001 /*
002 * This file is part of the Jikes RVM project (http://jikesrvm.org).
003 *
004 * This file is licensed to You under the Eclipse Public License (EPL);
005 * You may not use this file except in compliance with the License. You
006 * may obtain a copy of the License at
007 *
008 * http://www.opensource.org/licenses/eclipse-1.0.php
009 *
010 * See the COPYRIGHT.txt file distributed with this work for information
011 * regarding copyright ownership.
012 */
013 package org.jikesrvm.osr;
014
015 import org.jikesrvm.VM;
016
017 /**
018 * An iterator over an encoded OSR map.
019 * It is a bit odd to used now.
020 * <pre>
021 * while (it.hasMore()) {
022 * it.getKind();
023 * it.getNumber();
024 * it.getMethodId();
025 * it.getBcIndex();
026 * ....
027 *
028 * it.moveToNext();
029 * }
030 *</pre>
031 */
032
033 public class OSRMapIterator implements OSRConstants {
034 private int curidx;
035 private final int[] maps;
036 private int curmid;
037 private int curmpc;
038
039 private boolean moreMethId = false;
040 private boolean moreElemnt = false;
041
042 public OSRMapIterator(int[] mapcode, int index) {
043 // skip over the map of registers which are references.
044 this.curidx = index + 1;
045 this.maps = mapcode;
046
047 if ((mapcode[index] & NEXT_BIT) != 0) {
048 this.moreMethId = true;
049 moveToNextMethodId();
050 }
051 }
052
053 public boolean hasMore() {
054 return this.moreElemnt;
055 }
056
057 /**
058 * after finishing iteration of one method, move to the next,
059 * it if is empty, move further.
060 */
061 private void moveToNextMethodId() {
062 // VM.sysWriteln("move to next method id "+this.curidx);
063
064 this.curmid = maps[curidx] & ~NEXT_BIT;
065 this.moreMethId = (maps[curidx] & NEXT_BIT) != 0;
066
067 this.curidx++;
068 this.curmpc = maps[curidx] & ~NEXT_BIT;
069 this.moreElemnt = (maps[curidx] & NEXT_BIT) != 0;
070
071 this.curidx++;
072
073 // if this method id entry is empty, skip to the next
074 if (!hasMoreElements() && hasMoreMethodId()) {
075 moveToNextMethodId();
076 }
077 }
078
079 /** has next method id to iterate? */
080 private boolean hasMoreMethodId() {
081 return this.moreMethId;
082 }
083
084 /** has next element of this method id to iterate? */
085 private boolean hasMoreElements() {
086 return this.moreElemnt;
087 }
088
089 /**
090 * Moves the index to the next element, update more first because
091 * we use last element's bit to indicate whether this element is
092 * available.
093 */
094 public void moveToNext() {
095 if (VM.VerifyAssertions) VM._assert(this.hasMore());
096
097 this.moreElemnt = (maps[curidx] & NEXT_BIT) != 0;
098 this.curidx += 2;
099 if (!hasMoreElements() && hasMoreMethodId()) {
100 moveToNextMethodId();
101 }
102 }
103
104 /* for the current element, provide a list of queries. */
105
106 /** what kind. */
107 public boolean getKind() {
108 return (maps[curidx] & KIND_MASK) >> KIND_SHIFT != 0;
109 }
110
111 /** type code. */
112 public byte getTypeCode() {
113 return (byte)((maps[curidx] & TCODE_MASK) >> TCODE_SHIFT);
114 }
115
116 /** number */
117 public char getNumber() {
118 return (char)((maps[curidx] & NUM_MASK) >> NUM_SHIFT);
119 }
120
121 /** value type */
122 public byte getValueType() {
123 return (byte)((maps[curidx] & VTYPE_MASK) >> VTYPE_SHIFT);
124 }
125
126 /** value */
127 public int getValue() {
128 return maps[curidx + 1];
129 }
130
131 /** current mid */
132 public int getMethodId() {
133 return this.curmid;
134 }
135
136 /** current pc */
137 public int getBcIndex() {
138 return this.curmpc;
139 }
140 }