A generic slabbing thorn.

git-svn-id: http://svn.cactuscode.org/arrangements/CactusNumerical/Slab/trunk@2 2e825fa2-fb71-486d-8b7f-a5ff3f0f6cb8

1 files changed, 101 insertions, 0 deletions

diff --git a/src/slab.h b/src/slab.h
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+/* $Header$ */
+
+#ifndef SLAB_H
+#define SLAB_H
+
+#include "cctk.h"
+
+struct slabinfo {
+  int gsh;
+  int lbnd, lsh;
+  int lbbox, ubbox, nghostzones;
+  int off, str, len;
+};
+
+struct xferinfo {
+  struct slabinfo src, dst;
+  int xpose;
+  int flip;
+};
+
+/*
+  Slab_Transfer copies a slab from one array into a slab of another
+  array.
+  
+  The src and dst variables describe the source and the destination
+  slab, respectively.
+  
+  The variables gsh, lbnd, and lsh describe the shape and distribution
+  of the array containing the slab.  They are equivalent to the
+  corresponding quantities in the cGH structure.
+  
+  off, str, and len describe the location and shape of the slab within
+  the array.  off is the offset, i.e. the location of the "first"
+  corner of the slab.  str is the stride, i.e. the distance between to
+  grid points in the slab.  The stride can be negative.  len is the
+  length, i.e. the number of grid points making up the slab.  len does
+  not include the grid points that are skipped if the stride is larger
+  than one.
+  
+  xpose describes a possible permutation of the coordinate axes
+  between the slabs.  It is source-axis = xpose[destination-axis].
+  
+  flip describes a possible inversion of the coordinate axes (from the
+  point of view of the destination slab).  It is source-axis =
+  xpose[flip[destination-axis]].
+  
+  The corresponding lengths of the source and the destination slabs
+  must be equal, i.e. for all d: src.len[xpose[d]] = dst.len[d].
+  
+  The slabs are copied according to
+  
+  .   dst[dst.off + I * dst.str] = src[src.off + J * src.str]
+  
+  where the multi-indices I and J have the ranges specified by dst.len
+  and src.len, respectively, and I and J are related by the
+  transposition
+  
+  .   J = xpose[flip[I]]
+  
+  
+  
+  Restrictions:
+  
+  .   dim >= 0
+  
+  .   gsh >= 0
+  .   lbnd >= 0
+  .   lsh >= 0
+  .   lbnd + lsh <= gsh
+  .   lbbox and ubbox must be booleans, i.e. either 0 or 1
+  .   nghostzones >= 0
+  
+  .   len >= 0
+  .   str != 0
+  .   off >= 0
+  .   off < gsh
+  .   off + (len-1) * str >= 0
+  .   off + (len-1) * str < gsh
+  
+  .   xpose must be a permutation of 0 ... dim-1
+  .   flip must be a boolean, i.e. either 0 or 1
+  
+  The source and the destination arrays may be the same.
+  
+  
+  
+  To do:
+  
+  .   ignore ghostzones
+  .   use size_t instead of int
+*/
+
+int Slab_Transfer (cGH                   * const cctkGH,
+		   int                     const dim,
+		   struct xferinfo const * const xferinfo,
+		   int                     const srctype,
+		   void            const * const srcptr,
+		   int                     const dsttype,
+		   void                  * const dstptr);
+
+#endif /* defined SLAB_H */