[svn-r4005] Purpose:

    Bug fix/code improvement.
Description:
    'all' selections were (ab)using the array reading code and required that
    the internal data transfer buffer size be big enough to hold the an entire
    slab of the data, which was confusing and limiting for users.
Solution:
    Changed 'all' selections to use sequence reading code instead of array
    reading code.
Platforms tested:
    FreeBSD 4.3 (hawkwind)

5 files changed, 80 insertions, 250 deletions

diff --git a/src/H5D.c b/src/H5D.c
index dd1eaed..07da5b7 100644
--- a/src/H5D.c
+++ b/src/H5D.c
@@ -16,7 +16,7 @@
 #include "H5Iprivate.h"		/* IDs			  		*/
 #include "H5Dprivate.h"		/* Dataset functions			*/
 #include "H5Eprivate.h"		/* Error handling		  	*/
-#include "H5FLprivate.h"	/* Free Lists                           */
+#include "H5FLprivate.h"	/*Free Lists	  */
 #include "H5Gprivate.h"		/* Group headers		  	*/
 #include "H5HLprivate.h"	/* Name heap				*/
 #include "H5MMprivate.h"	/* Memory management			*/
@@ -35,7 +35,7 @@
 
 #ifdef H5_HAVE_PARALLEL
 /* Remove this if H5R_DATASET_REGION is no longer used in this file */
-#include "H5Rpublic.h"
+#   include "H5Rpublic.h"
 #endif
 
 #define PABLO_MASK	H5D_mask
@@ -1589,7 +1589,6 @@ H5D_read(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
     size_t		dst_type_size;	    /*size of destination type*/
     hsize_t		target_size;		/*desired buffer size	*/
     hsize_t		request_nelmts;		/*requested strip mine	*/
-    size_t		min_elem_out=1;     /*Minimum # of elements to output*/
     H5T_bkg_t	need_bkg;		    /*type of background buf*/
     H5S_t		*free_this_space=NULL;  /*data space to free	*/
     hbool_t     must_convert;       /*have to xfer the slow way*/
@@ -1775,15 +1774,15 @@ printf("%s: check 1.2, \n",FUNC);
     /*
      * This is the general case.  Figure out the strip mine size.
      */
-    if ((sconv->f->init)(&(dataset->layout), file_space, &file_iter, &min_elem_out)<0) {
+    if ((sconv->f->init)(&(dataset->layout), file_space, &file_iter)<0) {
         HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL,
 		     "unable to initialize file selection information");
     } 
-    if ((sconv->m->init)(&(dataset->layout), mem_space, &mem_iter, &min_elem_out)<0) {
+    if ((sconv->m->init)(&(dataset->layout), mem_space, &mem_iter)<0) {
         HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL,
 		     "unable to initialize memory selection information");
     } 
-    if ((sconv->m->init)(&(dataset->layout), mem_space, &bkg_iter, &min_elem_out)<0) {
+    if ((sconv->m->init)(&(dataset->layout), mem_space, &bkg_iter)<0) {
         HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL,
 		     "unable to initialize background selection information");
     } 
@@ -1792,12 +1791,10 @@ printf("%s: check 1.2, \n",FUNC);
     dst_type_size = H5T_get_size(mem_type);
     target_size = xfer_parms->buf_size;
 #ifdef QAK
-printf("%s: check 2.0, src_type_size=%d, dst_type_size=%d, target_size=%d, min_elem_out=%d\n",FUNC,(int)src_type_size,(int)dst_type_size,(int)target_size,(int)min_elem_out);
+printf("%s: check 2.0, src_type_size=%d, dst_type_size=%d, target_size=%d\n",FUNC,(int)src_type_size,(int)dst_type_size,(int)target_size);
 #endif /* QAK */
     request_nelmts = target_size / MAX(src_type_size, dst_type_size);
 
-    /* Adjust to the min. # of elements to output */
-    request_nelmts = (request_nelmts/min_elem_out)*min_elem_out;
 #ifdef QAK
     printf("%s: check 3.0, request_nelmts=%d\n",FUNC,(int)request_nelmts);
 #endif
@@ -2040,7 +2037,6 @@ H5D_write(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
     size_t		dst_type_size;	    /*size of destination type*/
     hsize_t		target_size;		/*desired buffer size	*/
     hsize_t		request_nelmts;		/*requested strip mine	*/
-    size_t		min_elem_out=1;     /*Minimum # of elements to output*/
     H5T_bkg_t	need_bkg;		    /*type of background buf*/
     H5S_t		*free_this_space=NULL;	/*data space to free	*/
     hbool_t     must_convert;       /*have to xfer the slow way*/
@@ -2160,7 +2156,7 @@ H5D_write(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
 	}
     }
 #ifdef QAK
-    printf("%s: after H5T_find, tpath=%p, tpath->name=%s\n",FUNC,tpath,tpath->name);
+    printf("%s: check 0.6, after H5T_find, tpath=%p, tpath->name=%s\n",FUNC,tpath,tpath->name);
 #endif /* QAK */
     if (NULL==(sconv=H5S_find(mem_space, file_space))) {
 	HGOTO_ERROR (H5E_DATASET, H5E_UNSUPPORTED, FAIL,
@@ -2188,6 +2184,10 @@ H5D_write(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
      * If there is no type conversion then try writing directly from
      * application buffer to file.
      */
+#ifdef QAK
+    printf("%s: check 0.7, H5T_IS_NOOP(path)=%d, sconv->write=%p\n", FUNC,
+	   (int)H5T_IS_NOOP(tpath), sconv->write);
+#endif /* QAK */
     if (H5T_IS_NOOP(tpath) && sconv->write) {
 #ifdef H5S_DEBUG
 	H5_timer_begin(&timer);
@@ -2251,15 +2251,15 @@ H5D_write(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
     /*
      * This is the general case.  Figure out the strip mine size.
      */
-    if ((sconv->f->init)(&(dataset->layout), file_space, &file_iter, &min_elem_out)<0) {
+    if ((sconv->f->init)(&(dataset->layout), file_space, &file_iter)<0) {
         HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL,
 		     "unable to initialize file selection information");
     } 
-    if ((sconv->m->init)(&(dataset->layout), mem_space, &mem_iter, &min_elem_out)<0) {
+    if ((sconv->m->init)(&(dataset->layout), mem_space, &mem_iter)<0) {
         HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL,
 		     "unable to initialize memory selection information");
     } 
-    if ((sconv->f->init)(&(dataset->layout), file_space, &bkg_iter, &min_elem_out)<0) {
+    if ((sconv->f->init)(&(dataset->layout), file_space, &bkg_iter)<0) {
         HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL,
 		     "unable to initialize memory selection information");
     }
@@ -2267,18 +2267,18 @@ H5D_write(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
     src_type_size = H5T_get_size(mem_type);
     dst_type_size = H5T_get_size(dataset->type);
     target_size = xfer_parms->buf_size;
+#ifdef QAK
+printf("%s: check 2.0, src_type_size=%d, dst_type_size=%d, target_size=%d\n",FUNC,(int)src_type_size,(int)dst_type_size,(int)target_size);
+#endif /* QAK */
     request_nelmts = target_size / MAX (src_type_size, dst_type_size);
 
-    /* Adjust to the min. # of elements to output */
-    request_nelmts = (request_nelmts/min_elem_out)*min_elem_out;
+#ifdef QAK
+    printf("%s: check 3.0, request_nelmts=%d, tpath->cdata.need_bkg=%d\n",FUNC,(int)request_nelmts,(int)tpath->cdata.need_bkg);
+#endif
     if (request_nelmts<=0) {
         HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL,
 		     "temporary buffer max size is too small");
     }
-    
-#ifdef QAK
-    printf("%s: check 3.0, request_nelmts=%d, tpath->cdata.need_bkg=%d\n",FUNC,(int)request_nelmts,(int)tpath->cdata.need_bkg);
-#endif
 
     /*
      * Get a temporary buffer for type conversion unless the app has already
diff --git a/src/H5Sall.c b/src/H5Sall.c
index 0d585a3..80abaea 100644
--- a/src/H5Sall.c
+++ b/src/H5Sall.c
@@ -1,6 +1,6 @@
 /*
- * Copyright (C) 1998 NCSA
- *                    All rights reserved.
+ * Copyright (C) 1998-2001 NCSA
+ *                         All rights reserved.
  *
  * Programmer:  Quincey Koziol <koziol@ncsa.uiuc.edu>
  *              Tuesday, June 16, 1998
@@ -23,7 +23,7 @@
 static intn             interface_initialize_g = 0;
 
 static herr_t H5S_all_init (const struct H5O_layout_t *layout,
-			    const H5S_t *space, H5S_sel_iter_t *iter, size_t *min_elem_out);
+			    const H5S_t *space, H5S_sel_iter_t *iter);
 static hsize_t H5S_all_favail (const H5S_t *space, const H5S_sel_iter_t *iter,
 			      hsize_t max);
 static hsize_t H5S_all_fgath (H5F_t *f, const struct H5O_layout_t *layout,
@@ -65,6 +65,7 @@ const H5S_mconv_t	H5S_ALL_MCONV[1] = {{
     H5S_all_mscat, 				/*scatter		*/
 }};
 
+
 /*-------------------------------------------------------------------------
  * Function:	H5S_all_init
  *
@@ -81,13 +82,8 @@ const H5S_mconv_t	H5S_ALL_MCONV[1] = {{
  */
 static herr_t
 H5S_all_init (const struct H5O_layout_t UNUSED *layout,
-	       const H5S_t *space, H5S_sel_iter_t *sel_iter, size_t *min_elem_out)
+	       const H5S_t *space, H5S_sel_iter_t *sel_iter)
 {
-    hsize_t	hsize[H5O_LAYOUT_NDIMS];	/*size of hyperslab	*/
-    intn	space_ndims;			/*dimensionality of space*/
-    hsize_t	acc;				    /*accumulator		*/
-    intn	i;				/*counters		*/
-
     FUNC_ENTER (H5S_all_init, FAIL);
 
     /* Check args */
@@ -101,21 +97,9 @@ H5S_all_init (const struct H5O_layout_t UNUSED *layout,
     /* Start at the upper left location */
     sel_iter->all.offset=0;
 
-    /* Get the dimensions of the space, to set the min. # of elements */
-    if ((space_ndims=H5S_get_simple_extent_dims (space, hsize, NULL))<0) {
-        HRETURN_ERROR (H5E_DATASPACE, H5E_CANTINIT, FAIL,
-		       "unable to retrieve hyperslab parameters");
-    }
-
-    /* Adjust the slowest varying dimension to account for strip mining */
-    for (i=1, acc=1; i<space_ndims; i++)
-        acc *= hsize[i];
-    
-    /* Set the minimum # of elements to output */
-    *min_elem_out=acc;
-    
     FUNC_LEAVE (SUCCEED);
 }
+
 
 /*-------------------------------------------------------------------------
  * Function:	H5S_all_favail
@@ -134,36 +118,20 @@ H5S_all_init (const struct H5O_layout_t UNUSED *layout,
  *-------------------------------------------------------------------------
  */
 static hsize_t
-H5S_all_favail (const H5S_t *space, const H5S_sel_iter_t *sel_iter, hsize_t max)
+H5S_all_favail (const H5S_t UNUSED *space, const H5S_sel_iter_t *sel_iter, hsize_t max)
 {
-    hsize_t	nelmts;
-    int		m_ndims;	/* file dimensionality	*/
-    hsize_t	size[H5O_LAYOUT_NDIMS];	/*size of selected hyperslab	*/
-    hsize_t	acc;
-    int		i;
-
     FUNC_ENTER (H5S_all_favail, 0);
 
     /* Check args */
     assert (space && H5S_SEL_ALL==space->select.type);
     assert (sel_iter);
 
-    /*
-     * The stripmine size is such that only the slowest varying dimension can
-     * be split up.  We choose the largest possible strip mine size which is
-     * not larger than the desired size.
-     */
-    m_ndims = H5S_get_simple_extent_dims (space, size, NULL);
-    for (i=m_ndims-1, acc=1; i>0; --i)
-        acc *= size[i];
-    nelmts = (max/acc) * acc;
-    if (nelmts<=0) {
-        HRETURN_ERROR (H5E_IO, H5E_UNSUPPORTED, 0,
-		       "strip mine buffer is too small");
-    }
-
-    FUNC_LEAVE (MIN(sel_iter->all.elmt_left,nelmts));
+#ifdef QAK
+    printf("%s: sel_iter->all.elmt_left=%u, max=%u\n",FUNC,(unsigned)sel_iter->all.elmt_left,(unsigned)max);
+#endif /* QAK */
+    FUNC_LEAVE (MIN(sel_iter->all.elmt_left,max));
 }   /* H5S_all_favail() */
+
 
 /*-------------------------------------------------------------------------
  * Function:	H5S_all_fgath
@@ -197,15 +165,10 @@ H5S_all_fgath (H5F_t *f, const struct H5O_layout_t *layout,
 	       const struct H5O_fill_t *fill, const struct H5O_efl_t *efl,
 	       size_t elmt_size, const H5S_t *file_space,
 	       H5S_sel_iter_t *file_iter, hsize_t nelmts, hid_t dxpl_id,
-	       void *_buf/*out*/)
+	       void *buf/*out*/)
 {
-    hssize_t	file_offset[H5O_LAYOUT_NDIMS];	/*offset of slab in file*/
-    hsize_t	hsize[H5O_LAYOUT_NDIMS];	/*size of hyperslab	*/
-    hssize_t	zero[H5O_LAYOUT_NDIMS];		/*zero			*/
-    uint8_t	*buf=(uint8_t*)_buf;		/*for pointer arithmetic*/
-    hsize_t	acc;				/*accumulator		*/
-    intn	space_ndims;			/*dimensionality of space*/
-    intn	i;				/*counters		*/
+    hsize_t     actual_bytes;       /* The actual number of bytes to read */
+    hsize_t	buf_off;            /* Dataset offset for copying memory */
 
     FUNC_ENTER (H5S_all_fgath, 0);
 
@@ -218,40 +181,15 @@ H5S_all_fgath (H5F_t *f, const struct H5O_layout_t *layout,
     assert (nelmts>0);
     assert (buf);
 
-    /*
-     * Get hyperslab information to determine what elements are being
-     * selected (there might eventually be other selection methods too).
-     * We only support hyperslabs with unit sample because there's no way to
-     * currently pass sample information into H5F_arr_read() much less
-     * H5F_istore_read().
-     */
-    if ((space_ndims=H5S_get_simple_extent_dims (file_space, hsize, NULL))<0) {
-        HRETURN_ERROR (H5E_DATASPACE, H5E_CANTINIT, 0,
-		       "unable to retrieve hyperslab parameters");
-    }
-
-    if(space_ndims>0) {
-        HDmemset(file_offset,0,sizeof(hssize_t)*space_ndims);
-
-        /* Adjust the slowest varying dimension to take care of strip mining */
-        for (i=1, acc=1; i<space_ndims; i++)
-            acc *= hsize[i];
-        assert (0==file_iter->all.offset % acc);
-        assert (0==nelmts % acc);
-        file_offset[0] += file_iter->all.offset / acc;
-        hsize[0] = nelmts / acc;
-    } /* end if */
-
-    /* The fastest varying dimension is for the data point itself */
-    file_offset[space_ndims] = 0;
-    hsize[space_ndims] = elmt_size;
-    HDmemset (zero, 0, (space_ndims+1)*sizeof(*zero));
+    /* Set the offset in the dataset and the number of bytes to read */
+    buf_off=file_iter->all.offset*elmt_size;
+    actual_bytes=elmt_size*nelmts;
 
     /*
-     * Gather from file.
+     * Read piece from file.
      */
-    if (H5F_arr_read(f, dxpl_id, layout, pline, fill, efl, hsize, hsize,
-		     zero, file_offset, buf/*out*/)<0) {
+    if (H5F_seq_read(f, dxpl_id, layout, pline, fill, efl, file_space,
+            elmt_size, actual_bytes, buf_off, buf/*out*/)<0) {
         HRETURN_ERROR(H5E_DATASPACE, H5E_READERROR, 0, "read error");
     }
 
@@ -261,6 +199,7 @@ H5S_all_fgath (H5F_t *f, const struct H5O_layout_t *layout,
     
     FUNC_LEAVE (nelmts);
 } /* H5S_all_fgath() */
+
 
 /*-------------------------------------------------------------------------
  * Function:	H5S_all_fscat
@@ -287,15 +226,10 @@ H5S_all_fscat (H5F_t *f, const struct H5O_layout_t *layout,
 	       const struct H5O_pline_t *pline, const struct H5O_fill_t *fill,
 	       const struct H5O_efl_t *efl, size_t elmt_size,
 	       const H5S_t *file_space, H5S_sel_iter_t *file_iter,
-	       hsize_t nelmts, hid_t dxpl_id, const void *_buf)
+	       hsize_t nelmts, hid_t dxpl_id, const void *buf)
 {
-    hssize_t	file_offset[H5O_LAYOUT_NDIMS];	/*offset of hyperslab	*/
-    hsize_t	hsize[H5O_LAYOUT_NDIMS];	/*size of hyperslab	*/
-    hssize_t	zero[H5O_LAYOUT_NDIMS];		/*zero vector		*/
-    const uint8_t *buf=(const uint8_t*)_buf;    /*for pointer arithmetic*/
-    hsize_t	acc;				/*accumulator		*/
-    intn	space_ndims;			/*space dimensionality	*/
-    intn	i;				/*counters		*/
+    hsize_t     actual_bytes;       /* The actual number of bytes to write */
+    hsize_t	buf_off;            /* Dataset offset for copying memory */
 
     FUNC_ENTER (H5S_all_fscat, FAIL);
 
@@ -308,37 +242,16 @@ H5S_all_fscat (H5F_t *f, const struct H5O_layout_t *layout,
     assert (nelmts>0);
     assert (buf);
 
-    /*
-     * Get information to determine what elements are being selected.
-     */
-    if ((space_ndims=H5S_get_simple_extent_dims (file_space, hsize, NULL))<0) {
-	HRETURN_ERROR (H5E_DATASPACE, H5E_CANTINIT, FAIL,
-		       "unable to retrieve hyperslab parameters");
-    }
-    
-    if(space_ndims>0) {
-        HDmemset(file_offset,0,sizeof(hssize_t)*space_ndims);
-
-        /* Adjust the slowest varying dimension to account for strip mining */
-        for (i=1, acc=1; i<space_ndims; i++)
-            acc *= hsize[i];
-        assert (0==file_iter->all.offset % acc);
-        assert (0==nelmts % acc);
-        file_offset[0] += file_iter->all.offset / acc;
-        hsize[0] = nelmts / acc;
-    } /* end if */
-    
-    /* The fastest varying dimension is for the data point itself */
-    file_offset[space_ndims] = 0;
-    hsize[space_ndims] = elmt_size;
-    HDmemset (zero, 0, (space_ndims+1)*sizeof(*zero));
+    /* Set the offset in the dataset and the number of bytes to write */
+    buf_off=file_iter->all.offset*elmt_size;
+    actual_bytes=elmt_size*nelmts;
 
     /*
-     * Scatter to file.
+     * Write piece from file.
      */
-    if (H5F_arr_write (f, dxpl_id, layout, pline, fill, efl, hsize, hsize,
-		       zero, file_offset, buf)<0) {
-        HRETURN_ERROR (H5E_DATASPACE, H5E_WRITEERROR, FAIL, "write error");
+    if (H5F_seq_write(f, dxpl_id, layout, pline, fill, efl, file_space,
+            elmt_size, actual_bytes, buf_off, buf/*out*/)<0) {
+        HRETURN_ERROR(H5E_DATASPACE, H5E_WRITEERROR, 0, "write error");
     }
 
     /* Advance iterator */
@@ -347,6 +260,7 @@ H5S_all_fscat (H5F_t *f, const struct H5O_layout_t *layout,
     
     FUNC_LEAVE (SUCCEED);
 }   /* H5S_all_fscat() */
+
 
 /*-------------------------------------------------------------------------
  * Function:	H5S_all_mgath
@@ -371,17 +285,10 @@ H5S_all_fscat (H5F_t *f, const struct H5O_layout_t *layout,
 static hsize_t
 H5S_all_mgath (const void *_buf, size_t elmt_size,
 	       const H5S_t *mem_space, H5S_sel_iter_t *mem_iter,
-	       hsize_t nelmts, void *_tconv_buf/*out*/)
+	       hsize_t nelmts, void *tconv_buf/*out*/)
 {
-    hssize_t	mem_offset[H5O_LAYOUT_NDIMS];	/*slab offset in app buf*/
-    hsize_t	mem_size[H5O_LAYOUT_NDIMS];	/*total size of app buf	*/
-    hsize_t	hsize[H5O_LAYOUT_NDIMS];	/*size of hyperslab	*/
-    hssize_t	zero[H5O_LAYOUT_NDIMS];		/*zero			*/
     const uint8_t *buf=(const uint8_t*)_buf;   /* Get local copies for address arithmetic */
-    uint8_t	*tconv_buf=(uint8_t*)_tconv_buf;
-    hsize_t	acc;				/*accumulator		*/
-    intn	space_ndims;			/*dimensionality of space*/
-    intn	i;				/*counters		*/
+    size_t      actual_bytes;       /* The actual number of bytes to read */
 
     FUNC_ENTER (H5S_all_mgath, 0);
 
@@ -393,45 +300,12 @@ H5S_all_mgath (const void *_buf, size_t elmt_size,
     assert (nelmts>0);
     assert (tconv_buf);
 
-    /*
-     * Retrieve information to determine what elements are being selected.
-     */
-    if ((space_ndims=H5S_get_simple_extent_dims (mem_space, hsize, NULL))<0) {
-        HRETURN_ERROR (H5E_DATASPACE, H5E_CANTINIT, 0,
-		       "unable to retrieve hyperslab parameters");
-    }
-    if(space_ndims>0) {
-        HDmemset(mem_offset,0,sizeof(hssize_t)*space_ndims);
-
-        if (H5S_get_simple_extent_dims (mem_space, mem_size, NULL)<0) {
-            HRETURN_ERROR (H5E_DATASPACE, H5E_CANTINIT, 0,
-                   "unable to retrieve data space dimensions");
-        }
-
-        /* Adjust the slowest varying dimension to account for strip mining */
-        for (i=1, acc=1; i<space_ndims; i++)
-            acc *= hsize[i];
-        assert (0==mem_iter->all.offset % acc);
-        assert (0==nelmts % acc);
-        mem_offset[0] += mem_iter->all.offset / acc;
-        hsize[0] = nelmts / acc;
-    } /* end if */
-    
-    /* The fastest varying dimension is for the data point itself */
-    mem_offset[space_ndims] = 0;
-    mem_size[space_ndims] = elmt_size;
-    hsize[space_ndims] = elmt_size;
-    HDmemset (zero, 0, (space_ndims+1)*sizeof(*zero));
+    /* Set the offset in the dataset and the number of bytes to read */
+    buf += mem_iter->all.offset*elmt_size;
+    actual_bytes=elmt_size*nelmts;
 
-    /*
-     * Scatter from conversion buffer to application memory.
-     */
-    H5_CHECK_OVERFLOW(space_ndims+1,intn,uintn);
-    if (H5V_hyper_copy ((uintn)(space_ndims+1), hsize, hsize, zero, tconv_buf,
-			mem_size, mem_offset, buf)<0) {
-        HRETURN_ERROR (H5E_DATASPACE, H5E_CANTINIT, 0,
-		       "unable to scatter data to memory");
-    }
+    /* "read" in the bytes from the source (buf) to the destination (tconv_buf) */
+    HDmemcpy(tconv_buf,buf,actual_bytes);
 
     /* Advance iterator */
     mem_iter->all.elmt_left-=nelmts;
@@ -440,6 +314,7 @@ H5S_all_mgath (const void *_buf, size_t elmt_size,
     FUNC_LEAVE (nelmts);
 }   /* H5S_all_mgath() */
 
+
 /*-------------------------------------------------------------------------
  * Function:	H5S_all_mscat
  *
@@ -458,19 +333,12 @@ H5S_all_mgath (const void *_buf, size_t elmt_size,
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5S_all_mscat (const void *_tconv_buf, size_t elmt_size,
+H5S_all_mscat (const void *tconv_buf, size_t elmt_size,
 	       const H5S_t *mem_space, H5S_sel_iter_t *mem_iter,
 	       hsize_t nelmts, void *_buf/*out*/)
 {
-    hssize_t	mem_offset[H5O_LAYOUT_NDIMS];	/*slab offset in app buf*/
-    hsize_t	mem_size[H5O_LAYOUT_NDIMS];	/*total size of app buf	*/
-    hsize_t	hsize[H5O_LAYOUT_NDIMS];	/*size of hyperslab	*/
-    hssize_t	zero[H5O_LAYOUT_NDIMS];		/*zero			*/
-    uint8_t	*buf=(uint8_t*)_buf;   /* Get local copies for address arithmetic */
-    const uint8_t *tconv_buf=(const uint8_t *)_tconv_buf;
-    hsize_t	acc;				/*accumulator		*/
-    intn	space_ndims;			/*dimensionality of space*/
-    intn	i;				/*counters		*/
+    uint8_t *buf=(uint8_t *)_buf;
+    size_t      actual_bytes;       /* The actual number of bytes to write */
 
     FUNC_ENTER (H5S_all_mscat, FAIL);
 
@@ -482,47 +350,12 @@ H5S_all_mscat (const void *_tconv_buf, size_t elmt_size,
     assert (nelmts>0);
     assert (buf);
 
-    /*
-     * Retrieve information to determine what elements are being selected.
-     */
-    if ((space_ndims=H5S_get_simple_extent_dims (mem_space, hsize, NULL))<0) {
-        HRETURN_ERROR (H5E_DATASPACE, H5E_CANTINIT, FAIL,
-		       "unable to retrieve hyperslab parameters");
-    }
-
-    if(space_ndims>0) {
-        HDmemset(mem_offset,0,sizeof(hssize_t)*space_ndims);
-
-        if (H5S_get_simple_extent_dims (mem_space, mem_size, NULL)<0) {
-            HRETURN_ERROR (H5E_DATASPACE, H5E_CANTINIT, FAIL,
-                   "unable to retrieve data space dimensions");
-        }
-
-        /* Adjust the slowest varying dimension to take care of strip mining */
-        for (i=1, acc=1; i<space_ndims; i++) {
-            acc *= hsize[i];
-        }
-        assert (0==mem_iter->all.offset % acc);
-        assert (0==nelmts % acc);
-        mem_offset[0] += mem_iter->all.offset / acc;
-        hsize[0] = nelmts / acc;
-    } /* end if */
-
-    /* The fastest varying dimension is for the data point itself */
-    mem_offset[space_ndims] = 0;
-    mem_size[space_ndims] = elmt_size;
-    hsize[space_ndims] = elmt_size;
-    HDmemset (zero, 0, (space_ndims+1)*sizeof(*zero));
+    /* Set the offset in the dataset and the number of bytes to write */
+    buf += mem_iter->all.offset*elmt_size;
+    actual_bytes=elmt_size*nelmts;
 
-    /*
-     * Scatter from conversion buffer to application memory.
-     */
-    H5_CHECK_OVERFLOW(space_ndims+1,intn,uintn);
-    if (H5V_hyper_copy ((uintn)(space_ndims+1), hsize, mem_size, mem_offset, buf,
-			hsize, zero, tconv_buf)<0) {
-	HRETURN_ERROR (H5E_DATASPACE, H5E_CANTINIT, FAIL,
-		       "unable to scatter data to memory");
-    }
+    /* "write" the bytes from the source (tconv_buf) to the destination (buf) */
+    HDmemcpy(buf,tconv_buf,actual_bytes);
 
     /* Advance iterator */
     mem_iter->all.elmt_left-=nelmts;
diff --git a/src/H5Shyper.c b/src/H5Shyper.c
index b47dd41..8e0fd0d 100644
--- a/src/H5Shyper.c
+++ b/src/H5Shyper.c
@@ -1,6 +1,6 @@
 /*
- * Copyright (C) 1998 NCSA
- *                    All rights reserved.
+ * Copyright (C) 1998-2001 NCSA
+ *                         All rights reserved.
  *
  * Programmer:  Quincey Koziol <koziol@ncsa.uiuc.edu>
  *              Thursday, June 18, 1998
@@ -77,7 +77,7 @@ static hsize_t H5S_hyper_fwrite_opt (H5F_t *f, const struct H5O_layout_t *layout
 		 const H5S_t *file_space, H5S_sel_iter_t *file_iter,
 		 hsize_t nelmts, hid_t dxpl_id, const void *_buf);
 static herr_t H5S_hyper_init (const struct H5O_layout_t *layout,
-			      const H5S_t *space, H5S_sel_iter_t *iter, size_t *min_elem_out);
+			      const H5S_t *space, H5S_sel_iter_t *iter);
 static hsize_t H5S_hyper_favail (const H5S_t *space, const H5S_sel_iter_t *iter,
 				hsize_t max);
 static hsize_t H5S_hyper_fgath (H5F_t *f, const struct H5O_layout_t *layout,
@@ -173,8 +173,7 @@ H5FL_BLK_DEFINE_STATIC(hyper_block);
  */
 static herr_t
 H5S_hyper_init (const struct H5O_layout_t UNUSED *layout,
-	       const H5S_t *space, H5S_sel_iter_t *sel_iter,
-		size_t UNUSED *min_elem_out)
+	       const H5S_t *space, H5S_sel_iter_t *sel_iter)
 {
     FUNC_ENTER (H5S_hyper_init, FAIL);
 
@@ -5408,7 +5407,6 @@ H5S_hyper_select_iterate(void *buf, hid_t type_id, H5S_t *space, H5D_operator_t
 {
     H5S_hyper_iter_info_t iter_info;  /* Block of parameters to pass into recursive calls */
     H5S_sel_iter_t	iter;   /* selection iteration info*/
-    size_t	min_elem_out=1; /* Minimum # of elements to output*/
     herr_t ret_value=FAIL;      /* return value */
 
     FUNC_ENTER (H5S_hyper_select_iterate, FAIL);
@@ -5419,7 +5417,7 @@ H5S_hyper_select_iterate(void *buf, hid_t type_id, H5S_t *space, H5D_operator_t
     assert(H5I_DATATYPE == H5I_get_type(type_id));
 
     /* Initialize the selection iterator */
-    if (H5S_hyper_init(NULL, space, &iter, &min_elem_out)<0) {
+    if (H5S_hyper_init(NULL, space, &iter)<0) {
         HGOTO_ERROR (H5E_DATASPACE, H5E_CANTINIT, FAIL,
 		     "unable to initialize selection information");
     } 
diff --git a/src/H5Spoint.c b/src/H5Spoint.c
index b9bcca7..072a5b7 100644
--- a/src/H5Spoint.c
+++ b/src/H5Spoint.c
@@ -1,6 +1,6 @@
 /*
- * Copyright (C) 1998 NCSA
- *                    All rights reserved.
+ * Copyright (C) 1998-2001 NCSA
+ *                         All rights reserved.
  *
  * Programmer:  Quincey Koziol <koziol@ncsa.uiuc.edu>
  *              Tuesday, June 16, 1998
@@ -24,7 +24,7 @@
 static intn             interface_initialize_g = 0;
 
 static herr_t H5S_point_init (const struct H5O_layout_t *layout,
-			      const H5S_t *space, H5S_sel_iter_t *iter, size_t *min_elem_out);
+			      const H5S_t *space, H5S_sel_iter_t *iter);
 static hsize_t H5S_point_favail (const H5S_t *space, const H5S_sel_iter_t *iter,
 				hsize_t max);
 static hsize_t H5S_point_fgath (H5F_t *f, const struct H5O_layout_t *layout,
@@ -87,8 +87,7 @@ const H5S_mconv_t	H5S_POINT_MCONV[1] = {{
  */
 static herr_t
 H5S_point_init (const struct H5O_layout_t UNUSED *layout,
-		const H5S_t *space, H5S_sel_iter_t *sel_iter,
-		size_t UNUSED *min_elem_out)
+		const H5S_t *space, H5S_sel_iter_t *sel_iter)
 {
     FUNC_ENTER (H5S_point_init, FAIL);
 
diff --git a/src/H5Sprivate.h b/src/H5Sprivate.h
index f315b77..1415229 100644
--- a/src/H5Sprivate.h
+++ b/src/H5Sprivate.h
@@ -82,7 +82,7 @@ typedef struct H5S_fconv_t {
     
     /* Initialize file element numbering information */
     herr_t (*init)(const struct H5O_layout_t *layout, const H5S_t *space,
-		   H5S_sel_iter_t *iter, size_t *min_elem_out);
+		   H5S_sel_iter_t *iter);
 
     /* Determine optimal number of elements to transfer */
     hsize_t (*avail)(const H5S_t *file_space, const H5S_sel_iter_t *file_iter,
@@ -112,7 +112,7 @@ typedef struct H5S_mconv_t {
     
     /* Initialize memory element numbering information */
     herr_t (*init)(const struct H5O_layout_t *layout, const H5S_t *space,
-		   H5S_sel_iter_t *iter, size_t *min_elem_out);
+		   H5S_sel_iter_t *iter);
 
     /* Gather elements from app buffer to type conversion buffer */
     hsize_t (*gath)(const void *buf, size_t elmt_size,