1 package org.jscsi.target.scsi.modeSense;
2
3
4 import org.jscsi.target.scsi.ISerializable;
5
6
7 /**
8 * Instances {@link ModeParameterHeader} are part of {@link ModeParameterList} objects and specify the layout and length
9 * of the following non-header fields.
10 *
11 * @author Andreas Ergenzinger
12 */
13 public abstract class ModeParameterHeader implements ISerializable {
14
15 /**
16 * When using the MODE SENSE command, the MODE DATA LENGTH field indicates the length in bytes of the following data
17 * that is available to be transferred. The mode data length does not include the number of bytes in the MODE DATA
18 * LENGTH field.
19 * <p>
20 * When using the MODE SELECT command, this field is reserved.
21 * <p>
22 * Logical units that support more than 256 bytes of block descriptors and mode pages may need to implement ten-byte
23 * mode commands. The mode data length field in the six-byte CDB header limits the returned data to 256 bytes.
24 */
25 protected final int modeDataLength;
26
27 /**
28 * The contents of the MEDIUM TYPE field are unique for each device type. For direct-access block devices, the value
29 * must be 0x00.
30 */
31 protected final byte mediumType = (byte) 0x00;
32
33 /**
34 * The DEVICE-SPECIFIC PARAMETER field is unique for each device type. For direct-access block devices the byte
35 * looks like this:
36 * <p>
37 * <code>
38 * +---+---+---+---+---+---+---+---+---+<br/>
39 * |bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |<br/>
40 * +---+---+---+---+---+---+---+---+---+<br/>
41 * |___|WP_|RESERV-|DPO|___RESERVED____|<br/>
42 * |___|___|__ED___|FUA|_______________|<br/>
43 * +---+---+---+---+---+---+---+---+---+
44 * </code>
45 * <p>
46 * When used with the MODE SELECT command, the write protect (WP) bit is not defined. When used with the MODE SENSE
47 * command, a WP bit set to one indicates that the medium is write-protected. A WP bit set to zero indicates that
48 * the medium is not write-protected. When the software write protect (SWP) bit in the Control mode page (see SPC-4)
49 * is set to one, the WP bit shall be set to one.
50 * <p>
51 * When the SWP bit in the Control mode page is set to zero, the WP bit shall be set to one if the medium is
52 * write-protected (e.g., due to mechanisms outside the scope of this standard) or zero if the medium is not
53 * write-protected.
54 * <p>
55 * When used with the MODE SELECT command, the DPOFUA bit is reserved. When used with the MODE SENSE command, a
56 * DPOFUA bit set to zero indicates that the device server does not support the DPO and FUA bits. When used with the
57 * MODE SENSE command, a DPOFUA bit set to one indicates that the device server supports the DPO and FUA bits.
58 * <p>
59 * So, the simulated logical unit of the jSCSI Target must always use a value of 0x00.
60 */
61 protected final byte deviceSpecificParameter = (byte) 0x00;
62
63 /**
64 * The BLOCK DESCRIPTOR LENGTH field contains the length in bytes of all the block descriptors. It is equal to the
65 * number of block descriptors times eight if the LONGLBA bit is set to zero or times sixteen if the LONGLBA bit is
66 * set to one, and does not include mode pages or vendor specific parameters (e.g., page code set to zero), if any,
67 * that may follow the last block descriptor. A block descriptor length of zero indicates that no block descriptors
68 * are included in the mode parameter list. This condition shall not be considered an error.
69 */
70 protected final int blockDescriptorLength;
71
72 /**
73 * The abstract constructor.
74 *
75 * @param modeDataLength the length in bytes of all MODE DATA list elements
76 * @param blockDescriptorLength the length in bytes of all BLOCK DESCRIPTOR list elements
77 */
78 public ModeParameterHeader (final int modeDataLength, final int blockDescriptorLength) {
79 this.modeDataLength = modeDataLength;
80 this.blockDescriptorLength = blockDescriptorLength;
81 }
82 }