1/*
2 * ProGuard -- shrinking, optimization, obfuscation, and preverification
3 *             of Java bytecode.
4 *
5 * Copyright (c) 2002-2009 Eric Lafortune (eric@graphics.cornell.edu)
6 *
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License as published by the Free
9 * Software Foundation; either version 2 of the License, or (at your option)
10 * any later version.
11 *
12 * This program is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
15 * more details.
16 *
17 * You should have received a copy of the GNU General Public License along
18 * with this program; if not, write to the Free Software Foundation, Inc.,
19 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 */
21package proguard.classfile.instruction;
22
23import proguard.classfile.*;
24import proguard.classfile.attribute.CodeAttribute;
25import proguard.classfile.instruction.visitor.InstructionVisitor;
26
27/**
28 * This Instruction represents a simple instruction without variable arguments
29 * or constant pool references.
30 *
31 * @author Eric Lafortune
32 */
33public class TableSwitchInstruction extends SwitchInstruction
34{
35    public int lowCase;
36    public int highCase;
37
38
39    /**
40     * Creates an uninitialized TableSwitchInstruction.
41     */
42    public TableSwitchInstruction() {}
43
44
45    /**
46     * Creates a new TableSwitchInstruction with the given arguments.
47     */
48    public TableSwitchInstruction(byte  opcode,
49                                  int   defaultOffset,
50                                  int   lowCase,
51                                  int   highCase,
52                                  int[] jumpOffsets)
53    {
54        this.opcode        = opcode;
55        this.defaultOffset = defaultOffset;
56        this.lowCase       = lowCase;
57        this.highCase      = highCase;
58        this.jumpOffsets   = jumpOffsets;
59    }
60
61
62    /**
63     * Copies the given instruction into this instruction.
64     * @param tableSwitchInstruction the instruction to be copied.
65     * @return this instruction.
66     */
67    public TableSwitchInstruction copy(TableSwitchInstruction tableSwitchInstruction)
68    {
69        this.opcode        = tableSwitchInstruction.opcode;
70        this.defaultOffset = tableSwitchInstruction.defaultOffset;
71        this.lowCase       = tableSwitchInstruction.lowCase;
72        this.highCase      = tableSwitchInstruction.highCase;
73        this.jumpOffsets   = tableSwitchInstruction.jumpOffsets;
74
75        return this;
76    }
77
78
79    // Implementations for Instruction.
80
81    public Instruction shrink()
82    {
83        // There aren't any ways to shrink this instruction.
84        return this;
85    }
86
87    protected void readInfo(byte[] code, int offset)
88    {
89        // Skip up to three padding bytes.
90        offset += -offset & 3;
91
92        // Read the three 32-bit arguments.
93        defaultOffset = readInt(code, offset); offset += 4;
94        lowCase       = readInt(code, offset); offset += 4;
95        highCase      = readInt(code, offset); offset += 4;
96
97        // Read the jump offsets.
98        jumpOffsets = new int[highCase - lowCase + 1];
99
100        for (int index = 0; index < jumpOffsets.length; index++)
101        {
102            jumpOffsets[index] = readInt(code, offset); offset += 4;
103        }
104    }
105
106
107    protected void writeInfo(byte[] code, int offset)
108    {
109        // Write up to three padding bytes.
110        while ((offset & 3) != 0)
111        {
112            writeByte(code, offset++, 0);
113        }
114
115        // Write the three 32-bit arguments.
116        writeInt(code, offset, defaultOffset); offset += 4;
117        writeInt(code, offset, lowCase);       offset += 4;
118        writeInt(code, offset, highCase);      offset += 4;
119
120        // Write the jump offsets.
121        int length = highCase - lowCase + 1;
122        for (int index = 0; index < length; index++)
123        {
124            writeInt(code, offset, jumpOffsets[index]); offset += 4;
125        }
126    }
127
128
129    public int length(int offset)
130    {
131        return 1 + (-(offset+1) & 3) + 12 + (highCase - lowCase + 1) * 4;
132    }
133
134
135    public void accept(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, InstructionVisitor instructionVisitor)
136    {
137        instructionVisitor.visitTableSwitchInstruction(clazz, method, codeAttribute, offset, this);
138    }
139}
140