001/*
002 * Copyright (c) 2009, 2011, Oracle and/or its affiliates. All rights reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation.
008 *
009 * This code is distributed in the hope that it will be useful, but WITHOUT
010 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
011 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
012 * version 2 for more details (a copy is included in the LICENSE file that
013 * accompanied this code).
014 *
015 * You should have received a copy of the GNU General Public License version
016 * 2 along with this work; if not, write to the Free Software Foundation,
017 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
018 *
019 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
020 * or visit www.oracle.com if you need additional information or have any
021 * questions.
022 */
023package com.oracle.graal.bytecode;
024
025/**
026 * A utility for processing {@link Bytecodes#LOOKUPSWITCH} bytecodes.
027 */
028public class BytecodeLookupSwitch extends BytecodeSwitch {
029
030    private static final int OFFSET_TO_NUMBER_PAIRS = 4;
031    private static final int OFFSET_TO_FIRST_PAIR_MATCH = 8;
032    private static final int OFFSET_TO_FIRST_PAIR_OFFSET = 12;
033    private static final int PAIR_SIZE = 8;
034
035    /**
036     * Constructor for a {@link BytecodeStream}.
037     *
038     * @param stream the {@code BytecodeStream} containing the switch instruction
039     * @param bci the index in the stream of the switch instruction
040     */
041    public BytecodeLookupSwitch(BytecodeStream stream, int bci) {
042        super(stream, bci);
043    }
044
045    @Override
046    public int offsetAt(int i) {
047        return stream.readInt(alignedBci + OFFSET_TO_FIRST_PAIR_OFFSET + PAIR_SIZE * i);
048    }
049
050    @Override
051    public int keyAt(int i) {
052        return stream.readInt(alignedBci + OFFSET_TO_FIRST_PAIR_MATCH + PAIR_SIZE * i);
053    }
054
055    @Override
056    public int numberOfCases() {
057        return stream.readInt(alignedBci + OFFSET_TO_NUMBER_PAIRS);
058    }
059
060    @Override
061    public int size() {
062        return alignedBci + OFFSET_TO_FIRST_PAIR_MATCH + PAIR_SIZE * numberOfCases() - bci;
063    }
064}