1 /*
2  * Copyright 2012, Google Inc.
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions are
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8  *
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10  * notice, this list of conditions and the following disclaimer.
11  *     * Redistributions in binary form must reproduce the above
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13  * in the documentation and/or other materials provided with the
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17  * this software without specific prior written permission.
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19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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29  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 package org.jf.dexlib2.util;
33 
34 import org.jf.dexlib2.iface.instruction.Instruction;
35 import org.jf.util.ExceptionWithContext;
36 
37 import javax.annotation.Nonnull;
38 import java.util.Arrays;
39 import java.util.List;
40 
41 public class InstructionOffsetMap {
42     @Nonnull private final int[] instructionCodeOffsets;
43 
InstructionOffsetMap(@onnull List<? extends Instruction> instructions)44     public InstructionOffsetMap(@Nonnull List<? extends Instruction> instructions) {
45         this.instructionCodeOffsets = new int[instructions.size()];
46 
47         int codeOffset = 0;
48         for (int i=0; i<instructions.size(); i++) {
49             instructionCodeOffsets[i] = codeOffset;
50             codeOffset += instructions.get(i).getCodeUnits();
51         }
52     }
53 
getInstructionIndexAtCodeOffset(int codeOffset)54     public int getInstructionIndexAtCodeOffset(int codeOffset) {
55         return getInstructionIndexAtCodeOffset(codeOffset, true);
56     }
57 
getInstructionIndexAtCodeOffset(int codeOffset, boolean exact)58     public int getInstructionIndexAtCodeOffset(int codeOffset, boolean exact) {
59         int index = Arrays.binarySearch(instructionCodeOffsets, codeOffset);
60         if (index < 0) {
61             if (exact) {
62                 throw new InvalidInstructionOffset(codeOffset);
63             } else {
64                 // This calculation would be incorrect if index was -1 (i.e. insertion point of 0). Luckily, we can
65                 // ignore this case, because codeOffset will always be non-negative, and the code offset of the first
66                 // instruction will always be 0.
67                 return (~index) - 1;
68             }
69         }
70         return index;
71     }
72 
getInstructionCodeOffset(int index)73     public int getInstructionCodeOffset(int index) {
74         if (index < 0 || index >= instructionCodeOffsets.length) {
75             throw new InvalidInstructionIndex(index);
76         }
77         return instructionCodeOffsets[index];
78     }
79 
80     public static class InvalidInstructionOffset extends ExceptionWithContext {
81         private final int instructionOffset;
82 
InvalidInstructionOffset(int instructionOffset)83         public InvalidInstructionOffset(int instructionOffset) {
84             super("No instruction at offset %d", instructionOffset);
85             this.instructionOffset = instructionOffset;
86         }
87 
getInstructionOffset()88         public int getInstructionOffset() {
89             return instructionOffset;
90         }
91     }
92 
93     public static class InvalidInstructionIndex extends ExceptionWithContext {
94         private final int instructionIndex;
95 
InvalidInstructionIndex(int instructionIndex)96         public InvalidInstructionIndex(int instructionIndex) {
97             super("Instruction index out of bounds: %d", instructionIndex);
98             this.instructionIndex = instructionIndex;
99         }
100 
getInstructionIndex()101         public int getInstructionIndex() {
102             return instructionIndex;
103         }
104     }
105 }
106