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

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.

Public Class Members

size_t dimension[ARRAY_LAYOUT_MAX_RANK];

An array containing the size of each dimension of the Layout

size_t stride[ARRAY_LAYOUT_MAX_RANK];

An array containing the stride for each dimension of the Layout

static constexpr bool is_extent_constructible = false;

A boolean to allow detection that this class is extent constructible

Public Typedefs

array_layout

A tag signifying that this models the Layout concept

Constructors

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 dimensions of the Layout

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

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();
}

Output:

Extents: 3 3 4
Strides: 1 5 20