[svn-r5834] Purpose:

    Large code cleanup/re-write

Description:
    This is phase 1 of the data I/O re-architecture, with the following changes:
        - Changed the selection drivers to not actually do any I/O, they
            only generate the sequences of offset/length pairs needed for
            the I/O (or memory access, in the case of iterating or filling
            a selection in a memory buffer)
        - Wrote more abstract I/O routines which get the sequence of offset/
            length pairs for each selection and access perform the I/O or
            memory access.

    Benefits of this change include:
        - Removed ~3400 lines of quite redundant code, with corresponding
            reduction in the size of library binary.
        - Any selection can now directly access memory when performing I/O,
            if no type conversions are required, instead of just "regular"
            hyperslab and 'all' selections, which speeds up I/O.
        - Sped up I/O for hyperslab selections which have contiguous lower
            dimensions by "flattening" them out into lesser dimensional objects
            for the I/O.

    No file format or API changes were necessary for this change.

    The next phase will be to create a "selection driver" for each type of
        selection, allowing each type of selection to directly call certain
        methods that only apply to that type of selection, instead of passing
        through dozens of functions which have switch statements to call the
        appropriate method for each selection type.  This will also reduce
        the amount of code in the library and speed things up a bit more.

    Phase 3 will involve generating an MPI datatype for all types of selections,
        instead of only "regular" hyperslab and 'all' selections.  This will
        allow collective parallel I/O for all I/O operations which don't
        require type conversions.  It will also open up the door for allowing
        collective I/O on datasets which require type conversion.

    Phase 4 will involve changing the access pattern to deal with chunked
        datasets in a more optimal way (in serial).

    Phase 5 will deal with accessing chunked datasets more optimally for
        collective parallel I/O operations.

Platforms tested:
    FreeBSD 4.6 (sleipnir) w/ parallel & C++ and IRIX64 6.5 (modi4) w/parallel

1 files changed, 62 insertions, 693 deletions

diff --git a/src/H5Sall.c b/src/H5Sall.c
index 9a4d80d..6b975d9 100644
--- a/src/H5Sall.c
+++ b/src/H5Sall.c
@@ -10,56 +10,17 @@
 
 #define H5S_PACKAGE		/*suppress error about including H5Spkg	  */
 
-#include "H5private.h"
-#include "H5Dprivate.h"
-#include "H5Eprivate.h"
-#include "H5Iprivate.h"
-#include "H5Spkg.h"
-#include "H5Tprivate.h"         /* Datatypes */
-#include "H5Vprivate.h"
+#include "H5private.h"		/* Generic Functions			  */
+#include "H5Eprivate.h"		/* Error handling		  */
+#include "H5Iprivate.h"		/* ID Functions		  */
+#include "H5Spkg.h"		/* Dataspace functions			  */
+#include "H5Vprivate.h"         /* Vector functions */
 
 /* Interface initialization */
 #define PABLO_MASK      H5Sall_mask
 #define INTERFACE_INIT  NULL
 static int             interface_initialize_g = 0;
 
-static herr_t H5S_all_init (const H5S_t *space, size_t elmt_size, 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,
-                             H5P_genplist_t *dc_plist, 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*/);
-static herr_t H5S_all_fscat (H5F_t *f, const struct H5O_layout_t *layout,
-                             H5P_genplist_t *dc_plist, 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);
-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*/);
-static herr_t 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*/);
-
-const H5S_fconv_t	H5S_ALL_FCONV[1] = {{
-    "all", 					/*name			*/
-    H5S_SEL_ALL,				/*selection type	*/
-    H5S_all_init,				/*initialize		*/
-    H5S_all_favail,				/*available		*/
-    H5S_all_fgath,				/*gather		*/
-    H5S_all_fscat,				/*scatter		*/
-}};
-
-const H5S_mconv_t	H5S_ALL_MCONV[1] = {{
-    "all", 					/*name			*/
-    H5S_SEL_ALL,				/*selection type	*/
-    H5S_all_init,				/*initialize		*/
-    H5S_all_mgath,				/*gather		*/
-    H5S_all_mscat, 				/*scatter		*/
-}};
-
 
 /*-------------------------------------------------------------------------
  * Function:	H5S_all_init
@@ -75,7 +36,7 @@ const H5S_mconv_t	H5S_ALL_MCONV[1] = {{
  *
  *-------------------------------------------------------------------------
  */
-static herr_t
+herr_t
 H5S_all_init (const H5S_t *space, size_t UNUSED elmt_size, H5S_sel_iter_t *sel_iter)
 {
     FUNC_ENTER_NOAPI(H5S_all_init, FAIL);
@@ -110,7 +71,7 @@ H5S_all_init (const H5S_t *space, size_t UNUSED elmt_size, H5S_sel_iter_t *sel_i
  *
  *-------------------------------------------------------------------------
  */
-static hsize_t
+hsize_t
 H5S_all_favail (const H5S_t * UNUSED space, const H5S_sel_iter_t *sel_iter, hsize_t max)
 {
     FUNC_ENTER_NOAPI(H5S_all_favail, 0);
@@ -123,532 +84,6 @@ H5S_all_favail (const H5S_t * UNUSED space, const H5S_sel_iter_t *sel_iter, hsiz
 }   /* H5S_all_favail() */
 
 
-/*-------------------------------------------------------------------------
- * Function:	H5S_all_fgath
- *
- * Purpose:	Gathers data points from file F and accumulates them in the
- *		type conversion buffer BUF.  The LAYOUT argument describes
- *		how the data is stored on disk and EFL describes how the data
- *		is organized in external files.  ELMT_SIZE is the size in
- *		bytes of a datum which this function treats as opaque.
- *		FILE_SPACE describes the data space of the dataset on disk
- *		and the elements that have been selected for reading (via
- *		hyperslab, etc).  This function will copy at most NELMTS
- *		elements.
- *
- * Return:	Success:	Number of elements copied.
- *
- *		Failure:	0
- *
- * Programmer:	Quincey Koziol
- *              Tuesday, June 16, 1998
- *
- * Modifications:
- *		Robb Matzke, 1999-08-03
- *		The data transfer properties are passed by ID since that's
- *		what the virtual file layer needs.
- *-------------------------------------------------------------------------
- */
-static hsize_t
-H5S_all_fgath (H5F_t *f, const struct H5O_layout_t *layout,
-               H5P_genplist_t *dc_plist,
-	       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*/)
-{
-    hsize_t     actual_bytes; /* The actual number of bytes to read */
-    hsize_t	buf_off;            /* Dataset offset for copying memory */
-
-    FUNC_ENTER_NOAPI(H5S_all_fgath, 0);
-
-    /* Check args */
-    assert (f);
-    assert (layout);
-    assert (elmt_size>0);
-    assert (file_space);
-    assert (file_iter);
-    assert (nelmts>0);
-    assert (buf);
-
-    /* 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;
-
-    /*
-     * Read piece from file.
-     */
-    H5_CHECK_OVERFLOW(actual_bytes,hsize_t,size_t);
-    if (H5F_seq_read(f, dxpl_id, layout, dc_plist, file_space,
-            elmt_size, (size_t)actual_bytes, buf_off, buf/*out*/)<0) {
-        HRETURN_ERROR(H5E_DATASPACE, H5E_READERROR, 0, "read error");
-    }
-
-    /* Advance iterator */
-    file_iter->all.elmt_left-=nelmts;
-    file_iter->all.offset+=nelmts;
-    
-    FUNC_LEAVE (nelmts);
-} /* H5S_all_fgath() */
-
-
-/*-------------------------------------------------------------------------
- * Function:	H5S_all_fscat
- *
- * Purpose:	Scatters dataset elements from the type conversion buffer BUF
- *		to the file F where the data points are arranged according to
- *		the file data space FILE_SPACE and stored according to
- *		LAYOUT and EFL. Each element is ELMT_SIZE bytes.
- *		The caller is requesting that NELMTS elements are copied.
- *
- * Return:	Non-negative on success/Negative on failure
- *
- * Programmer:	Quincey Koziol
- *              Tuesday, June 16, 1998
- *
- * Modifications:
- *		Robb Matzke, 1999-08-03
- *		The data transfer properties are passed by ID since that's
- *		what the virtual file layer needs.
- *-------------------------------------------------------------------------
- */
-static herr_t
-H5S_all_fscat (H5F_t *f, const struct H5O_layout_t *layout,
-               H5P_genplist_t *dc_plist, 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     actual_bytes;       /* The actual number of bytes to write */
-    hsize_t	buf_off;            /* Dataset offset for copying memory */
-
-    FUNC_ENTER_NOAPI(H5S_all_fscat, FAIL);
-
-    /* Check args */
-    assert (f);
-    assert (layout);
-    assert (elmt_size>0);
-    assert (file_space);
-    assert (file_iter);
-    assert (nelmts>0);
-    assert (buf);
-
-    /* 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;
-
-    /*
-     * Write piece from file.
-     */
-    H5_CHECK_OVERFLOW(actual_bytes,hsize_t,size_t);
-    if (H5F_seq_write(f, dxpl_id, layout, dc_plist, file_space,
-            elmt_size, (size_t)actual_bytes, buf_off, buf/*out*/)<0) {
-        HRETURN_ERROR(H5E_DATASPACE, H5E_WRITEERROR, 0, "write error");
-    }
-
-    /* Advance iterator */
-    file_iter->all.elmt_left-=nelmts;
-    file_iter->all.offset+=nelmts;
-    
-    FUNC_LEAVE (SUCCEED);
-}   /* H5S_all_fscat() */
-
-
-/*-------------------------------------------------------------------------
- * Function:	H5S_all_mgath
- *
- * Purpose:	Gathers dataset elements from application memory BUF and
- *		copies them into the data type conversion buffer TCONV_BUF.
- *		Each element is ELMT_SIZE bytes and arranged in application
- *		memory according to MEM_SPACE.  
- *		The caller is requesting that at most NELMTS be gathered.
- *
- * Return:	Success:	Number of elements copied.
- *
- *		Failure:	0
- *
- * Programmer:	Quincey Koziol
- *              Tuesday, June 16, 1998
- *
- * Modifications:
- *
- *-------------------------------------------------------------------------
- */
-static hsize_t
-H5S_all_mgath (const void *_buf, size_t elmt_size,
-	       const H5S_t UNUSED *mem_space, H5S_sel_iter_t *mem_iter,
-	       hsize_t nelmts, void *tconv_buf/*out*/)
-{
-    const uint8_t *buf=(const uint8_t*)_buf;   /* Get local copies for address arithmetic */
-    hsize_t      actual_bytes;       /* The actual number of bytes to read */
-
-    FUNC_ENTER_NOAPI(H5S_all_mgath, 0);
-
-    /* Check args */
-    assert (buf);
-    assert (elmt_size>0);
-    assert (mem_space && H5S_SEL_ALL==mem_space->select.type);
-    assert (mem_iter);
-    assert (nelmts>0);
-    assert (tconv_buf);
-
-    /* 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;
-
-    /* "read" in the bytes from the source (buf) to the destination (tconv_buf) */
-    H5_CHECK_OVERFLOW(actual_bytes,hsize_t,size_t);
-    HDmemcpy(tconv_buf,buf,(size_t)actual_bytes);
-
-    /* Advance iterator */
-    mem_iter->all.elmt_left-=nelmts;
-    mem_iter->all.offset+=nelmts;
-    
-    FUNC_LEAVE (nelmts);
-}   /* H5S_all_mgath() */
-
-
-/*-------------------------------------------------------------------------
- * Function:	H5S_all_mscat
- *
- * Purpose:	Scatters NELMTS data points from the type conversion buffer
- *		TCONV_BUF to the application buffer BUF.  Each element is
- *		ELMT_SIZE bytes and they are organized in application memory
- *		according to MEM_SPACE.
- *
- * Return:	Non-negative on success/Negative on failure
- *
- * Programmer:	Quincey Koziol
- *              Wednesday, June 17, 1998
- *
- * Modifications:
- *
- *-------------------------------------------------------------------------
- */
-static herr_t
-H5S_all_mscat (const void *tconv_buf, size_t elmt_size,
-	       const H5S_t UNUSED *mem_space, H5S_sel_iter_t *mem_iter,
-	       hsize_t nelmts, void *_buf/*out*/)
-{
-    uint8_t *buf=(uint8_t *)_buf;
-    hsize_t      actual_bytes;       /* The actual number of bytes to write */
-
-    FUNC_ENTER_NOAPI(H5S_all_mscat, FAIL);
-
-    /* Check args */
-    assert (tconv_buf);
-    assert (elmt_size>0);
-    assert (mem_space && H5S_SEL_ALL==mem_space->select.type);
-    assert (mem_iter);
-    assert (nelmts>0);
-    assert (buf);
-
-    /* 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;
-
-    /* "write" the bytes from the source (tconv_buf) to the destination (buf) */
-    H5_CHECK_OVERFLOW(actual_bytes,hsize_t,size_t);
-    HDmemcpy(buf,tconv_buf,(size_t)actual_bytes);
-
-    /* Advance iterator */
-    mem_iter->all.elmt_left-=nelmts;
-    mem_iter->all.offset+=nelmts;
-    
-    FUNC_LEAVE (SUCCEED);
-}
-
-
-/*-------------------------------------------------------------------------
- * Function:	H5S_all_opt_possible
- *
- * Purpose:	Checks if an direct I/O transfer is possible between memory and
- *                  the file.
- *
- * Return:	Success:        Non-negative: TRUE or FALSE
- *		Failure:	Negative
- *
- * Programmer:	Quincey Koziol
- *              Wednesday, April 3, 2002
- *
- * Modifications:
- *
- *-------------------------------------------------------------------------
- */
-htri_t
-H5S_all_opt_possible( const H5S_t *mem_space, const H5S_t *file_space, const unsigned UNUSED flags)
-{
-    htri_t c1,c2;               /* Flags whether a selection is optimizable */
-    htri_t ret_value=TRUE;
-
-    FUNC_ENTER_NOAPI(H5S_all_opt_possible, FAIL);
-
-    /* Check args */
-    assert(mem_space);
-    assert(file_space);
-
-    /* Check whether these are both simple dataspaces */
-    if (H5S_SIMPLE!=mem_space->extent.type || H5S_SIMPLE!=file_space->extent.type)
-        HGOTO_DONE(FALSE);
-
-    /* Check whether both selections are single blocks */
-    c1=H5S_select_single(file_space);
-    c2=H5S_select_single(mem_space);
-    if(c1==FAIL || c2==FAIL)
-        HGOTO_ERROR(H5E_DATASPACE, H5E_BADRANGE, FAIL, "invalid check for single selection blocks");
-    if(c1==FALSE || c2==FALSE)
-        HGOTO_DONE(FALSE);
-
-    /* Check whether the shape of each block is the same */
-    c1=H5S_select_shape_same(mem_space,file_space);
-    if(c1==FAIL)
-        HGOTO_ERROR(H5E_DATASPACE, H5E_BADRANGE, FAIL, "invalid check for selection blocks same");
-    if(c1==FALSE)
-        HGOTO_DONE(FALSE);
-
-done:
-    FUNC_LEAVE(ret_value);
-} /* H5S_all_opt_possible() */
-
-
-/*-------------------------------------------------------------------------
- * Function:	H5S_all_read
- *
- * Purpose:	Reads directly from file into application memory if possible.
- *
- * Return:	Success:	Non-negative. If data was read directly then
- *				MUST_CONVERT is set to zero, otherwise
- *				MUST_CONVERT is set to non-zero.
- *
- *		Failure:	Negative. Return value of MUST_CONVERT is
- *				undefined.
- *
- * Programmer:	Robb Matzke
- *              Thursday, April 22, 1999
- *
- * Modifications:
- *    		Quincey Koziol, 1999-05-25
- *		Modified to allow contiguous hyperslabs to be written out.
- *
- *		Robb Matzke, 1999-08-03
- *		The data transfer properties are passed by ID since that's
- *		what the virtual file layer needs.
- *-------------------------------------------------------------------------
- */
-herr_t
-H5S_all_read(H5F_t *f, const H5O_layout_t *layout, H5P_genplist_t *dc_plist,
-            size_t elmt_size, const H5S_t *file_space,
-	    const H5S_t *mem_space, hid_t dxpl_id, void *_buf/*out*/)
-{
-    H5S_hyper_span_t *file_span=NULL,*mem_span=NULL;     /* Hyperslab span node */
-    char       *buf=(char*)_buf;        /* Get pointer to buffer */
-    hsize_t	file_elmts;             /* Number of elements in each dimension of selection */
-    hssize_t	file_off,mem_off;       /* Offset (in elements) of selection */
-    hsize_t	mem_size[H5O_LAYOUT_NDIMS];     /* Size of memory buffer */
-    hsize_t	size[H5O_LAYOUT_NDIMS];         /* Size of selection */
-    hssize_t	file_offset[H5O_LAYOUT_NDIMS];  /* Offset of selection in file */
-    hssize_t	mem_offset[H5O_LAYOUT_NDIMS];   /* Offset of selection in memory */
-    unsigned	u;                              /* Index variable */
-    herr_t      ret_value=SUCCEED;
-
-    FUNC_ENTER_NOAPI(H5S_all_read, FAIL);
-
-    /* Get information about memory and file */
-    for (u=0; u<mem_space->extent.u.simple.rank; u++) {
-        switch(mem_space->select.type) {
-            case H5S_SEL_HYPERSLABS:
-                /* Check for a "regular" hyperslab selection */
-                if(mem_space->select.sel_info.hslab.diminfo != NULL) {
-                    mem_off=mem_space->select.sel_info.hslab.diminfo[u].start;
-                } /* end if */
-                else {
-                    mem_off=mem_span->low;
-                    mem_span=mem_span->down->head;
-                } /* end else */
-                mem_off+=mem_space->select.offset[u];
-                break;
-
-            case H5S_SEL_ALL:
-                mem_off=0;
-                break;
-
-            case H5S_SEL_POINTS:
-                mem_off=mem_space->select.sel_info.pnt_lst->head->pnt[u]
-                            +mem_space->select.offset[u];
-                break;
-
-            default:
-                assert(0 && "Invalid selection type!");
-        } /* end switch */
-
-        switch(file_space->select.type) {
-            case H5S_SEL_HYPERSLABS:
-                /* Check for a "regular" hyperslab selection */
-                if(file_space->select.sel_info.hslab.diminfo != NULL) {
-                    file_elmts=file_space->select.sel_info.hslab.diminfo[u].block;
-                    file_off=file_space->select.sel_info.hslab.diminfo[u].start;
-                } /* end if */
-                else {
-                    file_elmts=(file_span->high-file_span->low)+1;
-                    file_off=file_span->low;
-                    file_span=file_span->down->head;
-                } /* end else */
-                file_off+=file_space->select.offset[u];
-                break;
-
-            case H5S_SEL_ALL:
-                file_elmts=file_space->extent.u.simple.size[u];
-                file_off=0;
-                break;
-
-            case H5S_SEL_POINTS:
-                file_elmts=1;
-                file_off=file_space->select.sel_info.pnt_lst->head->pnt[u]
-                            +file_space->select.offset[u];
-                break;
-
-            default:
-                assert(0 && "Invalid selection type!");
-        } /* end switch */
-
-        mem_size[u]=mem_space->extent.u.simple.size[u];
-        size[u] = file_elmts;
-        file_offset[u] = file_off;
-        mem_offset[u] = mem_off;
-    }
-    mem_size[u]=elmt_size;
-    size[u] = elmt_size;
-    file_offset[u] = 0;
-    mem_offset[u] = 0;
-
-    /* Read data from the file */
-    if (H5F_arr_read(f, dxpl_id, layout, dc_plist, size,
-            mem_size, mem_offset, file_offset, buf/*out*/)<0)
-        HGOTO_ERROR(H5E_IO, H5E_READERROR, FAIL, "unable to read data from the file");
-
-done:
-    FUNC_LEAVE(ret_value);
-} /* end H5S_all_read() */
-
-
-/*-------------------------------------------------------------------------
- * Function:	H5S_all_write
- *
- * Purpose:	Writes data directly to the file if possible.
- *
- * Return:	Success:	Non-negative. If data was written directly
- *				then MUST_CONVERT is set to zero, otherwise
- *				MUST_CONVERT is set to non-zero.
- *
- *		Failure:	Negative. Return value of MUST_CONVERT is
- *				undefined.
- *
- * Programmer:	Robb Matzke
- *              Wednesday, April 21, 1999
- *
- * Modifications:
- * 		Quincey Koziol, 1999-05-25
- *		Modified to allow contiguous hyperslabs to be written out.
- *
- *		Robb Matzke, 1999-08-03
- *		The data transfer properties are passed by ID since that's
- *		what the virtual file layer needs.
- *-------------------------------------------------------------------------
- */
-herr_t
-H5S_all_write(H5F_t *f, const struct H5O_layout_t *layout, H5P_genplist_t *dc_plist,
-	     size_t elmt_size, const H5S_t *file_space,
-	     const H5S_t *mem_space, hid_t dxpl_id, const void *_buf)
-{
-    H5S_hyper_span_t *file_span=NULL,*mem_span=NULL;     /* Hyperslab span node */
-    const char *buf=(const char*)_buf;  /* Get pointer to buffer */
-    hsize_t	file_elmts;   /* Number of elements in each dimension of selection */
-    hssize_t	file_off,mem_off;       /* Offset (in elements) of selection */
-    hsize_t	mem_size[H5O_LAYOUT_NDIMS];     /* Size of memory buffer */
-    hsize_t	size[H5O_LAYOUT_NDIMS];         /* Size of selection */
-    hssize_t	file_offset[H5O_LAYOUT_NDIMS];  /* Offset of selection in file */
-    hssize_t	mem_offset[H5O_LAYOUT_NDIMS];   /* Offset of selection in memory */
-    unsigned	u;                              /* Index variable */
-    herr_t      ret_value=SUCCEED;
-    
-    FUNC_ENTER_NOAPI(H5S_all_write, FAIL);
-
-    /* Get information about memory and file */
-    for (u=0; u<mem_space->extent.u.simple.rank; u++) {
-        switch(mem_space->select.type) {
-            case H5S_SEL_HYPERSLABS:
-                /* Check for a "regular" hyperslab selection */
-                if(mem_space->select.sel_info.hslab.diminfo != NULL) {
-                    mem_off=mem_space->select.sel_info.hslab.diminfo[u].start;
-                } /* end if */
-                else {
-                    mem_off=mem_span->low;
-                    mem_span=mem_span->down->head;
-                } /* end else */
-                mem_off+=mem_space->select.offset[u];
-                break;
-
-            case H5S_SEL_ALL:
-                mem_off=0;
-                break;
-
-            case H5S_SEL_POINTS:
-                mem_off=mem_space->select.sel_info.pnt_lst->head->pnt[u]
-                            +mem_space->select.offset[u];
-                break;
-
-            default:
-                assert(0 && "Invalid selection type!");
-        } /* end switch */
-
-        switch(file_space->select.type) {
-            case H5S_SEL_HYPERSLABS:
-                /* Check for a "regular" hyperslab selection */
-                if(file_space->select.sel_info.hslab.diminfo != NULL) {
-                    file_elmts=file_space->select.sel_info.hslab.diminfo[u].block;
-                    file_off=file_space->select.sel_info.hslab.diminfo[u].start;
-                } /* end if */
-                else {
-                    file_elmts=(file_span->high-file_span->low)+1;
-                    file_off=file_span->low;
-                    file_span=file_span->down->head;
-                } /* end else */
-                file_off+=file_space->select.offset[u];
-                break;
-
-            case H5S_SEL_ALL:
-                file_elmts=file_space->extent.u.simple.size[u];
-                file_off=0;
-                break;
-
-            case H5S_SEL_POINTS:
-                file_elmts=1;
-                file_off=file_space->select.sel_info.pnt_lst->head->pnt[u]
-                            +file_space->select.offset[u];
-                break;
-
-            default:
-                assert(0 && "Invalid selection type!");
-        } /* end switch */
-
-        mem_size[u]=mem_space->extent.u.simple.size[u];
-        size[u] = file_elmts;
-        file_offset[u] = file_off;
-        mem_offset[u] = mem_off;
-    }
-    mem_size[u]=elmt_size;
-    size[u] = elmt_size;
-    file_offset[u] = 0;
-    mem_offset[u] = 0;
-
-    /* Write data to the file */
-    if (H5F_arr_write(f, dxpl_id, layout, dc_plist, size,
-            mem_size, mem_offset, file_offset, buf)<0)
-        HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "unable to write data to the file");
-
-done:
-    FUNC_LEAVE(ret_value);
-} /* end H5S_all_write() */
-
-
 /*--------------------------------------------------------------------------
  NAME
     H5S_all_release
@@ -925,147 +360,81 @@ done:
 
 /*--------------------------------------------------------------------------
  NAME
-    H5S_all_select_iterate
+    H5S_all_select_get_seq_list
  PURPOSE
-    Iterate over a "all" selection, calling a user's function for each
-        element.
+    Create a list of offsets & lengths for a selection
  USAGE
-    herr_t H5S_all_select_iterate(buf, type_id, space, op, operator_data)
-        void *buf;      IN/OUT: Buffer containing elements to iterate over
-        hid_t type_id;  IN: Datatype ID of BUF array.
-        H5S_t *space;   IN: Dataspace object containing selection to iterate over
-        H5D_operator_t op; IN: Function pointer to the routine to be
-                                called for each element in BUF iterated over.
-        void *operator_data;    IN/OUT: Pointer to any user-defined data
-                                associated with the operation.
+    herr_t H5S_all_select_get_seq_list(flags,space,iter,elem_size,maxseq,maxbytes,nseq,nbytes,off,len)
+        unsigned flags;         IN: Flags for extra information about operation
+        H5S_t *space;           IN: Dataspace containing selection to use.
+        H5S_sel_iter_t *iter;   IN/OUT: Selection iterator describing last
+                                    position of interest in selection.
+        size_t elem_size;       IN: Size of an element
+        size_t maxseq;          IN: Maximum number of sequences to generate
+        size_t maxbytes;        IN: Maximum number of bytes to include in the
+                                    generated sequences
+        size_t *nseq;           OUT: Actual number of sequences generated
+        size_t *nbytes;         OUT: Actual number of bytes in sequences generated
+        hsize_t *off;           OUT: Array of offsets
+        size_t *len;            OUT: Array of lengths
  RETURNS
-    Returns the return value of the last operator if it was non-zero, or zero
-    if all elements were processed. Otherwise returns a negative value.
+    Non-negative on success/Negative on failure.
  DESCRIPTION
-    Iterates over the selected elements in a memory buffer, calling the user's
-    callback function for each element.  The selection in the dataspace is
-    modified so that any elements already iterated over are removed from the
-    selection if the iteration is interrupted (by the H5D_operator_t function
-    returning non-zero) in the "middle" of the iteration and may be re-started
-    by the user where it left off.
-
-    NOTE: Until "subtracting" elements from a selection is implemented,
-        the selection is not modified.
+    Use the selection in the dataspace to generate a list of byte offsets and
+    lengths for the region(s) selected.  Start/Restart from the position in the
+    ITER parameter.  The number of sequences generated is limited by the MAXSEQ
+    parameter and the number of sequences actually generated is stored in the
+    NSEQ parameter.
  GLOBAL VARIABLES
  COMMENTS, BUGS, ASSUMPTIONS
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
 herr_t
-H5S_all_select_iterate(void *buf, hid_t type_id, H5S_t *space, H5D_operator_t op,
-        void *operator_data)
+H5S_all_select_get_seq_list(unsigned UNUSED flags, const H5S_t *space,H5S_sel_iter_t *iter,
+    size_t elem_size, size_t maxseq, size_t maxbytes, size_t *nseq, size_t *nbytes,
+    hsize_t *off, size_t *len)
 {
-    hsize_t	mem_size[H5O_LAYOUT_NDIMS]; /* Dataspace size */
-    hsize_t	mem_offset[H5O_LAYOUT_NDIMS]; /* current coordinates */
-    hsize_t offset;             /* offset of region in buffer */
-    hsize_t nelemts;            /* Number of elements to iterate through */
-    void *tmp_buf;              /* temporary location of the element in the buffer */
-    unsigned rank;              /* Dataspace rank */
-    int indx;                   /* Index to increment */
-    H5T_t *dt;                  /* Datatype structure */
-    herr_t ret_value=0;         /* return value */
+    hsize_t bytes_left;         /* The number of bytes left in the selection */
+    hsize_t elem_used;          /* The number of bytes used */
+    herr_t ret_value=SUCCEED;   /* return value */
 
-    FUNC_ENTER_NOAPI(H5S_all_select_iterate, 0);
+    FUNC_ENTER_NOAPI (H5S_all_select_get_seq_list, FAIL);
 
-    assert(buf);
+    /* Check args */
     assert(space);
-    assert(op);
-    assert(H5I_DATATYPE == H5I_get_type(type_id));
+    assert(iter);
+    assert(elem_size>0);
+    assert(maxseq>0);
+    assert(maxbytes>0);
+    assert(nseq);
+    assert(nbytes);
+    assert(off);
+    assert(len);
 
-    /* Get the dataspace extent rank */
-    rank=space->extent.u.simple.rank;
-
-    /* Set up the size of the memory space */
-    HDmemcpy(mem_size, space->extent.u.simple.size, rank*sizeof(hsize_t));
-
-    /* Set the size of the datatype */
-    if (NULL==(dt=H5I_object(type_id)))
-        HRETURN_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not an valid base datatype");
-    mem_size[rank]=H5T_get_size(dt);
+    /* Calculate the number of bytes left in the selection */
+    bytes_left=iter->all.elmt_left*elem_size;
 
-    /* Set the coordinates to zero */
-    HDmemset(mem_offset, 0, (rank+1)*sizeof(hsize_t));
+    /* "round" off the maxbytes allowed to a multiple of the element size */
+    maxbytes=(maxbytes/elem_size)*elem_size;
 
-    /* Get the number of elements to iterate through */
-    nelemts=H5S_get_simple_extent_npoints(space);
+    /* Compute the offset in the dataset */
+    off[0]=iter->all.offset*elem_size;
+    len[0]=MIN(maxbytes,bytes_left);
 
-    /* Iterate through the entire dataset */
-    while(nelemts>0 && ret_value==0) {
-        /* Get the offset in the memory buffer */
-        offset=H5V_array_offset(rank+1,mem_size,(const hssize_t *)mem_offset);
-        tmp_buf=((char *)buf+offset);
+    /* Should only need one sequence for 'all' selections */
+    *nseq=1;
 
-        ret_value=(*op)(tmp_buf,type_id,(hsize_t)rank,(hssize_t *)mem_offset,operator_data);
+    /* Set the number of bytes used */
+    *nbytes=len[0];
 
-        /* Decrement the number of elements to iterate through */
-        nelemts--;
-
-        /* Advance the coordinate (currently in C memory order) */
-        indx=rank-1; /* Leave the byte offset in the element alone */
-        while(indx>=0 && ++mem_offset[indx]==mem_size[indx]) {
-            mem_offset[indx]=0;
-            indx--;
-          } /* end while */
-      } /* end while */
-
-    FUNC_LEAVE (ret_value);
-}   /* H5S_all_select_iterate() */
-
-
-/*--------------------------------------------------------------------------
- NAME
-    H5S_all_select_fill
- PURPOSE
-    Fill an "all" selection in memory with a value
- USAGE
-    herr_t H5S_all_select_fill(fill,fill_size,space,buf)
-        const void *fill;       IN: Pointer to fill value to use
-        size_t fill_size;       IN: Size of elements in memory buffer & size of
-                                    fill value
-        H5S_t *space;           IN: Dataspace describing memory buffer &
-                                    containing selection to use.
-        void *buf;              IN/OUT: Memory buffer to fill selection in
- RETURNS
-    Non-negative on success/Negative on failure.
- DESCRIPTION
-    Use the selection in the dataspace to fill elements in a memory buffer.
- GLOBAL VARIABLES
- COMMENTS, BUGS, ASSUMPTIONS
-    The memory buffer elements are assumed to have the same datatype as the
-    fill value being placed into them.
- EXAMPLES
- REVISION LOG
---------------------------------------------------------------------------*/
-herr_t
-H5S_all_select_fill(const void *fill, size_t fill_size, const H5S_t *space, void *buf)
-{
-    hssize_t nelemts;          /* Number of elements in dataspace */
-    herr_t ret_value=SUCCEED;  /* return value */
-
-    FUNC_ENTER_NOAPI(H5S_all_select_fill, FAIL);
-
-    /* Check args */
-    assert(fill);
-    assert(fill_size>0);
-    assert(space);
-    assert(buf);
-
-    /* Fill the selection in the memory buffer */
-
-    /* Get the number of elements to iterate through */
-    if((nelemts=H5S_get_simple_extent_npoints(space))<0)
-        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOUNT, FAIL, "can't get number of elements");
-
-    /* Fill the elements in the buffer */
-    H5_CHECK_OVERFLOW(nelemts,hssize_t,size_t);
-    H5V_array_fill(buf, fill, fill_size, (size_t)nelemts);
+    /* Update the iterator */
+    elem_used=len[0]/elem_size;
+    iter->all.elmt_left-=elem_used;
+    iter->all.offset+=elem_used;
 
+#ifdef LATER
 done:
+#endif /* LATER */
     FUNC_LEAVE (ret_value);
-}   /* H5S_all_select_fill() */
-
+} /* end H5S_all_select_get_seq_list() */