anchor.diff:    (let* ((byte-1    (read-my-byte stream))
            (byte-2    (read-my-byte stream))
            (unsigned  (logior (ash byte-2 8) byte-1)))
  -    (declare (type fixnum unsigned))
       (if signed (unsigned-to-signed unsigned 2) unsigned)))
   
   (defun read-3-bytes-integer (stream  &key signed)
  
positive.code: (declaim (inline unsigned-to-signed read-fixed-length-integer))
  
  (defun unsigned-to-signed (byte n)
    (declare (type fixnum byte n))
    (logior byte (- (mask-field (byte 1 (1- (* n 8))) byte))))
  
  (defun read-2-bytes-integer (stream &key signed)
  
negative.code:                   (ash byte-9 64) (ash byte-8 56) (ash byte-7 48)
                    (ash byte-6 40) (ash byte-5 32) (ash byte-4 24)
                    (ash byte-3 16) (ash byte-2  8) byte-1)))
      (if signed (unsigned-to-signed unsigned 10) unsigned)))
  
  (defun write-fixed-length-integer (int length stream)
    "Write INT to STREAM as a LENGTH byte integer."
  