1 // This file is part of Eigen, a lightweight C++ template library 2 // for linear algebra. 3 // 4 // Copyright (C) 2007-2010 Benoit Jacob <[email protected]> 5 // Copyright (C) 2008 Gael Guennebaud <[email protected]> 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 PlainObjectTypeInnerSize = ((traits<PlainObjectType>::Flags&RowMajorBit)==RowMajorBit) 24 ? PlainObjectType::ColsAtCompileTime 25 : PlainObjectType::RowsAtCompileTime, 26 27 InnerStrideAtCompileTime = StrideType::InnerStrideAtCompileTime == 0 28 ? int(PlainObjectType::InnerStrideAtCompileTime) 29 : int(StrideType::InnerStrideAtCompileTime), 30 OuterStrideAtCompileTime = StrideType::OuterStrideAtCompileTime == 0 31 ? (InnerStrideAtCompileTime==Dynamic || PlainObjectTypeInnerSize==Dynamic 32 ? Dynamic 33 : int(InnerStrideAtCompileTime) * int(PlainObjectTypeInnerSize)) 34 : int(StrideType::OuterStrideAtCompileTime), 35 Alignment = int(MapOptions)&int(AlignedMask), 36 Flags0 = TraitsBase::Flags & (~NestByRefBit), 37 Flags = is_lvalue<PlainObjectType>::value ? int(Flags0) : (int(Flags0) & ~LvalueBit) 38 }; 39 private: 40 enum { Options }; // Expressions don't have Options 41 }; 42 } 43 44 /** \class Map 45 * \ingroup Core_Module 46 * 47 * \brief A matrix or vector expression mapping an existing array of data. 48 * 49 * \tparam PlainObjectType the equivalent matrix type of the mapped data 50 * \tparam MapOptions specifies the pointer alignment in bytes. It can be: \c #Aligned128, \c #Aligned64, \c #Aligned32, \c #Aligned16, \c #Aligned8 or \c #Unaligned. 51 * The default is \c #Unaligned. 52 * \tparam StrideType optionally specifies strides. By default, Map assumes the memory layout 53 * of an ordinary, contiguous array. This can be overridden by specifying strides. 54 * The type passed here must be a specialization of the Stride template, see examples below. 55 * 56 * This class represents a matrix or vector expression mapping an existing array of data. 57 * It can be used to let Eigen interface without any overhead with non-Eigen data structures, 58 * such as plain C arrays or structures from other libraries. By default, it assumes that the 59 * data is laid out contiguously in memory. You can however override this by explicitly specifying 60 * inner and outer strides. 61 * 62 * Here's an example of simply mapping a contiguous array as a \ref TopicStorageOrders "column-major" matrix: 63 * \include Map_simple.cpp 64 * Output: \verbinclude Map_simple.out 65 * 66 * If you need to map non-contiguous arrays, you can do so by specifying strides: 67 * 68 * Here's an example of mapping an array as a vector, specifying an inner stride, that is, the pointer 69 * increment between two consecutive coefficients. Here, we're specifying the inner stride as a compile-time 70 * fixed value. 71 * \include Map_inner_stride.cpp 72 * Output: \verbinclude Map_inner_stride.out 73 * 74 * Here's an example of mapping an array while specifying an outer stride. Here, since we're mapping 75 * as a column-major matrix, 'outer stride' means the pointer increment between two consecutive columns. 76 * Here, we're specifying the outer stride as a runtime parameter. Note that here \c OuterStride<> is 77 * a short version of \c OuterStride<Dynamic> because the default template parameter of OuterStride 78 * is \c Dynamic 79 * \include Map_outer_stride.cpp 80 * Output: \verbinclude Map_outer_stride.out 81 * 82 * For more details and for an example of specifying both an inner and an outer stride, see class Stride. 83 * 84 * \b Tip: to change the array of data mapped by a Map object, you can use the C++ 85 * placement new syntax: 86 * 87 * Example: \include Map_placement_new.cpp 88 * Output: \verbinclude Map_placement_new.out 89 * 90 * This class is the return type of PlainObjectBase::Map() but can also be used directly. 91 * 92 * \sa PlainObjectBase::Map(), \ref TopicStorageOrders 93 */ 94 template<typename PlainObjectType, int MapOptions, typename StrideType> class Map 95 : public MapBase<Map<PlainObjectType, MapOptions, StrideType> > 96 { 97 public: 98 99 typedef MapBase<Map> Base; 100 EIGEN_DENSE_PUBLIC_INTERFACE(Map) 101 102 typedef typename Base::PointerType PointerType; 103 typedef PointerType PointerArgType; 104 EIGEN_DEVICE_FUNC 105 inline PointerType cast_to_pointer_type(PointerArgType ptr) { return ptr; } 106 107 EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR 108 inline Index innerStride() const 109 { 110 return StrideType::InnerStrideAtCompileTime != 0 ? m_stride.inner() : 1; 111 } 112 113 EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR 114 inline Index outerStride() const 115 { 116 return StrideType::OuterStrideAtCompileTime != 0 ? m_stride.outer() 117 : internal::traits<Map>::OuterStrideAtCompileTime != Dynamic ? Index(internal::traits<Map>::OuterStrideAtCompileTime) 118 : IsVectorAtCompileTime ? (this->size() * innerStride()) 119 : int(Flags)&RowMajorBit ? (this->cols() * innerStride()) 120 : (this->rows() * innerStride()); 121 } 122 123 /** Constructor in the fixed-size case. 124 * 125 * \param dataPtr pointer to the array to map 126 * \param stride optional Stride object, passing the strides. 127 */ 128 EIGEN_DEVICE_FUNC 129 explicit inline Map(PointerArgType dataPtr, const StrideType& stride = StrideType()) 130 : Base(cast_to_pointer_type(dataPtr)), m_stride(stride) 131 { 132 PlainObjectType::Base::_check_template_params(); 133 } 134 135 /** Constructor in the dynamic-size vector case. 136 * 137 * \param dataPtr pointer to the array to map 138 * \param size the size of the vector expression 139 * \param stride optional Stride object, passing the strides. 140 */ 141 EIGEN_DEVICE_FUNC 142 inline Map(PointerArgType dataPtr, Index size, const StrideType& stride = StrideType()) 143 : Base(cast_to_pointer_type(dataPtr), size), m_stride(stride) 144 { 145 PlainObjectType::Base::_check_template_params(); 146 } 147 148 /** Constructor in the dynamic-size matrix case. 149 * 150 * \param dataPtr pointer to the array to map 151 * \param rows the number of rows of the matrix expression 152 * \param cols the number of columns of the matrix expression 153 * \param stride optional Stride object, passing the strides. 154 */ 155 EIGEN_DEVICE_FUNC 156 inline Map(PointerArgType dataPtr, Index rows, Index cols, const StrideType& stride = StrideType()) 157 : Base(cast_to_pointer_type(dataPtr), rows, cols), m_stride(stride) 158 { 159 PlainObjectType::Base::_check_template_params(); 160 } 161 162 EIGEN_INHERIT_ASSIGNMENT_OPERATORS(Map) 163 164 protected: 165 StrideType m_stride; 166 }; 167 168 169 } // end namespace Eigen 170 171 #endif // EIGEN_MAP_H 172