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
14namespace Eigen {
15
16namespace internal {
17template<typename PlainObjectType, int MapOptions, typename StrideType>
18struct 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 };
39private:
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 */
94template<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
108 inline Index innerStride() const
109 {
110 return StrideType::InnerStrideAtCompileTime != 0 ? m_stride.inner() : 1;
111 }
112
113 EIGEN_DEVICE_FUNC
114 inline Index outerStride() const
115 {
116 return int(StrideType::OuterStrideAtCompileTime) != 0 ? m_stride.outer()
117 : int(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