 template <int over>
 __global__ void
 //__launch_bounds__(256, 6)
-degrid_kernel_small_gcf(complexd* out, double3* in, size_t npts, complexd* img, 
-                              size_t img_dim, complexd* gcf, int gcf_dim) {
+degrid_kernel_small_gcf(complexd* out, const double3* in, size_t npts, const complexd* img, 
+                              size_t img_dim, const complexd* gcf, int gcf_dim) {
    
    //TODO remove hard-coded 32
    for (int n = 32*blockIdx.x; n<npts; n+= 32*gridDim.x) {

      complexd tmp;
      tmp.x = sum_r;
      tmp.y = sum_i;
      if (threadIdx.x == 0) {
         out[n+q] = tmp;
      }
   }

      complexd tmp;
      tmp.x = sum_r;
      tmp.y = sum_i;
      if (1 /* threadIdx.x == 0 */) {
         out[n+q] = tmp;
      }
   }
