1 | // This file is part of Eigen, a lightweight C++ template library
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2 | // for linear algebra.
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3 | //
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4 | // Copyright (C) 2010 Benoit Jacob <jacob.benoit.1@gmail.com>
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5 | //
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6 | // This Source Code Form is subject to the terms of the Mozilla
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7 | // Public License v. 2.0. If a copy of the MPL was not distributed
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8 | // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
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9 |
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10 | #ifndef EIGEN_STRIDE_H
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11 | #define EIGEN_STRIDE_H
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12 |
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13 | namespace Eigen {
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14 |
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15 | /** \class Stride
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16 | * \ingroup Core_Module
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17 | *
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18 | * \brief Holds strides information for Map
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19 | *
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20 | * This class holds the strides information for mapping arrays with strides with class Map.
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21 | *
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22 | * It holds two values: the inner stride and the outer stride.
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23 | *
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24 | * The inner stride is the pointer increment between two consecutive entries within a given row of a
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25 | * row-major matrix or within a given column of a column-major matrix.
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26 | *
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27 | * The outer stride is the pointer increment between two consecutive rows of a row-major matrix or
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28 | * between two consecutive columns of a column-major matrix.
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29 | *
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30 | * These two values can be passed either at compile-time as template parameters, or at runtime as
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31 | * arguments to the constructor.
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32 | *
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33 | * Indeed, this class takes two template parameters:
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34 | * \param _OuterStrideAtCompileTime the outer stride, or Dynamic if you want to specify it at runtime.
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35 | * \param _InnerStrideAtCompileTime the inner stride, or Dynamic if you want to specify it at runtime.
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36 | *
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37 | * Here is an example:
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38 | * \include Map_general_stride.cpp
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39 | * Output: \verbinclude Map_general_stride.out
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40 | *
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41 | * \sa class InnerStride, class OuterStride, \ref TopicStorageOrders
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42 | */
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43 | template<int _OuterStrideAtCompileTime, int _InnerStrideAtCompileTime>
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44 | class Stride
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45 | {
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46 | public:
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47 | typedef DenseIndex Index;
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48 | enum {
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49 | InnerStrideAtCompileTime = _InnerStrideAtCompileTime,
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50 | OuterStrideAtCompileTime = _OuterStrideAtCompileTime
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51 | };
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52 |
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53 | /** Default constructor, for use when strides are fixed at compile time */
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54 | Stride()
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55 | : m_outer(OuterStrideAtCompileTime), m_inner(InnerStrideAtCompileTime)
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56 | {
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57 | eigen_assert(InnerStrideAtCompileTime != Dynamic && OuterStrideAtCompileTime != Dynamic);
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58 | }
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59 |
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60 | /** Constructor allowing to pass the strides at runtime */
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61 | Stride(Index outerStride, Index innerStride)
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62 | : m_outer(outerStride), m_inner(innerStride)
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63 | {
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64 | eigen_assert(innerStride>=0 && outerStride>=0);
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65 | }
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66 |
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67 | /** Copy constructor */
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68 | Stride(const Stride& other)
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69 | : m_outer(other.outer()), m_inner(other.inner())
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70 | {}
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71 |
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72 | /** \returns the outer stride */
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73 | inline Index outer() const { return m_outer.value(); }
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74 | /** \returns the inner stride */
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75 | inline Index inner() const { return m_inner.value(); }
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76 |
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77 | protected:
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78 | internal::variable_if_dynamic<Index, OuterStrideAtCompileTime> m_outer;
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79 | internal::variable_if_dynamic<Index, InnerStrideAtCompileTime> m_inner;
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80 | };
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81 |
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82 | /** \brief Convenience specialization of Stride to specify only an inner stride
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83 | * See class Map for some examples */
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84 | template<int Value = Dynamic>
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85 | class InnerStride : public Stride<0, Value>
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86 | {
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87 | typedef Stride<0, Value> Base;
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88 | public:
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89 | typedef DenseIndex Index;
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90 | InnerStride() : Base() {}
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91 | InnerStride(Index v) : Base(0, v) {}
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92 | };
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93 |
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94 | /** \brief Convenience specialization of Stride to specify only an outer stride
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95 | * See class Map for some examples */
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96 | template<int Value = Dynamic>
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97 | class OuterStride : public Stride<Value, 0>
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98 | {
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99 | typedef Stride<Value, 0> Base;
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100 | public:
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101 | typedef DenseIndex Index;
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102 | OuterStride() : Base() {}
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103 | OuterStride(Index v) : Base(v,0) {}
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104 | };
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105 |
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106 | } // end namespace Eigen
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107 |
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108 | #endif // EIGEN_STRIDE_H
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