[svn-r1277] Added additional checks into the dataspace code to determine if the hyperslabs

being written out are contiguous in memory and on disk and write/read them as
one I/O operation (if the datatypes don't require conversion).  This should be
a good performance boost for those situations.  It's especially needed on the
ASCI Red (TFlops) machine.  - QAK (from Albert's account on modi4 :-)

1 files changed, 52 insertions, 0 deletions

diff --git a/src/H5Sselect.c b/src/H5Sselect.c
index e9c03c2..669cb94 100644
--- a/src/H5Sselect.c
+++ b/src/H5Sselect.c
@@ -1631,3 +1631,55 @@ H5Sget_select_bounds(hid_t spaceid, hsize_t *start, hsize_t *end)
 
     FUNC_LEAVE (ret_value);
 }   /* H5Sget_select_bounds() */
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5S_select_contiguous
+ PURPOSE
+    Check if the selection is contiguous within the dataspace extent.
+ USAGE
+    htri_t H5S_select_contiguous(space)
+        H5S_t *space;           IN: Dataspace pointer to check
+ RETURNS
+    TRUE/FALSE/FAIL
+ DESCRIPTION
+    Checks to see if the current selection in the dataspace is contiguous.
+    This is primarily used for reading the entire selection in one swoop.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+htri_t
+H5S_select_contiguous(const H5S_t *space)
+{
+    htri_t ret_value=FAIL;  /* return value */
+
+    FUNC_ENTER (H5S_select_contiguous, FAIL);
+
+    assert(space);
+
+    switch(space->select.type) {
+        case H5S_SEL_POINTS:         /* Sequence of points selected */
+            ret_value=H5S_point_select_contiguous(space);
+            break;
+
+        case H5S_SEL_HYPERSLABS:     /* Hyperslab selection defined */
+            ret_value=H5S_hyper_select_contiguous(space);
+            break;
+
+        case H5S_SEL_ALL:            /* Entire extent selected */
+            ret_value=TRUE;
+            break;
+
+        case H5S_SEL_NONE:           /* Nothing selected */
+            ret_value=FALSE;
+            break;
+
+        case H5S_SEL_ERROR:
+        case H5S_SEL_N:
+            break;
+    }
+
+    FUNC_LEAVE (ret_value);
+}   /* H5S_select_contiguous() */