source: source/ariba/overlay/modules/chord/detail/distances.hpp@ 3690

Last change on this file since 3690 was 3690, checked in by mies, 16 years ago

Merged 20090512-mies-connectors changes r3472:r3689 into trunk.

File size: 3.1 KB
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1// [License]
2// The Ariba-Underlay Copyright
3//
4// Copyright (c) 2008-2009, Institute of Telematics, UniversitÀt Karlsruhe (TH)
5//
6// Institute of Telematics
7// UniversitÀt Karlsruhe (TH)
8// Zirkel 2, 76128 Karlsruhe
9// Germany
10//
11// Redistribution and use in source and binary forms, with or without
12// modification, are permitted provided that the following conditions are
13// met:
14//
15// 1. Redistributions of source code must retain the above copyright
16// notice, this list of conditions and the following disclaimer.
17// 2. Redistributions in binary form must reproduce the above copyright
18// notice, this list of conditions and the following disclaimer in the
19// documentation and/or other materials provided with the distribution.
20//
21// THIS SOFTWARE IS PROVIDED BY THE INSTITUTE OF TELEMATICS ``AS IS'' AND
22// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
24// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OF TELEMATICS OR
25// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
26// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
27// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
28// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
29// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
30// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
31// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32//
33// The views and conclusions contained in the software and documentation
34// are those of the authors and should not be interpreted as representing
35// official policies, either expressed or implied, of the Institute of
36// Telematics.
37// [License]
38#ifndef DISTANCES_HPP_
39#define DISTANCES_HPP_
40
41/**
42 * TODO: Doc
43 *
44 * @author Sebastian Mies <mies@tm.uka.de>
45 */
46namespace distances {
47
48/// returns the maximum value of a type
49template<class T>
50T max_value() {
51 return ~(T)0;
52}
53
54/// returns the maximum value of a type
55template<class T>
56T min_value() {
57 return 0;
58}
59
60/// euclidean distance between two points (metric)
61struct default_distance {
62 template<typename T>
63 T operator ()(const T& x, const T& y) {
64 return abs(x - y);
65 }
66};
67
68/// xor distance (metric)
69struct xor_distance {
70 template<typename T>
71 T operator()(const T& x, const T& y) {
72 return x ^ y;
73 }
74};
75
76/// distance between two points on a ring (metric)
77struct ring_distance {
78 template<typename T>
79 T operator()(const T& x, const T& y) {
80 const T m = max_value<T>();
81 T d_nor = (x >= y) ? (x-y) : (y-x);
82 T d_inv = m - d_nor;
83 return d_nor < d_inv ? d_nor : d_inv;
84 }
85};
86
87/// distance from x to a predecessor y on a ring (not a metric!)
88struct ring_pred_distance {
89 template<typename T>
90 T operator ()(const T& x, const T& y) {
91 const T m = max_value<T>();
92 if (x >= y) return x - y;
93 else return m - y + x;
94 }
95};
96
97/// distance from x to a successor y on a ring (not a metric!)
98struct ring_succ_distance {
99 template<typename T>
100 T operator ()(const T& y, const T& x) {
101 const T m = max_value<T>();
102 if (x >= y) return x - y;
103 else return m - y + x;
104 }
105};
106
107}
108
109#endif /* DISTANCES_HPP_ */
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