BytecodeLookupSwitch.java revision 12651:6ef01bd40ce2 
1/*
2 * Copyright (c) 2009, 2011, 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 */
23package org.graalvm.compiler.bytecode;
24
25/**
26 * A utility for processing {@link Bytecodes#LOOKUPSWITCH} bytecodes.
27 */
28public class BytecodeLookupSwitch extends BytecodeSwitch {
29
30    private static final int OFFSET_TO_NUMBER_PAIRS = 4;
31    private static final int OFFSET_TO_FIRST_PAIR_MATCH = 8;
32    private static final int OFFSET_TO_FIRST_PAIR_OFFSET = 12;
33    private static final int PAIR_SIZE = 8;
34
35    /**
36     * Constructor for a {@link BytecodeStream}.
37     *
38     * @param stream the {@code BytecodeStream} containing the switch instruction
39     * @param bci the index in the stream of the switch instruction
40     */
41    public BytecodeLookupSwitch(BytecodeStream stream, int bci) {
42        super(stream, bci);
43    }
44
45    @Override
46    public int offsetAt(int i) {
47        return stream.readInt(alignedBci + OFFSET_TO_FIRST_PAIR_OFFSET + PAIR_SIZE * i);
48    }
49
50    @Override
51    public int keyAt(int i) {
52        return stream.readInt(alignedBci + OFFSET_TO_FIRST_PAIR_MATCH + PAIR_SIZE * i);
53    }
54
55    @Override
56    public int numberOfCases() {
57        return stream.readInt(alignedBci + OFFSET_TO_NUMBER_PAIRS);
58    }
59
60    @Override
61    public int size() {
62        return alignedBci + OFFSET_TO_FIRST_PAIR_MATCH + PAIR_SIZE * numberOfCases() - bci;
63    }
64}
65