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.compilers.opt.instrsched;
014
015 /**
016 * Describes a reservation on a particular resource.
017 * A reservation is for a continuous period of time.
018 * Used in OperatorClass.
019 *
020 * @see OperatorClass
021 */
022 final class ResourceReservation {
023 /**
024 * Resource Class.
025 */
026 private final int rclass;
027 /**
028 * Start Time.
029 */
030 final int start;
031 /**
032 * Duration of Use.
033 */
034 final int duration;
035
036 /**
037 * Creates a new reservation for specified resource class
038 * starting at 0 with given duration.
039 *
040 * @param rclass resource class
041 * @param duration duration
042 * @see #ResourceReservation(int,int,int)
043 */
044 public ResourceReservation(int rclass, int duration) {
045 this(rclass, 0, duration);
046 }
047
048 /**
049 * Creates a new reservation for specified resource class
050 * starting at specified time with given duration.
051 *
052 * @param rclass resource class
053 * @param start start time
054 * @param duration duration
055 */
056 public ResourceReservation(int rclass, int start, int duration) {
057 this.rclass = rclass;
058 this.start = start;
059 this.duration = duration;
060 }
061
062 /**
063 * The resource class of this reservation.
064 *
065 * @return resource class of this reservation
066 */
067 public int rclass() {
068 return (rclass & 0x7FFFFFFF);
069 }
070
071 /**
072 * Checks whether this reservation is for all available units of the class.
073 *
074 * @return true if it's a global reservation, false otherwise
075 */
076 public boolean isGlobal() {
077 return (rclass & 0x80000000) != 0;
078 }
079
080 /**
081 * Compares this reservation with another reservation.
082 * @param r the other reservation
083 * @return a negative int if this is less than the other reservation,
084 * a positive int if this is greater than the other and zero if
085 * they are equal
086 */
087 private int compareTo(ResourceReservation r) {
088 if (rclass() != r.rclass()) {
089 return rclass() - r.rclass();
090 }
091 if (rclass != r.rclass) {
092 // if either of them is global then global goes first
093 return r.rclass - rclass;
094 }
095 if (start != r.start) {
096 return start - r.start;
097 }
098 return duration - r.duration;
099 }
100
101 /**
102 * Sorts an array of reservations in accordance with internal ordering.
103 *
104 * @param usage array of reservations
105 */
106 public static void sort(ResourceReservation[] usage) {
107 // bubble sort
108 for (int i = 0; i < usage.length; i++) {
109 for (int j = i; j > 0 && usage[j - 1].compareTo(usage[j]) > 0; j--) {
110 ResourceReservation t = usage[j];
111 usage[j] = usage[j - 1];
112 usage[j - 1] = t;
113 }
114 }
115 }
116
117 /**
118 * Compares this object against the specified object.
119 *
120 * @param o The object to compare with
121 * @return <code>true</code> if the objects are the same; <code>false</code> otherwise.
122 */
123 @Override
124 public boolean equals(Object o) {
125 if (!(o instanceof ResourceReservation)) {
126 return false;
127 }
128 return compareTo((ResourceReservation) o) == 0;
129 }
130
131 /**
132 * Checks whether this reservation conflicts with specified reservation.
133 *
134 * @param rsrv the reservation to check
135 * @return {@code true} if the reservations conflict; {@code false} otherwise.
136 */
137 public boolean conflicts(ResourceReservation rsrv) {
138 return (rclass() == rsrv.rclass() && start < rsrv.start + rsrv.duration && start + duration > rsrv.start);
139 }
140 }
141
142
143