1/*
2 * Copyright (c) 2001, 2003, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25package sun.jvm.hotspot.interpreter;
26
27import sun.jvm.hotspot.oops.*;
28import sun.jvm.hotspot.utilities.*;
29
30public class BytecodeLookupswitch extends Bytecode {
31  BytecodeLookupswitch(Method method, int bci) {
32    super(method, bci);
33  }
34
35  // Attributes
36  public int defaultOffset() { return javaSignedWordAt(alignedOffset(1 + 0*jintSize)); }
37  public int numberOfPairs() { return javaSignedWordAt(alignedOffset(1 + 1*jintSize)); }
38  public LookupswitchPair pairAt(int i) {
39    if (Assert.ASSERTS_ENABLED) {
40      Assert.that(0 <= i && i < numberOfPairs(), "pair index out of bounds");
41    }
42    return new LookupswitchPair(method, bci + alignedOffset(1 + (1 + i)*2*jintSize));
43  }
44
45  public void verify() {
46    if (Assert.ASSERTS_ENABLED) {
47      Assert.that(isValid(), "check lookupswitch");
48    }
49  }
50
51  public boolean isValid() {
52    boolean result = javaCode() == Bytecodes._lookupswitch;
53    if (result == false) return false;
54    int i = numberOfPairs() - 1;
55    while (i-- > 0) {
56      if(pairAt(i).match() > pairAt(i+1).match())
57         return false; // unsorted lookup table
58    }
59    return true;
60  }
61
62  public static BytecodeLookupswitch at(Method method, int bci) {
63    BytecodeLookupswitch b = new BytecodeLookupswitch(method, bci);
64    if (Assert.ASSERTS_ENABLED) {
65      b.verify();
66    }
67    return b;
68  }
69
70  /** Like at, but returns null if the BCI is not at lookupswitch  */
71  public static BytecodeLookupswitch atCheck(Method method, int bci) {
72    BytecodeLookupswitch b = new BytecodeLookupswitch(method, bci);
73    return (b.isValid() ? b : null);
74  }
75
76  public static BytecodeLookupswitch at(BytecodeStream bcs) {
77    return new BytecodeLookupswitch(bcs.method(), bcs.bci());
78  }
79
80  public String toString() {
81    StringBuffer buf = new StringBuffer();
82    buf.append("lookupswitch");
83    buf.append(spaces);
84    buf.append("default: ");
85    buf.append(Integer.toString(bci() + defaultOffset()));
86    buf.append(comma);
87    int i = numberOfPairs() - 1;
88    while (i-- > 0) {
89      LookupswitchPair pair = pairAt(i);
90      buf.append("case ");
91      buf.append(Integer.toString(pair.match()));
92      buf.append(':');
93      buf.append(Integer.toString(bci() + pair.offset()));
94      buf.append(comma);
95    }
96
97    return buf.toString();
98  }
99}
100