1// This file is part of Eigen, a lightweight C++ template library
2// for linear algebra.
3//
4// Copyright (C) 2010 Benoit Jacob <jacob.benoit.1@gmail.com>
5//
6// This Source Code Form is subject to the terms of the Mozilla
7// Public License v. 2.0. If a copy of the MPL was not distributed
8// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
9
10#ifndef EIGEN_STRIDE_H
11#define EIGEN_STRIDE_H
12
13namespace Eigen {
14
15/** \class Stride
16 * \ingroup Core_Module
17 *
18 * \brief Holds strides information for Map
19 *
20 * This class holds the strides information for mapping arrays with strides with class Map.
21 *
22 * It holds two values: the inner stride and the outer stride.
23 *
24 * The inner stride is the pointer increment between two consecutive entries within a given row of a
25 * row-major matrix or within a given column of a column-major matrix.
26 *
27 * The outer stride is the pointer increment between two consecutive rows of a row-major matrix or
28 * between two consecutive columns of a column-major matrix.
29 *
30 * These two values can be passed either at compile-time as template parameters, or at runtime as
31 * arguments to the constructor.
32 *
33 * Indeed, this class takes two template parameters:
34 * \tparam _OuterStrideAtCompileTime the outer stride, or Dynamic if you want to specify it at runtime.
35 * \tparam _InnerStrideAtCompileTime the inner stride, or Dynamic if you want to specify it at runtime.
36 *
37 * Here is an example:
38 * \include Map_general_stride.cpp
39 * Output: \verbinclude Map_general_stride.out
40 *
41 * \sa class InnerStride, class OuterStride, \ref TopicStorageOrders
42 */
43template<int _OuterStrideAtCompileTime, int _InnerStrideAtCompileTime>
44class Stride
45{
46 public:
47 typedef Eigen::Index Index; ///< \deprecated since Eigen 3.3
48 enum {
49 InnerStrideAtCompileTime = _InnerStrideAtCompileTime,
50 OuterStrideAtCompileTime = _OuterStrideAtCompileTime
51 };
52
53 /** Default constructor, for use when strides are fixed at compile time */
54 EIGEN_DEVICE_FUNC
55 Stride()
56 : m_outer(OuterStrideAtCompileTime), m_inner(InnerStrideAtCompileTime)
57 {
58 eigen_assert(InnerStrideAtCompileTime != Dynamic && OuterStrideAtCompileTime != Dynamic);
59 }
60
61 /** Constructor allowing to pass the strides at runtime */
62 EIGEN_DEVICE_FUNC
63 Stride(Index outerStride, Index innerStride)
64 : m_outer(outerStride), m_inner(innerStride)
65 {
66 eigen_assert(innerStride>=0 && outerStride>=0);
67 }
68
69 /** Copy constructor */
70 EIGEN_DEVICE_FUNC
71 Stride(const Stride& other)
72 : m_outer(other.outer()), m_inner(other.inner())
73 {}
74
75 /** \returns the outer stride */
76 EIGEN_DEVICE_FUNC
77 inline Index outer() const { return m_outer.value(); }
78 /** \returns the inner stride */
79 EIGEN_DEVICE_FUNC
80 inline Index inner() const { return m_inner.value(); }
81
82 protected:
83 internal::variable_if_dynamic<Index, OuterStrideAtCompileTime> m_outer;
84 internal::variable_if_dynamic<Index, InnerStrideAtCompileTime> m_inner;
85};
86
87/** \brief Convenience specialization of Stride to specify only an inner stride
88 * See class Map for some examples */
89template<int Value>
90class InnerStride : public Stride<0, Value>
91{
92 typedef Stride<0, Value> Base;
93 public:
94 EIGEN_DEVICE_FUNC InnerStride() : Base() {}
95 EIGEN_DEVICE_FUNC InnerStride(Index v) : Base(0, v) {} // FIXME making this explicit could break valid code
96};
97
98/** \brief Convenience specialization of Stride to specify only an outer stride
99 * See class Map for some examples */
100template<int Value>
101class OuterStride : public Stride<Value, 0>
102{
103 typedef Stride<Value, 0> Base;
104 public:
105 EIGEN_DEVICE_FUNC OuterStride() : Base() {}
106 EIGEN_DEVICE_FUNC OuterStride(Index v) : Base(v,0) {} // FIXME making this explicit could break valid code
107};
108
109} // end namespace Eigen
110
111#endif // EIGEN_STRIDE_H
112