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 13 namespace 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 * \param _OuterStrideAtCompileTime the outer stride, or Dynamic if you want to specify it at runtime. 35 * \param _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 */ 43 template<int _OuterStrideAtCompileTime, int _InnerStrideAtCompileTime> 44 class Stride 45 { 46 public: 47 typedef DenseIndex Index; 48 enum { 49 InnerStrideAtCompileTime = _InnerStrideAtCompileTime, 50 OuterStrideAtCompileTime = _OuterStrideAtCompileTime 51 }; 52 53 /** Default constructor, for use when strides are fixed at compile time */ Stride()54 Stride() 55 : m_outer(OuterStrideAtCompileTime), m_inner(InnerStrideAtCompileTime) 56 { 57 eigen_assert(InnerStrideAtCompileTime != Dynamic && OuterStrideAtCompileTime != Dynamic); 58 } 59 60 /** Constructor allowing to pass the strides at runtime */ Stride(Index outerStride,Index innerStride)61 Stride(Index outerStride, Index innerStride) 62 : m_outer(outerStride), m_inner(innerStride) 63 { 64 eigen_assert(innerStride>=0 && outerStride>=0); 65 } 66 67 /** Copy constructor */ Stride(const Stride & other)68 Stride(const Stride& other) 69 : m_outer(other.outer()), m_inner(other.inner()) 70 {} 71 72 /** \returns the outer stride */ outer()73 inline Index outer() const { return m_outer.value(); } 74 /** \returns the inner stride */ inner()75 inline Index inner() const { return m_inner.value(); } 76 77 protected: 78 internal::variable_if_dynamic<Index, OuterStrideAtCompileTime> m_outer; 79 internal::variable_if_dynamic<Index, InnerStrideAtCompileTime> m_inner; 80 }; 81 82 /** \brief Convenience specialization of Stride to specify only an inner stride 83 * See class Map for some examples */ 84 template<int Value = Dynamic> 85 class InnerStride : public Stride<0, Value> 86 { 87 typedef Stride<0, Value> Base; 88 public: 89 typedef DenseIndex Index; InnerStride()90 InnerStride() : Base() {} InnerStride(Index v)91 InnerStride(Index v) : Base(0, v) {} 92 }; 93 94 /** \brief Convenience specialization of Stride to specify only an outer stride 95 * See class Map for some examples */ 96 template<int Value = Dynamic> 97 class OuterStride : public Stride<Value, 0> 98 { 99 typedef Stride<Value, 0> Base; 100 public: 101 typedef DenseIndex Index; OuterStride()102 OuterStride() : Base() {} OuterStride(Index v)103 OuterStride(Index v) : Base(v,0) {} 104 }; 105 106 } // end namespace Eigen 107 108 #endif // EIGEN_STRIDE_H 109