__kernel void template(__global double *buf1, __global double *buf2,
                       __global double *result, int mat1_w, int mat1_h, int k)
{

    int x = get_global_id(0);
    int y = get_global_id(1);

    int idx = x * mat1_h + y;
    if (idx >= mat1_h * mat1_w)
        return;

    double sum = 0.0;

    for (int kx = 0; kx < 2*k+1; kx++) {
    for (int ky = 0; ky < 2*k+1; ky++) {
            int overlap_x = x + kx - k;
            int overlap_y = y + ky - k;

            if (overlap_x < 0)
                overlap_x = 0;
            else if (overlap_x >= mat1_w)
                overlap_x = mat1_w - 1;

            if (overlap_y < 0)
                overlap_y = 0;
            else if (overlap_y >= mat1_h)
                overlap_y = mat1_h - 1;

            int idx1 = overlap_x * mat1_h + overlap_y;
            int idxk = kx * 2*k+1 + ky;

            if (idx1 >= mat1_h * mat1_w)
                return;
            sum += buf1[idx1] * buf2[idxk];
        }
    }


    result[idx] = sum;
}