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 
25 package sun.jvm.hotspot.interpreter;
26 
27 import sun.jvm.hotspot.oops.*;
28 import sun.jvm.hotspot.utilities.*;
29 
30 public class BytecodeLookupswitch extends Bytecode {
BytecodeLookupswitch(Method method, int bci)31   BytecodeLookupswitch(Method method, int bci) {
32     super(method, bci);
33   }
34 
35   // Attributes
defaultOffset()36   public int defaultOffset() { return javaSignedWordAt(alignedOffset(1 + 0*jintSize)); }
numberOfPairs()37   public int numberOfPairs() { return javaSignedWordAt(alignedOffset(1 + 1*jintSize)); }
pairAt(int i)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 
verify()45   public void verify() {
46     if (Assert.ASSERTS_ENABLED) {
47       Assert.that(isValid(), "check lookupswitch");
48     }
49   }
50 
isValid()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 
at(Method method, int bci)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  */
atCheck(Method method, int bci)71   public static BytecodeLookupswitch atCheck(Method method, int bci) {
72     BytecodeLookupswitch b = new BytecodeLookupswitch(method, bci);
73     return (b.isValid() ? b : null);
74   }
75 
at(BytecodeStream bcs)76   public static BytecodeLookupswitch at(BytecodeStream bcs) {
77     return new BytecodeLookupswitch(bcs.method(), bcs.bci());
78   }
79 
toString()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