aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/libs/icu/common/ucnv_u8.cpp
blob: cf3bb22a02a7f7b4ff60efedf9e036263b61ffaa (plain) (blame)
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
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*  
**********************************************************************
*   Copyright (C) 2002-2016, International Business Machines
*   Corporation and others.  All Rights Reserved.
**********************************************************************
*   file name:  ucnv_u8.c
*   encoding:   UTF-8
*   tab size:   8 (not used)
*   indentation:4
*
*   created on: 2002jul01
*   created by: Markus W. Scherer
*
*   UTF-8 converter implementation. Used to be in ucnv_utf.c.
*
*   Also, CESU-8 implementation, see UTR 26.
*   The CESU-8 converter uses all the same functions as the
*   UTF-8 converter, with a branch for converting supplementary code points.
*/

#include "unicode/utypes.h"

#if !UCONFIG_NO_CONVERSION

#include "unicode/ucnv.h"
#include "unicode/utf.h"
#include "unicode/utf8.h"
#include "unicode/utf16.h"
#include "uassert.h"
#include "ucnv_bld.h"
#include "ucnv_cnv.h"
#include "cmemory.h"
#include "ustr_imp.h"

/* Prototypes --------------------------------------------------------------- */

/* Keep these here to make finicky compilers happy */

U_CFUNC void ucnv_fromUnicode_UTF8(UConverterFromUnicodeArgs *args,
                                           UErrorCode *err);
U_CFUNC void ucnv_fromUnicode_UTF8_OFFSETS_LOGIC(UConverterFromUnicodeArgs *args,
                                                        UErrorCode *err);


/* UTF-8 -------------------------------------------------------------------- */

#define MAXIMUM_UCS2            0x0000FFFF

static const uint32_t offsetsFromUTF8[5] = {0,
  (uint32_t) 0x00000000, (uint32_t) 0x00003080, (uint32_t) 0x000E2080,
  (uint32_t) 0x03C82080
};

static UBool hasCESU8Data(const UConverter *cnv)
{
#if UCONFIG_ONLY_HTML_CONVERSION
    return false;
#else
    return (UBool)(cnv->sharedData == &_CESU8Data);
#endif
}
U_CDECL_BEGIN
static void  U_CALLCONV ucnv_toUnicode_UTF8 (UConverterToUnicodeArgs * args,
                                  UErrorCode * err)
{
    UConverter *cnv = args->converter;
    const unsigned char *mySource = (unsigned char *) args->source;
    char16_t *myTarget = args->target;
    const unsigned char *sourceLimit = (unsigned char *) args->sourceLimit;
    const char16_t *targetLimit = args->targetLimit;
    unsigned char *toUBytes = cnv->toUBytes;
    UBool isCESU8 = hasCESU8Data(cnv);
    uint32_t ch, ch2 = 0;
    int32_t i, inBytes;

    /* Restore size of current sequence */
    if (cnv->toULength > 0 && myTarget < targetLimit)
    {
        inBytes = cnv->mode;            /* restore # of bytes to consume */
        i = cnv->toULength;             /* restore # of bytes consumed */
        cnv->toULength = 0;

        ch = cnv->toUnicodeStatus;/*Stores the previously calculated ch from a previous call*/
        cnv->toUnicodeStatus = 0;
        goto morebytes;
    }


    while (mySource < sourceLimit && myTarget < targetLimit)
    {
        ch = *(mySource++);
        if (U8_IS_SINGLE(ch))        /* Simple case */
        {
            *(myTarget++) = (char16_t) ch;
        }
        else
        {
            /* store the first char */
            toUBytes[0] = (char)ch;
            inBytes = U8_COUNT_BYTES_NON_ASCII(ch); /* lookup current sequence length */
            i = 1;

morebytes:
            while (i < inBytes)
            {
                if (mySource < sourceLimit)
                {
                    toUBytes[i] = (char) (ch2 = *mySource);
                    if (!icu::UTF8::isValidTrail(ch, static_cast<uint8_t>(ch2), i, inBytes) &&
                            !(isCESU8 && i == 1 && ch == 0xed && U8_IS_TRAIL(ch2)))
                    {
                        break; /* i < inBytes */
                    }
                    ch = (ch << 6) + ch2;
                    ++mySource;
                    i++;
                }
                else
                {
                    /* stores a partially calculated target*/
                    cnv->toUnicodeStatus = ch;
                    cnv->mode = inBytes;
                    cnv->toULength = (int8_t) i;
                    goto donefornow;
                }
            }

            // In CESU-8, only surrogates, not supplementary code points, are encoded directly.
            if (i == inBytes && (!isCESU8 || i <= 3))
            {
                /* Remove the accumulated high bits */
                ch -= offsetsFromUTF8[inBytes];

                /* Normal valid byte when the loop has not prematurely terminated (i < inBytes) */
                if (ch <= MAXIMUM_UCS2) 
                {
                    /* fits in 16 bits */
                    *(myTarget++) = (char16_t) ch;
                }
                else
                {
                    /* write out the surrogates */
                    *(myTarget++) = U16_LEAD(ch);
                    ch = U16_TRAIL(ch);
                    if (myTarget < targetLimit)
                    {
                        *(myTarget++) = (char16_t)ch;
                    }
                    else
                    {
                        /* Put in overflow buffer (not handled here) */
                        cnv->UCharErrorBuffer[0] = (char16_t) ch;
                        cnv->UCharErrorBufferLength = 1;
                        *err = U_BUFFER_OVERFLOW_ERROR;
                        break;
                    }
                }
            }
            else
            {
                cnv->toULength = (int8_t)i;
                *err = U_ILLEGAL_CHAR_FOUND;
                break;
            }
        }
    }

donefornow:
    if (mySource < sourceLimit && myTarget >= targetLimit && U_SUCCESS(*err))
    {
        /* End of target buffer */
        *err = U_BUFFER_OVERFLOW_ERROR;
    }

    args->target = myTarget;
    args->source = (const char *) mySource;
}

static void  U_CALLCONV ucnv_toUnicode_UTF8_OFFSETS_LOGIC (UConverterToUnicodeArgs * args,
                                                UErrorCode * err)
{
    UConverter *cnv = args->converter;
    const unsigned char *mySource = (unsigned char *) args->source;
    char16_t *myTarget = args->target;
    int32_t *myOffsets = args->offsets;
    int32_t offsetNum = 0;
    const unsigned char *sourceLimit = (unsigned char *) args->sourceLimit;
    const char16_t *targetLimit = args->targetLimit;
    unsigned char *toUBytes = cnv->toUBytes;
    UBool isCESU8 = hasCESU8Data(cnv);
    uint32_t ch, ch2 = 0;
    int32_t i, inBytes;

    /* Restore size of current sequence */
    if (cnv->toULength > 0 && myTarget < targetLimit)
    {
        inBytes = cnv->mode;            /* restore # of bytes to consume */
        i = cnv->toULength;             /* restore # of bytes consumed */
        cnv->toULength = 0;

        ch = cnv->toUnicodeStatus;/*Stores the previously calculated ch from a previous call*/
        cnv->toUnicodeStatus = 0;
        goto morebytes;
    }

    while (mySource < sourceLimit && myTarget < targetLimit)
    {
        ch = *(mySource++);
        if (U8_IS_SINGLE(ch))        /* Simple case */
        {
            *(myTarget++) = (char16_t) ch;
            *(myOffsets++) = offsetNum++;
        }
        else
        {
            toUBytes[0] = (char)ch;
            inBytes = U8_COUNT_BYTES_NON_ASCII(ch);
            i = 1;

morebytes:
            while (i < inBytes)
            {
                if (mySource < sourceLimit)
                {
                    toUBytes[i] = (char) (ch2 = *mySource);
                    if (!icu::UTF8::isValidTrail(ch, static_cast<uint8_t>(ch2), i, inBytes) &&
                            !(isCESU8 && i == 1 && ch == 0xed && U8_IS_TRAIL(ch2)))
                    {
                        break; /* i < inBytes */
                    }
                    ch = (ch << 6) + ch2;
                    ++mySource;
                    i++;
                }
                else
                {
                    cnv->toUnicodeStatus = ch;
                    cnv->mode = inBytes;
                    cnv->toULength = (int8_t)i;
                    goto donefornow;
                }
            }

            // In CESU-8, only surrogates, not supplementary code points, are encoded directly.
            if (i == inBytes && (!isCESU8 || i <= 3))
            {
                /* Remove the accumulated high bits */
                ch -= offsetsFromUTF8[inBytes];

                /* Normal valid byte when the loop has not prematurely terminated (i < inBytes) */
                if (ch <= MAXIMUM_UCS2) 
                {
                    /* fits in 16 bits */
                    *(myTarget++) = (char16_t) ch;
                    *(myOffsets++) = offsetNum;
                }
                else
                {
                    /* write out the surrogates */
                    *(myTarget++) = U16_LEAD(ch);
                    *(myOffsets++) = offsetNum;
                    ch = U16_TRAIL(ch);
                    if (myTarget < targetLimit)
                    {
                        *(myTarget++) = (char16_t)ch;
                        *(myOffsets++) = offsetNum;
                    }
                    else
                    {
                        cnv->UCharErrorBuffer[0] = (char16_t) ch;
                        cnv->UCharErrorBufferLength = 1;
                        *err = U_BUFFER_OVERFLOW_ERROR;
                    }
                }
                offsetNum += i;
            }
            else
            {
                cnv->toULength = (int8_t)i;
                *err = U_ILLEGAL_CHAR_FOUND;
                break;
            }
        }
    }

donefornow:
    if (mySource < sourceLimit && myTarget >= targetLimit && U_SUCCESS(*err))
    {   /* End of target buffer */
        *err = U_BUFFER_OVERFLOW_ERROR;
    }

    args->target = myTarget;
    args->source = (const char *) mySource;
    args->offsets = myOffsets;
}
U_CDECL_END

U_CFUNC void  U_CALLCONV ucnv_fromUnicode_UTF8 (UConverterFromUnicodeArgs * args,
                                    UErrorCode * err)
{
    UConverter *cnv = args->converter;
    const char16_t *mySource = args->source;
    const char16_t *sourceLimit = args->sourceLimit;
    uint8_t *myTarget = (uint8_t *) args->target;
    const uint8_t *targetLimit = (uint8_t *) args->targetLimit;
    uint8_t *tempPtr;
    UChar32 ch;
    uint8_t tempBuf[4];
    int32_t indexToWrite;
    UBool isNotCESU8 = !hasCESU8Data(cnv);

    if (cnv->fromUChar32 && myTarget < targetLimit)
    {
        ch = cnv->fromUChar32;
        cnv->fromUChar32 = 0;
        goto lowsurrogate;
    }

    while (mySource < sourceLimit && myTarget < targetLimit)
    {
        ch = *(mySource++);

        if (ch < 0x80)        /* Single byte */
        {
            *(myTarget++) = (uint8_t) ch;
        }
        else if (ch < 0x800)  /* Double byte */
        {
            *(myTarget++) = (uint8_t) ((ch >> 6) | 0xc0);
            if (myTarget < targetLimit)
            {
                *(myTarget++) = (uint8_t) ((ch & 0x3f) | 0x80);
            }
            else
            {
                cnv->charErrorBuffer[0] = (uint8_t) ((ch & 0x3f) | 0x80);
                cnv->charErrorBufferLength = 1;
                *err = U_BUFFER_OVERFLOW_ERROR;
            }
        }
        else {
            /* Check for surrogates */
            if(U16_IS_SURROGATE(ch) && isNotCESU8) {
lowsurrogate:
                if (mySource < sourceLimit) {
                    /* test both code units */
                    if(U16_IS_SURROGATE_LEAD(ch) && U16_IS_TRAIL(*mySource)) {
                        /* convert and consume this supplementary code point */
                        ch=U16_GET_SUPPLEMENTARY(ch, *mySource);
                        ++mySource;
                        /* exit this condition tree */
                    }
                    else {
                        /* this is an unpaired trail or lead code unit */
                        /* callback(illegal) */
                        cnv->fromUChar32 = ch;
                        *err = U_ILLEGAL_CHAR_FOUND;
                        break;
                    }
                }
                else {
                    /* no more input */
                    cnv->fromUChar32 = ch;
                    break;
                }
            }

            /* Do we write the buffer directly for speed,
            or do we have to be careful about target buffer space? */
            tempPtr = (((targetLimit - myTarget) >= 4) ? myTarget : tempBuf);

            if (ch <= MAXIMUM_UCS2) {
                indexToWrite = 2;
                tempPtr[0] = (uint8_t) ((ch >> 12) | 0xe0);
            }
            else {
                indexToWrite = 3;
                tempPtr[0] = (uint8_t) ((ch >> 18) | 0xf0);
                tempPtr[1] = (uint8_t) (((ch >> 12) & 0x3f) | 0x80);
            }
            tempPtr[indexToWrite-1] = (uint8_t) (((ch >> 6) & 0x3f) | 0x80);
            tempPtr[indexToWrite] = (uint8_t) ((ch & 0x3f) | 0x80);

            if (tempPtr == myTarget) {
                /* There was enough space to write the codepoint directly. */
                myTarget += (indexToWrite + 1);
            }
            else {
                /* We might run out of room soon. Write it slowly. */
                for (; tempPtr <= (tempBuf + indexToWrite); tempPtr++) {
                    if (myTarget < targetLimit) {
                        *(myTarget++) = *tempPtr;
                    }
                    else {
                        cnv->charErrorBuffer[cnv->charErrorBufferLength++] = *tempPtr;
                        *err = U_BUFFER_OVERFLOW_ERROR;
                    }
                }
            }
        }
    }

    if (mySource < sourceLimit && myTarget >= targetLimit && U_SUCCESS(*err))
    {
        *err = U_BUFFER_OVERFLOW_ERROR;
    }

    args->target = (char *) myTarget;
    args->source = mySource;
}

U_CFUNC void  U_CALLCONV ucnv_fromUnicode_UTF8_OFFSETS_LOGIC (UConverterFromUnicodeArgs * args,
                                                  UErrorCode * err)
{
    UConverter *cnv = args->converter;
    const char16_t *mySource = args->source;
    int32_t *myOffsets = args->offsets;
    const char16_t *sourceLimit = args->sourceLimit;
    uint8_t *myTarget = (uint8_t *) args->target;
    const uint8_t *targetLimit = (uint8_t *) args->targetLimit;
    uint8_t *tempPtr;
    UChar32 ch;
    int32_t offsetNum, nextSourceIndex;
    int32_t indexToWrite;
    uint8_t tempBuf[4];
    UBool isNotCESU8 = !hasCESU8Data(cnv);

    if (cnv->fromUChar32 && myTarget < targetLimit)
    {
        ch = cnv->fromUChar32;
        cnv->fromUChar32 = 0;
        offsetNum = -1;
        nextSourceIndex = 0;
        goto lowsurrogate;
    } else {
        offsetNum = 0;
    }

    while (mySource < sourceLimit && myTarget < targetLimit)
    {
        ch = *(mySource++);

        if (ch < 0x80)        /* Single byte */
        {
            *(myOffsets++) = offsetNum++;
            *(myTarget++) = (char) ch;
        }
        else if (ch < 0x800)  /* Double byte */
        {
            *(myOffsets++) = offsetNum;
            *(myTarget++) = (uint8_t) ((ch >> 6) | 0xc0);
            if (myTarget < targetLimit)
            {
                *(myOffsets++) = offsetNum++;
                *(myTarget++) = (uint8_t) ((ch & 0x3f) | 0x80);
            }
            else
            {
                cnv->charErrorBuffer[0] = (uint8_t) ((ch & 0x3f) | 0x80);
                cnv->charErrorBufferLength = 1;
                *err = U_BUFFER_OVERFLOW_ERROR;
            }
        }
        else
        /* Check for surrogates */
        {
            nextSourceIndex = offsetNum + 1;

            if(U16_IS_SURROGATE(ch) && isNotCESU8) {
lowsurrogate:
                if (mySource < sourceLimit) {
                    /* test both code units */
                    if(U16_IS_SURROGATE_LEAD(ch) && U16_IS_TRAIL(*mySource)) {
                        /* convert and consume this supplementary code point */
                        ch=U16_GET_SUPPLEMENTARY(ch, *mySource);
                        ++mySource;
                        ++nextSourceIndex;
                        /* exit this condition tree */
                    }
                    else {
                        /* this is an unpaired trail or lead code unit */
                        /* callback(illegal) */
                        cnv->fromUChar32 = ch;
                        *err = U_ILLEGAL_CHAR_FOUND;
                        break;
                    }
                }
                else {
                    /* no more input */
                    cnv->fromUChar32 = ch;
                    break;
                }
            }

            /* Do we write the buffer directly for speed,
            or do we have to be careful about target buffer space? */
            tempPtr = (((targetLimit - myTarget) >= 4) ? myTarget : tempBuf);

            if (ch <= MAXIMUM_UCS2) {
                indexToWrite = 2;
                tempPtr[0] = (uint8_t) ((ch >> 12) | 0xe0);
            }
            else {
                indexToWrite = 3;
                tempPtr[0] = (uint8_t) ((ch >> 18) | 0xf0);
                tempPtr[1] = (uint8_t) (((ch >> 12) & 0x3f) | 0x80);
            }
            tempPtr[indexToWrite-1] = (uint8_t) (((ch >> 6) & 0x3f) | 0x80);
            tempPtr[indexToWrite] = (uint8_t) ((ch & 0x3f) | 0x80);

            if (tempPtr == myTarget) {
                /* There was enough space to write the codepoint directly. */
                myTarget += (indexToWrite + 1);
                myOffsets[0] = offsetNum;
                myOffsets[1] = offsetNum;
                myOffsets[2] = offsetNum;
                if (indexToWrite >= 3) {
                    myOffsets[3] = offsetNum;
                }
                myOffsets += (indexToWrite + 1);
            }
            else {
                /* We might run out of room soon. Write it slowly. */
                for (; tempPtr <= (tempBuf + indexToWrite); tempPtr++) {
                    if (myTarget < targetLimit)
                    {
                        *(myOffsets++) = offsetNum;
                        *(myTarget++) = *tempPtr;
                    }
                    else
                    {
                        cnv->charErrorBuffer[cnv->charErrorBufferLength++] = *tempPtr;
                        *err = U_BUFFER_OVERFLOW_ERROR;
                    }
                }
            }
            offsetNum = nextSourceIndex;
        }
    }

    if (mySource < sourceLimit && myTarget >= targetLimit && U_SUCCESS(*err))
    {
        *err = U_BUFFER_OVERFLOW_ERROR;
    }

    args->target = (char *) myTarget;
    args->source = mySource;
    args->offsets = myOffsets;
}

U_CDECL_BEGIN
static UChar32 U_CALLCONV ucnv_getNextUChar_UTF8(UConverterToUnicodeArgs *args,
                                               UErrorCode *err) {
    UConverter *cnv;
    const uint8_t *sourceInitial;
    const uint8_t *source;
    uint8_t myByte;
    UChar32 ch;
    int8_t i;

    /* UTF-8 only here, the framework handles CESU-8 to combine surrogate pairs */

    cnv = args->converter;
    sourceInitial = source = (const uint8_t *)args->source;
    if (source >= (const uint8_t *)args->sourceLimit)
    {
        /* no input */
        *err = U_INDEX_OUTOFBOUNDS_ERROR;
        return 0xffff;
    }

    myByte = (uint8_t)*(source++);
    if (U8_IS_SINGLE(myByte))
    {
        args->source = (const char *)source;
        return (UChar32)myByte;
    }

    uint16_t countTrailBytes = U8_COUNT_TRAIL_BYTES(myByte);
    if (countTrailBytes == 0) {
        cnv->toUBytes[0] = myByte;
        cnv->toULength = 1;
        *err = U_ILLEGAL_CHAR_FOUND;
        args->source = (const char *)source;
        return 0xffff;
    }

    /*The byte sequence is longer than the buffer area passed*/
    if (((const char *)source + countTrailBytes) > args->sourceLimit)
    {
        /* check if all of the remaining bytes are trail bytes */
        uint16_t extraBytesToWrite = countTrailBytes + 1;
        cnv->toUBytes[0] = myByte;
        i = 1;
        *err = U_TRUNCATED_CHAR_FOUND;
        while(source < (const uint8_t *)args->sourceLimit) {
            uint8_t b = *source;
            if(icu::UTF8::isValidTrail(myByte, b, i, extraBytesToWrite)) {
                cnv->toUBytes[i++] = b;
                ++source;
            } else {
                /* error even before we run out of input */
                *err = U_ILLEGAL_CHAR_FOUND;
                break;
            }
        }
        cnv->toULength = i;
        args->source = (const char *)source;
        return 0xffff;
    }

    ch = myByte << 6;
    if(countTrailBytes == 2) {
        uint8_t t1 = *source, t2;
        if(U8_IS_VALID_LEAD3_AND_T1(myByte, t1) && U8_IS_TRAIL(t2 = *++source)) {
            args->source = (const char *)(source + 1);
            return (((ch + t1) << 6) + t2) - offsetsFromUTF8[3];
        }
    } else if(countTrailBytes == 1) {
        uint8_t t1 = *source;
        if(U8_IS_TRAIL(t1)) {
            args->source = (const char *)(source + 1);
            return (ch + t1) - offsetsFromUTF8[2];
        }
    } else {  // countTrailBytes == 3
        uint8_t t1 = *source, t2, t3;
        if(U8_IS_VALID_LEAD4_AND_T1(myByte, t1) && U8_IS_TRAIL(t2 = *++source) &&
                U8_IS_TRAIL(t3 = *++source)) {
            args->source = (const char *)(source + 1);
            return (((((ch + t1) << 6) + t2) << 6) + t3) - offsetsFromUTF8[4];
        }
    }
    args->source = (const char *)source;

    for(i = 0; sourceInitial < source; ++i) {
        cnv->toUBytes[i] = *sourceInitial++;
    }
    cnv->toULength = i;
    *err = U_ILLEGAL_CHAR_FOUND;
    return 0xffff;
} 
U_CDECL_END

/* UTF-8-from-UTF-8 conversion functions ------------------------------------ */

U_CDECL_BEGIN
/* "Convert" UTF-8 to UTF-8: Validate and copy. Modified from ucnv_DBCSFromUTF8(). */
static void U_CALLCONV
ucnv_UTF8FromUTF8(UConverterFromUnicodeArgs *pFromUArgs,
                  UConverterToUnicodeArgs *pToUArgs,
                  UErrorCode *pErrorCode) {
    UConverter *utf8;
    const uint8_t *source, *sourceLimit;
    uint8_t *target;
    int32_t targetCapacity;
    int32_t count;

    int8_t oldToULength, toULength, toULimit;

    UChar32 c;
    uint8_t b, t1, t2;

    /* set up the local pointers */
    utf8=pToUArgs->converter;
    source=(uint8_t *)pToUArgs->source;
    sourceLimit=(uint8_t *)pToUArgs->sourceLimit;
    target=(uint8_t *)pFromUArgs->target;
    targetCapacity=(int32_t)(pFromUArgs->targetLimit-pFromUArgs->target);

    /* get the converter state from the UTF-8 UConverter */
    if(utf8->toULength > 0) {
        toULength=oldToULength=utf8->toULength;
        toULimit=(int8_t)utf8->mode;
        c=(UChar32)utf8->toUnicodeStatus;
    } else {
        toULength=oldToULength=toULimit=0;
        c = 0;
    }

    count=(int32_t)(sourceLimit-source)+oldToULength;
    if(count<toULimit) {
        /*
         * Not enough input to complete the partial character.
         * Jump to moreBytes below - it will not output to target.
         */
    } else if(targetCapacity<toULimit) {
        /*
         * Not enough target capacity to output the partial character.
         * Let the standard converter handle this.
         */
        *pErrorCode=U_USING_DEFAULT_WARNING;
        return;
    } else {
        // Use a single counter for source and target, counting the minimum of
        // the source length and the target capacity.
        // Let the standard converter handle edge cases.
        if(count>targetCapacity) {
            count=targetCapacity;
        }

        // The conversion loop checks count>0 only once per character.
        // If the buffer ends with a truncated sequence,
        // then we reduce the count to stop before that,
        // and collect the remaining bytes after the conversion loop.

        // Do not go back into the bytes that will be read for finishing a partial
        // sequence from the previous buffer.
        int32_t length=count-toULength;
        U8_TRUNCATE_IF_INCOMPLETE(source, 0, length);
        count=toULength+length;
    }

    if(c!=0) {
        utf8->toUnicodeStatus=0;
        utf8->toULength=0;
        goto moreBytes;
        /* See note in ucnv_SBCSFromUTF8() about this goto. */
    }

    /* conversion loop */
    while(count>0) {
        b=*source++;
        if(U8_IS_SINGLE(b)) {
            /* convert ASCII */
            *target++=b;
            --count;
            continue;
        } else {
            if(b>=0xe0) {
                if( /* handle U+0800..U+FFFF inline */
                    b<0xf0 &&
                    U8_IS_VALID_LEAD3_AND_T1(b, t1=source[0]) &&
                    U8_IS_TRAIL(t2=source[1])
                ) {
                    source+=2;
                    *target++=b;
                    *target++=t1;
                    *target++=t2;
                    count-=3;
                    continue;
                }
            } else {
                if( /* handle U+0080..U+07FF inline */
                    b>=0xc2 &&
                    U8_IS_TRAIL(t1=*source)
                ) {
                    ++source;
                    *target++=b;
                    *target++=t1;
                    count-=2;
                    continue;
                }
            }

            /* handle "complicated" and error cases, and continuing partial characters */
            oldToULength=0;
            toULength=1;
            toULimit=U8_COUNT_BYTES_NON_ASCII(b);
            c=b;
moreBytes:
            while(toULength<toULimit) {
                if(source<sourceLimit) {
                    b=*source;
                    if(icu::UTF8::isValidTrail(c, b, toULength, toULimit)) {
                        ++source;
                        ++toULength;
                        c=(c<<6)+b;
                    } else {
                        break; /* sequence too short, stop with toULength<toULimit */
                    }
                } else {
                    /* store the partial UTF-8 character, compatible with the regular UTF-8 converter */
                    source-=(toULength-oldToULength);
                    while(oldToULength<toULength) {
                        utf8->toUBytes[oldToULength++]=*source++;
                    }
                    utf8->toUnicodeStatus=c;
                    utf8->toULength=toULength;
                    utf8->mode=toULimit;
                    pToUArgs->source=(char *)source;
                    pFromUArgs->target=(char *)target;
                    return;
                }
            }

            if(toULength!=toULimit) {
                /* error handling: illegal UTF-8 byte sequence */
                source-=(toULength-oldToULength);
                while(oldToULength<toULength) {
                    utf8->toUBytes[oldToULength++]=*source++;
                }
                utf8->toULength=toULength;
                pToUArgs->source=(char *)source;
                pFromUArgs->target=(char *)target;
                *pErrorCode=U_ILLEGAL_CHAR_FOUND;
                return;
            }

            /* copy the legal byte sequence to the target */
            {
                int8_t i;

                for(i=0; i<oldToULength; ++i) {
                    *target++=utf8->toUBytes[i];
                }
                source-=(toULength-oldToULength);
                for(; i<toULength; ++i) {
                    *target++=*source++;
                }
                count-=toULength;
            }
        }
    }
    U_ASSERT(count>=0);

    if(U_SUCCESS(*pErrorCode) && source<sourceLimit) {
        if(target==(const uint8_t *)pFromUArgs->targetLimit) {
            *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
        } else {
            b=*source;
            toULimit=U8_COUNT_BYTES(b);
            if(toULimit>(sourceLimit-source)) {
                /* collect a truncated byte sequence */
                toULength=0;
                c=b;
                for(;;) {
                    utf8->toUBytes[toULength++]=b;
                    if(++source==sourceLimit) {
                        /* partial byte sequence at end of source */
                        utf8->toUnicodeStatus=c;
                        utf8->toULength=toULength;
                        utf8->mode=toULimit;
                        break;
                    } else if(!icu::UTF8::isValidTrail(c, b=*source, toULength, toULimit)) {
                        utf8->toULength=toULength;
                        *pErrorCode=U_ILLEGAL_CHAR_FOUND;
                        break;
                    }
                    c=(c<<6)+b;
                }
            } else {
                /* partial-sequence target overflow: fall back to the pivoting implementation */
                *pErrorCode=U_USING_DEFAULT_WARNING;
            }
        }
    }

    /* write back the updated pointers */
    pToUArgs->source=(char *)source;
    pFromUArgs->target=(char *)target;
}

U_CDECL_END

/* UTF-8 converter data ----------------------------------------------------- */

static const UConverterImpl _UTF8Impl={
    UCNV_UTF8,

    nullptr,
    nullptr,

    nullptr,
    nullptr,
    nullptr,

    ucnv_toUnicode_UTF8,
    ucnv_toUnicode_UTF8_OFFSETS_LOGIC,
    ucnv_fromUnicode_UTF8,
    ucnv_fromUnicode_UTF8_OFFSETS_LOGIC,
    ucnv_getNextUChar_UTF8,

    nullptr,
    nullptr,
    nullptr,
    nullptr,
    ucnv_getNonSurrogateUnicodeSet,

    ucnv_UTF8FromUTF8,
    ucnv_UTF8FromUTF8
};

/* The 1208 CCSID refers to any version of Unicode of UTF-8 */
static const UConverterStaticData _UTF8StaticData={
    sizeof(UConverterStaticData),
    "UTF-8",
    1208, UCNV_IBM, UCNV_UTF8,
    1, 3, /* max 3 bytes per char16_t from UTF-8 (4 bytes from surrogate _pair_) */
    { 0xef, 0xbf, 0xbd, 0 },3,false,false,
    0,
    0,
    { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 } /* reserved */
};


const UConverterSharedData _UTF8Data=
        UCNV_IMMUTABLE_SHARED_DATA_INITIALIZER(&_UTF8StaticData, &_UTF8Impl);

/* CESU-8 converter data ---------------------------------------------------- */

static const UConverterImpl _CESU8Impl={
    UCNV_CESU8,

    nullptr,
    nullptr,

    nullptr,
    nullptr,
    nullptr,

    ucnv_toUnicode_UTF8,
    ucnv_toUnicode_UTF8_OFFSETS_LOGIC,
    ucnv_fromUnicode_UTF8,
    ucnv_fromUnicode_UTF8_OFFSETS_LOGIC,
    nullptr,

    nullptr,
    nullptr,
    nullptr,
    nullptr,
    ucnv_getCompleteUnicodeSet,

    nullptr,
    nullptr
};

static const UConverterStaticData _CESU8StaticData={
    sizeof(UConverterStaticData),
    "CESU-8",
    9400, /* CCSID for CESU-8 */
    UCNV_UNKNOWN, UCNV_CESU8, 1, 3,
    { 0xef, 0xbf, 0xbd, 0 },3,false,false,
    0,
    0,
    { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 } /* reserved */
};


const UConverterSharedData _CESU8Data=
        UCNV_IMMUTABLE_SHARED_DATA_INITIALIZER(&_CESU8StaticData, &_CESU8Impl);

#endif