Initial implementation of the SymBase specification

git-svn-id: http://svn.cactuscode.org/arrangements/CactusBase/SymBase/trunk@2 906471b6-c639-44d1-9ea0-3e3d6879f074

11 files changed, 1395 insertions, 0 deletions

diff --git a/README b/README
new file mode 100644
index 0000000..fc21a92
--- /dev/null
+++ b/README
@@ -0,0 +1,10 @@
+CVS info   : $Header$
+
+Cactus Code Thorn SymBase
+Thorn Author(s)     : Erik Schnetter <schnetter@aei.mpg.de>
+Thorn Maintainer(s) : Cactus Maintainers <cactusmaint@cactuscode.org>
+--------------------------------------------------------------------------
+
+Purpose of the thorn:
+
+Provide generic handling of symmetries for grids and grid arrays.
diff --git a/doc/documentation.tex b/doc/documentation.tex
new file mode 100644
index 0000000..c37694e
--- /dev/null
+++ b/doc/documentation.tex
@@ -0,0 +1,302 @@
+% *======================================================================*
+%  Cactus Thorn template for ThornGuide documentation
+%  Author: Ian Kelley
+%  Date: Sun Jun 02, 2002
+%  $Header$
+%
+%  Thorn documentation in the latex file doc/documentation.tex
+%  will be included in ThornGuides built with the Cactus make system.
+%  The scripts employed by the make system automatically include
+%  pages about variables, parameters and scheduling parsed from the
+%  relevant thorn CCL files.
+%
+%  This template contains guidelines which help to assure that your
+%  documentation will be correctly added to ThornGuides. More
+%  information is available in the Cactus UsersGuide.
+%
+%  Guidelines:
+%   - Do not change anything before the line
+%       % START CACTUS THORNGUIDE",
+%     except for filling in the title, author, date, etc. fields.
+%        - Each of these fields should only be on ONE line.
+%        - Author names should be separated with a \\ or a comma.
+%   - You can define your own macros, but they must appear after
+%     the START CACTUS THORNGUIDE line, and must not redefine standard
+%     latex commands.
+%   - To avoid name clashes with other thorns, 'labels', 'citations',
+%     'references', and 'image' names should conform to the following
+%     convention:
+%       ARRANGEMENT_THORN_LABEL
+%     For example, an image wave.eps in the arrangement CactusWave and
+%     thorn WaveToyC should be renamed to CactusWave_WaveToyC_wave.eps
+%   - Graphics should only be included using the graphicx package.
+%     More specifically, with the "\includegraphics" command.  Do
+%     not specify any graphic file extensions in your .tex file. This
+%     will allow us to create a PDF version of the ThornGuide
+%     via pdflatex.
+%   - References should be included with the latex "\bibitem" command.
+%   - Use \begin{abstract}...\end{abstract} instead of \abstract{...}
+%   - Do not use \appendix, instead include any appendices you need as
+%     standard sections.
+%   - For the benefit of our Perl scripts, and for future extensions,
+%     please use simple latex.
+%
+% *======================================================================*
+%
+% Example of including a graphic image:
+%    \begin{figure}[ht]
+% 	\begin{center}
+%    	   \includegraphics[width=6cm]{MyArrangement_MyThorn_MyFigure}
+% 	\end{center}
+% 	\caption{Illustration of this and that}
+% 	\label{MyArrangement_MyThorn_MyLabel}
+%    \end{figure}
+%
+% Example of using a label:
+%   \label{MyArrangement_MyThorn_MyLabel}
+%
+% Example of a citation:
+%    \cite{MyArrangement_MyThorn_Author99}
+%
+% Example of including a reference
+%   \bibitem{MyArrangement_MyThorn_Author99}
+%   {J. Author, {\em The Title of the Book, Journal, or periodical}, 1 (1999),
+%   1--16. {\tt http://www.nowhere.com/}}
+%
+% *======================================================================*
+
+% If you are using CVS use this line to give version information
+% $Header$
+
+\documentclass{article}
+
+% Use the Cactus ThornGuide style file
+% (Automatically used from Cactus distribution, if you have a
+%  thorn without the Cactus Flesh download this from the Cactus
+%  homepage at www.cactuscode.org)
+\usepackage{../../../../doc/latex/cactus}
+
+\begin{document}
+
+% The author of the documentation
+\author{Erik Schnetter \textless schnetter@aei.mpg.de\textgreater}
+
+% The title of the document (not necessarily the name of the Thorn)
+\title{SymBase}
+
+% the date your document was last changed, if your document is in CVS,
+% please use:
+\date{$ $Date$ $}
+
+\maketitle
+
+% Do not delete next line
+% START CACTUS THORNGUIDE
+
+% Add all definitions used in this documentation here
+%   \def\mydef etc
+
+% Add an abstract for this thorn's documentation
+\begin{abstract}
+Thorn SymBase contains a registry for symmetry conditions and for
+symmetry faces.
+\end{abstract}
+
+% The following sections are suggestive only.
+% Remove them or add your own.
+
+
+
+\section{Introduction}
+
+Thorn SymBase contains a registry for symmetry conditions and for
+symmetry faces.  Other thorns that implement symmetry boundary
+conditions register themselves with this thorn and reserve certain
+faces of the grid, so that no other boundary condition is applied
+there.  Thorns that implement physical boundary conditions should
+query this thorn about the set of faces that have symmetry boundary
+conditions and should not apply the physical boundary condition there.
+
+
+
+\section{Registering Symmetry Conditions}
+
+Each thorn that implements a symmetry boundary condition should
+register itself with thorn SymBase.  This has no consequences per se,
+but it reservers a symmetry handle for later use.  The API for
+registering and querying symmetry names and handles is
+
+\begin{verbatim}
+CCTK_INT FUNCTION
+    SymmetryRegister (CCTK_STRING IN sym_name)
+
+CCTK_INT FUNCTION
+    SymmetryHandleOfName (CCTK_STRING IN sym_name)
+
+CCTK_POINTER_TO_CONST FUNCTION
+    SymmetryNameOfHandle (CCTK_INT IN sym_handle)
+\end{verbatim}
+
+The routine \texttt{SymmetryRegister} should be called in a routine
+that has been scheduled in the schedule group
+\texttt{SymmetryRegister}.
+
+\begin{quote}
+Note: We have the API in the specification, we have it in the
+interface file, in the source code, and in a header file, and I
+duplicated it into grdoc headers.  I refuse to write and describe and
+cross-check the API a \emph{sixth} time in latex.  At some point, we
+have to start using tools for that.  Please read the grdoc headers or
+the grdoc-produced html files for a detailed description.
+\end{quote}
+
+
+
+\section{Registering Symmetries for Faces}
+
+Thorn SymBase keeps two registries.  The first, described in the
+previous section, contains the set of symmetry boundary conditions
+that exist at all.  The second, described here, describes which face
+of the grids have which symmetry condition applied to it, if any.
+Each such mapping from grid face to symmetry condition is described by
+a symmetry table with the following entries:
+
+\begin{verbatim}
+CCTK_INT symmetry_handle[]
+CCTK_INT symmetry_zone_width[]
+\end{verbatim}
+
+Each of these arrays contains one element per face, numbered in the
+same way as the \texttt{cctk\_bbox} array.  The
+\texttt{symmetry\_handle} is a symmetry handle as described in the
+previous section, and the \texttt{symmetry\_zone\_width} is the width
+of the symmetry zone.
+
+Code outside SymBase should not modify these table entries.
+
+There is one such table for the grid hierarchy, which is valid for all
+grid functions.  There is additionally one such table for each grid
+array group.
+
+The API for registering symmetries for faces is
+
+\begin{verbatim}
+CCTK_INT FUNCTION
+    SymmetryRegisterGrid
+         (CCTK_POINTER IN cctkGH,
+          CCTK_INT IN sym_handle,
+          CCTK_INT IN ARRAY which_faces,
+          CCTK_INT IN ARRAY symmetry_zone_width)
+
+CCTK_INT FUNCTION
+    SymmetryRegisterGI
+        (CCTK_POINTER IN cctkGH,
+         CCTK_INT IN sym_handle,
+         CCTK_INT IN ARRAY which_faces,
+         CCTK_INT IN ARRAY symmetry_zone_width,
+         CCTK_INT IN group_index)
+
+CCTK_INT FUNCTION
+    SymmetryRegisterGN
+        (CCTK_POINTER IN cctkGH,
+         CCTK_INT IN sym_handle,
+         CCTK_INT IN ARRAY which_faces,
+         CCTK_INT IN ARRAY symmetry_zone_width,
+         CCTK_STRING IN group_name)
+\end{verbatim}
+
+The first routine registers a symmetry condition for certain faces for
+the grid hierarchy, the other two routines register for grid array
+groups.  \texttt{sym\_handle} must be a symmetry handle obtained as
+described in the previous section.  \texttt{which\_faces} and
+\texttt{symmetry\_zone\_width} are arrays with one element per face,
+numbered in the same way as the \texttt{cctk\_bbox} array.
+\texttt{which\_faces} selects which faces to register, and
+\texttt{symmetry\_zone\_width} sets the number of symmetry zones for
+these faces.
+
+It is obviously not possible to register multiple symmetry conditions
+for the same face.
+
+
+
+\section{Querying Symmetries of Faces}
+
+Physical boundary conditions need to know to which faces they should
+apply the boundary condition.  They need to query SymBase for the set
+of faces that have a symmetry boundary condition, and they must not
+apply their physical boundary condition there.  The API is
+
+\begin{verbatim}
+CCTK_INT FUNCTION
+    SymmetryTableHandleForGrid (CCTK_POINTER_TO_CONST IN cctkGH)
+
+CCTK_INT FUNCTION
+    SymmetryTableHandleForGI
+        (CCTK_POINTER_TO_CONST IN cctkGH,
+         CCTK_INT IN group_index)
+
+CCTK_INT FUNCTION
+    SymmetryTableHandleForGN
+        (CCTK_POINTER_TO_CONST IN cctkGH,
+         CCTK_STRING IN group_name)
+\end{verbatim}
+
+These functions return the the handle for the symmetry table for the
+grid hierarchy or for the grid array group, respectively.  The table
+entry \texttt{symmetry\_handle} contains the symmetry handle for the
+symmetry boundary condition, or a negative number if the face has no
+symmetry boundary condition associated with it.
+
+The code to find out which boundaries should have a physical boundary
+condition applied might look as follows:
+
+\begin{verbatim}
+#include <assert.h>
+#include "util_Table.h"
+
+CCTK_INT symtable;
+CCTK_INT symbnd[6];
+int face;
+int ierr;
+
+symtable = SymmetryTableHandleForGrid (cctkGH);
+assert (symtable>=0);
+
+ierr = Util_TableGetIntArray (symtable, 6, symbnd, "symmetry_handle");
+assert (ierr==6);
+
+for (face=0; face<6; ++face) {
+  if (cctk_bbox[face] && symbnd[face]<0) {
+    /* Apply physical boundary condition here */
+  }
+}
+\end{verbatim}
+
+\begin{verbatim}
+#include "util_Table.h"
+
+CCTK_INT symtable
+CCTK_INT symbnd(6)
+integer face
+integer ierr
+
+symtable = SymmetryTableHandleForGrid (cctkGH)
+if (symtable<0) call CCTK_WARN (0, "internal error")
+
+call Util_TableGetIntArray (ierr, int(symtable), 6, symbnd, "symmetry_handle")
+if (ierr/=6) call CCTK_WARN (0, "internal error")
+
+do face=1,6
+  if (cctk_bbox(face)/=0 .and. symbnd(face)<0) then
+    ! Apply physical boundary condition here
+  end if
+end do
+\end{verbatim}
+
+
+
+% Do not delete next line
+% END CACTUS THORNGUIDE
+
+\end{document}
diff --git a/interface.ccl b/interface.ccl
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--- /dev/null
+++ b/interface.ccl
@@ -0,0 +1,85 @@
+# Interface definition for thorn SymBase
+# $Header$
+
+IMPLEMENTS: SymBase
+
+
+
+# Register a symmetry, and query the symmetry name/handle mapping:
+
+CCTK_INT FUNCTION SymmetryRegister (CCTK_STRING IN sym_name)
+PROVIDES FUNCTION SymmetryRegister \
+     WITH SymBase_SymmetryRegister \
+     LANGUAGE C
+
+CCTK_INT FUNCTION SymmetryHandleOfName (CCTK_STRING IN sym_name)
+PROVIDES FUNCTION SymmetryHandleOfName \
+     WITH SymBase_SymmetryHandleOfName \
+     LANGUAGE C
+
+CCTK_POINTER_TO_CONST FUNCTION SymmetryNameOfHandle (CCTK_INT IN sym_handle)
+PROVIDES FUNCTION SymmetryNameOfHandle \
+     WITH SymBase_SymmetryNameOfHandle \
+     LANGUAGE C
+
+
+
+# Register a symmetry condition for a face:
+
+CCTK_INT FUNCTION                                  \
+    SymmetryRegisterGrid                           \
+         (CCTK_POINTER IN cctkGH,                  \
+          CCTK_INT IN sym_handle,                  \
+          CCTK_INT IN ARRAY which_faces,           \ # array [N_FACES]
+          CCTK_INT IN ARRAY symmetry_zone_width)     # array [N_FACES]
+PROVIDES FUNCTION SymmetryRegisterGrid \
+     WITH SymBase_SymmetryRegisterGrid \
+     LANGUAGE C
+
+CCTK_INT FUNCTION                                  \
+    SymmetryRegisterGI                             \
+        (CCTK_POINTER IN cctkGH,                   \
+         CCTK_INT IN sym_handle,                   \
+         CCTK_INT IN ARRAY which_faces,            \ # array [N_FACES]
+         CCTK_INT IN ARRAY symmetry_zone_width,    \ # array [N_FACES]
+         CCTK_INT IN group_index)
+PROVIDES FUNCTION SymmetryRegisterGI \
+     WITH SymBase_SymmetryRegisterGI \
+     LANGUAGE C
+
+CCTK_INT FUNCTION                                  \
+    SymmetryRegisterGN                             \
+        (CCTK_POINTER IN cctkGH,                   \
+         CCTK_INT IN sym_handle,                   \
+         CCTK_INT IN ARRAY which_faces,            \ # array [N_FACES]
+         CCTK_INT IN ARRAY symmetry_zone_width,    \ # array [N_FACES]
+         CCTK_STRING IN group_name)
+PROVIDES FUNCTION SymmetryRegisterGN \
+     WITH SymBase_SymmetryRegisterGN \
+     LANGUAGE C
+
+
+
+# Get the symmetry table handle for a grid or grid array:
+
+CCTK_INT FUNCTION \
+    SymmetryTableHandleForGrid (CCTK_POINTER_TO_CONST IN cctkGH)
+PROVIDES FUNCTION SymmetryTableHandleForGrid \
+     WITH SymBase_SymmetryTableHandleForGrid \
+     LANGUAGE C
+
+CCTK_INT FUNCTION                          \
+    SymmetryTableHandleForGI               \
+        (CCTK_POINTER_TO_CONST IN cctkGH,  \
+         CCTK_INT IN group_index)
+PROVIDES FUNCTION SymmetryTableHandleForGI \
+     WITH SymBase_SymmetryTableHandleForGI \
+     LANGUAGE C
+
+CCTK_INT FUNCTION                          \
+    SymmetryTableHandleForGN               \
+        (CCTK_POINTER_TO_CONST IN cctkGH,  \
+         CCTK_STRING IN group_name)
+PROVIDES FUNCTION SymmetryTableHandleForGN \
+     WITH SymBase_SymmetryTableHandleForGN \
+     LANGUAGE C
diff --git a/param.ccl b/param.ccl
new file mode 100644
index 0000000..e82ab1e
--- /dev/null
+++ b/param.ccl
@@ -0,0 +1,2 @@
+# Parameter definitions for thorn SymBase
+# $Header$
diff --git a/schedule.ccl b/schedule.ccl
new file mode 100644
index 0000000..f3d7f54
--- /dev/null
+++ b/schedule.ccl
@@ -0,0 +1,11 @@
+# Schedule definitions for thorn SymBase
+# $Header$
+
+SCHEDULE SymBase_Startup AT CCTK_STARTUP
+{
+  LANG: C
+} "Register GH Extension for SymBase"
+
+SCHEDULE GROUP SymmetryRegister AT CCTK_WRAGH
+{
+} "Register your symmetries here"
diff --git a/src/Faces.c b/src/Faces.c
new file mode 100644
index 0000000..6817c3f
--- /dev/null
+++ b/src/Faces.c
@@ -0,0 +1,362 @@
+/*@@
+  @file      $RCSfile$
+  @author    $Author$
+  @date      $Date$
+  @desc
+             Register a symmetry condition for a face
+  @version   $Header$
+  @enddesc
+@@*/
+
+#include <stdlib.h>
+
+#include "cctk.h"
+
+#include "util_Table.h"
+
+#include "SymBase.h"
+
+
+/* the rcs ID and its dummy function to use it */
+static const char *const rcsid = "$Header$";
+CCTK_FILEVERSION (CactusBase_SymBase_Faces_c);
+
+
+
+/*@@
+  @routine    SymBase_SymmetryRegisterFaces
+  @author     Erik Schnetter
+  @date       2004-03-06
+  @desc
+              Register a symmetry for certain faces
+  @enddesc
+  @var        sym_table
+  @vtype      CCTK_INT
+  @vdesc      Table which describes the grid or grid array
+  @vio        in
+  @endvar
+  @var        group_dim
+  @vtype      CCTK_INT
+  @vdesc      Dimension of the grid or grid array
+  @vio        in
+  @endvar
+  @var        sym_handle
+  @vtype      CCTK_INT
+  @vdesc      Symmetry handle
+  @vio        in
+  @endvar
+  @var        which_faces
+  @vtype      CCTK_INT[2*group_dim]
+  @vdesc      The set of faces
+  @vio        in
+  @endvar
+  @var        symmetry_zone_width
+  @vtype      CCTK_INT[2*group_dim]
+  @vdesc      Symmetry boundary width
+  @vio        in
+  @endvar
+  @returntype CCTK_INT
+  @returndesc
+              status code
+              0 for success
+              -1 if sym_table has an illegal value
+              -9 if group_dim has an illegal value
+              -2 if sym_handle has an illegal value
+              -3 if which_faces has an illegal value
+              -4 if symmetry_zone_width has an illegal value
+  @endreturndesc
+@@*/
+
+CCTK_INT
+SymBase_SymmetryRegisterFaces (CCTK_INT const sym_table,
+			       CCTK_INT const group_dim,
+			       CCTK_INT const sym_handle,
+			       CCTK_INT const *const which_faces,
+			       CCTK_INT const *const new_symmetry_zone_width)
+{
+  CCTK_INT symmetry_handle[100];
+  CCTK_INT symmetry_zone_width[100];
+  int face;
+  int ierr;
+
+  /* Check arguments */
+  if (sym_table < 0)
+  {
+    return -1;			/* illegal argument */
+  }
+  if (group_dim < 0)
+  {
+    return -9;			/* illegal argument */
+  }
+  if (sym_handle < 0 || sym_handle >= SymBase_num_symmetries)
+  {
+    return -2;			/* illegal argument */
+  }
+  if (!which_faces)
+  {
+    return -3;			/* illegal argument */
+  }
+  if (!symmetry_zone_width)
+  {
+    return -4;			/* illegal argument */
+  }
+
+  /* Get table entries */
+  if (2 * group_dim > 100)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+  ierr = Util_TableGetIntArray
+    (sym_table, 2 * group_dim, symmetry_handle, "symmetry_handle");
+  if (ierr != 2 * group_dim)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+  ierr = Util_TableGetIntArray
+    (sym_table, 2 * group_dim, symmetry_zone_width, "symmetry_zone_width");
+  if (ierr != 2 * group_dim)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+
+  /* Update table entries */
+  for (face = 0; face < 2 * group_dim; ++face)
+  {
+    if (which_faces[face])
+    {
+      if (symmetry_handle[face] != -1)
+      {
+	return -5;		/* The face is already taken */
+      }
+      symmetry_handle[face] = sym_handle;
+      symmetry_zone_width[face] = new_symmetry_zone_width[face];
+    }
+  }
+
+  /* Set table entries */
+  ierr = Util_TableSetIntArray
+    (sym_table, 2 * group_dim, symmetry_handle, "symmetry_handle");
+  if (ierr != 1)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+  ierr = Util_TableSetIntArray
+    (sym_table, 2 * group_dim, symmetry_zone_width, "symmetry_zone_width");
+  if (ierr != 1)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+
+  return 0;
+}
+
+
+
+/*@@
+  @routine    SymBase_SymmetryRegisterGrid
+  @author     Erik Schnetter
+  @date       2004-03-06
+  @desc
+              Register a symmetry for certain faces of the grid hierarchy
+  @enddesc
+  @var        cctkGH
+  @vtype      cGH *
+  @vdesc      The grid hierarchy
+  @vio        in
+  @endvar
+  @var        sym_handle
+  @vtype      CCTK_INT
+  @vdesc      Symmetry handle
+  @vio        in
+  @endvar
+  @var        which_faces
+  @vtype      CCTK_INT[2*group_dim]
+  @vdesc      The set of faces
+  @vio        in
+  @endvar
+  @var        symmetry_zone_width
+  @vtype      CCTK_INT[2*group_dim]
+  @vdesc      Symmetry boundary width
+  @vio        in
+  @endvar
+  @returntype CCTK_INT
+  @returndesc
+              status code
+              0 for success
+              Error codes of SymBase_SymmetryRegisterFaces
+  @endreturndesc
+@@*/
+
+CCTK_INT
+SymBase_SymmetryRegisterGrid (CCTK_POINTER const cctkGH_,
+			      CCTK_INT const sym_handle,
+			      CCTK_INT const *const which_faces,
+			      CCTK_INT const *const new_symmetry_zone_width)
+{
+  cGH const *const cctkGH = cctkGH_;
+  struct SymBase const *symdata;
+
+  if (!cctkGH)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+
+  symdata = CCTK_GHExtension (cctkGH, "SymBase");
+  if (!symdata)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+
+  return SymBase_SymmetryRegisterFaces
+    (symdata->sym_table, cctkGH->cctk_dim,
+     sym_handle, which_faces, new_symmetry_zone_width);
+}
+
+
+
+/*@@
+  @routine    SymBase_SymmetryRegisterGI
+  @author     Erik Schnetter
+  @date       2004-03-06
+  @desc
+              Register a symmetry for certain faces of grid arrays
+  @enddesc
+  @var        cctkGH
+  @vtype      cGH *
+  @vdesc      The grid hierarchy
+  @vio        in
+  @endvar
+  @var        sym_handle
+  @vtype      CCTK_INT
+  @vdesc      Symmetry handle
+  @vio        in
+  @endvar
+  @var        which_faces
+  @vtype      CCTK_INT[2*group_dim]
+  @vdesc      The set of faces
+  @vio        in
+  @endvar
+  @var        symmetry_zone_width
+  @vtype      CCTK_INT[2*group_dim]
+  @vdesc      Symmetry boundary width
+  @vio        in
+  @endvar
+  @var        group_index
+  @vtype      CCTK_INT
+  @vdesc      Grid array group
+  @vio        in
+  @endvar
+  @returntype CCTK_INT
+  @returndesc
+              status code
+              0 for success
+              -6 if group_index has an illegal value
+              -7 if the group has an illegal type
+              -8 internal error
+              Error codes of SymBase_SymmetryRegisterFaces
+  @endreturndesc
+@@*/
+
+CCTK_INT
+SymBase_SymmetryRegisterGI (CCTK_POINTER const cctkGH_,
+			    CCTK_INT const sym_handle,
+			    CCTK_INT const *const which_faces,
+			    CCTK_INT const *const new_symmetry_zone_width,
+			    CCTK_INT const group_index)
+{
+  cGH const *const cctkGH = cctkGH_;
+  struct SymBase const *symdata;
+
+  if (!cctkGH)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+
+  symdata = CCTK_GHExtension (cctkGH, "SymBase");
+  if (!symdata)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+
+  if (group_index < 0 || group_index >= CCTK_NumGroups ())
+  {
+    return -6;			/* illegal argument */
+  }
+
+  switch (CCTK_GroupTypeI (group_index))
+  {
+  case CCTK_GF:
+    return -7;			/* illegal group type */
+  case CCTK_SCALAR:
+  case CCTK_ARRAY:
+    return SymBase_SymmetryRegisterFaces
+      (symdata->array_sym_tables[group_index], CCTK_GroupDimI (group_index),
+       sym_handle, which_faces, new_symmetry_zone_width);
+  default:
+    CCTK_WARN (0, "internal error");
+  }
+
+  return -8;			/* internal error */
+}
+
+
+
+/*@@
+  @routine    SymBase_SymmetryRegisterGI
+  @author     Erik Schnetter
+  @date       2004-03-06
+  @desc
+              Register a symmetry for certain faces of grid arrays
+  @enddesc
+  @var        cctkGH
+  @vtype      cGH *
+  @vdesc      The grid hierarchy
+  @vio        in
+  @endvar
+  @var        sym_handle
+  @vtype      CCTK_INT
+  @vdesc      Symmetry handle
+  @vio        in
+  @endvar
+  @var        which_faces
+  @vtype      CCTK_INT[2*group_dim]
+  @vdesc      The set of faces
+  @vio        in
+  @endvar
+  @var        symmetry_zone_width
+  @vtype      CCTK_INT[2*group_dim]
+  @vdesc      Symmetry boundary width
+  @vio        in
+  @endvar
+  @var        group_name
+  @vtype      CCTK_STRING
+  @vdesc      Grid array group
+  @vio        in
+  @endvar
+  @returntype CCTK_INT
+  @returndesc
+              status code
+              0 for success
+              Error codes of CCTK_GroupIndex
+              Error codes of SymBase_SymmetryRegisterGI
+  @endreturndesc
+@@*/
+
+CCTK_INT
+SymBase_SymmetryRegisterGN (CCTK_POINTER const cctkGH_,
+			    CCTK_INT const sym_handle,
+			    CCTK_INT const *const which_faces,
+			    CCTK_INT const *const new_symmetry_zone_width,
+			    CCTK_STRING const group_name)
+{
+  int group_index;
+
+  group_index = CCTK_GroupIndex (group_name);
+  if (group_index < 0)
+  {
+    return group_index;		/* illegal argument */
+  }
+
+  return SymBase_SymmetryRegisterGI
+    (cctkGH_, sym_handle, which_faces, new_symmetry_zone_width, group_index);
+}
diff --git a/src/Handles.c b/src/Handles.c
new file mode 100644
index 0000000..22b0a1a
--- /dev/null
+++ b/src/Handles.c
@@ -0,0 +1,164 @@
+/*@@
+  @file      $RCSfile$
+  @author    $Author$
+  @date      $Date$
+  @desc
+             Register a symmetry, and query the symmetry name/handle mapping
+  @version   $Header$
+  @enddesc
+@@*/
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "cctk.h"
+
+#include "SymBase.h"
+
+
+
+/* the rcs ID and its dummy function to use it */
+static const char *const rcsid = "$Header$";
+CCTK_FILEVERSION (CactusBase_SymBase_Handles_c);
+
+
+
+/* Number of registered symmetries */
+size_t SymBase_num_symmetries;
+
+/* The names of these symmetries */
+const char **SymBase_symmetry_names;
+
+
+
+/*@@
+  @routine    SymBase_SymmetryRegister
+  @author     Erik Schnetter
+  @date       2004-03-06
+  @desc
+              Register a symmetry
+  @enddesc
+  @var        sym_name
+  @vtype      CCTK_STRING
+  @vdesc      Name of the symmetry
+  @vio        in
+  @endvar
+  @returntype CCTK_INT
+  @returndesc
+              >=0 symmetry handle
+              -1 if sym_name has an illegal value
+              -2 if a symmetry with the same name has already been registered
+  @endreturndesc
+@@*/
+
+CCTK_INT
+SymBase_SymmetryRegister (CCTK_STRING const sym_name)
+{
+  int n;
+
+  if (!sym_name)
+  {
+    return -1;			/* illegal argument */
+  }
+
+  for (n = 0; n < SymBase_num_symmetries; ++n)
+  {
+    if (strcmp (sym_name, SymBase_symmetry_names[n]) == 0)
+    {
+      return -2;		/* symmetry exists already */
+    }
+  }
+
+  SymBase_symmetry_names
+    = realloc (SymBase_symmetry_names,
+	       (SymBase_num_symmetries + 1) * sizeof *SymBase_symmetry_names);
+  if (!SymBase_symmetry_names)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+
+  SymBase_symmetry_names[SymBase_num_symmetries] = strdup (sym_name);
+  if (!SymBase_symmetry_names[SymBase_num_symmetries])
+  {
+    CCTK_WARN (0, "internal error");
+  }
+
+  ++SymBase_num_symmetries;
+
+  return SymBase_num_symmetries - 1;
+}
+
+
+
+/*@@
+  @routine    SymBase_SymmetryHandleOfName
+  @author     Erik Schnetter
+  @date       2004-03-06
+  @desc
+              Map a symmetry name to a symmetry handle
+  @enddesc
+  @var        sym_name
+  @vtype      CCTK_STRING
+  @vdesc      Name of the symmetry
+  @vio        in
+  @endvar
+  @returntype CCTK_INT
+  @returndesc
+              >=0 symmetry handle
+              -1 if sym_name has an illegal value
+              -2 if no symmetry with that name has been registered
+  @endreturndesc
+@@*/
+
+CCTK_INT
+SymBase_SymmetryHandleOfName (CCTK_STRING const sym_name)
+{
+  int n;
+
+  if (!sym_name)
+  {
+    return -1;			/* illegal argument */
+  }
+
+  for (n = 0; n < SymBase_num_symmetries; ++n)
+  {
+    if (strcmp (sym_name, SymBase_symmetry_names[n]) == 0)
+    {
+      return n;			/* found */
+    }
+  }
+
+  return -2;			/* not found */
+}
+
+
+
+/*@@
+  @routine    SymBase_SymmetryNameOfHandle
+  @author     Erik Schnetter
+  @date       2004-03-06
+  @desc
+              Map a symmetry handle to a symmetry name
+  @enddesc
+  @var        sym_handle
+  @vtype      CCTK_INT
+  @vdesc      Symmetry name
+  @vio        in
+  @endvar
+  @returntype CCTK_POINTER_TO_CONST
+  @returndesc
+              char const * containing the symmetry name
+              NULL if no symmetry with that handle has been registered
+  @endreturndesc
+@@*/
+
+CCTK_POINTER_TO_CONST
+SymBase_SymmetryNameOfHandle (CCTK_INT const sym_handle)
+{
+  if (sym_handle < 0 || sym_handle >= SymBase_num_symmetries)
+  {
+    return NULL;		/* illegal argument */
+  }
+
+  return SymBase_symmetry_names[sym_handle];
+}
diff --git a/src/Startup.c b/src/Startup.c
new file mode 100644
index 0000000..b09c7e3
--- /dev/null
+++ b/src/Startup.c
@@ -0,0 +1,198 @@
+/*@@
+  @file      $RCSfile$
+  @author    $Author$
+  @date      $Date$
+  @desc
+             Thorn startup
+  @version   $Header$
+  @enddesc
+@@*/
+
+#include <stdlib.h>
+
+#include "cctk.h"
+
+#include "util_Table.h"
+
+#include "SymBase.h"
+
+
+
+/* the rcs ID and its dummy function to use it */
+static const char *const rcsid = "$Header$";
+CCTK_FILEVERSION (CactusBase_SymBase_Startup_c);
+
+
+
+/*@@
+  @routine    SymBase_Startup
+  @author     Erik Schnetter
+  @date       2004-03-06
+  @desc
+              Register a GH extension and initialise the global variables
+  @enddesc
+  @returntype int
+  @returndesc
+              status code
+              0 for success
+  @endreturndesc
+@@*/
+
+int
+SymBase_Startup (void)
+{
+  int handle;
+  int ierr;
+
+  handle = CCTK_RegisterGHExtension ("SymBase");
+  if (handle < 0)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+
+  ierr = CCTK_RegisterGHExtensionSetupGH (handle, SymBase_Setup);
+  if (ierr != 1)
+  {				/* strange error code convention */
+    CCTK_WARN (0, "internal error");
+  }
+
+  SymBase_num_symmetries = 0;
+  SymBase_symmetry_names = NULL;
+
+  return 0;			/* no error */
+}
+
+
+
+/*@@
+  @routine    SymBase_Setup
+  @author     Erik Schnetter
+  @date       2004-03-06
+  @desc
+              Initialise the GH extension
+  @enddesc
+  @var        config
+  @vtype      tFleshConfig *
+  @vdesc      Internal flesh information, unused
+  @vio        in
+  @endvar
+  @var        convlev
+  @vtype      int
+  @vdesc      Convergence level, unused
+  @vio        in
+  @endvar
+  @var        cctkGH
+  @vtype      cGH *
+  @vdesc      Grid hierarchy
+  @vio        in
+  @endvar
+@@*/
+
+void *
+SymBase_Setup (tFleshConfig * const config,
+	       int const convlev, cGH * const cctkGH)
+{
+  struct SymBase *symdata;
+  CCTK_INT symmetry_handle[100];
+  CCTK_INT symmetry_zone_width[100];
+  int group;
+  int face;
+  int ierr;
+
+  /* Create GH extension */
+  symdata = malloc (sizeof *symdata);
+  if (!symdata)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+
+  /* Initialise handle and zone width arrays */
+  for (face = 0; face < 100; ++face)
+  {
+    symmetry_handle[face] = -1;
+    symmetry_zone_width[face] = 0;
+  }
+
+  /* Create grid symmetry table */
+  symdata->sym_table = Util_TableCreate (UTIL_TABLE_FLAGS_CASE_INSENSITIVE);
+  if (symdata->sym_table < 0)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+
+  if (2 * cctkGH->cctk_dim > 100)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+  ierr = Util_TableSetIntArray
+    (symdata->sym_table,
+     2 * cctkGH->cctk_dim, symmetry_handle, "symmetry_handle");
+  if (ierr)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+  ierr = Util_TableSetIntArray
+    (symdata->sym_table,
+     2 * cctkGH->cctk_dim, symmetry_zone_width, "symmetry_zone_width");
+  if (ierr)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+
+  /* Create grid array symmetry tables */
+  symdata->array_sym_tables
+    = malloc (CCTK_NumGroups () * sizeof *symdata->array_sym_tables);
+  if (!symdata->array_sym_tables)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+
+  for (group = 0; group < CCTK_NumGroups (); ++group)
+  {
+    switch (CCTK_GroupTypeI (group))
+    {
+    case CCTK_GF:
+
+      /* No table */
+      symdata->array_sym_tables[group] = -1;
+      break;
+
+    case CCTK_SCALAR:
+    case CCTK_ARRAY:
+
+      /* Create array symmetry table */
+      symdata->array_sym_tables[group]
+	= Util_TableCreate (UTIL_TABLE_FLAGS_CASE_INSENSITIVE);
+      if (symdata->array_sym_tables[group] < 0)
+      {
+	CCTK_WARN (0, "internal error");
+      }
+
+      if (2 * CCTK_GroupDimI (group) > 100)
+      {
+	CCTK_WARN (0, "internal error");
+      }
+      ierr = Util_TableSetIntArray
+	(symdata->array_sym_tables[group],
+	 2 * CCTK_GroupDimI (group), symmetry_handle, "symmetry_handle");
+      if (ierr)
+      {
+	CCTK_WARN (0, "internal error");
+      }
+      ierr = Util_TableSetIntArray
+	(symdata->array_sym_tables[group],
+	 2 * CCTK_GroupDimI (group), symmetry_zone_width,
+         "symmetry_zone_width");
+      if (ierr)
+      {
+	CCTK_WARN (0, "internal error");
+      }
+      break;
+
+    default:
+      CCTK_WARN (0, "internal error");
+    }
+  }
+
+  return symdata;
+}
diff --git a/src/SymBase.h b/src/SymBase.h
new file mode 100644
index 0000000..d343fee
--- /dev/null
+++ b/src/SymBase.h
@@ -0,0 +1,88 @@
+/*@@
+  @file      $RCSfile$
+  @author    $Author$
+  @date      $Date$
+  @desc
+             Declarations for thorn SymBase
+  @version   $Header$
+  @enddesc
+@@*/
+
+#ifndef SYMBASE_H
+#define SYMBASE_H
+
+
+
+#include "cctk.h"
+
+
+
+/* SymBase's GH extension */
+struct SymBase
+{
+  /* Grid symmetry table handle */
+  int sym_table;
+
+  /* Grid array symmetry table handles */
+  int *array_sym_tables;
+};
+
+
+
+/* Number of registered symmetries */
+extern size_t SymBase_num_symmetries;
+
+/* The names of these symmetries */
+extern const char **SymBase_symmetry_names;
+
+
+
+/* Startup.c */
+int SymBase_Startup (void);
+void *SymBase_Setup (tFleshConfig * const config,
+		     int const convlev, cGH * const cctkGH);
+
+/* Handles.c */
+CCTK_INT SymBase_SymmetryRegister (CCTK_STRING const sym_name);
+CCTK_INT SymBase_SymmetryHandleOfName (CCTK_STRING const sym_name);
+CCTK_POINTER_TO_CONST SymBase_SymmetryNameOfHandle (CCTK_INT const
+						    sym_handle);
+
+/* Faces.c */
+CCTK_INT
+SymBase_SymmetryRegisterFaces (CCTK_INT const sym_table,
+			       CCTK_INT const group_dim,
+			       CCTK_INT const sym_handle,
+			       CCTK_INT const *const which_faces,
+			       CCTK_INT const *const new_symmetry_zone_width);
+CCTK_INT
+SymBase_SymmetryRegisterGrid (CCTK_POINTER const cctkGH_,
+			      CCTK_INT const sym_handle,
+			      CCTK_INT const *const which_faces,
+			      CCTK_INT const *const new_symmetry_zone_width);
+CCTK_INT
+SymBase_SymmetryRegisterGI (CCTK_POINTER const cctkGH_,
+			    CCTK_INT const sym_handle,
+			    CCTK_INT const *const which_faces,
+			    CCTK_INT const *const new_symmetry_zone_width,
+			    CCTK_INT const group_index);
+CCTK_INT
+SymBase_SymmetryRegisterGN (CCTK_POINTER const cctkGH_,
+			    CCTK_INT const sym_handle,
+			    CCTK_INT const *const which_faces,
+			    CCTK_INT const *const new_symmetry_zone_width,
+			    CCTK_STRING const group_name);
+
+/* Table.c */
+CCTK_INT
+SymBase_SymmetryTableHandleForGrid (CCTK_POINTER_TO_CONST const cctkGH_);
+CCTK_INT
+SymBase_SymmetryTableHandleForGI (CCTK_POINTER_TO_CONST const cctkGH_,
+				  CCTK_INT const group_index);
+CCTK_INT
+SymBase_SymmetryTableHandleForGN (CCTK_POINTER_TO_CONST const cctkGH_,
+				  CCTK_STRING const group_name);
+
+
+
+#endif /* ! defined SYMBASE_H */
diff --git a/src/Table.c b/src/Table.c
new file mode 100644
index 0000000..3d88f07
--- /dev/null
+++ b/src/Table.c
@@ -0,0 +1,165 @@
+/*@@
+  @file      $RCSfile$
+  @author    $Author$
+  @date      $Date$
+  @desc
+             Get the symmetry table handle for a grid or grid array
+  @version   $Header$
+  @enddesc
+@@*/
+
+#include "cctk.h"
+
+#include "SymBase.h"
+
+
+
+/* the rcs ID and its dummy function to use it */
+static const char *const rcsid = "$Header$";
+CCTK_FILEVERSION (CactusBase_SymBase_Table_c);
+
+
+
+/*@@
+  @routine    SymBase_SymmetryTableHandleForGrid
+  @author     Erik Schnetter
+  @date       2004-03-06
+  @desc
+              Return the symmetry table handle for the grid hierarchy
+  @enddesc
+  @var        cctkGH
+  @vtype      CCTK_POINTER_TO_CONST
+  @vdesc      Grid hierarchy
+  @vio        in
+  @endvar
+  @returntype CCTK_INT
+  @returndesc
+              >=0 symmetry table handle
+  @endreturndesc
+@@*/
+
+CCTK_INT
+SymBase_SymmetryTableHandleForGrid (CCTK_POINTER_TO_CONST const cctkGH_)
+{
+  cGH const *const cctkGH = cctkGH_;
+  struct SymBase const *symdata;
+
+  if (!cctkGH)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+
+  symdata = CCTK_GHExtension (cctkGH, "SymBase");
+  if (!symdata)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+
+  return symdata->sym_table;
+}
+
+
+
+/*@@
+  @routine    SymBase_SymmetryTableHandleForGI
+  @author     Erik Schnetter
+  @date       2004-03-06
+  @desc
+              Return the symmetry table handle for a grid array
+  @enddesc
+  @var        cctkGH
+  @vtype      CCTK_POINTER_TO_CONST
+  @vdesc      Grid hierarchy
+  @vio        in
+  @endvar
+  @var        group_index
+  @vtype      CCTK_INT
+  @vdesc      Group
+  @vio        in
+  @endvar
+  @returntype CCTK_INT
+  @returndesc
+              >=0 symmetry table handle
+              -6 if group_index has an illegal value
+              -7 if the group type has an illegal value
+              -8 if there was an internal error
+  @endreturndesc
+@@*/
+
+CCTK_INT
+SymBase_SymmetryTableHandleForGI (CCTK_POINTER_TO_CONST const cctkGH_,
+				  CCTK_INT const group_index)
+{
+  cGH const *const cctkGH = cctkGH_;
+  struct SymBase const *symdata;
+
+  if (!cctkGH)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+
+  symdata = CCTK_GHExtension (cctkGH, "SymBase");
+  if (!symdata)
+  {
+    CCTK_WARN (0, "internal error");
+  }
+
+  if (group_index < 0 || group_index >= CCTK_NumGroups ())
+  {
+    return -6;			/* illegal argument */
+  }
+
+  switch (CCTK_GroupTypeI (group_index))
+  {
+  case CCTK_GF:
+    return -7;			/* illegal group type */
+  case CCTK_SCALAR:
+  case CCTK_ARRAY:
+    return symdata->array_sym_tables[group_index];
+  default:
+    CCTK_WARN (0, "internal error");
+  }
+
+  return -8;			/* internal error */
+}
+
+
+
+/*@@
+  @routine    SymBase_SymmetryTableHandleForGN
+  @author     Erik Schnetter
+  @date       2004-03-06
+  @desc
+              Return the symmetry table handle for a grid array
+  @enddesc
+  @var        cctkGH
+  @vtype      CCTK_POINTER_TO_CONST
+  @vdesc      Grid hierarchy
+  @vio        in
+  @endvar
+  @var        group_name
+  @vtype      CCTK_STRING
+  @vdesc      Group
+  @vio        in
+  @endvar
+  @returntype CCTK_INT
+  @returndesc
+              >=0 symmetry table handle
+              Error codes of CCTK_GroupIndex
+              Error codes of SymBase_SymmetryTableHandleForGI
+  @endreturndesc
+@@*/
+CCTK_INT
+SymBase_SymmetryTableHandleForGN (CCTK_POINTER_TO_CONST const cctkGH_,
+				  CCTK_STRING const group_name)
+{
+  int group_index;
+
+  group_index = CCTK_GroupIndex (group_name);
+  if (group_index < 0)
+  {
+    return group_index;		/* illegal argument */
+  }
+
+  return SymBase_SymmetryTableHandleForGI (cctkGH_, group_index);
+}
diff --git a/src/make.code.defn b/src/make.code.defn
new file mode 100644
index 0000000..84b3c24
--- /dev/null
+++ b/src/make.code.defn
@@ -0,0 +1,8 @@
+# Main make.code.defn file for thorn SymBase
+# $Header$
+
+# Source files in this directory
+SRCS = Faces.c Handles.c Startup.c Table.c
+
+# Subdirectories containing source files
+SUBDIRS =