1 // This file is part of Eigen, a lightweight C++ template library 2 // for linear algebra. 3 // 4 // Copyright (C) 2007-2010 Benoit Jacob <jacob.benoit.1@gmail.com> 5 // Copyright (C) 2008 Gael Guennebaud <gael.guennebaud@inria.fr> 6 // 7 // This Source Code Form is subject to the terms of the Mozilla 8 // Public License v. 2.0. If a copy of the MPL was not distributed 9 // with this file, You can obtain one at http://mozilla.org/MPL/2.0/. 10 11 #ifndef EIGEN_MAP_H 12 #define EIGEN_MAP_H 13 14 namespace Eigen { 15 16 namespace internal { 17 template<typename PlainObjectType, int MapOptions, typename StrideType> 18 struct traits<Map<PlainObjectType, MapOptions, StrideType> > 19 : public traits<PlainObjectType> 20 { 21 typedef traits<PlainObjectType> TraitsBase; 22 enum { 23 InnerStrideAtCompileTime = StrideType::InnerStrideAtCompileTime == 0 24 ? int(PlainObjectType::InnerStrideAtCompileTime) 25 : int(StrideType::InnerStrideAtCompileTime), 26 OuterStrideAtCompileTime = StrideType::OuterStrideAtCompileTime == 0 27 ? int(PlainObjectType::OuterStrideAtCompileTime) 28 : int(StrideType::OuterStrideAtCompileTime), 29 Alignment = int(MapOptions)&int(AlignedMask), 30 Flags0 = TraitsBase::Flags & (~NestByRefBit), 31 Flags = is_lvalue<PlainObjectType>::value ? int(Flags0) : (int(Flags0) & ~LvalueBit) 32 }; 33 private: 34 enum { Options }; // Expressions don't have Options 35 }; 36 } 37 38 /** \class Map 39 * \ingroup Core_Module 40 * 41 * \brief A matrix or vector expression mapping an existing array of data. 42 * 43 * \tparam PlainObjectType the equivalent matrix type of the mapped data 44 * \tparam MapOptions specifies the pointer alignment in bytes. It can be: \c #Aligned128, , \c #Aligned64, \c #Aligned32, \c #Aligned16, \c #Aligned8 or \c #Unaligned. 45 * The default is \c #Unaligned. 46 * \tparam StrideType optionally specifies strides. By default, Map assumes the memory layout 47 * of an ordinary, contiguous array. This can be overridden by specifying strides. 48 * The type passed here must be a specialization of the Stride template, see examples below. 49 * 50 * This class represents a matrix or vector expression mapping an existing array of data. 51 * It can be used to let Eigen interface without any overhead with non-Eigen data structures, 52 * such as plain C arrays or structures from other libraries. By default, it assumes that the 53 * data is laid out contiguously in memory. You can however override this by explicitly specifying 54 * inner and outer strides. 55 * 56 * Here's an example of simply mapping a contiguous array as a \ref TopicStorageOrders "column-major" matrix: 57 * \include Map_simple.cpp 58 * Output: \verbinclude Map_simple.out 59 * 60 * If you need to map non-contiguous arrays, you can do so by specifying strides: 61 * 62 * Here's an example of mapping an array as a vector, specifying an inner stride, that is, the pointer 63 * increment between two consecutive coefficients. Here, we're specifying the inner stride as a compile-time 64 * fixed value. 65 * \include Map_inner_stride.cpp 66 * Output: \verbinclude Map_inner_stride.out 67 * 68 * Here's an example of mapping an array while specifying an outer stride. Here, since we're mapping 69 * as a column-major matrix, 'outer stride' means the pointer increment between two consecutive columns. 70 * Here, we're specifying the outer stride as a runtime parameter. Note that here \c OuterStride<> is 71 * a short version of \c OuterStride<Dynamic> because the default template parameter of OuterStride 72 * is \c Dynamic 73 * \include Map_outer_stride.cpp 74 * Output: \verbinclude Map_outer_stride.out 75 * 76 * For more details and for an example of specifying both an inner and an outer stride, see class Stride. 77 * 78 * \b Tip: to change the array of data mapped by a Map object, you can use the C++ 79 * placement new syntax: 80 * 81 * Example: \include Map_placement_new.cpp 82 * Output: \verbinclude Map_placement_new.out 83 * 84 * This class is the return type of PlainObjectBase::Map() but can also be used directly. 85 * 86 * \sa PlainObjectBase::Map(), \ref TopicStorageOrders 87 */ 88 template<typename PlainObjectType, int MapOptions, typename StrideType> class Map 89 : public MapBase<Map<PlainObjectType, MapOptions, StrideType> > 90 { 91 public: 92 93 typedef MapBase<Map> Base; 94 EIGEN_DENSE_PUBLIC_INTERFACE(Map) 95 96 typedef typename Base::PointerType PointerType; 97 typedef PointerType PointerArgType; 98 EIGEN_DEVICE_FUNC 99 inline PointerType cast_to_pointer_type(PointerArgType ptr) { return ptr; } 100 101 EIGEN_DEVICE_FUNC 102 inline Index innerStride() const 103 { 104 return StrideType::InnerStrideAtCompileTime != 0 ? m_stride.inner() : 1; 105 } 106 107 EIGEN_DEVICE_FUNC 108 inline Index outerStride() const 109 { 110 return StrideType::OuterStrideAtCompileTime != 0 ? m_stride.outer() 111 : IsVectorAtCompileTime ? this->size() 112 : int(Flags)&RowMajorBit ? this->cols() 113 : this->rows(); 114 } 115 116 /** Constructor in the fixed-size case. 117 * 118 * \param dataPtr pointer to the array to map 119 * \param stride optional Stride object, passing the strides. 120 */ 121 EIGEN_DEVICE_FUNC 122 explicit inline Map(PointerArgType dataPtr, const StrideType& stride = StrideType()) 123 : Base(cast_to_pointer_type(dataPtr)), m_stride(stride) 124 { 125 PlainObjectType::Base::_check_template_params(); 126 } 127 128 /** Constructor in the dynamic-size vector case. 129 * 130 * \param dataPtr pointer to the array to map 131 * \param size the size of the vector expression 132 * \param stride optional Stride object, passing the strides. 133 */ 134 EIGEN_DEVICE_FUNC 135 inline Map(PointerArgType dataPtr, Index size, const StrideType& stride = StrideType()) 136 : Base(cast_to_pointer_type(dataPtr), size), m_stride(stride) 137 { 138 PlainObjectType::Base::_check_template_params(); 139 } 140 141 /** Constructor in the dynamic-size matrix case. 142 * 143 * \param dataPtr pointer to the array to map 144 * \param rows the number of rows of the matrix expression 145 * \param cols the number of columns of the matrix expression 146 * \param stride optional Stride object, passing the strides. 147 */ 148 EIGEN_DEVICE_FUNC 149 inline Map(PointerArgType dataPtr, Index rows, Index cols, const StrideType& stride = StrideType()) 150 : Base(cast_to_pointer_type(dataPtr), rows, cols), m_stride(stride) 151 { 152 PlainObjectType::Base::_check_template_params(); 153 } 154 155 EIGEN_INHERIT_ASSIGNMENT_OPERATORS(Map) 156 157 protected: 158 StrideType m_stride; 159 }; 160 161 162 } // end namespace Eigen 163 164 #endif // EIGEN_MAP_H 165