facet_normal_kernel.h

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#ifndef __BC_FACET_NORMAL_KERNEL__
#define __BC_FACET_NORMAL_KERNEL__
 
#define coef_normal_area_idx(i, j, k, l, lx, nf) \
  (((i) + (lx) * (((j) - 1) + (lx) * (((k) - 1) + (nf) * (((l) - 1))))) - 1)
 
__device__
void nonlinear_index(const int idx, const int lx, int *index) {
  const int idx2 = idx -1;
  index[3] = idx2/(lx * lx * lx) ;
  index[2] = (idx2 - (lx*lx*lx)*index[3])/(lx * lx);
  index[1] = (idx2 - (lx*lx*lx)*index[3] - (lx*lx) * index[2]) / lx;
  index[0] = (idx2 - (lx*lx*lx)*index[3] - (lx*lx) * index[2]) - lx*index[1];
  index[0]++;
  index[1]++;
  index[2]++;
  index[3]++;
}
 
 
template< typename T >
__global__
void facet_normal_apply_surfvec_kernel(const int * __restrict__ msk,
                                       const int * __restrict__ facet,
                                       T * __restrict__ x,
                                       T * __restrict__ y,
                                       T * __restrict__ z,
                                       const T * __restrict__ u,
                                       const T * __restrict__ v,
                                       const T * __restrict__ w,
                                       const T * __restrict__ nx,
                                       const T * __restrict__ ny,
                                       const T * __restrict__ nz,
                                       const T * __restrict__ area,
                                       const int lx,
                                       const int m) {
  int index[4];
  const int idx = blockIdx.x * blockDim.x + threadIdx.x;
  const int str = blockDim.x * gridDim.x;
 
  for (int i = (idx + 1); i < m; i += str) {
    const int k = (msk[i] - 1);
    const int f = (facet[i]);
    nonlinear_index(msk[i], lx, index);
 
 
    switch(f) {
    case 1:
    case 2:
      {
        const int na_idx = coef_normal_area_idx(index[1], index[2],
                                                f, index[3], lx, 6);
        x[k] = u[k] * nx[na_idx] * area[na_idx];
        y[k] = v[k] * ny[na_idx] * area[na_idx];
        z[k] = w[k] * nz[na_idx] * area[na_idx];
        break;
      }
    case 3:
    case 4:
      {
        const int na_idx = coef_normal_area_idx(index[0], index[2],
                                                f, index[3], lx, 6);
        x[k] = u[k] * nx[na_idx] * area[na_idx];
        y[k] = v[k] * ny[na_idx] * area[na_idx];
        z[k] = w[k] * nz[na_idx] * area[na_idx];
        break;
      }
    case 5:
    case 6:
      {
        const int na_idx = coef_normal_area_idx(index[0], index[1],
                                                f, index[3], lx, 6);
        x[k] = u[k] * nx[na_idx] * area[na_idx];
        y[k] = v[k] * ny[na_idx] * area[na_idx];
        z[k] = w[k] * nz[na_idx] * area[na_idx];
        break;
      }    
    }
  }
}
 
#endif // __BC_FACET_NORMAL_KERNEL__