x+size                    <-- HIGH
          +-------------+
x+size-1  |             |
          +-------------+
          |             |
          +-------------+
          . Ring Buffer .
          .             .
          .             .
          +-------------+
          |             |
          +-------------+
          |             | <-- PUT  <-- GET
x         +-------------+
                                          0
                          Byte count:   ______