Method used to unmarshall the datain buffer.
Get a reference to the sense buffer
Get a reference to the dataout buffer (possibly null)
Get a reference to the datain buffer (possibly null)
Get a reference ot the CDB
Get the SCSIDevice
Allocate the CDB and set the opcode field. Opcode is used to determine cdb length.
Execute the SCSI command on the device (using device.sgio_execute), then unmarshalls the datain buffer with a call to unmarshall().
Abstract method used to unmarshall the datain buffer.
ReadCapacity16 class to send a read capacity