summaryrefslogtreecommitdiffstats
path: root/src/H5Dscatgath.c
blob: 7cc075ed35c44c398565d2af1736f6012ea8c7d1 (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
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by The HDF Group.                                               *
 * Copyright by the Board of Trustees of the University of Illinois.         *
 * All rights reserved.                                                      *
 *                                                                           *
 * This file is part of HDF5.  The full HDF5 copyright notice, including     *
 * terms governing use, modification, and redistribution, is contained in    *
 * the COPYING file, which can be found at the root of the source code       *
 * distribution tree, or in https://www.hdfgroup.org/licenses.               *
 * If you do not have access to either file, you may request a copy from     *
 * help@hdfgroup.org.                                                        *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/****************/
/* Module Setup */
/****************/

#include "H5Dmodule.h" /* This source code file is part of the H5D module */

/***********/
/* Headers */
/***********/
#include "H5private.h"   /* Generic Functions			*/
#include "H5CXprivate.h" /* API Contexts                         */
#include "H5Dpkg.h"      /* Dataset functions			*/
#include "H5Eprivate.h"  /* Error handling		  	*/
#include "H5FLprivate.h" /* Free Lists                           */
#include "H5Iprivate.h"  /* IDs                                  */
#include "H5MMprivate.h" /* Memory management			*/

/****************/
/* Local Macros */
/****************/

/******************/
/* Local Typedefs */
/******************/

/********************/
/* Local Prototypes */
/********************/
static herr_t H5D__scatter_file(const H5D_io_info_t *io_info, const H5D_dset_io_info_t *dset_info,
                                H5S_sel_iter_t *file_iter, size_t nelmts, const void *buf);
static size_t H5D__gather_file(const H5D_io_info_t *io_info, const H5D_dset_io_info_t *dset_info,
                               H5S_sel_iter_t *file_iter, size_t nelmts, void *buf);
static herr_t H5D__compound_opt_read(size_t nelmts, H5S_sel_iter_t *iter, const H5D_type_info_t *type_info,
                                     uint8_t *tconv_buf, void *user_buf /*out*/);
static herr_t H5D__compound_opt_write(size_t nelmts, const H5D_type_info_t *type_info, uint8_t *tconv_buf);

/*********************/
/* Package Variables */
/*********************/

/*******************/
/* Local Variables */
/*******************/

/* Declare extern free list to manage the H5S_sel_iter_t struct */
H5FL_EXTERN(H5S_sel_iter_t);

/* Declare extern free list to manage sequences of size_t */
H5FL_SEQ_EXTERN(size_t);

/* Declare extern free list to manage sequences of hsize_t */
H5FL_SEQ_EXTERN(hsize_t);

/*-------------------------------------------------------------------------
 * Function:	H5D__scatter_file
 *
 * Purpose:	Scatters dataset elements from the type conversion buffer BUF
 *		to the file F where the data points are arranged according to
 *		the file dataspace FILE_SPACE and stored according to
 *		LAYOUT and EFL. Each element is ELMT_SIZE bytes.
 *		The caller is requesting that NELMTS elements are copied.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *              Thursday, June 20, 2002
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__scatter_file(const H5D_io_info_t *_io_info, const H5D_dset_io_info_t *_dset_info, H5S_sel_iter_t *iter,
                  size_t nelmts, const void *_buf)
{
    H5D_io_info_t      tmp_io_info;           /* Temporary I/O info object */
    H5D_dset_io_info_t tmp_dset_info;         /* Temporary I/O info object */
    hsize_t           *off = NULL;            /* Pointer to sequence offsets */
    hsize_t            mem_off;               /* Offset in memory */
    size_t             mem_curr_seq;          /* "Current sequence" in memory */
    size_t             dset_curr_seq;         /* "Current sequence" in dataset */
    size_t            *len = NULL;            /* Array to store sequence lengths */
    size_t             orig_mem_len, mem_len; /* Length of sequence in memory */
    size_t             nseq;                  /* Number of sequences generated */
    size_t             nelem;                 /* Number of elements used in sequences */
    size_t             dxpl_vec_size;         /* Vector length from API context's DXPL */
    size_t             vec_size;              /* Vector length */
    herr_t             ret_value = SUCCEED;   /* Return value */

    FUNC_ENTER_PACKAGE

    /* Check args */
    HDassert(_io_info);
    HDassert(_dset_info);
    HDassert(_dset_info->dset);
    HDassert(_dset_info->store);
    HDassert(iter);
    HDassert(nelmts > 0);
    HDassert(_buf);

    /* Set up temporary I/O info object */
    H5MM_memcpy(&tmp_io_info, _io_info, sizeof(*_io_info));
    HDmemcpy(&tmp_dset_info, _dset_info, sizeof(*_dset_info));
    tmp_io_info.op_type    = H5D_IO_OP_WRITE;
    tmp_dset_info.buf.cvp  = _buf;
    tmp_io_info.dsets_info = &tmp_dset_info;

    /* Get info from API context */
    if (H5CX_get_vec_size(&dxpl_vec_size) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't retrieve I/O vector size")

    /* Allocate the vector I/O arrays */
    if (dxpl_vec_size > H5D_IO_VECTOR_SIZE)
        vec_size = dxpl_vec_size;
    else
        vec_size = H5D_IO_VECTOR_SIZE;
    if (NULL == (len = H5FL_SEQ_MALLOC(size_t, vec_size)))
        HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, FAIL, "can't allocate I/O length vector array")
    if (NULL == (off = H5FL_SEQ_MALLOC(hsize_t, vec_size)))
        HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, FAIL, "can't allocate I/O offset vector array")

    /* Loop until all elements are written */
    while (nelmts > 0) {
        /* Get list of sequences for selection to write */
        if (H5S_SELECT_ITER_GET_SEQ_LIST(iter, vec_size, nelmts, &nseq, &nelem, off, len) < 0)
            HGOTO_ERROR(H5E_INTERNAL, H5E_UNSUPPORTED, FAIL, "sequence length generation failed")

        /* Reset the current sequence information */
        mem_curr_seq = dset_curr_seq = 0;
        orig_mem_len = mem_len = nelem * iter->elmt_size;
        mem_off                = 0;

        /* Write sequence list out */
        if ((*tmp_dset_info.layout_ops.writevv)(&tmp_io_info, &tmp_dset_info, nseq, &dset_curr_seq, len, off,
                                                (size_t)1, &mem_curr_seq, &mem_len, &mem_off) < 0)
            HGOTO_ERROR(H5E_DATASPACE, H5E_WRITEERROR, FAIL, "write error")

        /* Update buffer */
        tmp_dset_info.buf.cvp = (const uint8_t *)tmp_dset_info.buf.cvp + orig_mem_len;

        /* Decrement number of elements left to process */
        nelmts -= nelem;
    } /* end while */

done:
    /* Release resources, if allocated */
    if (len)
        len = H5FL_SEQ_FREE(size_t, len);
    if (off)
        off = H5FL_SEQ_FREE(hsize_t, off);

    FUNC_LEAVE_NOAPI(ret_value)
} /* H5D__scatter_file() */

/*-------------------------------------------------------------------------
 * Function:	H5D__gather_file
 *
 * Purpose:	Gathers data points from file F and accumulates them in the
 *		type conversion buffer BUF.  The LAYOUT argument describes
 *		how the data is stored on disk and EFL describes how the data
 *		is organized in external files.  ELMT_SIZE is the size in
 *		bytes of a datum which this function treats as opaque.
 *		FILE_SPACE describes the dataspace of the dataset on disk
 *		and the elements that have been selected for reading (via
 *		hyperslab, etc).  This function will copy at most NELMTS
 *		elements.
 *
 * Return:	Success:	Number of elements copied.
 *		Failure:	0
 *
 * Programmer:	Quincey Koziol
 *              Monday, June 24, 2002
 *
 *-------------------------------------------------------------------------
 */
static size_t
H5D__gather_file(const H5D_io_info_t *_io_info, const H5D_dset_io_info_t *_dset_info, H5S_sel_iter_t *iter,
                 size_t nelmts, void *_buf /*out*/)
{
    H5D_io_info_t      tmp_io_info;           /* Temporary I/O info object */
    H5D_dset_io_info_t tmp_dset_info;         /* Temporary I/O info object */
    hsize_t           *off = NULL;            /* Pointer to sequence offsets */
    hsize_t            mem_off;               /* Offset in memory */
    size_t             mem_curr_seq;          /* "Current sequence" in memory */
    size_t             dset_curr_seq;         /* "Current sequence" in dataset */
    size_t            *len = NULL;            /* Pointer to sequence lengths */
    size_t             orig_mem_len, mem_len; /* Length of sequence in memory */
    size_t             nseq;                  /* Number of sequences generated */
    size_t             nelem;                 /* Number of elements used in sequences */
    size_t             dxpl_vec_size;         /* Vector length from API context's DXPL */
    size_t             vec_size;              /* Vector length */
    size_t             ret_value = nelmts;    /* Return value */

    FUNC_ENTER_PACKAGE

    /* Check args */
    HDassert(_io_info);
    HDassert(_dset_info);
    HDassert(_dset_info->dset);
    HDassert(_dset_info->store);
    HDassert(iter);
    HDassert(nelmts > 0);
    HDassert(_buf);

    /* Set up temporary I/O info object */
    H5MM_memcpy(&tmp_io_info, _io_info, sizeof(*_io_info));
    HDmemcpy(&tmp_dset_info, _dset_info, sizeof(*_dset_info));
    tmp_io_info.op_type    = H5D_IO_OP_READ;
    tmp_dset_info.buf.vp   = _buf;
    tmp_io_info.dsets_info = &tmp_dset_info;

    /* Get info from API context */
    if (H5CX_get_vec_size(&dxpl_vec_size) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, 0, "can't retrieve I/O vector size")

    /* Allocate the vector I/O arrays */
    if (dxpl_vec_size > H5D_IO_VECTOR_SIZE)
        vec_size = dxpl_vec_size;
    else
        vec_size = H5D_IO_VECTOR_SIZE;
    if (NULL == (len = H5FL_SEQ_MALLOC(size_t, vec_size)))
        HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, 0, "can't allocate I/O length vector array")
    if (NULL == (off = H5FL_SEQ_MALLOC(hsize_t, vec_size)))
        HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, 0, "can't allocate I/O offset vector array")

    /* Loop until all elements are read */
    while (nelmts > 0) {
        /* Get list of sequences for selection to read */
        if (H5S_SELECT_ITER_GET_SEQ_LIST(iter, vec_size, nelmts, &nseq, &nelem, off, len) < 0)
            HGOTO_ERROR(H5E_INTERNAL, H5E_UNSUPPORTED, 0, "sequence length generation failed")

        /* Reset the current sequence information */
        mem_curr_seq = dset_curr_seq = 0;
        orig_mem_len = mem_len = nelem * iter->elmt_size;
        mem_off                = 0;

        /* Read sequence list in */
        if ((*tmp_dset_info.layout_ops.readvv)(&tmp_io_info, &tmp_dset_info, nseq, &dset_curr_seq, len, off,
                                               (size_t)1, &mem_curr_seq, &mem_len, &mem_off) < 0)
            HGOTO_ERROR(H5E_DATASPACE, H5E_READERROR, 0, "read error")

        /* Update buffer */
        tmp_dset_info.buf.vp = (uint8_t *)tmp_dset_info.buf.vp + orig_mem_len;

        /* Decrement number of elements left to process */
        nelmts -= nelem;
    } /* end while */

done:
    /* Release resources, if allocated */
    if (len)
        len = H5FL_SEQ_FREE(size_t, len);
    if (off)
        off = H5FL_SEQ_FREE(hsize_t, off);

    FUNC_LEAVE_NOAPI(ret_value)
} /* H5D__gather_file() */

/*-------------------------------------------------------------------------
 * Function:	H5D__scatter_mem
 *
 * Purpose:	Scatters NELMTS data points from the scatter buffer
 *		TSCAT_BUF to the application buffer BUF.  Each element is
 *		ELMT_SIZE bytes and they are organized in application memory
 *		according to SPACE.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *              Monday, July 8, 2002
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5D__scatter_mem(const void *_tscat_buf, H5S_sel_iter_t *iter, size_t nelmts, void *_buf /*out*/)
{
    uint8_t       *buf       = (uint8_t *)_buf; /* Get local copies for address arithmetic */
    const uint8_t *tscat_buf = (const uint8_t *)_tscat_buf;
    hsize_t       *off       = NULL;    /* Pointer to sequence offsets */
    size_t        *len       = NULL;    /* Pointer to sequence lengths */
    size_t         curr_len;            /* Length of bytes left to process in sequence */
    size_t         nseq;                /* Number of sequences generated */
    size_t         curr_seq;            /* Current sequence being processed */
    size_t         nelem;               /* Number of elements used in sequences */
    size_t         dxpl_vec_size;       /* Vector length from API context's DXPL */
    size_t         vec_size;            /* Vector length */
    herr_t         ret_value = SUCCEED; /* Number of elements scattered */

    FUNC_ENTER_PACKAGE

    /* Check args */
    HDassert(tscat_buf);
    HDassert(iter);
    HDassert(nelmts > 0);
    HDassert(buf);

    /* Get info from API context */
    if (H5CX_get_vec_size(&dxpl_vec_size) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't retrieve I/O vector size")

    /* Allocate the vector I/O arrays */
    if (dxpl_vec_size > H5D_IO_VECTOR_SIZE)
        vec_size = dxpl_vec_size;
    else
        vec_size = H5D_IO_VECTOR_SIZE;
    if (NULL == (len = H5FL_SEQ_MALLOC(size_t, vec_size)))
        HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, FAIL, "can't allocate I/O length vector array")
    if (NULL == (off = H5FL_SEQ_MALLOC(hsize_t, vec_size)))
        HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, FAIL, "can't allocate I/O offset vector array")

    /* Loop until all elements are written */
    while (nelmts > 0) {
        /* Get list of sequences for selection to write */
        if (H5S_SELECT_ITER_GET_SEQ_LIST(iter, vec_size, nelmts, &nseq, &nelem, off, len) < 0)
            HGOTO_ERROR(H5E_INTERNAL, H5E_UNSUPPORTED, 0, "sequence length generation failed")

        /* Loop, while sequences left to process */
        for (curr_seq = 0; curr_seq < nseq; curr_seq++) {
            /* Get the number of bytes in sequence */
            curr_len = len[curr_seq];

            H5MM_memcpy(buf + off[curr_seq], tscat_buf, curr_len);

            /* Advance offset in destination buffer */
            tscat_buf += curr_len;
        } /* end for */

        /* Decrement number of elements left to process */
        nelmts -= nelem;
    } /* end while */

done:
    /* Release resources, if allocated */
    if (len)
        len = H5FL_SEQ_FREE(size_t, len);
    if (off)
        off = H5FL_SEQ_FREE(hsize_t, off);

    FUNC_LEAVE_NOAPI(ret_value)
} /* H5D__scatter_mem() */

/*-------------------------------------------------------------------------
 * Function:	H5D__gather_mem
 *
 * Purpose:	Gathers dataset elements from application memory BUF and
 *		copies them into the gather buffer TGATH_BUF.
 *		Each element is ELMT_SIZE bytes and arranged in application
 *		memory according to SPACE.
 *		The caller is requesting that exactly NELMTS be gathered.
 *
 * Return:	Success:	Number of elements copied.
 *		Failure:	0
 *
 * Programmer:	Quincey Koziol
 *              Monday, June 24, 2002
 *
 *-------------------------------------------------------------------------
 */
size_t
H5D__gather_mem(const void *_buf, H5S_sel_iter_t *iter, size_t nelmts, void *_tgath_buf /*out*/)
{
    const uint8_t *buf       = (const uint8_t *)_buf; /* Get local copies for address arithmetic */
    uint8_t       *tgath_buf = (uint8_t *)_tgath_buf;
    hsize_t       *off       = NULL;   /* Pointer to sequence offsets */
    size_t        *len       = NULL;   /* Pointer to sequence lengths */
    size_t         curr_len;           /* Length of bytes left to process in sequence */
    size_t         nseq;               /* Number of sequences generated */
    size_t         curr_seq;           /* Current sequence being processed */
    size_t         nelem;              /* Number of elements used in sequences */
    size_t         dxpl_vec_size;      /* Vector length from API context's DXPL */
    size_t         vec_size;           /* Vector length */
    size_t         ret_value = nelmts; /* Number of elements gathered */

    FUNC_ENTER_PACKAGE

    /* Check args */
    HDassert(buf);
    HDassert(iter);
    HDassert(nelmts > 0);
    HDassert(tgath_buf);

    /* Get info from API context */
    if (H5CX_get_vec_size(&dxpl_vec_size) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, 0, "can't retrieve I/O vector size")

    /* Allocate the vector I/O arrays */
    if (dxpl_vec_size > H5D_IO_VECTOR_SIZE)
        vec_size = dxpl_vec_size;
    else
        vec_size = H5D_IO_VECTOR_SIZE;
    if (NULL == (len = H5FL_SEQ_MALLOC(size_t, vec_size)))
        HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, 0, "can't allocate I/O length vector array")
    if (NULL == (off = H5FL_SEQ_MALLOC(hsize_t, vec_size)))
        HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, 0, "can't allocate I/O offset vector array")

    /* Loop until all elements are written */
    while (nelmts > 0) {
        /* Get list of sequences for selection to write */
        if (H5S_SELECT_ITER_GET_SEQ_LIST(iter, vec_size, nelmts, &nseq, &nelem, off, len) < 0)
            HGOTO_ERROR(H5E_INTERNAL, H5E_UNSUPPORTED, 0, "sequence length generation failed")

        /* Loop, while sequences left to process */
        for (curr_seq = 0; curr_seq < nseq; curr_seq++) {
            /* Get the number of bytes in sequence */
            curr_len = len[curr_seq];

            H5MM_memcpy(tgath_buf, buf + off[curr_seq], curr_len);

            /* Advance offset in gather buffer */
            tgath_buf += curr_len;
        } /* end for */

        /* Decrement number of elements left to process */
        nelmts -= nelem;
    } /* end while */

done:
    /* Release resources, if allocated */
    if (len)
        len = H5FL_SEQ_FREE(size_t, len);
    if (off)
        off = H5FL_SEQ_FREE(hsize_t, off);

    FUNC_LEAVE_NOAPI(ret_value)
} /* H5D__gather_mem() */

/*-------------------------------------------------------------------------
 * Function:	H5D__scatgath_read
 *
 * Purpose:	Perform scatter/gather ead from a contiguous [piece of a] dataset.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		Thursday, March  6, 2008
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5D__scatgath_read(const H5D_io_info_t *io_info, const H5D_dset_io_info_t *dset_info)
{
    void           *buf;                    /* Local pointer to application buffer */
    H5S_sel_iter_t *mem_iter       = NULL;  /* Memory selection iteration info*/
    hbool_t         mem_iter_init  = FALSE; /* Memory selection iteration info has been initialized */
    H5S_sel_iter_t *bkg_iter       = NULL;  /* Background iteration info*/
    hbool_t         bkg_iter_init  = FALSE; /* Background iteration info has been initialized */
    H5S_sel_iter_t *file_iter      = NULL;  /* File selection iteration info*/
    hbool_t         file_iter_init = FALSE; /* File selection iteration info has been initialized */
    hsize_t         smine_start;            /* Strip mine start loc	*/
    size_t          smine_nelmts;           /* Elements per strip	*/
    herr_t          ret_value = SUCCEED;    /* Return value		*/

    FUNC_ENTER_PACKAGE

    /* Sanity check */
    HDassert(io_info);
    HDassert(dset_info);
    HDassert(dset_info->mem_space);
    HDassert(dset_info->file_space);
    HDassert(dset_info->buf.vp);

    /* Set buf pointer */
    buf = dset_info->buf.vp;

    /* Check for NOOP read */
    if (dset_info->nelmts == 0)
        HGOTO_DONE(SUCCEED)

    /* Allocate the iterators */
    if (NULL == (mem_iter = H5FL_MALLOC(H5S_sel_iter_t)))
        HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, FAIL, "can't allocate memory iterator")
    if (NULL == (bkg_iter = H5FL_MALLOC(H5S_sel_iter_t)))
        HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, FAIL, "can't allocate background iterator")
    if (NULL == (file_iter = H5FL_MALLOC(H5S_sel_iter_t)))
        HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, FAIL, "can't allocate file iterator")

    /* Figure out the strip mine size. */
    if (H5S_select_iter_init(file_iter, dset_info->file_space, dset_info->type_info.src_type_size,
                             H5S_SEL_ITER_GET_SEQ_LIST_SORTED) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize file selection information")
    file_iter_init = TRUE; /*file selection iteration info has been initialized */
    if (H5S_select_iter_init(mem_iter, dset_info->mem_space, dset_info->type_info.dst_type_size, 0) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize memory selection information")
    mem_iter_init = TRUE; /*file selection iteration info has been initialized */
    if (H5S_select_iter_init(bkg_iter, dset_info->mem_space, dset_info->type_info.dst_type_size, 0) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize background selection information")
    bkg_iter_init = TRUE; /*file selection iteration info has been initialized */

    /* Start strip mining... */
    for (smine_start = 0; smine_start < dset_info->nelmts; smine_start += smine_nelmts) {
        size_t n; /* Elements operated on */

        /* Go figure out how many elements to read from the file */
        HDassert(H5S_SELECT_ITER_NELMTS(file_iter) == (dset_info->nelmts - smine_start));
        smine_nelmts = (size_t)MIN(dset_info->type_info.request_nelmts, (dset_info->nelmts - smine_start));

        /*
         * Gather the data from disk into the datatype conversion
         * buffer. Also gather data from application to background buffer
         * if necessary.
         */

        /*
         * Gather data
         */
        n = H5D__gather_file(io_info, dset_info, file_iter, smine_nelmts, io_info->tconv_buf /*out*/);
        if (n != smine_nelmts)
            HGOTO_ERROR(H5E_IO, H5E_READERROR, FAIL, "file gather failed")

        /* If the source and destination are compound types and subset of each other
         * and no conversion is needed, copy the data directly into user's buffer and
         * bypass the rest of steps.
         */
        if (dset_info->type_info.cmpd_subset &&
            H5T_SUBSET_FALSE != dset_info->type_info.cmpd_subset->subset) {
            if (H5D__compound_opt_read(smine_nelmts, mem_iter, &dset_info->type_info, io_info->tconv_buf,
                                       buf /*out*/) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "datatype conversion failed")
        } /* end if */
        else {
            if (H5T_BKG_YES == dset_info->type_info.need_bkg) {
                n = H5D__gather_mem(buf, bkg_iter, smine_nelmts, dset_info->type_info.bkg_buf /*out*/);
                if (n != smine_nelmts)
                    HGOTO_ERROR(H5E_IO, H5E_READERROR, FAIL, "mem gather failed")
            } /* end if */

            /*
             * Perform datatype conversion.
             */
            if (H5T_convert(dset_info->type_info.tpath, dset_info->type_info.src_type_id,
                            dset_info->type_info.dst_type_id, smine_nelmts, (size_t)0, (size_t)0,
                            io_info->tconv_buf, dset_info->type_info.bkg_buf) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_CANTCONVERT, FAIL, "datatype conversion failed")

            /* Do the data transform after the conversion (since we're using type mem_type) */
            if (!dset_info->type_info.is_xform_noop) {
                H5Z_data_xform_t *data_transform; /* Data transform info */

                /* Retrieve info from API context */
                if (H5CX_get_data_transform(&data_transform) < 0)
                    HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get data transform info")

                if (H5Z_xform_eval(data_transform, io_info->tconv_buf, smine_nelmts,
                                   dset_info->type_info.mem_type) < 0)
                    HGOTO_ERROR(H5E_DATASET, H5E_BADVALUE, FAIL, "Error performing data transform")
            }

            /* Scatter the data into memory */
            if (H5D__scatter_mem(io_info->tconv_buf, mem_iter, smine_nelmts, buf /*out*/) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "scatter failed")
        } /* end else */
    }     /* end for */

done:
    /* Release selection iterators */
    if (file_iter_init && H5S_SELECT_ITER_RELEASE(file_iter) < 0)
        HDONE_ERROR(H5E_DATASET, H5E_CANTFREE, FAIL, "Can't release selection iterator")
    if (file_iter)
        file_iter = H5FL_FREE(H5S_sel_iter_t, file_iter);
    if (mem_iter_init && H5S_SELECT_ITER_RELEASE(mem_iter) < 0)
        HDONE_ERROR(H5E_DATASET, H5E_CANTFREE, FAIL, "Can't release selection iterator")
    if (mem_iter)
        mem_iter = H5FL_FREE(H5S_sel_iter_t, mem_iter);
    if (bkg_iter_init && H5S_SELECT_ITER_RELEASE(bkg_iter) < 0)
        HDONE_ERROR(H5E_DATASET, H5E_CANTFREE, FAIL, "Can't release selection iterator")
    if (bkg_iter)
        bkg_iter = H5FL_FREE(H5S_sel_iter_t, bkg_iter);

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__scatgath_read() */

/*-------------------------------------------------------------------------
 * Function:	H5D__scatgath_write
 *
 * Purpose:	Perform scatter/gather write to a contiguous [piece of a] dataset.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		Thursday, March  6, 2008
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5D__scatgath_write(const H5D_io_info_t *io_info, const H5D_dset_io_info_t *dset_info)
{
    const void     *buf;                    /* Local pointer to application buffer */
    H5S_sel_iter_t *mem_iter       = NULL;  /* Memory selection iteration info*/
    hbool_t         mem_iter_init  = FALSE; /* Memory selection iteration info has been initialized */
    H5S_sel_iter_t *bkg_iter       = NULL;  /* Background iteration info*/
    hbool_t         bkg_iter_init  = FALSE; /* Background iteration info has been initialized */
    H5S_sel_iter_t *file_iter      = NULL;  /* File selection iteration info*/
    hbool_t         file_iter_init = FALSE; /* File selection iteration info has been initialized */
    hsize_t         smine_start;            /* Strip mine start loc	*/
    size_t          smine_nelmts;           /* Elements per strip	*/
    herr_t          ret_value = SUCCEED;    /* Return value		*/

    FUNC_ENTER_PACKAGE

    /* Sanity check */
    HDassert(io_info);
    HDassert(dset_info);
    HDassert(dset_info->mem_space);
    HDassert(dset_info->file_space);
    HDassert(dset_info->buf.vp);

    /* Set buf pointer */
    buf = dset_info->buf.cvp;

    /* Check for NOOP write */
    if (dset_info->nelmts == 0)
        HGOTO_DONE(SUCCEED)

    /* Allocate the iterators */
    if (NULL == (mem_iter = H5FL_MALLOC(H5S_sel_iter_t)))
        HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, FAIL, "can't allocate memory iterator")
    if (NULL == (bkg_iter = H5FL_MALLOC(H5S_sel_iter_t)))
        HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, FAIL, "can't allocate background iterator")
    if (NULL == (file_iter = H5FL_MALLOC(H5S_sel_iter_t)))
        HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, FAIL, "can't allocate file iterator")

    /* Figure out the strip mine size. */
    if (H5S_select_iter_init(file_iter, dset_info->file_space, dset_info->type_info.dst_type_size,
                             H5S_SEL_ITER_GET_SEQ_LIST_SORTED) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize file selection information")
    file_iter_init = TRUE; /*file selection iteration info has been initialized */
    if (H5S_select_iter_init(mem_iter, dset_info->mem_space, dset_info->type_info.src_type_size, 0) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize memory selection information")
    mem_iter_init = TRUE; /*file selection iteration info has been initialized */
    if (H5S_select_iter_init(bkg_iter, dset_info->file_space, dset_info->type_info.dst_type_size,
                             H5S_SEL_ITER_GET_SEQ_LIST_SORTED) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize background selection information")
    bkg_iter_init = TRUE; /*file selection iteration info has been initialized */

    /* Start strip mining... */
    for (smine_start = 0; smine_start < dset_info->nelmts; smine_start += smine_nelmts) {
        size_t n; /* Elements operated on */

        /* Go figure out how many elements to read from the file */
        HDassert(H5S_SELECT_ITER_NELMTS(file_iter) == (dset_info->nelmts - smine_start));
        smine_nelmts = (size_t)MIN(dset_info->type_info.request_nelmts, (dset_info->nelmts - smine_start));

        /*
         * Gather data from application buffer into the datatype conversion
         * buffer. Also gather data from the file into the background buffer
         * if necessary.
         */
        n = H5D__gather_mem(buf, mem_iter, smine_nelmts, io_info->tconv_buf /*out*/);
        if (n != smine_nelmts)
            HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "mem gather failed")

        /* If the source and destination are compound types and the destination is
         * is a subset of the source and no conversion is needed, copy the data
         * directly into user's buffer and bypass the rest of steps.  If the source
         * is a subset of the destination, the optimization is done in conversion
         * function H5T_conv_struct_opt to protect the background data.
         */
        if (dset_info->type_info.cmpd_subset && H5T_SUBSET_DST == dset_info->type_info.cmpd_subset->subset &&
            dset_info->type_info.dst_type_size == dset_info->type_info.cmpd_subset->copy_size) {
            if (H5D__compound_opt_write(smine_nelmts, &dset_info->type_info, io_info->tconv_buf) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "datatype conversion failed")
        } /* end if */
        else {
            if (H5T_BKG_YES == dset_info->type_info.need_bkg) {
                n = H5D__gather_file(io_info, dset_info, bkg_iter, smine_nelmts,
                                     dset_info->type_info.bkg_buf /*out*/);
                if (n != smine_nelmts)
                    HGOTO_ERROR(H5E_IO, H5E_READERROR, FAIL, "file gather failed")
            } /* end if */

            /* Do the data transform before the type conversion (since
             * transforms must be done in the memory type). */
            if (!dset_info->type_info.is_xform_noop) {
                H5Z_data_xform_t *data_transform; /* Data transform info */

                /* Retrieve info from API context */
                if (H5CX_get_data_transform(&data_transform) < 0)
                    HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get data transform info")

                if (H5Z_xform_eval(data_transform, io_info->tconv_buf, smine_nelmts,
                                   dset_info->type_info.mem_type) < 0)
                    HGOTO_ERROR(H5E_DATASET, H5E_BADVALUE, FAIL, "Error performing data transform")
            }

            /*
             * Perform datatype conversion.
             */
            if (H5T_convert(dset_info->type_info.tpath, dset_info->type_info.src_type_id,
                            dset_info->type_info.dst_type_id, smine_nelmts, (size_t)0, (size_t)0,
                            io_info->tconv_buf, dset_info->type_info.bkg_buf) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_CANTCONVERT, FAIL, "datatype conversion failed")
        } /* end else */

        /*
         * Scatter the data out to the file.
         */
        if (H5D__scatter_file(io_info, dset_info, file_iter, smine_nelmts, io_info->tconv_buf) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "scatter failed")
    } /* end for */

done:
    /* Release selection iterators */
    if (file_iter_init && H5S_SELECT_ITER_RELEASE(file_iter) < 0)
        HDONE_ERROR(H5E_DATASET, H5E_CANTFREE, FAIL, "Can't release selection iterator")
    if (file_iter)
        file_iter = H5FL_FREE(H5S_sel_iter_t, file_iter);
    if (mem_iter_init && H5S_SELECT_ITER_RELEASE(mem_iter) < 0)
        HDONE_ERROR(H5E_DATASET, H5E_CANTFREE, FAIL, "Can't release selection iterator")
    if (mem_iter)
        mem_iter = H5FL_FREE(H5S_sel_iter_t, mem_iter);
    if (bkg_iter_init && H5S_SELECT_ITER_RELEASE(bkg_iter) < 0)
        HDONE_ERROR(H5E_DATASET, H5E_CANTFREE, FAIL, "Can't release selection iterator")
    if (bkg_iter)
        bkg_iter = H5FL_FREE(H5S_sel_iter_t, bkg_iter);

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__scatgath_write() */

/*-------------------------------------------------------------------------
 * Function:	H5D__compound_opt_read
 *
 * Purpose:	A special optimization case when the source and
 *              destination members are a subset of each other, and
 *              the order is the same, and no conversion is needed.
 *              For example:
 *                  struct source {            struct destination {
 *                      TYPE1 A;      -->          TYPE1 A;
 *                      TYPE2 B;      -->          TYPE2 B;
 *                      TYPE3 C;      -->          TYPE3 C;
 *                  };                             TYPE4 D;
 *                                                 TYPE5 E;
 *                                             };
 *              or
 *                  struct destination {       struct source {
 *                      TYPE1 A;      <--          TYPE1 A;
 *                      TYPE2 B;      <--          TYPE2 B;
 *                      TYPE3 C;      <--          TYPE3 C;
 *                  };                             TYPE4 D;
 *                                                 TYPE5 E;
 *                                             };
 *              The optimization is simply moving data to the appropriate
 *              places in the buffer.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Raymond Lu
 *		11 June 2007
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__compound_opt_read(size_t nelmts, H5S_sel_iter_t *iter, const H5D_type_info_t *type_info,
                       uint8_t *tconv_buf, void *user_buf /*out*/)
{
    uint8_t *ubuf = (uint8_t *)user_buf; /* Cast for pointer arithmetic	*/
    uint8_t *xdbuf;                      /* Pointer into dataset buffer */
    hsize_t *off = NULL;                 /* Pointer to sequence offsets */
    size_t  *len = NULL;                 /* Pointer to sequence lengths */
    size_t   src_stride, dst_stride, copy_size;
    size_t   dxpl_vec_size;       /* Vector length from API context's DXPL */
    size_t   vec_size;            /* Vector length */
    herr_t   ret_value = SUCCEED; /* Return value		*/

    FUNC_ENTER_PACKAGE

    /* Check args */
    HDassert(nelmts > 0);
    HDassert(iter);
    HDassert(type_info);
    HDassert(type_info->cmpd_subset);
    HDassert(H5T_SUBSET_SRC == type_info->cmpd_subset->subset ||
             H5T_SUBSET_DST == type_info->cmpd_subset->subset);
    HDassert(user_buf);

    /* Get info from API context */
    if (H5CX_get_vec_size(&dxpl_vec_size) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't retrieve I/O vector size")

    /* Allocate the vector I/O arrays */
    if (dxpl_vec_size > H5D_IO_VECTOR_SIZE)
        vec_size = dxpl_vec_size;
    else
        vec_size = H5D_IO_VECTOR_SIZE;
    if (NULL == (len = H5FL_SEQ_MALLOC(size_t, vec_size)))
        HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, FAIL, "can't allocate I/O length vector array")
    if (NULL == (off = H5FL_SEQ_MALLOC(hsize_t, vec_size)))
        HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, FAIL, "can't allocate I/O offset vector array")

    /* Get source & destination strides */
    src_stride = type_info->src_type_size;
    dst_stride = type_info->dst_type_size;

    /* Get the size, in bytes, to copy for each element */
    copy_size = type_info->cmpd_subset->copy_size;

    /* Loop until all elements are written */
    xdbuf = tconv_buf;
    while (nelmts > 0) {
        size_t nseq;     /* Number of sequences generated */
        size_t curr_seq; /* Current sequence being processed */
        size_t elmtno;   /* Element counter */

        /* Get list of sequences for selection to write */
        if (H5S_SELECT_ITER_GET_SEQ_LIST(iter, vec_size, nelmts, &nseq, &elmtno, off, len) < 0)
            HGOTO_ERROR(H5E_INTERNAL, H5E_UNSUPPORTED, 0, "sequence length generation failed")

        /* Loop, while sequences left to process */
        for (curr_seq = 0; curr_seq < nseq; curr_seq++) {
            size_t   curr_off;    /* Offset of bytes left to process in sequence */
            size_t   curr_len;    /* Length of bytes left to process in sequence */
            size_t   curr_nelmts; /* Number of elements to process in sequence   */
            uint8_t *xubuf;
            size_t   i; /* Local index variable */

            /* Get the number of bytes and offset in sequence */
            curr_len = len[curr_seq];
            H5_CHECK_OVERFLOW(off[curr_seq], hsize_t, size_t);
            curr_off = (size_t)off[curr_seq];

            /* Decide the number of elements and position in the buffer. */
            curr_nelmts = curr_len / dst_stride;
            xubuf       = ubuf + curr_off;

            /* Copy the data into the right place. */
            for (i = 0; i < curr_nelmts; i++) {
                HDmemmove(xubuf, xdbuf, copy_size);

                /* Update pointers */
                xdbuf += src_stride;
                xubuf += dst_stride;
            } /* end for */
        }     /* end for */

        /* Decrement number of elements left to process */
        nelmts -= elmtno;
    } /* end while */

done:
    /* Release resources, if allocated */
    if (len)
        len = H5FL_SEQ_FREE(size_t, len);
    if (off)
        off = H5FL_SEQ_FREE(hsize_t, off);

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__compound_opt_read() */

/*-------------------------------------------------------------------------
 * Function:	H5D__compound_opt_write
 *
 * Purpose:	A special optimization case when the source and
 *              destination members are a subset of each other, and
 *              the order is the same, and no conversion is needed.
 *              For example:
 *                  struct source {            struct destination {
 *                      TYPE1 A;      -->          TYPE1 A;
 *                      TYPE2 B;      -->          TYPE2 B;
 *                      TYPE3 C;      -->          TYPE3 C;
 *                  };                             TYPE4 D;
 *                                                 TYPE5 E;
 *                                             };
 *              or
 *                  struct destination {       struct source {
 *                      TYPE1 A;      <--          TYPE1 A;
 *                      TYPE2 B;      <--          TYPE2 B;
 *                      TYPE3 C;      <--          TYPE3 C;
 *                  };                             TYPE4 D;
 *                                                 TYPE5 E;
 *                                             };
 *              The optimization is simply moving data to the appropriate
 *              places in the buffer.
 *
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Raymond Lu
 *		11 June 2007
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__compound_opt_write(size_t nelmts, const H5D_type_info_t *type_info, uint8_t *tconv_buf)
{
    uint8_t *xsbuf, *xdbuf;          /* Source & destination pointers into dataset buffer */
    size_t   src_stride, dst_stride; /* Strides through source & destination datatypes */
    size_t   i;                      /* Local index variable */

    FUNC_ENTER_PACKAGE_NOERR

    /* Check args */
    HDassert(nelmts > 0);
    HDassert(type_info);

    /* Initialize values for loop */
    src_stride = type_info->src_type_size;
    dst_stride = type_info->dst_type_size;

    /* Loop until all elements are written */
    xsbuf = tconv_buf;
    xdbuf = tconv_buf;
    for (i = 0; i < nelmts; i++) {
        HDmemmove(xdbuf, xsbuf, dst_stride);

        /* Update pointers */
        xsbuf += src_stride;
        xdbuf += dst_stride;
    } /* end for */

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5D__compound_opt_write() */