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  */
  23 
  24 
  25 package org.graalvm.compiler.bytecode;
  26 
  27 /**
  28  * A utility for processing {@link Bytecodes#TABLESWITCH} bytecodes.
  29  */
  30 public class BytecodeTableSwitch extends BytecodeSwitch {
  31 
  32     private static final int OFFSET_TO_LOW_KEY = 4;
  33     private static final int OFFSET_TO_HIGH_KEY = 8;
  34     private static final int OFFSET_TO_FIRST_JUMP_OFFSET = 12;
  35     private static final int JUMP_OFFSET_SIZE = 4;
  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 BytecodeTableSwitch(BytecodeStream stream, int bci) {
  44         super(stream, bci);
  45     }
  46 
  47     /**
  48      * Gets the low key of the table switch.
  49      *
  50      * @return the low key
  51      */
  52     public int lowKey() {
  53         return stream.readInt(alignedBci + OFFSET_TO_LOW_KEY);
  54     }
  55 
  56     /**
  57      * Gets the high key of the table switch.
  58      *
  59      * @return the high key
  60      */
  61     public int highKey() {
  62         return stream.readInt(alignedBci + OFFSET_TO_HIGH_KEY);
  63     }
  64 
  65     @Override
  66     public int keyAt(int i) {
  67         return lowKey() + i;
  68     }
  69 
  70     @Override
  71     public int offsetAt(int i) {
  72         return stream.readInt(alignedBci + OFFSET_TO_FIRST_JUMP_OFFSET + JUMP_OFFSET_SIZE * i);
  73     }
  74 
  75     @Override
  76     public int numberOfCases() {
  77         return highKey() - lowKey() + 1;
  78     }
  79 
  80     @Override
  81     public int size() {
  82         return alignedBci + OFFSET_TO_FIRST_JUMP_OFFSET + JUMP_OFFSET_SIZE * numberOfCases() - bci;
  83     }
  84 }