1 /*
   2  * Copyright (c) 2009, 2018, 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 org.graalvm.compiler.bytecode;
  26 
  27 /**
  28  * A utility for processing {@link Bytecodes#LOOKUPSWITCH} bytecodes.
  29  */
  30 public class BytecodeLookupSwitch extends BytecodeSwitch {
  31 
  32     private static final int OFFSET_TO_NUMBER_PAIRS = 4;
  33     private static final int OFFSET_TO_FIRST_PAIR_MATCH = 8;
  34     private static final int OFFSET_TO_FIRST_PAIR_OFFSET = 12;
  35     private static final int PAIR_SIZE = 8;
  36 
  37     /**
  38      * Constructor for a {@link BytecodeStream}.
  39      *
  40      * @param stream the {@code BytecodeStream} containing the switch instruction
  41      * @param bci the index in the stream of the switch instruction
  42      */
  43     public BytecodeLookupSwitch(BytecodeStream stream, int bci) {
  44         super(stream, bci);
  45     }
  46 
  47     @Override
  48     public int offsetAt(int i) {
  49         return stream.readInt(alignedBci + OFFSET_TO_FIRST_PAIR_OFFSET + PAIR_SIZE * i);
  50     }
  51 
  52     @Override
  53     public int keyAt(int i) {
  54         return stream.readInt(alignedBci + OFFSET_TO_FIRST_PAIR_MATCH + PAIR_SIZE * i);
  55     }
  56 
  57     @Override
  58     public int numberOfCases() {
  59         return stream.readInt(alignedBci + OFFSET_TO_NUMBER_PAIRS);
  60     }
  61 
  62     @Override
  63     public int size() {
  64         return alignedBci + OFFSET_TO_FIRST_PAIR_MATCH + PAIR_SIZE * numberOfCases() - bci;
  65     }
  66 }