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 package org.graalvm.compiler.bytecode;
  24 
  25 /**
  26  * A utility for processing {@link Bytecodes#TABLESWITCH} bytecodes.
  27  */
  28 public class BytecodeTableSwitch extends BytecodeSwitch {
  29 
  30     private static final int OFFSET_TO_LOW_KEY = 4;
  31     private static final int OFFSET_TO_HIGH_KEY = 8;
  32     private static final int OFFSET_TO_FIRST_JUMP_OFFSET = 12;
  33     private static final int JUMP_OFFSET_SIZE = 4;
  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 BytecodeTableSwitch(BytecodeStream stream, int bci) {
  42         super(stream, bci);
  43     }
  44 
  45     /**
  46      * Gets the low key of the table switch.
  47      *
  48      * @return the low key
  49      */
  50     public int lowKey() {
  51         return stream.readInt(alignedBci + OFFSET_TO_LOW_KEY);
  52     }
  53 
  54     /**
  55      * Gets the high key of the table switch.
  56      *
  57      * @return the high key
  58      */
  59     public int highKey() {
  60         return stream.readInt(alignedBci + OFFSET_TO_HIGH_KEY);
  61     }
  62 
  63     @Override
  64     public int keyAt(int i) {
  65         return lowKey() + i;
  66     }
  67 
  68     @Override
  69     public int offsetAt(int i) {
  70         return stream.readInt(alignedBci + OFFSET_TO_FIRST_JUMP_OFFSET + JUMP_OFFSET_SIZE * i);
  71     }
  72 
  73     @Override
  74     public int numberOfCases() {
  75         return highKey() - lowKey() + 1;
  76     }
  77 
  78     @Override
  79     public int size() {
  80         return alignedBci + OFFSET_TO_FIRST_JUMP_OFFSET + JUMP_OFFSET_SIZE * numberOfCases() - bci;
  81     }
  82 }