[svn-r4181] Purpose:

    Bug Fix, Code Cleanup, Code Optimization, etc.
Description:
    Fold in the hyperslab speedups, clean up compile warnings and change a
    few things from using 'unsigned' or 'hsize_t' to use 'size_t' instead.
Platforms tested:
    FreeBSD 4.3 (hawkwind), Solaris 2.7 (arabica), Irix64 6.5 (modi4)

1 files changed, 544 insertions, 610 deletions

diff --git a/src/H5Dseq.c b/src/H5Dseq.c
index 3868202..1c05dcf 100644
--- a/src/H5Dseq.c
+++ b/src/H5Dseq.c
@@ -52,6 +52,7 @@ static intn interface_initialize_g = 0;
  *              Thursday, September 28, 2000
  *
  * Modifications:
+ *              Re-written to use new vector I/O call - QAK, 7/7/01
  *
  *-------------------------------------------------------------------------
  */
@@ -59,28 +60,118 @@ herr_t
 H5F_seq_read(H5F_t *f, hid_t dxpl_id, const struct H5O_layout_t *layout,
          const struct H5O_pline_t *pline, const H5O_fill_t *fill,
          const struct H5O_efl_t *efl, const H5S_t *file_space, size_t elmt_size,
-         hsize_t seq_len, hsize_t file_offset, void *buf/*out*/)
+         size_t seq_len, hsize_t file_offset, void *buf/*out*/)
 {
+    FUNC_ENTER(H5F_seq_read, FAIL);
+
+    /* Check args */
+    assert(f);
+    assert(layout);
+    assert(buf);
+
+    if (H5F_seq_readv(f, dxpl_id, layout, pline, fill, efl, file_space, elmt_size, 1, &seq_len, &file_offset, buf)<0)
+        HRETURN_ERROR(H5E_IO, H5E_READERROR, FAIL, "vector read failed");
+
+    FUNC_LEAVE(SUCCEED);
+}   /* H5F_seq_read() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5F_seq_write
+ *
+ * Purpose:	Writes a sequence of bytes to a file dataset from a buffer in
+ *      in memory.  The data is written to file F and the array's size and
+ *      storage information is in LAYOUT.  External files are described
+ *      according to the external file list, EFL.  The sequence offset is 
+ *      FILE_OFFSET in the file (offsets are
+ *      in terms of bytes) and the size of the hyperslab is SEQ_LEN. The
+ *		total size of the file array is implied in the LAYOUT argument.
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:	Quincey Koziol
+ *              Monday, October 9, 2000
+ *
+ * Modifications:
+ *              Re-written to use new vector I/O routine - QAK, 7/7/01
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5F_seq_write(H5F_t *f, hid_t dxpl_id, const struct H5O_layout_t *layout,
+         const struct H5O_pline_t *pline, const H5O_fill_t *fill,
+         const struct H5O_efl_t *efl, const H5S_t *file_space, size_t elmt_size,
+         size_t seq_len, hsize_t file_offset, const void *buf)
+{
+    FUNC_ENTER(H5F_seq_write, FAIL);
+
+    /* Check args */
+    assert(f);
+    assert(layout);
+    assert(buf);
+
+    if (H5F_seq_writev(f, dxpl_id, layout, pline, fill, efl, file_space, elmt_size, 1, &seq_len, &file_offset, buf)<0)
+        HRETURN_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "vector write failed");
+
+    FUNC_LEAVE(SUCCEED);
+}   /* H5F_seq_write() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5F_seq_readv
+ *
+ * Purpose:	Reads in a vector of byte sequences from a file dataset into a
+ *      buffer in in memory.  The data is read from file F and the array's size
+ *      and storage information is in LAYOUT.  External files are described
+ *      according to the external file list, EFL.  The vector of byte sequences
+ *      offsets is in the FILE_OFFSET array into the dataset (offsets are in
+ *      terms of bytes) and the size of each sequence is in the SEQ_LEN array.
+ *      The total size of the file array is implied in the LAYOUT argument.
+ *      Bytes read into BUF are sequentially stored in the buffer, each sequence
+ *      from the vector stored directly after the previous.  The number of
+ *      sequences is NSEQ.
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:	Quincey Koziol
+ *              Wednesday, May 1, 2001
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5F_seq_readv(H5F_t *f, hid_t dxpl_id, const struct H5O_layout_t *layout,
+         const struct H5O_pline_t *pline, const H5O_fill_t *fill,
+         const struct H5O_efl_t *efl, const H5S_t *file_space, size_t elmt_size,
+         size_t nseq, size_t seq_len_arr[], hsize_t file_offset_arr[],
+         void *_buf/*out*/)
+{
+    unsigned char *real_buf=(unsigned char *)_buf;   /* Local pointer to buffer to fill */
+    unsigned char *buf;                         /* Local pointer to buffer to fill */
+    hsize_t file_offset;                /* Offset in dataset */
+    hsize_t seq_len;                    /* Number of bytes to read */
     hsize_t	dset_dims[H5O_LAYOUT_NDIMS];	/* dataspace dimensions */
     hssize_t    coords[H5O_LAYOUT_NDIMS];	/* offset of hyperslab in dataspace */
     hsize_t	hslab_size[H5O_LAYOUT_NDIMS];	/* hyperslab size in dataspace*/
     hsize_t     down_size[H5O_LAYOUT_NDIMS];    /* Cumulative yperslab sizes (in elements) */
     hsize_t     acc;    /* Accumulator for hyperslab sizes (in elements) */
     intn ndims;
-    hsize_t	max_data = 0;			/*bytes in dataset	*/
+    hsize_t	max_data;    			/*bytes in dataset	*/
     haddr_t	addr=0;				/*address in file	*/
     uintn	u;				/*counters		*/
+    size_t      v;                              /*counters              */
     intn	i,j;				/*counters		*/
 #ifdef H5_HAVE_PARALLEL
     H5FD_mpio_xfer_t xfer_mode=H5FD_MPIO_INDEPENDENT;
 #endif
    
-    FUNC_ENTER(H5F_seq_read, FAIL);
+    FUNC_ENTER(H5F_seq_readv, FAIL);
 
     /* Check args */
     assert(f);
     assert(layout);
-    assert(buf);
+    assert(real_buf);
 
 #ifdef H5_HAVE_PARALLEL
     {
@@ -110,30 +201,11 @@ H5F_seq_read(H5F_t *f, hid_t dxpl_id, const struct H5O_layout_t *layout,
                       "filters are not allowed for contiguous data");
             }
             
-            /*
-             * Initialize loop variables.  The loop is a multi-dimensional loop
-             * that counts from SIZE down to zero and IDX is the counter.  Each
-             * element of IDX is treated as a digit with IDX[0] being the least
-             * significant digit.
-             */
-            if (efl && efl->nused>0) {
-                addr = 0;
-            } else {
-                addr = layout->addr;
 
-                /* Compute the size of the dataset in bytes */
-                for(u=0, max_data=1; u<layout->ndims; u++)
-                    max_data *= layout->dim[u];
-
-                /* Adjust the maximum size of the data by the offset into it */
-                max_data -= file_offset;
-            }
-            addr += file_offset;
-
-            /*
-             * Now begin to walk through the array, copying data from disk to
-             * memory.
-             */
+            /* Read directly from file if the dataset is in an external file */
+            if (efl && efl->nused>0) {
+                /* Iterate through the sequence vectors */
+                for(v=0; v<nseq; v++) {
 #ifdef H5_HAVE_PARALLEL
             if (H5FD_MPIO_COLLECTIVE==xfer_mode) {
                 /*
@@ -143,8 +215,8 @@ H5F_seq_read(H5F_t *f, hid_t dxpl_id, const struct H5O_layout_t *layout,
                  */
                 unsigned long max, min, temp;
 
-                temp = seq_len;
-                assert(temp==seq_len);	/* verify no overflow */
+                temp = seq_len_arr[v];
+                assert(temp==seq_len_arr[v]);	/* verify no overflow */
                 MPI_Allreduce(&temp, &max, 1, MPI_UNSIGNED_LONG, MPI_MAX,
                       H5FD_mpio_communicator(f->shared->lf));
                 MPI_Allreduce(&temp, &min, 1, MPI_UNSIGNED_LONG, MPI_MIN,
@@ -157,20 +229,26 @@ H5F_seq_read(H5F_t *f, hid_t dxpl_id, const struct H5O_layout_t *layout,
                       "collective access with unequal number of blocks not supported yet");
             }
 #endif
+                    /* Note: We can't use data sieve buffers for datasets in external files
+                     *  because the 'addr' of all external files is set to 0 (above) and
+                     *  all datasets in external files would alias to the same set of
+                     *  file offsets, totally mixing up the data sieve buffer information. -QAK
+                     */
+                    if (H5O_efl_read(f, efl, file_offset_arr[v], seq_len_arr[v], real_buf)<0) {
+                        HRETURN_ERROR(H5E_IO, H5E_READERROR, FAIL,
+                              "external data read failed");
+                    }
 
-            /* Read directly from file if the dataset is in an external file */
-            if (efl && efl->nused>0) {
-                /* Note: We can't use data sieve buffers for datasets in external files
-                 *  because the 'addr' of all external files is set to 0 (above) and
-                 *  all datasets in external files would alias to the same set of
-                 *  file offsets, totally mixing up the data sieve buffer information. -QAK
-                 */
-                if (H5O_efl_read(f, efl, addr, seq_len, buf)<0) {
-                    HRETURN_ERROR(H5E_IO, H5E_READERROR, FAIL,
-                          "external data read failed");
-                }
+                    /* Increment offset in buffer */
+                    real_buf += seq_len_arr[v];
+                } /* end for */
             } else {
-                if (H5F_contig_read(f, max_data, H5FD_MEM_DRAW, addr, seq_len, dxpl_id, buf)<0) {
+                /* Compute the size of the dataset in bytes */
+                for(u=1, max_data=layout->dim[0]; u<layout->ndims; u++)
+                    max_data *= layout->dim[u];
+
+                /* Pass along the vector of sequences to read */
+                if (H5F_contig_readv(f, max_data, H5FD_MEM_DRAW, layout->addr, nseq, seq_len_arr, file_offset_arr, dxpl_id, real_buf)<0) {
                     HRETURN_ERROR(H5E_IO, H5E_READERROR, FAIL,
                               "block read failed");
                 }
@@ -178,289 +256,218 @@ H5F_seq_read(H5F_t *f, hid_t dxpl_id, const struct H5O_layout_t *layout,
             break;
 
         case H5D_CHUNKED:
-        {
-            /*
-             * This method is unable to access external raw data files 
-             */
-            if (efl && efl->nused>0) {
-                HRETURN_ERROR(H5E_IO, H5E_UNSUPPORTED, FAIL,
-                      "chunking and external files are mutually exclusive");
-            }
-            /* Compute the file offset coordinates and hyperslab size */
-            if((ndims=H5S_get_simple_extent_dims(file_space,dset_dims,NULL))<0)
-                HRETURN_ERROR(H5E_IO, H5E_UNSUPPORTED, FAIL, "unable to retrieve dataspace dimensions");
-            
-#ifdef QAK
-            /* The library shouldn't be reading partial elements currently */
-            assert(seq_len%elmt_size!=0);
-            assert(addr%elmt_size!=0);
-#endif /* QAK */
-
-#ifdef QAK
-/* Print out the file offsets & hyperslab sizes */
-{
-    static int count=0;
-
-    if(count<1000000) {
-        printf("%s: elmt_size=%d, addr=%d, seq_len=%d\n",FUNC,(int)elmt_size,(int)addr,(int)seq_len);
-        printf("%s: file_offset=%d\n",FUNC,(int)file_offset);
-        count++;
-    }
-}
-#endif /* QAK */
-            /* Set location in dataset from the file_offset */
-            addr=file_offset;
-
-            /* Convert the bytes into elements */
-            seq_len/=elmt_size;
-            addr/=elmt_size;
-
-            /* Build the array of cumulative hyperslab sizes */
-            for(acc=1, i=(ndims-1); i>=0; i--) {
-                down_size[i]=acc;
-                acc*=dset_dims[i];
-#ifdef QAK
-printf("%s: acc=%ld, down_size[%d]=%ld\n",FUNC,(long)acc,i,(long)down_size[i]);
-#endif /* QAK */
-            } /* end for */
+            /* Brute-force, stupid way to implement the vectors, but too complex to do other ways... */
+            for(v=0; v<nseq; v++) {
+                file_offset=file_offset_arr[v];
+                seq_len=seq_len_arr[v];
+                buf=real_buf;
+
+                {
+                    /*
+                     * This method is unable to access external raw data files 
+                     */
+                    if (efl && efl->nused>0) {
+                        HRETURN_ERROR(H5E_IO, H5E_UNSUPPORTED, FAIL,
+                              "chunking and external files are mutually exclusive");
+                    }
+                    /* Compute the file offset coordinates and hyperslab size */
+                    if((ndims=H5S_get_simple_extent_dims(file_space,dset_dims,NULL))<0)
+                        HRETURN_ERROR(H5E_IO, H5E_UNSUPPORTED, FAIL, "unable to retrieve dataspace dimensions");
+                    
+
+                    /* Set location in dataset from the file_offset */
+                    addr=file_offset;
+
+                    /* Convert the bytes into elements */
+                    seq_len/=elmt_size;
+                    addr/=elmt_size;
+
+                    /* Build the array of cumulative hyperslab sizes */
+                    for(acc=1, i=(ndims-1); i>=0; i--) {
+                        down_size[i]=acc;
+                        acc*=dset_dims[i];
+                    } /* end for */
 
-            /* Compute the hyperslab offset from the address given */
-            for(i=ndims-1; i>=0; i--) {
-                coords[i]=addr%dset_dims[i];
-                addr/=dset_dims[i];
-#ifdef QAK
-printf("%s: addr=%lu, coords[%d]=%ld\n",FUNC,(unsigned long)addr,i,(long)coords[i]);
-#endif /* QAK */
-            } /* end for */
-            coords[ndims]=0;   /* No offset for element info */
-#ifdef QAK
-printf("%s: addr=%lu, coords[%d]=%ld\n",FUNC,(unsigned long)addr,ndims,(long)coords[ndims]);
-#endif /* QAK */
-
-            /*
-             * Peel off initial partial hyperslabs until we've got a hyperslab which starts
-             *      at coord[n]==0 for dimensions 1->(ndims-1)  (i.e. starting at coordinate
-             *      zero for all dimensions except the slowest changing one
-             */
-            for(i=ndims-1; i>0 && seq_len>=down_size[i]; i--) {
-                hsize_t partial_size;       /* Size of the partial hyperslab in bytes */
-
-                /* Check if we have a partial hyperslab in this lower dimension */
-                if(coords[i]>0) {
-#ifdef QAK
-printf("%s: Need to get hyperslab, seq_len=%ld, coords[%d]=%ld\n",FUNC,(long)seq_len,i,(long)coords[i]);
-#endif /* QAK */
-                    /* Reset the partial hyperslab size */
-                    partial_size=1;
-
-                    /* Build the partial hyperslab information */
-                    for(j=0; j<ndims; j++) {
-                        if(i==j)
-                            hslab_size[j]=MIN(seq_len/down_size[i],dset_dims[i]-coords[i]);
-                        else
-                            if(j>i)
-                                hslab_size[j]=dset_dims[j];
-                            else
-                                hslab_size[j]=1;
-                        partial_size*=hslab_size[j];
-#ifdef QAK
-printf("%s: partial_size=%lu, hslab_size[%d]=%ld\n",FUNC,(unsigned long)partial_size,j,(long)hslab_size[j]);
-#endif /* QAK */
+                    /* Compute the hyperslab offset from the address given */
+                    for(i=ndims-1; i>=0; i--) {
+                        coords[i]=addr%dset_dims[i];
+                        addr/=dset_dims[i];
+                    } /* end for */
+                    coords[ndims]=0;   /* No offset for element info */
+
+                    /*
+                     * Peel off initial partial hyperslabs until we've got a hyperslab which starts
+                     *      at coord[n]==0 for dimensions 1->(ndims-1)  (i.e. starting at coordinate
+                     *      zero for all dimensions except the slowest changing one
+                     */
+                    for(i=ndims-1; i>0 && seq_len>=down_size[i]; i--) {
+                        hsize_t partial_size;       /* Size of the partial hyperslab in bytes */
+
+                        /* Check if we have a partial hyperslab in this lower dimension */
+                        if(coords[i]>0) {
+                            /* Reset the partial hyperslab size */
+                            partial_size=1;
+
+                            /* Build the partial hyperslab information */
+                            for(j=0; j<ndims; j++) {
+                                if(i==j)
+                                    hslab_size[j]=MIN(seq_len/down_size[i],dset_dims[i]-coords[i]);
+                                else
+                                    if(j>i)
+                                        hslab_size[j]=dset_dims[j];
+                                    else
+                                        hslab_size[j]=1;
+                                partial_size*=hslab_size[j];
+                            } /* end for */
+                            hslab_size[ndims]=elmt_size;   /* basic hyperslab size is the element */
+
+                            /* Read in the partial hyperslab */
+                            if (H5F_istore_read(f, dxpl_id, layout, pline, fill, coords,
+                                         hslab_size, buf)<0) {
+                                HRETURN_ERROR(H5E_IO, H5E_READERROR, FAIL, "chunked read failed");
+                            }
+
+                            /* Increment the buffer offset */
+                            buf=(unsigned char *)buf+partial_size;
+
+                            /* Decrement the length of the sequence to read */
+                            seq_len-=partial_size;
+
+                            /* Correct the coords array */
+                            coords[i]=0;
+                            coords[i-1]++;
+                        } /* end if */
                     } /* end for */
-                    hslab_size[ndims]=elmt_size;   /* basic hyperslab size is the element */
-#ifdef QAK
-printf("%s: partial_size=%lu, hslab_size[%d]=%ld\n",FUNC,(unsigned long)partial_size,ndims,(long)hslab_size[ndims]);
-#endif /* QAK */
-
-                    /* Read in the partial hyperslab */
-                    if (H5F_istore_read(f, dxpl_id, layout, pline, fill, coords,
-                                 hslab_size, buf)<0) {
-                        HRETURN_ERROR(H5E_IO, H5E_READERROR, FAIL, "chunked read failed");
-                    }
 
-                    /* Increment the buffer offset */
-                    buf=(unsigned char *)buf+partial_size;
+                    /* Check if there is more than just a partial hyperslab to read */
+                    if(seq_len>=down_size[0]) {
+                        hsize_t tmp_seq_len;    /* Temp. size of the sequence in elements */
+                        hsize_t full_size;      /* Size of the full hyperslab in bytes */
 
-                    /* Decrement the length of the sequence to read */
-                    seq_len-=partial_size;
+                        /* Get the sequence length for computing the hyperslab sizes */
+                        tmp_seq_len=seq_len;
 
-                    /* Correct the coords array */
-                    coords[i]=0;
-                    coords[i-1]++;
-                } /* end if */
-            } /* end for */
-#ifdef QAK
-printf("%s: after reading initial partial hyperslabs, seq_len=%lu\n",FUNC,(unsigned long)seq_len);
-#endif /* QAK */
-
-            /* Check if there is more than just a partial hyperslab to read */
-            if(seq_len>=down_size[0]) {
-                hsize_t tmp_seq_len;    /* Temp. size of the sequence in elements */
-                hsize_t full_size;      /* Size of the full hyperslab in bytes */
-
-                /* Get the sequence length for computing the hyperslab sizes */
-                tmp_seq_len=seq_len;
-
-                /* Reset the size of the hyperslab read in */
-                full_size=1;
-
-                /* Compute the hyperslab size from the length given */
-                for(i=ndims-1; i>=0; i--) {
-                    /* Check if the hyperslab is wider than the width of the dimension */
-                    if(tmp_seq_len>dset_dims[i]) {
-                        assert(0==coords[i]);
-                        hslab_size[i]=dset_dims[i];
-                    } /* end if */
-                    else 
-                        hslab_size[i]=tmp_seq_len;
+                        /* Reset the size of the hyperslab read in */
+                        full_size=1;
 
-                    /* compute the number of elements read in */
-                    full_size*=hslab_size[i];
+                        /* Compute the hyperslab size from the length given */
+                        for(i=ndims-1; i>=0; i--) {
+                            /* Check if the hyperslab is wider than the width of the dimension */
+                            if(tmp_seq_len>dset_dims[i]) {
+                                assert(0==coords[i]);
+                                hslab_size[i]=dset_dims[i];
+                            } /* end if */
+                            else 
+                                hslab_size[i]=tmp_seq_len;
 
-                    /* Fold the length into the length in the next highest dimension */
-                    tmp_seq_len/=dset_dims[i];
-#ifdef QAK
-printf("%s: tmp_seq_len=%lu, hslab_size[%d]=%ld\n",FUNC,(unsigned long)tmp_seq_len,i,(long)hslab_size[i]);
-#endif /* QAK */
+                            /* compute the number of elements read in */
+                            full_size*=hslab_size[i];
 
-                    /* Make certain the hyperslab sizes don't go less than 1 for dimensions less than 0*/
-                    assert(tmp_seq_len>=1 || i==0);
-                } /* end for */
-                hslab_size[ndims]=elmt_size;   /* basic hyperslab size is the element */
+                            /* Fold the length into the length in the next highest dimension */
+                            tmp_seq_len/=dset_dims[i];
 
-#ifdef QAK
-/* Print out the file offsets & hyperslab sizes */
-{
-    static int count=0;
-
-    if(count<1000000) {
-        printf("%s: elmt_size=%d, addr=%d, full_size=%ld, tmp_seq_len=%ld seq_len=%ld\n",FUNC,(int)elmt_size,(int)addr,(long)full_size,(long)tmp_seq_len,(long)seq_len);
-        for(i=0; i<ndims; i++)
-            printf("%s: dset_dims[%d]=%d\n",FUNC,i,(int)dset_dims[i]);
-        for(i=0; i<=ndims; i++)
-            printf("%s: coords[%d]=%d, hslab_size[%d]=%d\n",FUNC,i,(int)coords[i],(int)i,(int)hslab_size[i]);
-        count++;
-    }
-}
-#endif /* QAK */
+                            /* Make certain the hyperslab sizes don't go less than 1 for dimensions less than 0*/
+                            assert(tmp_seq_len>=1 || i==0);
+                        } /* end for */
+                        hslab_size[ndims]=elmt_size;   /* basic hyperslab size is the element */
 
-                /* Read the full hyperslab in */
-                if (H5F_istore_read(f, dxpl_id, layout, pline, fill, coords,
-                             hslab_size, buf)<0) {
-                    HRETURN_ERROR(H5E_IO, H5E_READERROR, FAIL, "chunked read failed");
-                }
+                        /* Read the full hyperslab in */
+                        if (H5F_istore_read(f, dxpl_id, layout, pline, fill, coords,
+                                     hslab_size, buf)<0) {
+                            HRETURN_ERROR(H5E_IO, H5E_READERROR, FAIL, "chunked read failed");
+                        }
 
-                /* Increment the buffer offset */
-                buf=(unsigned char *)buf+full_size;
+                        /* Increment the buffer offset */
+                        buf=(unsigned char *)buf+full_size;
 
-                /* Decrement the sequence length left */
-                seq_len-=full_size;
+                        /* Decrement the sequence length left */
+                        seq_len-=full_size;
 
-                /* Increment coordinate of slowest changing dimension */
-                coords[0]+=hslab_size[0];
+                        /* Increment coordinate of slowest changing dimension */
+                        coords[0]+=hslab_size[0];
 
-            } /* end if */
-#ifdef QAK
-printf("%s: after reading 'middle' full hyperslabs, seq_len=%lu\n",FUNC,(unsigned long)seq_len);
-#endif /* QAK */
+                    } /* end if */
 
-            /*
-             * Peel off final partial hyperslabs until we've finished reading all the data
-             */
-            if(seq_len>0) {
-                hsize_t partial_size;       /* Size of the partial hyperslab in bytes */
+                    /*
+                     * Peel off final partial hyperslabs until we've finished reading all the data
+                     */
+                    if(seq_len>0) {
+                        hsize_t partial_size;       /* Size of the partial hyperslab in bytes */
+
+                        /*
+                         * Peel off remaining partial hyperslabs, from the next-slowest dimension
+                         *  on down to the next-to-fastest changing dimension
+                         */
+                        for(i=1; i<(ndims-1); i++) {
+                            /* Check if there are enough elements to read in a row in this dimension */
+                            if(seq_len>=down_size[i]) {
+                                /* Reset the partial hyperslab size */
+                                partial_size=1;
+
+                                /* Build the partial hyperslab information */
+                                for(j=0; j<ndims; j++) {
+                                    if(j<i)
+                                        hslab_size[j]=1;
+                                    else
+                                        if(j==i)
+                                            hslab_size[j]=seq_len/down_size[j];
+                                        else
+                                            hslab_size[j]=dset_dims[j];
+
+                                    partial_size*=hslab_size[j];
+                                } /* end for */
+                                hslab_size[ndims]=elmt_size;   /* basic hyperslab size is the element */
+
+                                /* Read in the partial hyperslab */
+                                if (H5F_istore_read(f, dxpl_id, layout, pline, fill, coords,
+                                             hslab_size, buf)<0) {
+                                    HRETURN_ERROR(H5E_IO, H5E_READERROR, FAIL, "chunked read failed");
+                                }
+
+                                /* Increment the buffer offset */
+                                buf=(unsigned char *)buf+partial_size;
+
+                                /* Decrement the length of the sequence to read */
+                                seq_len-=partial_size;
+
+                                /* Correct the coords array */
+                                coords[i]=hslab_size[i];
+                            } /* end if */
+                        } /* end for */
 
-                /*
-                 * Peel off remaining partial hyperslabs, from the next-slowest dimension
-                 *  on down to the next-to-fastest changing dimension
-                 */
-                for(i=1; i<(ndims-1); i++) {
-                    /* Check if there are enough elements to read in a row in this dimension */
-                    if(seq_len>=down_size[i]) {
-#ifdef QAK
-printf("%s: seq_len=%ld, down_size[%d]=%ld\n",FUNC,(long)seq_len,i+1,(long)down_size[i+1]);
-#endif /* QAK */
-                        /* Reset the partial hyperslab size */
-                        partial_size=1;
-
-                        /* Build the partial hyperslab information */
-                        for(j=0; j<ndims; j++) {
-                            if(j<i)
-                                hslab_size[j]=1;
-                            else
-                                if(j==i)
-                                    hslab_size[j]=seq_len/down_size[j];
-                                else
-                                    hslab_size[j]=dset_dims[j];
+                        /* Handle fastest changing dimension if there are any elements left */
+                        if(seq_len>0) {
+                            assert(seq_len<dset_dims[ndims-1]);
 
-                            partial_size*=hslab_size[j];
-#ifdef QAK
-printf("%s: partial_size=%lu, coords[%d]=%ld, hslab_size[%d]=%ld\n",FUNC,(unsigned long)partial_size,j,(long)coords[j],j,(long)hslab_size[j]);
-#endif /* QAK */
-                        } /* end for */
-                        hslab_size[ndims]=elmt_size;   /* basic hyperslab size is the element */
-#ifdef QAK
-printf("%s: partial_size=%lu, coords[%d]=%ld, hslab_size[%d]=%ld\n",FUNC,(unsigned long)partial_size,ndims,(long)coords[ndims],ndims,(long)hslab_size[ndims]);
-#endif /* QAK */
+                            /* Reset the partial hyperslab size */
+                            partial_size=1;
 
-                        /* Read in the partial hyperslab */
-                        if (H5F_istore_read(f, dxpl_id, layout, pline, fill, coords,
-                                     hslab_size, buf)<0) {
-                            HRETURN_ERROR(H5E_IO, H5E_READERROR, FAIL, "chunked read failed");
-                        }
+                            /* Build the partial hyperslab information */
+                            for(j=0; j<ndims; j++) {
+                                if(j==(ndims-1))
+                                    hslab_size[j]=seq_len;
+                                else
+                                    hslab_size[j]=1;
 
-                        /* Increment the buffer offset */
-                        buf=(unsigned char *)buf+partial_size;
+                                partial_size*=hslab_size[j];
+                            } /* end for */
+                            hslab_size[ndims]=elmt_size;   /* basic hyperslab size is the element */
 
-                        /* Decrement the length of the sequence to read */
-                        seq_len-=partial_size;
+                            /* Read in the partial hyperslab */
+                            if (H5F_istore_read(f, dxpl_id, layout, pline, fill, coords,
+                                         hslab_size, buf)<0) {
+                                HRETURN_ERROR(H5E_IO, H5E_READERROR, FAIL, "chunked read failed");
+                            }
 
-                        /* Correct the coords array */
-                        coords[i]=hslab_size[i];
+                            /* Double-check the amount read in */
+                            assert(seq_len==partial_size);
+                        } /* end if */
                     } /* end if */
-                } /* end for */
-#ifdef QAK
-printf("%s: after reading trailing hyperslabs for all but the last dimension, seq_len=%ld\n",FUNC,(long)seq_len);
-#endif /* QAK */
-
-                /* Handle fastest changing dimension if there are any elements left */
-                if(seq_len>0) {
-#ifdef QAK
-printf("%s: i=%d, seq_len=%ld\n",FUNC,ndims-1,(long)seq_len);
-#endif /* QAK */
-                    assert(seq_len<dset_dims[ndims-1]);
-
-                    /* Reset the partial hyperslab size */
-                    partial_size=1;
-
-                    /* Build the partial hyperslab information */
-                    for(j=0; j<ndims; j++) {
-                        if(j==(ndims-1))
-                            hslab_size[j]=seq_len;
-                        else
-                            hslab_size[j]=1;
-
-                        partial_size*=hslab_size[j];
-#ifdef QAK
-printf("%s: partial_size=%lu, coords[%d]=%ld, hslab_size[%d]=%ld\n",FUNC,(unsigned long)partial_size,j,(long)coords[j],j,(long)hslab_size[j]);
-#endif /* QAK */
-                    } /* end for */
-                    hslab_size[ndims]=elmt_size;   /* basic hyperslab size is the element */
-#ifdef QAK
-printf("%s: partial_size=%lu, coords[%d]=%ld, hslab_size[%d]=%ld\n",FUNC,(unsigned long)partial_size,ndims,(long)coords[ndims],ndims,(long)hslab_size[ndims]);
-#endif /* QAK */
-
-                    /* Read in the partial hyperslab */
-                    if (H5F_istore_read(f, dxpl_id, layout, pline, fill, coords,
-                                 hslab_size, buf)<0) {
-                        HRETURN_ERROR(H5E_IO, H5E_READERROR, FAIL, "chunked read failed");
-                    }
+                }
+                /* Increment offset in buffer */
+                real_buf += seq_len_arr[v];
+            } /* end for */
 
-                    /* Double-check the amount read in */
-                    assert(seq_len==partial_size);
-                } /* end if */
-            } /* end if */
-        }
             break;
 
         default:
@@ -469,55 +476,64 @@ printf("%s: partial_size=%lu, coords[%d]=%ld, hslab_size[%d]=%ld\n",FUNC,(unsign
     }   /* end switch() */
 
     FUNC_LEAVE(SUCCEED);
-}   /* H5F_seq_read() */
+}   /* H5F_seq_readv() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5F_seq_write
+ * Function:	H5F_seq_writev
  *
- * Purpose:	Writes a sequence of bytes to a file dataset from a buffer in
- *      in memory.  The data is written to file F and the array's size and
- *      storage information is in LAYOUT.  External files are described
- *      according to the external file list, EFL.  The sequence offset is 
- *      FILE_OFFSET in the file (offsets are
- *      in terms of bytes) and the size of the hyperslab is SEQ_LEN. The
- *		total size of the file array is implied in the LAYOUT argument.
+ * Purpose:	Writes a vector of byte sequences from a buffer in memory into
+ *      a file dataset.  The data is written to file F and the array's size
+ *      and storage information is in LAYOUT.  External files are described
+ *      according to the external file list, EFL.  The vector of byte sequences
+ *      offsets is in the FILE_OFFSET array into the dataset (offsets are in
+ *      terms of bytes) and the size of each sequence is in the SEQ_LEN array.
+ *      The total size of the file array is implied in the LAYOUT argument.
+ *      Bytes written from BUF are sequentially stored in the buffer, each sequence
+ *      from the vector stored directly after the previous.  The number of
+ *      sequences is NSEQ.
  *
  * Return:	Non-negative on success/Negative on failure
  *
  * Programmer:	Quincey Koziol
- *              Monday, October 9, 2000
+ *              Friday, July 6, 2001
  *
  * Modifications:
  *
  *-------------------------------------------------------------------------
  */
 herr_t
-H5F_seq_write(H5F_t *f, hid_t dxpl_id, const struct H5O_layout_t *layout,
+H5F_seq_writev(H5F_t *f, hid_t dxpl_id, const struct H5O_layout_t *layout,
          const struct H5O_pline_t *pline, const H5O_fill_t *fill,
          const struct H5O_efl_t *efl, const H5S_t *file_space, size_t elmt_size,
-         hsize_t seq_len, hsize_t file_offset, const void *buf)
+         size_t nseq, size_t seq_len_arr[], hsize_t file_offset_arr[],
+         const void *_buf)
 {
+    const unsigned char *real_buf=(const unsigned char *)_buf;   /* Local pointer to buffer to fill */
+    const unsigned char *buf;                         /* Local pointer to buffer to fill */
+    hsize_t file_offset;                /* Offset in dataset */
+    hsize_t seq_len;                    /* Number of bytes to read */
     hsize_t	dset_dims[H5O_LAYOUT_NDIMS];	/* dataspace dimensions */
     hssize_t    coords[H5O_LAYOUT_NDIMS];	/* offset of hyperslab in dataspace */
     hsize_t	hslab_size[H5O_LAYOUT_NDIMS];	/* hyperslab size in dataspace*/
     hsize_t     down_size[H5O_LAYOUT_NDIMS];    /* Cumulative hyperslab sizes (in elements) */
-    hsize_t     acc;            /* Accumulator for hyperslab sizes (in elements) */
+    hsize_t     acc;    /* Accumulator for hyperslab sizes (in elements) */
     intn ndims;
-    hsize_t	max_data = 0;			/*bytes in dataset	*/
+    hsize_t	max_data;    			/*bytes in dataset	*/
     haddr_t	addr;				/*address in file	*/
     uintn	u;				/*counters		*/
+    size_t      v;                              /*counters              */
     intn	i,j;				/*counters		*/
 #ifdef H5_HAVE_PARALLEL
     H5FD_mpio_xfer_t xfer_mode=H5FD_MPIO_INDEPENDENT;
 #endif
    
-    FUNC_ENTER(H5F_seq_write, FAIL);
+    FUNC_ENTER(H5F_seq_writev, FAIL);
 
     /* Check args */
     assert(f);
     assert(layout);
-    assert(buf);
+    assert(real_buf);
 
 #ifdef H5_HAVE_PARALLEL
     {
@@ -547,30 +563,11 @@ H5F_seq_write(H5F_t *f, hid_t dxpl_id, const struct H5O_layout_t *layout,
                       "filters are not allowed for contiguous data");
             }
             
-            /*
-             * Initialize loop variables.  The loop is a multi-dimensional loop
-             * that counts from SIZE down to zero and IDX is the counter.  Each
-             * element of IDX is treated as a digit with IDX[0] being the least
-             * significant digit.
-             */
-            if (efl && efl->nused>0) {
-                addr = 0;
-            } else {
-                addr = layout->addr;
 
-                /* Compute the size of the dataset in bytes */
-                for(u=0, max_data=1; u<layout->ndims; u++)
-                    max_data *= layout->dim[u];
-
-                /* Adjust the maximum size of the data by the offset into it */
-                max_data -= file_offset;
-            }
-            addr += file_offset;
-
-            /*
-             * Now begin to walk through the array, copying data from disk to
-             * memory.
-             */
+            /* Write directly to file if the dataset is in an external file */
+            if (efl && efl->nused>0) {
+                /* Iterate through the sequence vectors */
+                for(v=0; v<nseq; v++) {
 #ifdef H5_HAVE_PARALLEL
             if (H5FD_MPIO_COLLECTIVE==xfer_mode) {
                 /*
@@ -580,8 +577,8 @@ H5F_seq_write(H5F_t *f, hid_t dxpl_id, const struct H5O_layout_t *layout,
                  */
                 unsigned long max, min, temp;
 
-                temp = seq_len;
-                assert(temp==seq_len);	/* verify no overflow */
+                temp = seq_len_arr[v];
+                assert(temp==seq_len_arr[v]);	/* verify no overflow */
                 MPI_Allreduce(&temp, &max, 1, MPI_UNSIGNED_LONG, MPI_MAX,
                       H5FD_mpio_communicator(f->shared->lf));
                 MPI_Allreduce(&temp, &min, 1, MPI_UNSIGNED_LONG, MPI_MIN,
@@ -594,20 +591,26 @@ H5F_seq_write(H5F_t *f, hid_t dxpl_id, const struct H5O_layout_t *layout,
                       "collective access with unequal number of blocks not supported yet");
             }
 #endif
+                    /* Note: We can't use data sieve buffers for datasets in external files
+                     *  because the 'addr' of all external files is set to 0 (above) and
+                     *  all datasets in external files would alias to the same set of
+                     *  file offsets, totally mixing up the data sieve buffer information. -QAK
+                     */
+                    if (H5O_efl_write(f, efl, file_offset_arr[v], seq_len_arr[v], real_buf)<0) {
+                        HRETURN_ERROR(H5E_IO, H5E_WRITEERROR, FAIL,
+                              "external data write failed");
+                    }
 
-            /* Write directly to file if the dataset is in an external file */
-            if (efl && efl->nused>0) {
-                /* Note: We can't use data sieve buffers for datasets in external files
-                 *  because the 'addr' of all external files is set to 0 (above) and
-                 *  all datasets in external files would alias to the same set of
-                 *  file offsets, totally mixing up the data sieve buffer information. -QAK
-                 */
-                if (H5O_efl_write(f, efl, addr, seq_len, buf)<0) {
-                    HRETURN_ERROR(H5E_IO, H5E_WRITEERROR, FAIL,
-                          "external data write failed");
-                }
+                    /* Increment offset in buffer */
+                    real_buf += seq_len_arr[v];
+                } /* end for */
             } else {
-                if (H5F_contig_write(f, max_data, H5FD_MEM_DRAW, addr, seq_len, dxpl_id, buf)<0) {
+                /* Compute the size of the dataset in bytes */
+                for(u=1, max_data=layout->dim[0]; u<layout->ndims; u++)
+                    max_data *= layout->dim[u];
+
+                /* Pass along the vector of sequences to write */
+                if (H5F_contig_writev(f, max_data, H5FD_MEM_DRAW, layout->addr, nseq, seq_len_arr, file_offset_arr, dxpl_id, real_buf)<0) {
                     HRETURN_ERROR(H5E_IO, H5E_WRITEERROR, FAIL,
                               "block write failed");
                 }
@@ -615,286 +618,217 @@ H5F_seq_write(H5F_t *f, hid_t dxpl_id, const struct H5O_layout_t *layout,
             break;
 
         case H5D_CHUNKED:
-        {
-            /*
-             * This method is unable to access external raw data files 
-             */
-            if (efl && efl->nused>0) {
-                HRETURN_ERROR(H5E_IO, H5E_UNSUPPORTED, FAIL,
-                      "chunking and external files are mutually exclusive");
-            }
-            /* Compute the file offset coordinates and hyperslab size */
-            if((ndims=H5S_get_simple_extent_dims(file_space,dset_dims,NULL))<0)
-                HRETURN_ERROR(H5E_IO, H5E_UNSUPPORTED, FAIL, "unable to retrieve dataspace dimensions");
-            
-#ifdef QAK
-/* Print out the file offsets & hyperslab sizes */
-{
-    static int count=0;
-
-    if(count<1000000) {
-        printf("%s: elmt_size=%d, addr=%d, seq_len=%lu\n",FUNC,(int)elmt_size,(int)addr,(unsigned long)seq_len);
-        printf("%s: file_offset=%d\n",FUNC,(int)file_offset);
-        count++;
-    }
-}
-#endif /* QAK */
-#ifdef QAK
-            /* The library shouldn't be reading partial elements currently */
-            assert((seq_len%elmt_size)!=0);
-            assert((addr%elmt_size)!=0);
-#endif /* QAK */
-
-            /* Set location in dataset from the file_offset */
-            addr=file_offset;
-
-            /* Convert the bytes into elements */
-            seq_len/=elmt_size;
-            addr/=elmt_size;
-
-            /* Build the array of cumulative hyperslab sizes */
-            for(acc=1, i=(ndims-1); i>=0; i--) {
-                down_size[i]=acc;
-                acc*=dset_dims[i];
-#ifdef QAK
-printf("%s: acc=%ld, down_size[%d]=%ld\n",FUNC,(long)acc,i,(long)down_size[i]);
-#endif /* QAK */
-            } /* end for */
-
-            /* Compute the hyperslab offset from the address given */
-            for(i=ndims-1; i>=0; i--) {
-                coords[i]=addr%dset_dims[i];
-                addr/=dset_dims[i];
-#ifdef QAK
-printf("%s: addr=%lu, dset_dims[%d]=%ld, coords[%d]=%ld\n",FUNC,(unsigned long)addr,i,(long)dset_dims[i],i,(long)coords[i]);
-#endif /* QAK */
-            } /* end for */
-            coords[ndims]=0;   /* No offset for element info */
-#ifdef QAK
-printf("%s: addr=%lu, coords[%d]=%ld\n",FUNC,(unsigned long)addr,ndims,(long)coords[ndims]);
-#endif /* QAK */
-
-            /*
-             * Peel off initial partial hyperslabs until we've got a hyperslab which starts
-             *      at coord[n]==0 for dimensions 1->(ndims-1)  (i.e. starting at coordinate
-             *      zero for all dimensions except the slowest changing one
-             */
-            for(i=ndims-1; i>0 && seq_len>=down_size[i]; i--) {
-                hsize_t partial_size;       /* Size of the partial hyperslab in bytes */
-
-                /* Check if we have a partial hyperslab in this lower dimension */
-                if(coords[i]>0) {
-#ifdef QAK
-printf("%s: Need to get hyperslab, seq_len=%ld, coords[%d]=%ld\n",FUNC,(long)seq_len,i,(long)coords[i]);
-#endif /* QAK */
-                    /* Reset the partial hyperslab size */
-                    partial_size=1;
-
-                    /* Build the partial hyperslab information */
-                    for(j=0; j<ndims; j++) {
-                        if(i==j)
-                            hslab_size[j]=MIN(seq_len/down_size[i],dset_dims[i]-coords[i]);
-                        else
-                            if(j>i)
-                                hslab_size[j]=dset_dims[j];
-                            else
-                                hslab_size[j]=1;
-                        partial_size*=hslab_size[j];
-#ifdef QAK
-printf("%s: partial_size=%lu, hslab_size[%d]=%ld\n",FUNC,(unsigned long)partial_size,j,(long)hslab_size[j]);
-#endif /* QAK */
-                    } /* end for */
-                    hslab_size[ndims]=elmt_size;   /* basic hyperslab size is the element */
-#ifdef QAK
-printf("%s: partial_size=%lu, hslab_size[%d]=%ld\n",FUNC,(unsigned long)partial_size,ndims,(long)hslab_size[ndims]);
-#endif /* QAK */
-
-                    /* Write out the partial hyperslab */
-                    if (H5F_istore_write(f, dxpl_id, layout, pline, fill, coords,
-                                 hslab_size, buf)<0) {
-                        HRETURN_ERROR(H5E_IO, H5E_READERROR, FAIL, "chunked write failed");
+            /* Brute-force, stupid way to implement the vectors, but too complex to do other ways... */
+            for(v=0; v<nseq; v++) {
+                file_offset=file_offset_arr[v];
+                seq_len=seq_len_arr[v];
+                buf=real_buf;
+
+                {
+                    /*
+                     * This method is unable to access external raw data files 
+                     */
+                    if (efl && efl->nused>0) {
+                        HRETURN_ERROR(H5E_IO, H5E_UNSUPPORTED, FAIL,
+                              "chunking and external files are mutually exclusive");
                     }
+                    /* Compute the file offset coordinates and hyperslab size */
+                    if((ndims=H5S_get_simple_extent_dims(file_space,dset_dims,NULL))<0)
+                        HRETURN_ERROR(H5E_IO, H5E_UNSUPPORTED, FAIL, "unable to retrieve dataspace dimensions");
 
-                    /* Increment the buffer offset */
-                    buf=(const unsigned char *)buf+partial_size;
+                    /* Set location in dataset from the file_offset */
+                    addr=file_offset;
 
-                    /* Decrement the length of the sequence to read */
-                    seq_len-=partial_size;
-
-                    /* Correct the coords array */
-                    coords[i]=0;
-                    coords[i-1]++;
-                } /* end if */
-            } /* end for */
-#ifdef QAK
-printf("%s: seq_len=%lu\n",FUNC,(unsigned long)seq_len);
-#endif /* QAK */
-
-            /* Check if there is more than just a partial hyperslab to read */
-            if(seq_len>=down_size[0]) {
-                hsize_t tmp_seq_len;    /* Temp. size of the sequence in elements */
-                hsize_t full_size;      /* Size of the full hyperslab in bytes */
-
-                /* Get the sequence length for computing the hyperslab sizes */
-                tmp_seq_len=seq_len;
-
-                /* Reset the size of the hyperslab read in */
-                full_size=1;
-
-                /* Compute the hyperslab size from the length given */
-                for(i=ndims-1; i>=0; i--) {
-                    /* Check if the hyperslab is wider than the width of the dimension */
-                    if(tmp_seq_len>dset_dims[i]) {
-                        assert(0==coords[i]);
-                        hslab_size[i]=dset_dims[i];
-                    } /* end if */
-                    else 
-                        hslab_size[i]=tmp_seq_len;
+                    /* Convert the bytes into elements */
+                    seq_len/=elmt_size;
+                    addr/=elmt_size;
 
-                    /* compute the number of elements read in */
-                    full_size*=hslab_size[i];
-
-                    /* Fold the length into the length in the next highest dimension */
-                    tmp_seq_len/=dset_dims[i];
-#ifdef QAK
-printf("%s: tmp_seq_len=%lu, hslab_size[%d]=%ld\n",FUNC,(unsigned long)tmp_seq_len,i,(long)hslab_size[i]);
-#endif /* QAK */
-
-                    /* Make certain the hyperslab sizes don't go less than 1 for dimensions less than 0*/
-                    assert(tmp_seq_len>=1 || i==0);
-                } /* end for */
-                hslab_size[ndims]=elmt_size;   /* basic hyperslab size is the element */
-
-#ifdef QAK
-/* Print out the file offsets & hyperslab sizes */
-{
-    static int count=0;
-
-    if(count<1000000) {
-        printf("%s: elmt_size=%d, addr=%d, full_size=%ld, tmp_seq_len=%ld seq_len=%ld\n",FUNC,(int)elmt_size,(int)addr,(long)full_size,(long)tmp_seq_len,(long)seq_len);
-        for(i=0; i<ndims; i++)
-            printf("%s: dset_dims[%d]=%d\n",FUNC,i,(int)dset_dims[i]);
-        for(i=0; i<=ndims; i++)
-            printf("%s: coords[%d]=%d, hslab_size[%d]=%d\n",FUNC,i,(int)coords[i],(int)i,(int)hslab_size[i]);
-        count++;
-    }
-}
-#endif /* QAK */
+                    /* Build the array of cumulative hyperslab sizes */
+                    for(acc=1, i=(ndims-1); i>=0; i--) {
+                        down_size[i]=acc;
+                        acc*=dset_dims[i];
+                    } /* end for */
 
-                /* Write the full hyperslab in */
-                if (H5F_istore_write(f, dxpl_id, layout, pline, fill, coords,
-                             hslab_size, buf)<0) {
-                    HRETURN_ERROR(H5E_IO, H5E_READERROR, FAIL, "chunked write failed");
-                }
+                    /* Compute the hyperslab offset from the address given */
+                    for(i=ndims-1; i>=0; i--) {
+                        coords[i]=addr%dset_dims[i];
+                        addr/=dset_dims[i];
+                    } /* end for */
+                    coords[ndims]=0;   /* No offset for element info */
+
+                    /*
+                     * Peel off initial partial hyperslabs until we've got a hyperslab which starts
+                     *      at coord[n]==0 for dimensions 1->(ndims-1)  (i.e. starting at coordinate
+                     *      zero for all dimensions except the slowest changing one
+                     */
+                    for(i=ndims-1; i>0 && seq_len>=down_size[i]; i--) {
+                        hsize_t partial_size;       /* Size of the partial hyperslab in bytes */
+
+                        /* Check if we have a partial hyperslab in this lower dimension */
+                        if(coords[i]>0) {
+                            /* Reset the partial hyperslab size */
+                            partial_size=1;
+
+                            /* Build the partial hyperslab information */
+                            for(j=0; j<ndims; j++) {
+                                if(i==j)
+                                    hslab_size[j]=MIN(seq_len/down_size[i],dset_dims[i]-coords[i]);
+                                else
+                                    if(j>i)
+                                        hslab_size[j]=dset_dims[j];
+                                    else
+                                        hslab_size[j]=1;
+                                partial_size*=hslab_size[j];
+                            } /* end for */
+                            hslab_size[ndims]=elmt_size;   /* basic hyperslab size is the element */
+
+                            /* Write out the partial hyperslab */
+                            if (H5F_istore_write(f, dxpl_id, layout, pline, fill, coords,
+                                         hslab_size, buf)<0) {
+                                HRETURN_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "chunked write failed");
+                            }
+
+                            /* Increment the buffer offset */
+                            buf=(const unsigned char *)buf+partial_size;
+
+                            /* Decrement the length of the sequence to read */
+                            seq_len-=partial_size;
+
+                            /* Correct the coords array */
+                            coords[i]=0;
+                            coords[i-1]++;
+                        } /* end if */
+                    } /* end for */
 
-                /* Increment the buffer offset */
-                buf=(const unsigned char *)buf+full_size;
+                    /* Check if there is more than just a partial hyperslab to read */
+                    if(seq_len>=down_size[0]) {
+                        hsize_t tmp_seq_len;    /* Temp. size of the sequence in elements */
+                        hsize_t full_size;      /* Size of the full hyperslab in bytes */
 
-                /* Decrement the sequence length left */
-                seq_len-=full_size;
+                        /* Get the sequence length for computing the hyperslab sizes */
+                        tmp_seq_len=seq_len;
 
-                /* Increment coordinate of slowest changing dimension */
-                coords[0]+=hslab_size[0];
+                        /* Reset the size of the hyperslab read in */
+                        full_size=1;
 
-            } /* end if */
-#ifdef QAK
-printf("%s: seq_len=%lu\n",FUNC,(unsigned long)seq_len);
-#endif /* QAK */
+                        /* Compute the hyperslab size from the length given */
+                        for(i=ndims-1; i>=0; i--) {
+                            /* Check if the hyperslab is wider than the width of the dimension */
+                            if(tmp_seq_len>dset_dims[i]) {
+                                assert(0==coords[i]);
+                                hslab_size[i]=dset_dims[i];
+                            } /* end if */
+                            else 
+                                hslab_size[i]=tmp_seq_len;
 
-            /*
-             * Peel off final partial hyperslabs until we've finished reading all the data
-             */
-            if(seq_len>0) {
-                hsize_t partial_size;       /* Size of the partial hyperslab in bytes */
+                            /* compute the number of elements read in */
+                            full_size*=hslab_size[i];
 
-                /*
-                 * Peel off remaining partial hyperslabs, from the next-slowest dimension
-                 *  on down to the next-to-fastest changing dimension
-                 */
-                for(i=1; i<(ndims-1); i++) {
-                    /* Check if there are enough elements to read in a row in this dimension */
-                    if(seq_len>=down_size[i]) {
-#ifdef QAK
-printf("%s: seq_len=%ld, down_size[%d]=%ld\n",FUNC,(long)seq_len,i+1,(long)down_size[i+1]);
-#endif /* QAK */
-                        /* Reset the partial hyperslab size */
-                        partial_size=1;
-
-                        /* Build the partial hyperslab information */
-                        for(j=0; j<ndims; j++) {
-                            if(j<i)
-                                hslab_size[j]=1;
-                            else
-                                if(j==i)
-                                    hslab_size[j]=seq_len/down_size[j];
-                                else
-                                    hslab_size[j]=dset_dims[j];
+                            /* Fold the length into the length in the next highest dimension */
+                            tmp_seq_len/=dset_dims[i];
 
-                            partial_size*=hslab_size[j];
-#ifdef QAK
-printf("%s: partial_size=%lu, coords[%d]=%ld, hslab_size[%d]=%ld\n",FUNC,(unsigned long)partial_size,j,(long)coords[j],j,(long)hslab_size[j]);
-#endif /* QAK */
+                            /* Make certain the hyperslab sizes don't go less than 1 for dimensions less than 0*/
+                            assert(tmp_seq_len>=1 || i==0);
                         } /* end for */
                         hslab_size[ndims]=elmt_size;   /* basic hyperslab size is the element */
-#ifdef QAK
-printf("%s: partial_size=%lu, coords[%d]=%ld, hslab_size[%d]=%ld\n",FUNC,(unsigned long)partial_size,ndims,(long)coords[ndims],ndims,(long)hslab_size[ndims]);
-#endif /* QAK */
 
-                        /* Write out the partial hyperslab */
+                        /* Write the full hyperslab in */
                         if (H5F_istore_write(f, dxpl_id, layout, pline, fill, coords,
                                      hslab_size, buf)<0) {
-                            HRETURN_ERROR(H5E_IO, H5E_READERROR, FAIL, "chunked write failed");
+                            HRETURN_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "chunked write failed");
                         }
 
                         /* Increment the buffer offset */
-                        buf=(const unsigned char *)buf+partial_size;
+                        buf=(const unsigned char *)buf+full_size;
+
+                        /* Decrement the sequence length left */
+                        seq_len-=full_size;
 
-                        /* Decrement the length of the sequence to read */
-                        seq_len-=partial_size;
+                        /* Increment coordinate of slowest changing dimension */
+                        coords[0]+=hslab_size[0];
 
-                        /* Correct the coords array */
-                        coords[i]=hslab_size[i];
                     } /* end if */
-                } /* end for */
 
-                /* Handle fastest changing dimension if there are any elements left */
-                if(seq_len>0) {
-#ifdef QAK
-printf("%s: i=%d, seq_len=%ld\n",FUNC,ndims-1,(long)seq_len);
-#endif /* QAK */
-                    assert(seq_len<dset_dims[ndims-1]);
-
-                    /* Reset the partial hyperslab size */
-                    partial_size=1;
-
-                    /* Build the partial hyperslab information */
-                    for(j=0; j<ndims; j++) {
-                        if(j==(ndims-1))
-                            hslab_size[j]=seq_len;
-                        else
-                            hslab_size[j]=1;
-
-                        partial_size*=hslab_size[j];
-#ifdef QAK
-printf("%s: partial_size=%lu, coords[%d]=%ld, hslab_size[%d]=%ld\n",FUNC,(unsigned long)partial_size,j,(long)coords[j],j,(long)hslab_size[j]);
-#endif /* QAK */
-                    } /* end for */
-                    hslab_size[ndims]=elmt_size;   /* basic hyperslab size is the element */
-#ifdef QAK
-printf("%s: partial_size=%lu, coords[%d]=%ld, hslab_size[%d]=%ld\n",FUNC,(unsigned long)partial_size,ndims,(long)coords[ndims],ndims,(long)hslab_size[ndims]);
-#endif /* QAK */
-
-                    /* Write in the final partial hyperslab */
-                    if (H5F_istore_write(f, dxpl_id, layout, pline, fill, coords,
-                                 hslab_size, buf)<0) {
-                        HRETURN_ERROR(H5E_IO, H5E_READERROR, FAIL, "chunked write failed");
-                    }
+                    /*
+                     * Peel off final partial hyperslabs until we've finished reading all the data
+                     */
+                    if(seq_len>0) {
+                        hsize_t partial_size;       /* Size of the partial hyperslab in bytes */
+
+                        /*
+                         * Peel off remaining partial hyperslabs, from the next-slowest dimension
+                         *  on down to the next-to-fastest changing dimension
+                         */
+                        for(i=1; i<(ndims-1); i++) {
+                            /* Check if there are enough elements to read in a row in this dimension */
+                            if(seq_len>=down_size[i]) {
+                                /* Reset the partial hyperslab size */
+                                partial_size=1;
+
+                                /* Build the partial hyperslab information */
+                                for(j=0; j<ndims; j++) {
+                                    if(j<i)
+                                        hslab_size[j]=1;
+                                    else
+                                        if(j==i)
+                                            hslab_size[j]=seq_len/down_size[j];
+                                        else
+                                            hslab_size[j]=dset_dims[j];
+
+                                    partial_size*=hslab_size[j];
+                                } /* end for */
+                                hslab_size[ndims]=elmt_size;   /* basic hyperslab size is the element */
+
+                                /* Write out the partial hyperslab */
+                                if (H5F_istore_write(f, dxpl_id, layout, pline, fill, coords,
+                                             hslab_size, buf)<0) {
+                                    HRETURN_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "chunked write failed");
+                                }
+
+                                /* Increment the buffer offset */
+                                buf=(const unsigned char *)buf+partial_size;
+
+                                /* Decrement the length of the sequence to read */
+                                seq_len-=partial_size;
+
+                                /* Correct the coords array */
+                                coords[i]=hslab_size[i];
+                            } /* end if */
+                        } /* end for */
+
+                        /* Handle fastest changing dimension if there are any elements left */
+                        if(seq_len>0) {
+                            assert(seq_len<dset_dims[ndims-1]);
+
+                            /* Reset the partial hyperslab size */
+                            partial_size=1;
+
+                            /* Build the partial hyperslab information */
+                            for(j=0; j<ndims; j++) {
+                                if(j==(ndims-1))
+                                    hslab_size[j]=seq_len;
+                                else
+                                    hslab_size[j]=1;
+
+                                partial_size*=hslab_size[j];
+                            } /* end for */
+                            hslab_size[ndims]=elmt_size;   /* basic hyperslab size is the element */
+
+                            /* Write out the final partial hyperslab */
+                            if (H5F_istore_write(f, dxpl_id, layout, pline, fill, coords,
+                                         hslab_size, buf)<0) {
+                                HRETURN_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "chunked write failed");
+                            }
+
+                            /* Double-check the amount read in */
+                            assert(seq_len==partial_size);
+                        } /* end if */
+                    } /* end if */
+                }
+                /* Increment offset in buffer */
+                real_buf += seq_len_arr[v];
+            } /* end for */
 
-                    /* Double-check the amount read in */
-                    assert(seq_len==partial_size);
-                } /* end if */
-            } /* end if */
-        }
             break;
 
         default:
@@ -903,5 +837,5 @@ printf("%s: partial_size=%lu, coords[%d]=%ld, hslab_size[%d]=%ld\n",FUNC,(unsign
     }   /* end switch() */
 
     FUNC_LEAVE(SUCCEED);
-}   /* H5F_seq_write() */
+}   /* H5F_seq_writev() */