IJ_layout.h

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#ifndef IJ_layout_included
#define IJ_layout_included
 
 
/*! @brief : This class describes an IJ plane of an IJK_Field_local.
 *
 * It just encapsulates the offset computation: j * j_stride_ + i
 *   with bound checking in debug... This class is usefull to safely optimize the code !
 *
 */
class IJ_layout
{
public:
  int ni() const { return ni_; }
  int nj() const { return nj_; }
  int ghost() const { return ghost_; }
  int j_stride() const { return j_stride_; }
 
  template <typename T>
  IJ_layout(const T& f) : ni_(f.ni()), nj_(f.nj()), ghost_(f.ghost()), j_stride_(f.j_stride()) { }
 
  // origin points to x(0,0,k) for an IJK_Field
  template <typename T>
  T& operator()(T *origin, int i, int j) const
  {
    assert(i >= -ghost_ && i < ni_ + ghost_);
    assert(j >= -ghost_ && j < nj_ + ghost_);
    return origin[j * j_stride_ + i];
  }
 
  // origin points to x(0,0,k) for an IJK_Field
  template <typename T>
  const T& operator()(const T *origin, int i, int j) const
  {
    assert(i >= -ghost_ && i < ni_ + ghost_);
    assert(j >= -ghost_ && j < nj_ + ghost_);
    return origin[j * j_stride_ + i];
  }
 
  // linear index of cell (i=0,j=0) is zero origin points to x(0,0,k) for an IJK_Field
  template <typename T>
  T& linear(T *origin, int linear_index) const
  {
    assert(linear_index >= -ghost_ * (j_stride_ + 1));
    assert(linear_index < (ni_ + ghost_) + j_stride_ * (nj_ + ghost_ - 1));
    return origin[linear_index];
  }
 
  template <typename T>
  const T& linear(const T *origin, int linear_index) const
  {
    assert(linear_index >= -ghost_ * (j_stride_ + 1));
    assert(linear_index < (ni_ + ghost_) + j_stride_ * (nj_ + ghost_ - 1));
    return origin[linear_index];
  }
 
  void linear_to_ij(int linear_index, int& i, int& j) const
  {
    assert(linear_index >= -ghost_ * (j_stride_ + 1));
    assert(linear_index < (ni_ + ghost_) + j_stride_ * (nj_ + ghost_ - 1));
    int l = linear_index + ghost_ * (j_stride_ + 1);
    j = (l / j_stride_) - ghost_;
    i = (l % j_stride_) - ghost_;
  }
 
  // ghost_ is the number of ghost cells allocated in memory in I and J directions
  int ni_, nj_, ghost_, j_stride_;
};
 
 
#endif /* IJ_layout_included */