1 // This file is part of Eigen, a lightweight C++ template library 2 // for linear algebra. 3 // 4 // Copyright (C) 2010 Benoit Jacob <[email protected]> 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 * \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 * Both strides can be negative, however, a negative stride of -1 cannot be specified at compiletime 42 * because of the ambiguity with Dynamic which is defined to -1 (historically, negative strides were 43 * not allowed). 44 * 45 * \sa class InnerStride, class OuterStride, \ref TopicStorageOrders 46 */ 47 template<int _OuterStrideAtCompileTime, int _InnerStrideAtCompileTime> 48 class Stride 49 { 50 public: 51 typedef Eigen::Index Index; ///< \deprecated since Eigen 3.3 52 enum { 53 InnerStrideAtCompileTime = _InnerStrideAtCompileTime, 54 OuterStrideAtCompileTime = _OuterStrideAtCompileTime 55 }; 56 57 /** Default constructor, for use when strides are fixed at compile time */ 58 EIGEN_DEVICE_FUNC Stride()59 Stride() 60 : m_outer(OuterStrideAtCompileTime), m_inner(InnerStrideAtCompileTime) 61 { 62 // FIXME: for Eigen 4 we should use DynamicIndex instead of Dynamic. 63 // FIXME: for Eigen 4 we should also unify this API with fix<> 64 eigen_assert(InnerStrideAtCompileTime != Dynamic && OuterStrideAtCompileTime != Dynamic); 65 } 66 67 /** Constructor allowing to pass the strides at runtime */ 68 EIGEN_DEVICE_FUNC Stride(Index outerStride,Index innerStride)69 Stride(Index outerStride, Index innerStride) 70 : m_outer(outerStride), m_inner(innerStride) 71 { 72 } 73 74 /** Copy constructor */ 75 EIGEN_DEVICE_FUNC Stride(const Stride & other)76 Stride(const Stride& other) 77 : m_outer(other.outer()), m_inner(other.inner()) 78 {} 79 80 /** \returns the outer stride */ 81 EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR outer()82 inline Index outer() const { return m_outer.value(); } 83 /** \returns the inner stride */ 84 EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR inner()85 inline Index inner() const { return m_inner.value(); } 86 87 protected: 88 internal::variable_if_dynamic<Index, OuterStrideAtCompileTime> m_outer; 89 internal::variable_if_dynamic<Index, InnerStrideAtCompileTime> m_inner; 90 }; 91 92 /** \brief Convenience specialization of Stride to specify only an inner stride 93 * See class Map for some examples */ 94 template<int Value> 95 class InnerStride : public Stride<0, Value> 96 { 97 typedef Stride<0, Value> Base; 98 public: InnerStride()99 EIGEN_DEVICE_FUNC InnerStride() : Base() {} InnerStride(Index v)100 EIGEN_DEVICE_FUNC InnerStride(Index v) : Base(0, v) {} // FIXME making this explicit could break valid code 101 }; 102 103 /** \brief Convenience specialization of Stride to specify only an outer stride 104 * See class Map for some examples */ 105 template<int Value> 106 class OuterStride : public Stride<Value, 0> 107 { 108 typedef Stride<Value, 0> Base; 109 public: OuterStride()110 EIGEN_DEVICE_FUNC OuterStride() : Base() {} OuterStride(Index v)111 EIGEN_DEVICE_FUNC OuterStride(Index v) : Base(v,0) {} // FIXME making this explicit could break valid code 112 }; 113 114 } // end namespace Eigen 115 116 #endif // EIGEN_STRIDE_H 117