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1 | /******************************************************************************* |
2 | * Copyright (c) 2013 École Polytechnique de Montréal | |
3 | * | |
4 | * All rights reserved. This program and the accompanying materials are made | |
5 | * available under the terms of the Eclipse Public License v1.0 which | |
6 | * accompanies this distribution, and is available at | |
7 | * http://www.eclipse.org/legal/epl-v10.html | |
8 | * | |
9 | * Contributors: | |
10 | * Geneviève Bastien - Initial implementation and API | |
11 | *******************************************************************************/ | |
12 | ||
13 | package org.eclipse.linuxtools.tmf.core.synchronization; | |
14 | ||
15 | import java.io.Serializable; | |
16 | import java.math.BigDecimal; | |
17 | import java.math.MathContext; | |
18 | ||
19 | import org.eclipse.linuxtools.tmf.core.timestamp.ITmfTimestamp; | |
20 | import org.eclipse.linuxtools.tmf.core.timestamp.TmfTimestamp; | |
21 | ||
22 | /** | |
23 | * Class implementing a linear timestamp transform, with a slope and/or offset | |
24 | * | |
25 | * f(t) = alpha*t + beta | |
26 | * | |
27 | * @author Geneviève Bastien | |
28 | * @since 3.0 | |
29 | */ | |
30 | public class TmfTimestampTransformLinear implements ITmfTimestampTransform, Serializable { | |
31 | ||
32 | /** | |
33 | * Generated serial UID | |
34 | */ | |
35 | private static final long serialVersionUID = -4756608071358979461L; | |
36 | ||
37 | /** | |
38 | * Respectively the slope and offset and this linear equation. | |
39 | * | |
40 | * FIXME: Maybe doubles will be enough, for the whole synchronization | |
41 | * package as well, I think BigDecimal is a remnant of past trials and | |
42 | * errors | |
43 | */ | |
44 | private final BigDecimal fAlpha; | |
45 | private final BigDecimal fBeta; | |
46 | ||
47 | private static final MathContext fMc = MathContext.DECIMAL128; | |
48 | ||
49 | /** | |
50 | * Default constructor | |
51 | */ | |
52 | public TmfTimestampTransformLinear() { | |
53 | fAlpha = BigDecimal.ONE; | |
54 | fBeta = BigDecimal.ZERO; | |
55 | } | |
56 | ||
57 | /** | |
58 | * Constructor with alpha and beta | |
59 | * | |
60 | * @param alpha | |
61 | * The slope of the linear transform | |
62 | * @param beta | |
63 | * The initial offset of the linear transform | |
64 | */ | |
65 | public TmfTimestampTransformLinear(final double alpha, final double beta) { | |
66 | fAlpha = BigDecimal.valueOf(alpha); | |
67 | fBeta = BigDecimal.valueOf(beta); | |
68 | } | |
69 | ||
70 | /** | |
71 | * Constructor with alpha and beta in big decimal | |
72 | * | |
73 | * @param fAlpha2 | |
74 | * The slope of the linear transform | |
75 | * @param fBeta2 | |
76 | * The initial offset of the linear transform | |
77 | */ | |
78 | public TmfTimestampTransformLinear(final BigDecimal fAlpha2, final BigDecimal fBeta2) { | |
79 | if (fAlpha2 != null) { | |
80 | fAlpha = fAlpha2; | |
81 | } else { | |
82 | fAlpha = BigDecimal.ONE; | |
83 | } | |
84 | if (fBeta2 != null) { | |
85 | fBeta = fBeta2; | |
86 | } else { | |
87 | fBeta = BigDecimal.ZERO; | |
88 | } | |
89 | } | |
90 | ||
91 | @Override | |
92 | public ITmfTimestamp transform(ITmfTimestamp timestamp) { | |
93 | BigDecimal newvalue = BigDecimal.valueOf(timestamp.getValue()).multiply(fAlpha, fMc).add(fBeta); | |
94 | return new TmfTimestamp(timestamp, newvalue.longValue()); | |
95 | } | |
96 | ||
97 | @Override | |
98 | public long transform(long timestamp) { | |
99 | BigDecimal t = BigDecimal.valueOf(timestamp).multiply(fAlpha, fMc).add(fBeta); | |
100 | return t.longValue(); | |
101 | } | |
102 | ||
103 | @Override | |
104 | public ITmfTimestampTransform composeWith(ITmfTimestampTransform composeWith) { | |
105 | if (composeWith.equals(TmfTimestampTransform.IDENTITY)) { | |
106 | /* If composing with identity, just return this */ | |
107 | return this; | |
108 | } else if (composeWith instanceof TmfTimestampTransformLinear) { | |
109 | /* If composeWith is a linear transform, add the two together */ | |
110 | TmfTimestampTransformLinear ttl = (TmfTimestampTransformLinear) composeWith; | |
111 | BigDecimal newAlpha = fAlpha.multiply(ttl.fAlpha, fMc); | |
112 | BigDecimal newBeta = fAlpha.multiply(ttl.fBeta, fMc).add(fBeta); | |
113 | return new TmfTimestampTransformLinear(newAlpha, newBeta); | |
114 | } else { | |
115 | /* | |
116 | * We do not know what to do with this kind of transform, just | |
117 | * return this | |
118 | */ | |
119 | return this; | |
120 | } | |
121 | } | |
122 | ||
123 | @Override | |
124 | public boolean equals(Object other) { | |
125 | boolean result = false; | |
126 | if (other instanceof TmfTimestampTransformLinear) { | |
127 | TmfTimestampTransformLinear that = (TmfTimestampTransformLinear) other; | |
128 | result = ((that.fAlpha.equals(fAlpha)) && (that.fBeta.equals(fBeta))); | |
129 | } | |
130 | return result; | |
131 | } | |
132 | ||
133 | @Override | |
134 | public int hashCode() { | |
135 | final int prime = 31; | |
136 | int result = 1; | |
137 | result = (prime * result) + (fBeta.multiply(fAlpha).intValue()); | |
138 | return result; | |
139 | } | |
140 | ||
141 | @Override | |
142 | public String toString() { | |
143 | return "TmfTimestampLinear [ alpha = " + fAlpha.toString() + //$NON-NLS-1$ | |
144 | ", beta = " + fBeta.toString() + //$NON-NLS-1$ | |
145 | " ]"; //$NON-NLS-1$ | |
146 | } | |
147 | ||
148 | } |