Example 3

Example 3 demonstrates the declaration of a Structure of Arrays (SoA) interacting with a forward dependency.

#include <stdio.h>
#include <sdlt/primitive.h>
#include <sdlt/soa1d_container.h>

#define N 1024

typedef struct RGBs {
    float r;
    float g;
    float b;
} RGBTy;

SDLT_PRIMITIVE(RGBTy, r, g, b)

void main()
{
    // RGBTy a[N];  // AOS data layout

    sdlt::soa1d_container<RGBTy> aContainer(N);
    auto a = aContainer.access();    // SOA data layout

    // use SDLT access method to access struct members r, g, and b.
    // with unit-stride access  after vectorization
    #pragma omp simd
    for (int k = 0; k<N; k++) {
        a[k].r() = k*1.5;
        a[k].g() = k*2.5;
        a[k].b() = k*3.5;
    }

    // Test forward-dependency on SOA memory access
    #pragma omp simd
    for (int i = 0; i<N - 1; i++) {
        sdlt::linear_index k(i);
        a[k].r() = a[k + 1].r() + k*1.5;
        a[k].g() = a[k + 1].g() + k*2.5;
        a[k].b() = a[k + 1].b() + k*3.5;
    }
    std::cout << "k =" << 10 <<
        ", a[k].r =" << a[10].r() <<
        ", a[k].g =" << a[10].g() <<
        ", a[k].b =" << a[10].b() << std::endl;
}