1 package org.jscsi.target.scsi.cdb;
2
3
4 import java.nio.ByteBuffer;
5
6 import org.jscsi.target.storage.IStorageModule;
7
8
9 /**
10 * This abstract class represents Command Descriptor Blocks for the <code>READ</code> and <code>WRITE</code> SCSI
11 * commands. This grouping makes sense, since, apart from the different values of the OPERATION CODE field, Read and
12 * Write CDBs are identical.
13 *
14 * @author Andreas Ergenzinger
15 */
16 public abstract class ReadOrWriteCdb extends CommandDescriptorBlock {
17
18 /**
19 * The logical block address of the first logical block of data, where data shall be read from or written to.
20 *
21 * @see #transferLength
22 */
23 private final long logicalBlockAddress;
24
25 /**
26 * The TRANSFER LENGTH field specifies the number of contiguous logical blocks of data that shall be read/written
27 * and transferred to/from the (initiator's) data-in buffer, starting with the logical block specified by the
28 * {@link #logicalBlockAddress} field.
29 */
30 private final int transferLength;
31
32 public ReadOrWriteCdb (ByteBuffer buffer) {
33 super(buffer);
34 logicalBlockAddress = deserializeLogicalBlockAddress(buffer);
35 transferLength = deserializeTransferLength(buffer);
36 }
37
38 /**
39 * Deserializes the value of the {@link #logicalBlockAddress} field.
40 *
41 * @param buffer the {@link ByteBuffer} containing the CDB
42 * @return value of the {@link #logicalBlockAddress} field
43 */
44 protected abstract long deserializeLogicalBlockAddress (final ByteBuffer buffer);
45
46 /**
47 * Deserializes the value of the {@link #transferLength} field.
48 *
49 * @param buffer the {@link ByteBuffer} containing the CDB
50 * @return value of the {@link #transferLength} field
51 */
52 protected abstract int deserializeTransferLength (final ByteBuffer buffer);
53
54 /**
55 * Returns the value of {@link #logicalBlockAddress}.
56 *
57 * @return the value of {@link #logicalBlockAddress}
58 */
59 public final long getLogicalBlockAddress () {
60 return logicalBlockAddress;
61 }
62
63 /**
64 * Returns the value of {@link #transferLength}.
65 *
66 * @return the value of {@link #transferLength}
67 */
68 public final int getTransferLength () {
69 return transferLength;
70 }
71
72 /**
73 * Returns the index position of the first byte used for encoding the {@link #logicalBlockAddress} field.
74 *
75 * @return the index position of the first byte used for encoding the {@link #logicalBlockAddress} field
76 */
77 protected abstract int getLogicalBlockAddressFieldIndex ();
78
79 /**
80 * Returns the index position of the first byte used for encoding the {@link #transferLength} field.
81 *
82 * @return the index position of the first byte used for encoding the {@link #transferLength} field
83 */
84 protected abstract int getTransferLengthFieldIndex ();
85
86 /**
87 * This method is used for signaling an illegal value of the {@link #logicalBlockAddress} variable.
88 * <p>
89 * This method must be called if the {@link #logicalBlockAddress} lies outside the bounds of the used medium.
90 *
91 * @see #getIllegalFieldPointers()
92 * @see IStorageModule#checkBounds(long, int)
93 */
94 public final void addIllegalFieldPointerForLogicalBlockAddress () {
95 addIllegalFieldPointer(getLogicalBlockAddressFieldIndex());
96 }
97
98 /**
99 * This method is used for signaling an illegal value of the {@link #transferLength} variable.
100 * <p>
101 * This method must be called if the {@link #transferLength} field value would result in accessing of out-of-bounds
102 * blocks of the storage medium.
103 *
104 * @see #getIllegalFieldPointers()
105 * @see IStorageModule#checkBounds(long, int)
106 */
107 public final void addIllegalFieldPointerForTransferLength () {
108 addIllegalFieldPointer(getTransferLengthFieldIndex());
109 }
110 }