layoutStride.rst

LayoutStride

Header File: <Kokkos_Layout.hpp>

Usage

Kokkos::View<float***> full_mesh; // an entire mesh
Kokkos::View<float**, Kokkos::LayoutStride> mesh_subcomponent;
mesh_subcomponent = Kokkos::subview(full_mesh,Kokkos::ALL(), 0, Kokkos::ALL()); // take x and z components

Description

.. cpp:class:: LayoutStride

   When provided to a multidimensional View, lays out memory with an arbitrary stride.
   Most frequently encountered when taking a noncontiguous subview of some larger view.

   .. rubric:: Public Class Members

   .. cppkokkos:member:: size_t dimension[ARRAY_LAYOUT_MAX_RANK];

      An array containing the size of each dimension of the Layout

   .. cppkokkos:member:: size_t stride[ARRAY_LAYOUT_MAX_RANK];

      An array containing the stride for each dimension of the Layout

   .. cppkokkos:member:: static constexpr bool is_extent_constructible = false;

      A boolean to allow detection that this class is extent constructible

   .. rubric:: Public Typedefs

   .. cppkokkos:type:: array_layout

      A tag signifying that this models the Layout concept

   .. rubric:: Constructors

   .. cppkokkos:kokkosinlinefunction:: explicit constexpr LayoutStride(size_t N0 = 0, size_t S0 = 0, \
                           size_t N1 = 0, \
                           size_t S1 = 0, size_t N2 = 0, size_t S2 = 0, \
                           size_t N3 = 0, size_t S3 = 0, size_t N4 = 0, \
                           size_t S4 = 0, size_t N5 = 0, size_t S5 = 0, \
                           size_t N6 = 0, size_t S6 = 0, size_t N7 = 0, size_t S7 = 0);

      Constructor that takes in up to 8 sizes, to set the sizes of the corresponding dimensions of the Layout

   .. cppkokkos:function:: LayoutStride(LayoutStride const&) = default;

      Default copy constructor, element-wise copies the other Layout

   .. cppkokkos:function:: LayoutStride(LayoutStride&&) = default;

      Default move constructor, element-wise moves the other Layout

   .. rubric:: Assignment operators

   .. cppkokkos:function:: LayoutStride& operator=(LayoutStride const&) = default;

      Default copy assignment, element-wise copies the other Layout

   .. cppkokkos:function:: LayoutStride& operator=(LayoutStride&&) = default;

      Default move assignment, element-wise moves the other Layout

   .. rubric:: Functions

   .. cppkokkos:kokkosinlinefunction:: static LayoutStride order_dimensions(int const rank, \
                   iTypeOrder const* const order, iTypeDimen const* const dimen);

      Calculates the strides given ordered dimensions

Example

Creating a 3D unmanaged strided view around a ptr. (You can also just have a view allocate itself by providing a label)

#include<Kokkos_Core.hpp>
int main(int argc, char* argv[]) {
    Kokkos::initialize(argc,argv);
    {
        // Some storage
        int* ptr = new int[80];
        // Creating a layout object
        Kokkos::LayoutStride layout(3,1,3,5,4,20);
        // Create a unmanaged view from a pointer and a layout
        Kokkos::View<int***, Kokkos::LayoutStride, Kokkos::HostSpace> a(ptr,layout);

        // Get strides
        int strides[8];
        a.stride(strides);

        // Print extents and strides
        printf("Extents: %d %d %d\n",a.extent(0),a.extent(1),a.extent(2));
        printf("Strides: %i %i %i\n",strides[0],strides[1],strides[2]);

        // delete storage
        delete [] ptr;
    }
    Kokkos::finalize();
}

Output:

Extents: 3 3 4
Strides: 1 5 20