Get a string from buffer where the string spans the length of the buffer. The span does not need to be null-terminated.
Decode the byte in the buffer given the offset and bitmask. We find the byte, '&' with the mask, then right-shift to get the final result.
Simple helper function to create the second byte of the CDB for read(10), read(12), and read(16). For a description of the arguments, see the Read(XX) commands.