From faa526b62885a9e9f6ecad7c928cb4c89df39f66 Mon Sep 17 00:00:00 2001
From: schnetter <schnetter@2e825fa2-fb71-486d-8b7f-a5ff3f0f6cb8>
Date: Wed, 23 Oct 2002 13:21:35 +0000
Subject: Added "TODO" point. Added a bit more documentation. Added some
 restrict qualifiers.

git-svn-id: http://svn.cactuscode.org/arrangements/CactusNumerical/Slab/trunk@7 2e825fa2-fb71-486d-8b7f-a5ff3f0f6cb8
---
 doc/documentation.tex | 11 ++++++++---
 src/slab.c            | 44 ++++++++++++++++++++++++++------------------
 src/slab.h            | 14 +++++++-------
 3 files changed, 41 insertions(+), 28 deletions(-)

diff --git a/doc/documentation.tex b/doc/documentation.tex
index 4c5b203..7ccf999 100644
--- a/doc/documentation.tex
+++ b/doc/documentation.tex
@@ -100,11 +100,12 @@ The Slab thorn provides generic slabbing facilities.  A slab is a
 sub-array of another array.  Both can be multidimensional, and the
 slab can have a non-unit stride.  The Slab thorn provides a routine to
 copy a slab from one array into a slab of another array, while
-possibly transposing or inverting the slab.  This combines get-slab
-and put-slab interfaces.
+possibly transposing or inverting the slab.  The distribution of the
+arrays can be specified freely, so that the Slab thorn can also be
+used to interface to non-Cactus libraries with different data layouts.
 
 The Slab thorn is driver independent, i.e.\ not tied to PUGH or
-Carpet, and does not require MPI.
+Carpet, and does not require MPI for single-processor configurations.
 \end{abstract}
 
 % The following sections are suggestive only.
@@ -112,6 +113,10 @@ Carpet, and does not require MPI.
 
 \section{Introduction}
 
+A \emph{Slab} is a subarray of another array.  This concept is used in
+many places with many different names.  Fortran has so-called ``array
+subscript triplets'', which are the same thing.
+
 \section{Physical System}
 
 \section{Numerical Implementation}
diff --git a/src/slab.c b/src/slab.c
index af5e8f9..27f6258 100644
--- a/src/slab.c
+++ b/src/slab.c
@@ -7,6 +7,7 @@
   Test slabbing without MPI
   Allow using / not setting the ghost zones
   Allow not using / not setting the boundaries
+  Allow different ghost zones at the lower and upper boundary
 */
 
 
@@ -155,6 +156,23 @@ MPI_Alltoallv (void * sendbuf, int * sendcnt, int * sendoff, int sendtype,
 
 
 
+static MPI_Comm get_mpi_comm (cGH * restrict const cctkGH)
+{
+#ifdef CCTK_MPI
+#  if defined CARPET_CARPET
+  return CarpetMPIComm ();
+#  elif defined CACTUSPUGH_PUGH
+  return PUGH_pGH(cctkGH)->PUGH_COMM_WORLD;
+#  else
+#    error "No supported driver thorn included"
+#  endif
+#else
+  return 0;
+#endif
+}
+
+
+
 struct bbox {
   int off, len, str;
 };
@@ -337,13 +355,13 @@ static void bbox_xform (struct bbox       * restrict const ydst,
 
 
 
-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)
+int Slab_Transfer (cGH                   * restrict const cctkGH,
+		   int                              const dim,
+		   struct xferinfo const *          const xferinfo,
+		   int                              const srctype,
+		   void            const *          const srcptr,
+		   int                              const dsttype,
+		   void                  *          const dstptr)
 {
   struct info * restrict info;
   size_t srclentot, dstlentot;
@@ -426,17 +444,7 @@ int Slab_Transfer (cGH                   * const cctkGH,
   
   
   
-#ifdef CCTK_MPI
-#  if defined CARPET_CARPET
-  comm = CarpetMPIComm ();
-#  elif defined CACTUSPUGH_PUGH
-  comm = PUGH_pGH(cctkGH)->PUGH_COMM_WORLD;
-#  else
-#    error "No supported driver thorn included"
-#  endif
-#else
-  comm = 0;
-#endif
+  comm = get_mpi_comm (cctkGH);
   
   ifcheck {
     ifdebug fflush (stdout);
diff --git a/src/slab.h b/src/slab.h
index 4e1051b..b79af0a 100644
--- a/src/slab.h
+++ b/src/slab.h
@@ -83,12 +83,12 @@ struct xferinfo {
   The source and the destination arrays may be the same.
 */
 
-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);
+int Slab_Transfer (cGH                   * restrict 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 */
-- 
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