1 package org.jscsi.target.scsi.modeSense;
2
3
4 import java.nio.ByteBuffer;
5
6 import org.jscsi.target.scsi.ISerializable;
7 import org.jscsi.target.util.BitManip;
8
9
10 /**
11 * MODE PAGEs are sent in response to successful <code>MODE SENSE</code> SCSI commands. There are two different,
12 * command-specific formats for MODE PAGEs - the PAGE_0 FORMAT and the SUB-PAGE FORMAT, represented by the non-abstract
13 * children of this class, {@link Page_0FormatModePage} and {@link SubPageFormatModePage}, respectively.
14 *
15 * @author Andreas Ergenzinger
16 */
17 public abstract class ModePage implements ISerializable {
18
19 /**
20 * This value plus {@link #pageLength} equals the length in bytes of a MODE PAGE using the SUB-PAGE FORMAT.
21 */
22 private static final int SUB_PAGE_FORMAT_PAGE_LENGTH_MODIFIER = 4;
23
24 /**
25 * This value plus {@link #pageLength} equals the length in bytes of a MODE PAGE using the PAGE_0 FORMAT.
26 */
27 private static final int PAGE_0_FORMAT_PAGE_LENGTH_MODIFIER = 2;
28
29 /**
30 * When using the MODE SENSE command, a parameters saveable (PS) bit set to one indicates that the mode page may be
31 * saved by the logical unit in a nonvolatile, vendor specific location. A PS bit set to zero indicates that the
32 * device server is not able to save the supporte parameters. When using the MODE SELECT command, the PS bit is
33 * reserved.
34 */
35 private final boolean parametersSaveable;
36
37 /**
38 * A SubPage Format (SPF) bit set to <code>false</code>/zero indicates that the page_0 mode page format is being
39 * used. A SPF bit set to <code>true</code>/one indicates that the sub_page mode page format is being used.
40 */
41 private final boolean subPageFormat;
42
43 /**
44 * Specifies what kind of information is contained in the MODE PAGE.
45 */
46 private final int pageCode;
47
48 /**
49 * The number of bytes following the PAGE LENGTH field.
50 */
51 protected final int pageLength;
52
53 /**
54 * This value plus {@link #pageLength} equals the length in bytes of the MODE PAGE.
55 */
56 private final int pageLengthModifier;
57
58 /**
59 * The abstract constructor.
60 *
61 * @param parametersSaveable value of the PARAMETERS SAVEABLE bit
62 * @param subPageFormat <code>true</code> if and only if the SUB-PAGE FORMAT is to be used
63 * @param pageCode specifies the kind of information is contained in the MODE PAGE
64 * @param pageLength the value of the PAGE LENGTH field
65 */
66 public ModePage (final boolean parametersSaveable, final boolean subPageFormat, final int pageCode, final int pageLength) {
67 this.parametersSaveable = parametersSaveable;
68 this.subPageFormat = subPageFormat;
69 if (subPageFormat)
70 pageLengthModifier = SUB_PAGE_FORMAT_PAGE_LENGTH_MODIFIER;
71 else
72 pageLengthModifier = PAGE_0_FORMAT_PAGE_LENGTH_MODIFIER;
73 this.pageCode = pageCode;
74 this.pageLength = pageLength;
75 }
76
77 public final void serialize (final ByteBuffer byteBuffer, final int index) {
78 // serialize first byte
79 // (for convenience reasons from least significant to most significant
80 // field)
81 byte b = (byte) pageCode;// PAGE CODE
82 b = BitManip.getByteWithBitSet(b, 6, subPageFormat);// SPF
83 b = BitManip.getByteWithBitSet(b, 7, parametersSaveable);// PS
84 byteBuffer.position(index);
85 byteBuffer.put(b);
86 // serialize remaining fields
87 serializeSubPageCode(byteBuffer, index);
88 serializePageLength(byteBuffer, index);
89 serializeModeParameters(byteBuffer, index);
90 }
91
92 /**
93 * This method serializes the SUBPAGE CODE field, if the mode page format says this field exists (only for the
94 * sub_page mode page format).
95 *
96 * @param buffer where to insert the serialized object representation
97 * @param index the position of the first byte of the serialized object in the {@link ByteBuffer}
98 */
99 protected abstract void serializeSubPageCode (final ByteBuffer buffer, final int index);
100
101 /**
102 * Serializes the PAGE LENGTH field.
103 *
104 * @param buffer where to insert the serialized object representation
105 * @param index the position of the first byte of the serialized object in the {@link ByteBuffer}
106 */
107 protected abstract void serializePageLength (final ByteBuffer buffer, final int index);
108
109 /**
110 * @param buffer where to insert the serialized object representation
111 * @param index the position of the first byte of the serialized object in the {@link ByteBuffer}
112 */
113 protected abstract void serializeModeParameters (final ByteBuffer buffer, final int index);
114
115 public final int size () {
116 return pageLength + pageLengthModifier;
117 }
118 }