Kokkos::LayoutStride

`Kokkos::LayoutStride`

Header File: Kokkos_Layout.hpp

This Kokkos Layout, 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.

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

Synopsis

struct LayoutStride {
  typedef LayoutStride array_layout;

  size_t dimension[ARRAY_LAYOUT_MAX_RANK];
  size_t stride[ARRAY_LAYOUT_MAX_RANK];

  enum { is_extent_constructible = false };

  LayoutStride(LayoutStride const&) = default;
  LayoutStride(LayoutStride&&)      = default;
  LayoutStride& operator=(LayoutStride const&) = default;
  LayoutStride& operator=(LayoutStride&&) = default;

  template <typename iTypeOrder, typename iTypeDimen>
  KOKKOS_INLINE_FUNCTION static LayoutStride order_dimensions(
      int const rank, iTypeOrder const* const order,
      iTypeDimen const* const dimen);

  KOKKOS_INLINE_FUNCTION
  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);
};

Public Class Members

dimension

An array containing the size of each dimension of the Layout
stride

An array containing the stride for each dimension of the Layout

Typedefs

array_layout

A tag signifying that this models the Layout concept

Enums

is_extent_constructible

A boolean enum to allow detection that this class is extent constructible

Constructors

LayoutStride(LayoutStride const&) = default;

Default copy constructor, element-wise copies the other Layout
LayoutStride(LayoutStride&&) = default;

Default move constructor, element-wise moves the other Layout

KOKKOS_INLINE_FUNCTION
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 dimenesions of the Layout

Assignment operators

LayoutStride& operator=(LayoutStride const&) = default;

Default copy assignment, element-wise copies the other Layout
LayoutStride& operator=(LayoutStride&&) = default;

Default move assignment, element-wise moves the other Layout

Functions

    KOKKOS_INLINE_FUNCTION 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();
}