263 and 263 - 1, inclusive.
Throws RangeError if byteOffset
is negative, or
byteOffset + 8
is greater than the length of this object.
Implementation
int getInt64(int byteOffset, [Endian endian = Endian.big]);