summaryrefslogtreecommitdiffstats
path: root/src/H5Fseq.c
blob: 56026e2ec6be74d5772161fa08829132de01d9db (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
/*
 * Copyright (C) 2000 NCSA
 *		      All rights reserved.
 *
 * Programmer: 	Quincey Koziol <koziol@ncsa.uiuc.edu>
 *	       	Thursday, September 28, 2000
 *
 * Purpose:	Provides I/O facilities for sequences of bytes stored with various 
 *      layout policies.  These routines are similar to the H5Farray.c routines,
 *      these deal in terms of byte offsets and lengths, not coordinates and
 *      hyperslab sizes.
 *
 */

#define H5F_PACKAGE		/*suppress error about including H5Fpkg	  */

#include <H5private.h>
#include <H5Dprivate.h>
#include <H5Eprivate.h>
#include <H5Fpkg.h>
#include <H5FDprivate.h>	/*file driver				  */
#include <H5Iprivate.h>
#include <H5MFprivate.h>
#include <H5MMprivate.h>	/*memory management			  */
#include <H5Oprivate.h>
#include <H5Pprivate.h>
#include <H5Vprivate.h>

/* MPIO driver functions are needed for some special checks */
#include <H5FDmpio.h>

/* Interface initialization */
#define PABLO_MASK	H5Fseq_mask
#define INTERFACE_INIT	NULL
static intn interface_initialize_g = 0;


/*-------------------------------------------------------------------------
 * Function:	H5F_seq_read
 *
 * Purpose:	Reads a sequence of bytes 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 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
 *              Thursday, September 28, 2000
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
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*/)
{
    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;
    haddr_t	addr=0;				/*address in file	*/
    intn	i,j;				/*counters		*/
#ifdef H5_HAVE_PARALLEL
    H5FD_mpio_xfer_t xfer_mode=H5FD_MPIO_INDEPENDENT;
#endif
   
    FUNC_ENTER(H5F_seq_read, FAIL);

    /* Check args */
    assert(f);
    assert(layout);
    assert(buf);

#ifdef H5_HAVE_PARALLEL
    {
        /* Get the transfer mode */
        H5D_xfer_t *dxpl;
        H5FD_mpio_dxpl_t *dx;

        if (H5P_DEFAULT!=dxpl_id && (dxpl=H5I_object(dxpl_id)) &&
                H5FD_MPIO==dxpl->driver_id && (dx=dxpl->driver_info) &&
                H5FD_MPIO_INDEPENDENT!=dx->xfer_mode) {
            xfer_mode = dx->xfer_mode;
        }
    }

    /* Collective MPIO access is unsupported for non-contiguous datasets */
    if (H5D_CONTIGUOUS!=layout->type && H5FD_MPIO_COLLECTIVE==xfer_mode) {
        HRETURN_ERROR (H5E_DATASET, H5E_READERROR, FAIL,
           "collective access on non-contiguous datasets not supported yet");
    }
#endif

    switch (layout->type) {
        case H5D_CONTIGUOUS:
            /* Filters cannot be used for contiguous data. */
            if (pline && pline->nfilters>0) {
                HRETURN_ERROR(H5E_IO, H5E_READERROR, FAIL,
                      "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;
            }
            addr += file_offset;

            /*
             * Now begin to walk through the array, copying data from disk to
             * memory.
             */
#ifdef H5_HAVE_PARALLEL
            if (H5FD_MPIO_COLLECTIVE==xfer_mode) {
                /*
                 * Currently supports same number of collective access. Need to
                 * be changed LATER to combine all reads into one collective MPIO
                 * call.
                 */
                unsigned long max, min, temp;

                temp = seq_len;
                assert(temp==seq_len);	/* 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,
                      H5FD_mpio_communicator(f->shared->lf));
#ifdef AKC
                printf("seq_len=%lu, min=%lu, max=%lu\n", temp, min, max);
#endif
                if (max != min)
                    HRETURN_ERROR(H5E_DATASET, H5E_READERROR, FAIL,
                      "collective access with unequal number of blocks not supported yet");
            }
#endif

            /* Read directly from file if the dataset is in an external file */
            /* 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 (efl && efl->nused>0) {
                if (H5O_efl_read(f, efl, addr, seq_len, buf)<0) {
                    HRETURN_ERROR(H5E_IO, H5E_READERROR, FAIL,
                          "external data read failed");
                }
            } else {
                if (H5F_contig_read(f, H5FD_MEM_DRAW, addr, seq_len, dxpl_id, buf)<0) {
                    HRETURN_ERROR(H5E_IO, H5E_READERROR, FAIL,
                              "block read failed");
                }
            } /* end else */
            break;

        case H5D_CHUNKED:
        {
            uintn       leading_partials;       /* Flag set if there are leading partial hyperslabs to take care of */

            /*
             * 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 */

            /* Compute the hyperslab offset from the address given */
            leading_partials=0;
            for(i=ndims-1; i>=0; i--) {
                coords[i]=addr%dset_dims[i];
                addr/=dset_dims[i];
                if(i>0 && coords[i]>0)
                    leading_partials=1;
#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]);
printf("%s: leading_partials=%u\n",FUNC,leading_partials);
#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,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 */

                    /* 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 */
#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;

                    /* 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 */

                /* 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;

                /* Decrement the sequence length left */
                seq_len-=full_size;

                /* 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 */

            /*
             * 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]) {
#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];

                            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 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 */
#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");
                    }

                    /* Double-check the amount read in */
                    assert(seq_len==partial_size);
                } /* end if */
            } /* end if */
        }
            break;

        default:
            assert("not implemented yet" && 0);
            HRETURN_ERROR(H5E_IO, H5E_UNSUPPORTED, FAIL, "unsupported storage layout");
    }   /* end switch() */

    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:
 *
 *-------------------------------------------------------------------------
 */
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,
         hsize_t seq_len, hsize_t file_offset, const void *buf)
{
    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) */
    intn ndims;
    haddr_t	addr;				/*address in file	*/
    intn	i,j;				/*counters		*/
#ifdef H5_HAVE_PARALLEL
    H5FD_mpio_xfer_t xfer_mode=H5FD_MPIO_INDEPENDENT;
#endif
   
    FUNC_ENTER(H5F_seq_write, FAIL);

    /* Check args */
    assert(f);
    assert(layout);
    assert(buf);

#ifdef H5_HAVE_PARALLEL
    {
        /* Get the transfer mode */
        H5D_xfer_t *dxpl;
        H5FD_mpio_dxpl_t *dx;

        if (H5P_DEFAULT!=dxpl_id && (dxpl=H5I_object(dxpl_id)) &&
                H5FD_MPIO==dxpl->driver_id && (dx=dxpl->driver_info) &&
                H5FD_MPIO_INDEPENDENT!=dx->xfer_mode) {
            xfer_mode = dx->xfer_mode;
        }
    }

    /* Collective MPIO access is unsupported for non-contiguous datasets */
    if (H5D_CONTIGUOUS!=layout->type && H5FD_MPIO_COLLECTIVE==xfer_mode) {
        HRETURN_ERROR (H5E_DATASET, H5E_WRITEERROR, FAIL,
           "collective access on non-contiguous datasets not supported yet");
    }
#endif

    switch (layout->type) {
        case H5D_CONTIGUOUS:
            /* Filters cannot be used for contiguous data. */
            if (pline && pline->nfilters>0) {
                HRETURN_ERROR(H5E_IO, H5E_WRITEERROR, FAIL,
                      "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;
            }
            addr += file_offset;

            /*
             * Now begin to walk through the array, copying data from disk to
             * memory.
             */
#ifdef H5_HAVE_PARALLEL
            if (H5FD_MPIO_COLLECTIVE==xfer_mode) {
                /*
                 * Currently supports same number of collective access. Need to
                 * be changed LATER to combine all reads into one collective MPIO
                 * call.
                 */
                unsigned long max, min, temp;

                temp = seq_len;
                assert(temp==seq_len);	/* 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,
                      H5FD_mpio_communicator(f->shared->lf));
#ifdef AKC
                printf("seq_len=%lu, min=%lu, max=%lu\n", temp, min, max);
#endif
                if (max != min)
                    HRETURN_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL,
                      "collective access with unequal number of blocks not supported yet");
            }
#endif

            /* Write directly to file if the dataset is in an external file */
            /* 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 (efl && efl->nused>0) {
                if (H5O_efl_write(f, efl, addr, seq_len, buf)<0) {
                    HRETURN_ERROR(H5E_IO, H5E_WRITEERROR, FAIL,
                          "external data write failed");
                }
            } else {
                if (H5F_contig_write(f, H5FD_MEM_DRAW, addr, seq_len, dxpl_id, buf)<0) {
                    HRETURN_ERROR(H5E_IO, H5E_WRITEERROR, FAIL,
                              "block write failed");
                }
            } /* end else */
            break;

        case H5D_CHUNKED:
        {
            uintn       leading_partials;       /* Flag set if there are leading partial hyperslabs to take care of */

            /*
             * 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 */
            leading_partials=0;
            for(i=ndims-1; i>=0; i--) {
                coords[i]=addr%dset_dims[i];
                addr/=dset_dims[i];
                if(i>0 && coords[i]>0)
                    leading_partials=1;
#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]);
printf("%s: leading_partials=%u\n",FUNC,leading_partials);
#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,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");
                    }

                    /* 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 */
#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;

                    /* 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 */

                /* 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");
                }

                /* Increment the buffer offset */
                buf=(const unsigned char *)buf+full_size;

                /* Decrement the sequence length left */
                seq_len-=full_size;

                /* Increment coordinate of slowest changing dimension */
                coords[0]+=hslab_size[0];

            } /* end if */
#ifdef QAK
printf("%s: seq_len=%lu\n",FUNC,(unsigned long)seq_len);
#endif /* QAK */

            /*
             * 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]) {
#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];

                            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 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");
                        }

                        /* 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) {
#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");
                    }

                    /* Double-check the amount read in */
                    assert(seq_len==partial_size);
                } /* end if */
            } /* end if */
        }
            break;

        default:
            assert("not implemented yet" && 0);
            HRETURN_ERROR(H5E_IO, H5E_UNSUPPORTED, FAIL, "unsupported storage layout");
    }   /* end switch() */

    FUNC_LEAVE(SUCCEED);
}   /* H5F_seq_write() */