fdm_kernel.h

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#ifndef __MATH_FDM_KERNEL_H__
#define __MATH_FDM_KERNEL_H__
/*
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*/
 
template< typename T, const int NL >
__global__ void fdm_do_fast_kernel(T  * __restrict__ e,
                                   T * __restrict__ r,
                                   T * __restrict__ s,
                                   T * __restrict__ d) {
  __shared__ T shwork[NL*NL*NL];
  __shared__ T shwork2[NL*NL*NL];
  __shared__ T A[NL*NL];
  __shared__ T Bt[NL*NL];
  __shared__ T Ct[NL*NL];
 
  const int idx = threadIdx.x;
  const int str = blockDim.x;
  const int el = blockIdx.x;
  if( idx < NL*NL){
     A[idx] = s[idx+NL*NL+el*NL*NL*3*2];
    Bt[idx] = s[idx+2*NL*NL+el*NL*NL*3*2];
    Ct[idx] = s[idx+2*2*NL*NL+el*NL*NL*3*2];
  }    
  __syncthreads();
 
  for (int ii = idx; ii< NL*NL*NL; ii += str){
    T tmp = 0.0;
    int j = ii/NL;
    int i = ii - j*NL;
    for( int l = 0; l < NL; l++){
      tmp += A[i+l*NL]*r[l+NL*j+el*NL*NL*NL];
    }
    shwork[ii] = tmp;
  }
  __syncthreads();
  for (int ijk = idx; ijk< NL*NL*NL; ijk += str){
    const int jk = ijk / NL;
    const int i = ijk - jk * NL;
    const int k = jk / NL;
    const int j = jk - k * NL;
    T tmp = 0.0;
    const int ik2 = i + k*NL*NL; 
    for( int l = 0; l < NL; l++){
      tmp += Bt[l+j*NL]*shwork[l*NL+ik2];
    }
    shwork2[ijk] = tmp;
  }
  __syncthreads();
  for (int ijk = idx; ijk< NL*NL*NL; ijk += str){
    const int jk = ijk / NL;
    const int i = ijk - jk * NL;
    const int k = jk / NL;
    const int j = jk - k * NL;
    T tmp = 0.0;
    const int ij2 = i + j*NL; 
    for( int l = 0; l < NL; l++){
      tmp += Ct[l+k*NL]*shwork2[ij2 + l*NL*NL];
    }
    r[ijk+el*NL*NL*NL] = tmp*d[ijk+el*NL*NL*NL];
  }
  __syncthreads();
  if( idx < NL*NL){
     A[idx] = s[idx+el*NL*NL*3*2];
    Bt[idx] = s[idx+NL*NL+2*NL*NL+el*NL*NL*3*2];
    Ct[idx] = s[idx+NL*NL+2*2*NL*NL+el*NL*NL*3*2];
  }  
  __syncthreads();
 
  for (int ii = idx; ii< NL*NL*NL; ii += str){
    T tmp = 0.0;
    int j = ii/NL;
    int i = ii - j*NL;
    for( int l = 0; l < NL; l++){
      tmp += A[i+l*NL]*r[l+NL*j+el*NL*NL*NL];
    }
    shwork[ii] = tmp;
  }
  __syncthreads();
  for (int ijk = idx; ijk< NL*NL*NL; ijk += str){
    const int jk = ijk / NL;
    const int i = ijk - jk * NL;
    const int k = jk / NL;
    const int j = jk - k * NL;
    T tmp = 0.0;
    const int ik2 = i + k*NL*NL; 
    for( int l = 0; l < NL; l++){
      tmp += Bt[l+j*NL]*shwork[l*NL+ik2];
    }
    shwork2[ijk] = tmp;
  }
  __syncthreads();
  for (int ijk = idx; ijk< NL*NL*NL; ijk += str){
    const int jk = ijk / NL;
    const int i = ijk - jk * NL;
    const int k = jk / NL;
    const int j = jk - k * NL;
    T tmp = 0.0;
    const int ij2 = i + j*NL; 
    for( int l = 0; l < NL; l++){
      tmp += Ct[l+k*NL]*shwork2[ij2 + l*NL*NL];
    }
    e[ijk+el*NL*NL*NL] = tmp;
  }
 
}
 
 
 
#endif // __MATH_FDM_KERNEL_H__