Allow hyperslab requests with a zero-extent. It does nothing but return 0

for the hyperslab size.

Closes PR CactusPUGH/414.


git-svn-id: http://svn.cactuscode.org/arrangements/CactusPUGH/PUGHSlab/trunk@66 10716dce-81a3-4424-a2c8-48026a0d3035

1 files changed, 23 insertions, 5 deletions

diff --git a/src/Hyperslab.c b/src/Hyperslab.c
index 3a8603a..9c482e6 100644
--- a/src/Hyperslab.c
+++ b/src/Hyperslab.c
@@ -297,6 +297,28 @@ int Hyperslab_GetLocalHyperslab (const cGH *GH,
   /* set the default return code */
   retval = 0;
 
+  /* check for zero-size hyperslab */
+  totals = 1;
+  for (vdim = 0; vdim < hdim; vdim++)
+  {
+    totals *= extents[vdim];
+  }
+  if (totals == 0)
+  {
+    /* initialize output parameters to all zeros */
+    for (vdim = 0; vdim < hdim; vdim++)
+    {
+      hsize[vdim] = hsize_global[vdim] = 0;
+      if (hoffset_global)
+      {
+        hoffset_global[vdim] = 0;
+      }
+    }
+    *hdata = NULL;
+
+    return (retval);
+  }
+
   /* get the info on the variable to extract a hyperslab from */
   CCTK_GroupData (CCTK_GroupIndexFromVarI (vindex), &vinfo);
 
@@ -1088,13 +1110,9 @@ static const char *checkParameters (const cGH *GH, int vindex, int vtimelvl,
     return ("NULL pointer(s) passed as parameters");
   }
 
-  /* check the extent and downsample parameters */
+  /* check the downsample parameter */
   for (dim = 0; dim < hdim; dim++)
   {
-    if (extents[dim] == 0)
-    {
-      return ("Invalid hyperslab extent parameters");
-    }
     if (downsample_[dim] <= 0)
     {
       return ( "Invalid hyperslab downsample parameters");