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1 /*
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2 * Copyright 2001-2003 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 package sun.jvm.hotspot.interpreter;
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26
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27 import sun.jvm.hotspot.oops.*;
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28 import sun.jvm.hotspot.utilities.*;
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29
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30 public class BytecodeLookupswitch extends Bytecode {
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31 BytecodeLookupswitch(Method method, int bci) {
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32 super(method, bci);
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33 }
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34
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35 // Attributes
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36 public int defaultOffset() { return javaSignedWordAt(alignedOffset(1 + 0*jintSize)); }
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37 public int numberOfPairs() { return javaSignedWordAt(alignedOffset(1 + 1*jintSize)); }
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38 public LookupswitchPair pairAt(int i) {
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39 if (Assert.ASSERTS_ENABLED) {
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40 Assert.that(0 <= i && i < numberOfPairs(), "pair index out of bounds");
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41 }
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42 return new LookupswitchPair(method, bci + alignedOffset(1 + (1 + i)*2*jintSize));
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43 }
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44
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45 public void verify() {
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46 if (Assert.ASSERTS_ENABLED) {
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47 Assert.that(isValid(), "check lookupswitch");
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48 }
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49 }
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50
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51 public boolean isValid() {
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52 boolean result = javaCode() == Bytecodes._lookupswitch;
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53 if (result == false) return false;
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54 int i = numberOfPairs() - 1;
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55 while (i-- > 0) {
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56 if(pairAt(i).match() > pairAt(i+1).match())
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57 return false; // unsorted lookup table
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58 }
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59 return true;
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60 }
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61
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62 public static BytecodeLookupswitch at(Method method, int bci) {
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63 BytecodeLookupswitch b = new BytecodeLookupswitch(method, bci);
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64 if (Assert.ASSERTS_ENABLED) {
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65 b.verify();
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66 }
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67 return b;
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68 }
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69
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70 /** Like at, but returns null if the BCI is not at lookupswitch */
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71 public static BytecodeLookupswitch atCheck(Method method, int bci) {
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72 BytecodeLookupswitch b = new BytecodeLookupswitch(method, bci);
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73 return (b.isValid() ? b : null);
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74 }
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75
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76 public static BytecodeLookupswitch at(BytecodeStream bcs) {
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77 return new BytecodeLookupswitch(bcs.method(), bcs.bci());
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78 }
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79
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80 public String toString() {
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81 StringBuffer buf = new StringBuffer();
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82 buf.append("lookupswitch");
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83 buf.append(spaces);
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84 buf.append("default: ");
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85 buf.append(Integer.toString(bci() + defaultOffset()));
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86 buf.append(comma);
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87 int i = numberOfPairs() - 1;
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88 while (i-- > 0) {
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89 LookupswitchPair pair = pairAt(i);
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90 buf.append("case ");
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91 buf.append(Integer.toString(pair.match()));
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92 buf.append(':');
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93 buf.append(Integer.toString(bci() + pair.offset()));
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94 buf.append(comma);
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95 }
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96
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97 return buf.toString();
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98 }
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99 }
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