1 package org.jscsi.target.scsi.sense.senseDataDescriptor;
2
3
4 import java.nio.ByteBuffer;
5
6 import org.jscsi.target.scsi.ISerializable;
7
8
9 /**
10 * Sense data descriptors are part of sense data and provide specific sense information. A given type of sense data
11 * descriptor shall be included in the sense data only when the information it contains is valid.
12 *
13 * @author Andreas Ergenzinger
14 */
15 public abstract class SenseDataDescriptor implements ISerializable {
16
17 /**
18 * This value plus the length of all sub-class-specific fields equal the length in bytes of the serialized sense
19 * data descriptor.
20 */
21 private static final int COMMON_FIELDS_LENGTH = 2;
22
23 /**
24 * The descriptor type field determines sense data descriptor's (non-abstract) class.
25 *
26 * @see SenseDataDescriptorType
27 */
28 private final SenseDataDescriptorType descriptorType;
29
30 /**
31 * The ADDITIONAL LENGTH field indicates the number of sense data descriptor specific bytes that follow in the sense
32 * data descriptor.
33 */
34 private final int additionalLength;
35
36 /**
37 * The abstract constructor.
38 *
39 * @param descriptorType determines the specific type of the sense data descriptor
40 * @param additionalLength the length in bytes of all additional fields
41 * @see #COMMON_FIELDS_LENGTH
42 */
43 public SenseDataDescriptor (final SenseDataDescriptorType descriptorType, final int additionalLength) {
44 this.descriptorType = descriptorType;
45 this.additionalLength = additionalLength;
46 }
47
48 /**
49 * Serializes the fields common to all sense data descriptors.
50 *
51 * @param byteBuffer where the serialized fields will be stored
52 * @param index the position of the first byte of the sense data descriptor in the {@link ByteBuffer}
53 */
54 private final void serializeCommonFields (final ByteBuffer byteBuffer, final int index) {
55 byteBuffer.position(index);
56 byteBuffer.put(descriptorType.getValue());
57 byteBuffer.put((byte) additionalLength);
58 }
59
60 /**
61 * Serializes all fields which are not common to all sense data descriptors, which means those that are
62 * sub-type-specific.
63 *
64 * @param byteBuffer where the serialized fields will be stored
65 * @param index the position of the first byte of the sense data descriptor in the {@link ByteBuffer}
66 */
67 protected abstract void serializeSpecificFields (ByteBuffer byteBuffer, final int index);
68
69 private final int getAdditionalLength () {
70 return additionalLength;
71 }
72
73 public void serialize (ByteBuffer byteBuffer, int index) {
74 serializeCommonFields(byteBuffer, index);
75 serializeSpecificFields(byteBuffer, index);
76 }
77
78 public int size () {
79 return COMMON_FIELDS_LENGTH + getAdditionalLength();
80 }
81 }