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      1 // Copyright (C) 2016 and later: Unicode, Inc. and others.
      2 // License & terms of use: http://www.unicode.org/copyright.html
      3 /*
      4 ******************************************************************************
      5 *
      6 *   Copyright (C) 2003-2016, International Business Machines
      7 *   Corporation and others.  All Rights Reserved.
      8 *
      9 ******************************************************************************
     10 *   file name:  ucnv_ext.cpp
     11 *   encoding:   US-ASCII
     12 *   tab size:   8 (not used)
     13 *   indentation:4
     14 *
     15 *   created on: 2003jun13
     16 *   created by: Markus W. Scherer
     17 *
     18 *   Conversion extensions
     19 */
     20 
     21 #include "unicode/utypes.h"
     22 
     23 #if !UCONFIG_NO_CONVERSION && !UCONFIG_NO_LEGACY_CONVERSION
     24 
     25 #include "unicode/uset.h"
     26 #include "ucnv_bld.h"
     27 #include "ucnv_cnv.h"
     28 #include "ucnv_ext.h"
     29 #include "cmemory.h"
     30 #include "uassert.h"
     31 
     32 /* to Unicode --------------------------------------------------------------- */
     33 
     34 /*
     35  * @return lookup value for the byte, if found; else 0
     36  */
     37 static inline uint32_t
     38 ucnv_extFindToU(const uint32_t *toUSection, int32_t length, uint8_t byte) {
     39     uint32_t word0, word;
     40     int32_t i, start, limit;
     41 
     42     /* check the input byte against the lowest and highest section bytes */
     43     start=(int32_t)UCNV_EXT_TO_U_GET_BYTE(toUSection[0]);
     44     limit=(int32_t)UCNV_EXT_TO_U_GET_BYTE(toUSection[length-1]);
     45     if(byte<start || limit<byte) {
     46         return 0; /* the byte is out of range */
     47     }
     48 
     49     if(length==((limit-start)+1)) {
     50         /* direct access on a linear array */
     51         return UCNV_EXT_TO_U_GET_VALUE(toUSection[byte-start]); /* could be 0 */
     52     }
     53 
     54     /* word0 is suitable for <=toUSection[] comparison, word for <toUSection[] */
     55     word0=UCNV_EXT_TO_U_MAKE_WORD(byte, 0);
     56 
     57     /*
     58      * Shift byte once instead of each section word and add 0xffffff.
     59      * We will compare the shifted/added byte (bbffffff) against
     60      * section words which have byte values in the same bit position.
     61      * If and only if byte bb < section byte ss then bbffffff<ssvvvvvv
     62      * for all v=0..f
     63      * so we need not mask off the lower 24 bits of each section word.
     64      */
     65     word=word0|UCNV_EXT_TO_U_VALUE_MASK;
     66 
     67     /* binary search */
     68     start=0;
     69     limit=length;
     70     for(;;) {
     71         i=limit-start;
     72         if(i<=1) {
     73             break; /* done */
     74         }
     75         /* start<limit-1 */
     76 
     77         if(i<=4) {
     78             /* linear search for the last part */
     79             if(word0<=toUSection[start]) {
     80                 break;
     81             }
     82             if(++start<limit && word0<=toUSection[start]) {
     83                 break;
     84             }
     85             if(++start<limit && word0<=toUSection[start]) {
     86                 break;
     87             }
     88             /* always break at start==limit-1 */
     89             ++start;
     90             break;
     91         }
     92 
     93         i=(start+limit)/2;
     94         if(word<toUSection[i]) {
     95             limit=i;
     96         } else {
     97             start=i;
     98         }
     99     }
    100 
    101     /* did we really find it? */
    102     if(start<limit && byte==UCNV_EXT_TO_U_GET_BYTE(word=toUSection[start])) {
    103         return UCNV_EXT_TO_U_GET_VALUE(word); /* never 0 */
    104     } else {
    105         return 0; /* not found */
    106     }
    107 }
    108 
    109 /*
    110  * TRUE if not an SI/SO stateful converter,
    111  * or if the match length fits with the current converter state
    112  */
    113 #define UCNV_EXT_TO_U_VERIFY_SISO_MATCH(sisoState, match) \
    114     ((sisoState)<0 || ((sisoState)==0) == (match==1))
    115 
    116 /*
    117  * this works like ucnv_extMatchFromU() except
    118  * - the first character is in pre
    119  * - no trie is used
    120  * - the returned matchLength is not offset by 2
    121  */
    122 static int32_t
    123 ucnv_extMatchToU(const int32_t *cx, int8_t sisoState,
    124                  const char *pre, int32_t preLength,
    125                  const char *src, int32_t srcLength,
    126                  uint32_t *pMatchValue,
    127                  UBool /*useFallback*/, UBool flush) {
    128     const uint32_t *toUTable, *toUSection;
    129 
    130     uint32_t value, matchValue;
    131     int32_t i, j, idx, length, matchLength;
    132     uint8_t b;
    133 
    134     if(cx==NULL || cx[UCNV_EXT_TO_U_LENGTH]<=0) {
    135         return 0; /* no extension data, no match */
    136     }
    137 
    138     /* initialize */
    139     toUTable=UCNV_EXT_ARRAY(cx, UCNV_EXT_TO_U_INDEX, uint32_t);
    140     idx=0;
    141 
    142     matchValue=0;
    143     i=j=matchLength=0;
    144 
    145     if(sisoState==0) {
    146         /* SBCS state of an SI/SO stateful converter, look at only exactly 1 byte */
    147         if(preLength>1) {
    148             return 0; /* no match of a DBCS sequence in SBCS mode */
    149         } else if(preLength==1) {
    150             srcLength=0;
    151         } else /* preLength==0 */ {
    152             if(srcLength>1) {
    153                 srcLength=1;
    154             }
    155         }
    156         flush=TRUE;
    157     }
    158 
    159     /* we must not remember fallback matches when not using fallbacks */
    160 
    161     /* match input units until there is a full match or the input is consumed */
    162     for(;;) {
    163         /* go to the next section */
    164         toUSection=toUTable+idx;
    165 
    166         /* read first pair of the section */
    167         value=*toUSection++;
    168         length=UCNV_EXT_TO_U_GET_BYTE(value);
    169         value=UCNV_EXT_TO_U_GET_VALUE(value);
    170         if( value!=0 &&
    171             (UCNV_EXT_TO_U_IS_ROUNDTRIP(value) ||
    172              TO_U_USE_FALLBACK(useFallback)) &&
    173             UCNV_EXT_TO_U_VERIFY_SISO_MATCH(sisoState, i+j)
    174         ) {
    175             /* remember longest match so far */
    176             matchValue=value;
    177             matchLength=i+j;
    178         }
    179 
    180         /* match pre[] then src[] */
    181         if(i<preLength) {
    182             b=(uint8_t)pre[i++];
    183         } else if(j<srcLength) {
    184             b=(uint8_t)src[j++];
    185         } else {
    186             /* all input consumed, partial match */
    187             if(flush || (length=(i+j))>UCNV_EXT_MAX_BYTES) {
    188                 /*
    189                  * end of the entire input stream, stop with the longest match so far
    190                  * or: partial match must not be longer than UCNV_EXT_MAX_BYTES
    191                  * because it must fit into state buffers
    192                  */
    193                 break;
    194             } else {
    195                 /* continue with more input next time */
    196                 return -length;
    197             }
    198         }
    199 
    200         /* search for the current UChar */
    201         value=ucnv_extFindToU(toUSection, length, b);
    202         if(value==0) {
    203             /* no match here, stop with the longest match so far */
    204             break;
    205         } else {
    206             if(UCNV_EXT_TO_U_IS_PARTIAL(value)) {
    207                 /* partial match, continue */
    208                 idx=(int32_t)UCNV_EXT_TO_U_GET_PARTIAL_INDEX(value);
    209             } else {
    210                 if( (UCNV_EXT_TO_U_IS_ROUNDTRIP(value) ||
    211                      TO_U_USE_FALLBACK(useFallback)) &&
    212                     UCNV_EXT_TO_U_VERIFY_SISO_MATCH(sisoState, i+j)
    213                 ) {
    214                     /* full match, stop with result */
    215                     matchValue=value;
    216                     matchLength=i+j;
    217                 } else {
    218                     /* full match on fallback not taken, stop with the longest match so far */
    219                 }
    220                 break;
    221             }
    222         }
    223     }
    224 
    225     if(matchLength==0) {
    226         /* no match at all */
    227         return 0;
    228     }
    229 
    230     /* return result */
    231     *pMatchValue=UCNV_EXT_TO_U_MASK_ROUNDTRIP(matchValue);
    232     return matchLength;
    233 }
    234 
    235 static inline void
    236 ucnv_extWriteToU(UConverter *cnv, const int32_t *cx,
    237                  uint32_t value,
    238                  UChar **target, const UChar *targetLimit,
    239                  int32_t **offsets, int32_t srcIndex,
    240                  UErrorCode *pErrorCode) {
    241     /* output the result */
    242     if(UCNV_EXT_TO_U_IS_CODE_POINT(value)) {
    243         /* output a single code point */
    244         ucnv_toUWriteCodePoint(
    245             cnv, UCNV_EXT_TO_U_GET_CODE_POINT(value),
    246             target, targetLimit,
    247             offsets, srcIndex,
    248             pErrorCode);
    249     } else {
    250         /* output a string - with correct data we have resultLength>0 */
    251         ucnv_toUWriteUChars(
    252             cnv,
    253             UCNV_EXT_ARRAY(cx, UCNV_EXT_TO_U_UCHARS_INDEX, UChar)+
    254                 UCNV_EXT_TO_U_GET_INDEX(value),
    255             UCNV_EXT_TO_U_GET_LENGTH(value),
    256             target, targetLimit,
    257             offsets, srcIndex,
    258             pErrorCode);
    259     }
    260 }
    261 
    262 /*
    263  * get the SI/SO toU state (state 0 is for SBCS, 1 for DBCS),
    264  * or 1 for DBCS-only,
    265  * or -1 if the converter is not SI/SO stateful
    266  *
    267  * Note: For SI/SO stateful converters getting here,
    268  * cnv->mode==0 is equivalent to firstLength==1.
    269  */
    270 #define UCNV_SISO_STATE(cnv) \
    271     ((cnv)->sharedData->mbcs.outputType==MBCS_OUTPUT_2_SISO ? (int8_t)(cnv)->mode : \
    272      (cnv)->sharedData->mbcs.outputType==MBCS_OUTPUT_DBCS_ONLY ? 1 : -1)
    273 
    274 /*
    275  * target<targetLimit; set error code for overflow
    276  */
    277 U_CFUNC UBool
    278 ucnv_extInitialMatchToU(UConverter *cnv, const int32_t *cx,
    279                         int32_t firstLength,
    280                         const char **src, const char *srcLimit,
    281                         UChar **target, const UChar *targetLimit,
    282                         int32_t **offsets, int32_t srcIndex,
    283                         UBool flush,
    284                         UErrorCode *pErrorCode) {
    285     uint32_t value = 0;  /* initialize output-only param to 0 to silence gcc */
    286     int32_t match;
    287 
    288     /* try to match */
    289     match=ucnv_extMatchToU(cx, (int8_t)UCNV_SISO_STATE(cnv),
    290                            (const char *)cnv->toUBytes, firstLength,
    291                            *src, (int32_t)(srcLimit-*src),
    292                            &value,
    293                            cnv->useFallback, flush);
    294     if(match>0) {
    295         /* advance src pointer for the consumed input */
    296         *src+=match-firstLength;
    297 
    298         /* write result to target */
    299         ucnv_extWriteToU(cnv, cx,
    300                          value,
    301                          target, targetLimit,
    302                          offsets, srcIndex,
    303                          pErrorCode);
    304         return TRUE;
    305     } else if(match<0) {
    306         /* save state for partial match */
    307         const char *s;
    308         int32_t j;
    309 
    310         /* copy the first code point */
    311         s=(const char *)cnv->toUBytes;
    312         cnv->preToUFirstLength=(int8_t)firstLength;
    313         for(j=0; j<firstLength; ++j) {
    314             cnv->preToU[j]=*s++;
    315         }
    316 
    317         /* now copy the newly consumed input */
    318         s=*src;
    319         match=-match;
    320         for(; j<match; ++j) {
    321             cnv->preToU[j]=*s++;
    322         }
    323         *src=s; /* same as *src=srcLimit; because we reached the end of input */
    324         cnv->preToULength=(int8_t)match;
    325         return TRUE;
    326     } else /* match==0 no match */ {
    327         return FALSE;
    328     }
    329 }
    330 
    331 U_CFUNC UChar32
    332 ucnv_extSimpleMatchToU(const int32_t *cx,
    333                        const char *source, int32_t length,
    334                        UBool useFallback) {
    335     uint32_t value = 0;  /* initialize output-only param to 0 to silence gcc */
    336     int32_t match;
    337 
    338     if(length<=0) {
    339         return 0xffff;
    340     }
    341 
    342     /* try to match */
    343     match=ucnv_extMatchToU(cx, -1,
    344                            source, length,
    345                            NULL, 0,
    346                            &value,
    347                            useFallback, TRUE);
    348     if(match==length) {
    349         /* write result for simple, single-character conversion */
    350         if(UCNV_EXT_TO_U_IS_CODE_POINT(value)) {
    351             return UCNV_EXT_TO_U_GET_CODE_POINT(value);
    352         }
    353     }
    354 
    355     /*
    356      * return no match because
    357      * - match>0 && value points to string: simple conversion cannot handle multiple code points
    358      * - match>0 && match!=length: not all input consumed, forbidden for this function
    359      * - match==0: no match found in the first place
    360      * - match<0: partial match, not supported for simple conversion (and flush==TRUE)
    361      */
    362     return 0xfffe;
    363 }
    364 
    365 /*
    366  * continue partial match with new input
    367  * never called for simple, single-character conversion
    368  */
    369 U_CFUNC void
    370 ucnv_extContinueMatchToU(UConverter *cnv,
    371                          UConverterToUnicodeArgs *pArgs, int32_t srcIndex,
    372                          UErrorCode *pErrorCode) {
    373     uint32_t value = 0;  /* initialize output-only param to 0 to silence gcc */
    374     int32_t match, length;
    375 
    376     match=ucnv_extMatchToU(cnv->sharedData->mbcs.extIndexes, (int8_t)UCNV_SISO_STATE(cnv),
    377                            cnv->preToU, cnv->preToULength,
    378                            pArgs->source, (int32_t)(pArgs->sourceLimit-pArgs->source),
    379                            &value,
    380                            cnv->useFallback, pArgs->flush);
    381     if(match>0) {
    382         if(match>=cnv->preToULength) {
    383             /* advance src pointer for the consumed input */
    384             pArgs->source+=match-cnv->preToULength;
    385             cnv->preToULength=0;
    386         } else {
    387             /* the match did not use all of preToU[] - keep the rest for replay */
    388             length=cnv->preToULength-match;
    389             uprv_memmove(cnv->preToU, cnv->preToU+match, length);
    390             cnv->preToULength=(int8_t)-length;
    391         }
    392 
    393         /* write result */
    394         ucnv_extWriteToU(cnv, cnv->sharedData->mbcs.extIndexes,
    395                          value,
    396                          &pArgs->target, pArgs->targetLimit,
    397                          &pArgs->offsets, srcIndex,
    398                          pErrorCode);
    399     } else if(match<0) {
    400         /* save state for partial match */
    401         const char *s;
    402         int32_t j;
    403 
    404         /* just _append_ the newly consumed input to preToU[] */
    405         s=pArgs->source;
    406         match=-match;
    407         for(j=cnv->preToULength; j<match; ++j) {
    408             cnv->preToU[j]=*s++;
    409         }
    410         pArgs->source=s; /* same as *src=srcLimit; because we reached the end of input */
    411         cnv->preToULength=(int8_t)match;
    412     } else /* match==0 */ {
    413         /*
    414          * no match
    415          *
    416          * We need to split the previous input into two parts:
    417          *
    418          * 1. The first codepage character is unmappable - that's how we got into
    419          *    trying the extension data in the first place.
    420          *    We need to move it from the preToU buffer
    421          *    to the error buffer, set an error code,
    422          *    and prepare the rest of the previous input for 2.
    423          *
    424          * 2. The rest of the previous input must be converted once we
    425          *    come back from the callback for the first character.
    426          *    At that time, we have to try again from scratch to convert
    427          *    these input characters.
    428          *    The replay will be handled by the ucnv.c conversion code.
    429          */
    430 
    431         /* move the first codepage character to the error field */
    432         uprv_memcpy(cnv->toUBytes, cnv->preToU, cnv->preToUFirstLength);
    433         cnv->toULength=cnv->preToUFirstLength;
    434 
    435         /* move the rest up inside the buffer */
    436         length=cnv->preToULength-cnv->preToUFirstLength;
    437         if(length>0) {
    438             uprv_memmove(cnv->preToU, cnv->preToU+cnv->preToUFirstLength, length);
    439         }
    440 
    441         /* mark preToU for replay */
    442         cnv->preToULength=(int8_t)-length;
    443 
    444         /* set the error code for unassigned */
    445         *pErrorCode=U_INVALID_CHAR_FOUND;
    446     }
    447 }
    448 
    449 /* from Unicode ------------------------------------------------------------- */
    450 
    451 // Use roundtrips, "good one-way" mappings, and some normal fallbacks.
    452 static inline UBool
    453 extFromUUseMapping(UBool useFallback, uint32_t value, UChar32 firstCP) {
    454     return
    455         ((value&UCNV_EXT_FROM_U_STATUS_MASK)!=0 ||
    456             FROM_U_USE_FALLBACK(useFallback, firstCP)) &&
    457         (value&UCNV_EXT_FROM_U_RESERVED_MASK)==0;
    458 }
    459 
    460 /*
    461  * @return index of the UChar, if found; else <0
    462  */
    463 static inline int32_t
    464 ucnv_extFindFromU(const UChar *fromUSection, int32_t length, UChar u) {
    465     int32_t i, start, limit;
    466 
    467     /* binary search */
    468     start=0;
    469     limit=length;
    470     for(;;) {
    471         i=limit-start;
    472         if(i<=1) {
    473             break; /* done */
    474         }
    475         /* start<limit-1 */
    476 
    477         if(i<=4) {
    478             /* linear search for the last part */
    479             if(u<=fromUSection[start]) {
    480                 break;
    481             }
    482             if(++start<limit && u<=fromUSection[start]) {
    483                 break;
    484             }
    485             if(++start<limit && u<=fromUSection[start]) {
    486                 break;
    487             }
    488             /* always break at start==limit-1 */
    489             ++start;
    490             break;
    491         }
    492 
    493         i=(start+limit)/2;
    494         if(u<fromUSection[i]) {
    495             limit=i;
    496         } else {
    497             start=i;
    498         }
    499     }
    500 
    501     /* did we really find it? */
    502     if(start<limit && u==fromUSection[start]) {
    503         return start;
    504     } else {
    505         return -1; /* not found */
    506     }
    507 }
    508 
    509 /*
    510  * @param cx pointer to extension data; if NULL, returns 0
    511  * @param firstCP the first code point before all the other UChars
    512  * @param pre UChars that must match; !initialMatch: partial match with them
    513  * @param preLength length of pre, >=0
    514  * @param src UChars that can be used to complete a match
    515  * @param srcLength length of src, >=0
    516  * @param pMatchValue [out] output result value for the match from the data structure
    517  * @param useFallback "use fallback" flag, usually from cnv->useFallback
    518  * @param flush TRUE if the end of the input stream is reached
    519  * @return >1: matched, return value=total match length (number of input units matched)
    520  *          1: matched, no mapping but request for <subchar1>
    521  *             (only for the first code point)
    522  *          0: no match
    523  *         <0: partial match, return value=negative total match length
    524  *             (partial matches are never returned for flush==TRUE)
    525  *             (partial matches are never returned as being longer than UCNV_EXT_MAX_UCHARS)
    526  *         the matchLength is 2 if only firstCP matched, and >2 if firstCP and
    527  *         further code units matched
    528  */
    529 static int32_t
    530 ucnv_extMatchFromU(const int32_t *cx,
    531                    UChar32 firstCP,
    532                    const UChar *pre, int32_t preLength,
    533                    const UChar *src, int32_t srcLength,
    534                    uint32_t *pMatchValue,
    535                    UBool useFallback, UBool flush) {
    536     const uint16_t *stage12, *stage3;
    537     const uint32_t *stage3b;
    538 
    539     const UChar *fromUTableUChars, *fromUSectionUChars;
    540     const uint32_t *fromUTableValues, *fromUSectionValues;
    541 
    542     uint32_t value, matchValue;
    543     int32_t i, j, idx, length, matchLength;
    544     UChar c;
    545 
    546     if(cx==NULL) {
    547         return 0; /* no extension data, no match */
    548     }
    549 
    550     /* trie lookup of firstCP */
    551     idx=firstCP>>10; /* stage 1 index */
    552     if(idx>=cx[UCNV_EXT_FROM_U_STAGE_1_LENGTH]) {
    553         return 0; /* the first code point is outside the trie */
    554     }
    555 
    556     stage12=UCNV_EXT_ARRAY(cx, UCNV_EXT_FROM_U_STAGE_12_INDEX, uint16_t);
    557     stage3=UCNV_EXT_ARRAY(cx, UCNV_EXT_FROM_U_STAGE_3_INDEX, uint16_t);
    558     idx=UCNV_EXT_FROM_U(stage12, stage3, idx, firstCP);
    559 
    560     stage3b=UCNV_EXT_ARRAY(cx, UCNV_EXT_FROM_U_STAGE_3B_INDEX, uint32_t);
    561     value=stage3b[idx];
    562     if(value==0) {
    563         return 0;
    564     }
    565 
    566     /*
    567      * Tests for (value&UCNV_EXT_FROM_U_RESERVED_MASK)==0:
    568      * Do not interpret values with reserved bits used, for forward compatibility,
    569      * and do not even remember intermediate results with reserved bits used.
    570      */
    571 
    572     if(UCNV_EXT_TO_U_IS_PARTIAL(value)) {
    573         /* partial match, enter the loop below */
    574         idx=(int32_t)UCNV_EXT_FROM_U_GET_PARTIAL_INDEX(value);
    575 
    576         /* initialize */
    577         fromUTableUChars=UCNV_EXT_ARRAY(cx, UCNV_EXT_FROM_U_UCHARS_INDEX, UChar);
    578         fromUTableValues=UCNV_EXT_ARRAY(cx, UCNV_EXT_FROM_U_VALUES_INDEX, uint32_t);
    579 
    580         matchValue=0;
    581         i=j=matchLength=0;
    582 
    583         /* we must not remember fallback matches when not using fallbacks */
    584 
    585         /* match input units until there is a full match or the input is consumed */
    586         for(;;) {
    587             /* go to the next section */
    588             fromUSectionUChars=fromUTableUChars+idx;
    589             fromUSectionValues=fromUTableValues+idx;
    590 
    591             /* read first pair of the section */
    592             length=*fromUSectionUChars++;
    593             value=*fromUSectionValues++;
    594             if(value!=0 && extFromUUseMapping(useFallback, value, firstCP)) {
    595                 /* remember longest match so far */
    596                 matchValue=value;
    597                 matchLength=2+i+j;
    598             }
    599 
    600             /* match pre[] then src[] */
    601             if(i<preLength) {
    602                 c=pre[i++];
    603             } else if(j<srcLength) {
    604                 c=src[j++];
    605             } else {
    606                 /* all input consumed, partial match */
    607                 if(flush || (length=(i+j))>UCNV_EXT_MAX_UCHARS) {
    608                     /*
    609                      * end of the entire input stream, stop with the longest match so far
    610                      * or: partial match must not be longer than UCNV_EXT_MAX_UCHARS
    611                      * because it must fit into state buffers
    612                      */
    613                     break;
    614                 } else {
    615                     /* continue with more input next time */
    616                     return -(2+length);
    617                 }
    618             }
    619 
    620             /* search for the current UChar */
    621             idx=ucnv_extFindFromU(fromUSectionUChars, length, c);
    622             if(idx<0) {
    623                 /* no match here, stop with the longest match so far */
    624                 break;
    625             } else {
    626                 value=fromUSectionValues[idx];
    627                 if(UCNV_EXT_FROM_U_IS_PARTIAL(value)) {
    628                     /* partial match, continue */
    629                     idx=(int32_t)UCNV_EXT_FROM_U_GET_PARTIAL_INDEX(value);
    630                 } else {
    631                     if(extFromUUseMapping(useFallback, value, firstCP)) {
    632                         /* full match, stop with result */
    633                         matchValue=value;
    634                         matchLength=2+i+j;
    635                     } else {
    636                         /* full match on fallback not taken, stop with the longest match so far */
    637                     }
    638                     break;
    639                 }
    640             }
    641         }
    642 
    643         if(matchLength==0) {
    644             /* no match at all */
    645             return 0;
    646         }
    647     } else /* result from firstCP trie lookup */ {
    648         if(extFromUUseMapping(useFallback, value, firstCP)) {
    649             /* full match, stop with result */
    650             matchValue=value;
    651             matchLength=2;
    652         } else {
    653             /* fallback not taken */
    654             return 0;
    655         }
    656     }
    657 
    658     /* return result */
    659     if(matchValue==UCNV_EXT_FROM_U_SUBCHAR1) {
    660         return 1; /* assert matchLength==2 */
    661     }
    662 
    663     *pMatchValue=matchValue;
    664     return matchLength;
    665 }
    666 
    667 /*
    668  * @param value fromUnicode mapping table value; ignores roundtrip and reserved bits
    669  */
    670 static inline void
    671 ucnv_extWriteFromU(UConverter *cnv, const int32_t *cx,
    672                    uint32_t value,
    673                    char **target, const char *targetLimit,
    674                    int32_t **offsets, int32_t srcIndex,
    675                    UErrorCode *pErrorCode) {
    676     uint8_t buffer[1+UCNV_EXT_MAX_BYTES];
    677     const uint8_t *result;
    678     int32_t length, prevLength;
    679 
    680     length=UCNV_EXT_FROM_U_GET_LENGTH(value);
    681     value=(uint32_t)UCNV_EXT_FROM_U_GET_DATA(value);
    682 
    683     /* output the result */
    684     if(length<=UCNV_EXT_FROM_U_MAX_DIRECT_LENGTH) {
    685         /*
    686          * Generate a byte array and then write it below.
    687          * This is not the fastest possible way, but it should be ok for
    688          * extension mappings, and it is much simpler.
    689          * Offset and overflow handling are only done once this way.
    690          */
    691         uint8_t *p=buffer+1; /* reserve buffer[0] for shiftByte below */
    692         switch(length) {
    693         case 3:
    694             *p++=(uint8_t)(value>>16);
    695             U_FALLTHROUGH;
    696         case 2:
    697             *p++=(uint8_t)(value>>8);
    698             U_FALLTHROUGH;
    699         case 1:
    700             *p++=(uint8_t)value;
    701             U_FALLTHROUGH;
    702         default:
    703             break; /* will never occur */
    704         }
    705         result=buffer+1;
    706     } else {
    707         result=UCNV_EXT_ARRAY(cx, UCNV_EXT_FROM_U_BYTES_INDEX, uint8_t)+value;
    708     }
    709 
    710     /* with correct data we have length>0 */
    711 
    712     if((prevLength=cnv->fromUnicodeStatus)!=0) {
    713         /* handle SI/SO stateful output */
    714         uint8_t shiftByte;
    715 
    716         if(prevLength>1 && length==1) {
    717             /* change from double-byte mode to single-byte */
    718             shiftByte=(uint8_t)UCNV_SI;
    719             cnv->fromUnicodeStatus=1;
    720         } else if(prevLength==1 && length>1) {
    721             /* change from single-byte mode to double-byte */
    722             shiftByte=(uint8_t)UCNV_SO;
    723             cnv->fromUnicodeStatus=2;
    724         } else {
    725             shiftByte=0;
    726         }
    727 
    728         if(shiftByte!=0) {
    729             /* prepend the shift byte to the result bytes */
    730             buffer[0]=shiftByte;
    731             if(result!=buffer+1) {
    732                 uprv_memcpy(buffer+1, result, length);
    733             }
    734             result=buffer;
    735             ++length;
    736         }
    737     }
    738 
    739     ucnv_fromUWriteBytes(cnv, (const char *)result, length,
    740                          target, targetLimit,
    741                          offsets, srcIndex,
    742                          pErrorCode);
    743 }
    744 
    745 /*
    746  * target<targetLimit; set error code for overflow
    747  */
    748 U_CFUNC UBool
    749 ucnv_extInitialMatchFromU(UConverter *cnv, const int32_t *cx,
    750                           UChar32 cp,
    751                           const UChar **src, const UChar *srcLimit,
    752                           char **target, const char *targetLimit,
    753                           int32_t **offsets, int32_t srcIndex,
    754                           UBool flush,
    755                           UErrorCode *pErrorCode) {
    756     uint32_t value = 0;  /* initialize output-only param to 0 to silence gcc */
    757     int32_t match;
    758 
    759     /* try to match */
    760     match=ucnv_extMatchFromU(cx, cp,
    761                              NULL, 0,
    762                              *src, (int32_t)(srcLimit-*src),
    763                              &value,
    764                              cnv->useFallback, flush);
    765 
    766     /* reject a match if the result is a single byte for DBCS-only */
    767     if( match>=2 &&
    768         !(UCNV_EXT_FROM_U_GET_LENGTH(value)==1 &&
    769           cnv->sharedData->mbcs.outputType==MBCS_OUTPUT_DBCS_ONLY)
    770     ) {
    771         /* advance src pointer for the consumed input */
    772         *src+=match-2; /* remove 2 for the initial code point */
    773 
    774         /* write result to target */
    775         ucnv_extWriteFromU(cnv, cx,
    776                            value,
    777                            target, targetLimit,
    778                            offsets, srcIndex,
    779                            pErrorCode);
    780         return TRUE;
    781     } else if(match<0) {
    782         /* save state for partial match */
    783         const UChar *s;
    784         int32_t j;
    785 
    786         /* copy the first code point */
    787         cnv->preFromUFirstCP=cp;
    788 
    789         /* now copy the newly consumed input */
    790         s=*src;
    791         match=-match-2; /* remove 2 for the initial code point */
    792         for(j=0; j<match; ++j) {
    793             cnv->preFromU[j]=*s++;
    794         }
    795         *src=s; /* same as *src=srcLimit; because we reached the end of input */
    796         cnv->preFromULength=(int8_t)match;
    797         return TRUE;
    798     } else if(match==1) {
    799         /* matched, no mapping but request for <subchar1> */
    800         cnv->useSubChar1=TRUE;
    801         return FALSE;
    802     } else /* match==0 no match */ {
    803         return FALSE;
    804     }
    805 }
    806 
    807 /*
    808  * Used by ISO 2022 implementation.
    809  * @return number of bytes in *pValue; negative number if fallback; 0 for no mapping
    810  */
    811 U_CFUNC int32_t
    812 ucnv_extSimpleMatchFromU(const int32_t *cx,
    813                          UChar32 cp, uint32_t *pValue,
    814                          UBool useFallback) {
    815     uint32_t value;
    816     int32_t match;
    817 
    818     /* try to match */
    819     match=ucnv_extMatchFromU(cx,
    820                              cp,
    821                              NULL, 0,
    822                              NULL, 0,
    823                              &value,
    824                              useFallback, TRUE);
    825     if(match>=2) {
    826         /* write result for simple, single-character conversion */
    827         int32_t length;
    828         int isRoundtrip;
    829 
    830         isRoundtrip=UCNV_EXT_FROM_U_IS_ROUNDTRIP(value);
    831         length=UCNV_EXT_FROM_U_GET_LENGTH(value);
    832         value=(uint32_t)UCNV_EXT_FROM_U_GET_DATA(value);
    833 
    834         if(length<=UCNV_EXT_FROM_U_MAX_DIRECT_LENGTH) {
    835             *pValue=value;
    836             return isRoundtrip ? length : -length;
    837 #if 0 /* not currently used */
    838         } else if(length==4) {
    839             /* de-serialize a 4-byte result */
    840             const uint8_t *result=UCNV_EXT_ARRAY(cx, UCNV_EXT_FROM_U_BYTES_INDEX, uint8_t)+value;
    841             *pValue=
    842                 ((uint32_t)result[0]<<24)|
    843                 ((uint32_t)result[1]<<16)|
    844                 ((uint32_t)result[2]<<8)|
    845                 result[3];
    846             return isRoundtrip ? 4 : -4;
    847 #endif
    848         }
    849     }
    850 
    851     /*
    852      * return no match because
    853      * - match>1 && resultLength>4: result too long for simple conversion
    854      * - match==1: no match found, <subchar1> preferred
    855      * - match==0: no match found in the first place
    856      * - match<0: partial match, not supported for simple conversion (and flush==TRUE)
    857      */
    858     return 0;
    859 }
    860 
    861 /*
    862  * continue partial match with new input, requires cnv->preFromUFirstCP>=0
    863  * never called for simple, single-character conversion
    864  */
    865 U_CFUNC void
    866 ucnv_extContinueMatchFromU(UConverter *cnv,
    867                            UConverterFromUnicodeArgs *pArgs, int32_t srcIndex,
    868                            UErrorCode *pErrorCode) {
    869     uint32_t value = 0;  /* initialize output-only param to 0 to silence gcc */
    870     int32_t match;
    871 
    872     match=ucnv_extMatchFromU(cnv->sharedData->mbcs.extIndexes,
    873                              cnv->preFromUFirstCP,
    874                              cnv->preFromU, cnv->preFromULength,
    875                              pArgs->source, (int32_t)(pArgs->sourceLimit-pArgs->source),
    876                              &value,
    877                              cnv->useFallback, pArgs->flush);
    878     if(match>=2) {
    879         match-=2; /* remove 2 for the initial code point */
    880 
    881         if(match>=cnv->preFromULength) {
    882             /* advance src pointer for the consumed input */
    883             pArgs->source+=match-cnv->preFromULength;
    884             cnv->preFromULength=0;
    885         } else {
    886             /* the match did not use all of preFromU[] - keep the rest for replay */
    887             int32_t length=cnv->preFromULength-match;
    888             u_memmove(cnv->preFromU, cnv->preFromU+match, length);
    889             cnv->preFromULength=(int8_t)-length;
    890         }
    891 
    892         /* finish the partial match */
    893         cnv->preFromUFirstCP=U_SENTINEL;
    894 
    895         /* write result */
    896         ucnv_extWriteFromU(cnv, cnv->sharedData->mbcs.extIndexes,
    897                            value,
    898                            &pArgs->target, pArgs->targetLimit,
    899                            &pArgs->offsets, srcIndex,
    900                            pErrorCode);
    901     } else if(match<0) {
    902         /* save state for partial match */
    903         const UChar *s;
    904         int32_t j;
    905 
    906         /* just _append_ the newly consumed input to preFromU[] */
    907         s=pArgs->source;
    908         match=-match-2; /* remove 2 for the initial code point */
    909         for(j=cnv->preFromULength; j<match; ++j) {
    910             U_ASSERT(j>=0);
    911             cnv->preFromU[j]=*s++;
    912         }
    913         pArgs->source=s; /* same as *src=srcLimit; because we reached the end of input */
    914         cnv->preFromULength=(int8_t)match;
    915     } else /* match==0 or 1 */ {
    916         /*
    917          * no match
    918          *
    919          * We need to split the previous input into two parts:
    920          *
    921          * 1. The first code point is unmappable - that's how we got into
    922          *    trying the extension data in the first place.
    923          *    We need to move it from the preFromU buffer
    924          *    to the error buffer, set an error code,
    925          *    and prepare the rest of the previous input for 2.
    926          *
    927          * 2. The rest of the previous input must be converted once we
    928          *    come back from the callback for the first code point.
    929          *    At that time, we have to try again from scratch to convert
    930          *    these input characters.
    931          *    The replay will be handled by the ucnv.c conversion code.
    932          */
    933 
    934         if(match==1) {
    935             /* matched, no mapping but request for <subchar1> */
    936             cnv->useSubChar1=TRUE;
    937         }
    938 
    939         /* move the first code point to the error field */
    940         cnv->fromUChar32=cnv->preFromUFirstCP;
    941         cnv->preFromUFirstCP=U_SENTINEL;
    942 
    943         /* mark preFromU for replay */
    944         cnv->preFromULength=-cnv->preFromULength;
    945 
    946         /* set the error code for unassigned */
    947         *pErrorCode=U_INVALID_CHAR_FOUND;
    948     }
    949 }
    950 
    951 static UBool
    952 extSetUseMapping(UConverterUnicodeSet which, int32_t minLength, uint32_t value) {
    953     if(which==UCNV_ROUNDTRIP_SET) {
    954         // Add only code points for which the roundtrip flag is set.
    955         // Do not add any fallbacks, even if ucnv_fromUnicode() would use them
    956         // (fallbacks from PUA). See the API docs for ucnv_getUnicodeSet().
    957         //
    958         // By analogy, also do not add "good one-way" mappings.
    959         //
    960         // Do not add entries with reserved bits set.
    961         if(((value&(UCNV_EXT_FROM_U_ROUNDTRIP_FLAG|UCNV_EXT_FROM_U_RESERVED_MASK))!=
    962                 UCNV_EXT_FROM_U_ROUNDTRIP_FLAG)) {
    963             return FALSE;
    964         }
    965     } else /* UCNV_ROUNDTRIP_AND_FALLBACK_SET */ {
    966         // Do not add entries with reserved bits set.
    967         if((value&UCNV_EXT_FROM_U_RESERVED_MASK)!=0) {
    968             return FALSE;
    969         }
    970     }
    971     // Do not add <subchar1> entries or other (future?) pseudo-entries
    972     // with an output length of 0.
    973     return UCNV_EXT_FROM_U_GET_LENGTH(value)>=minLength;
    974 }
    975 
    976 static void
    977 ucnv_extGetUnicodeSetString(const UConverterSharedData *sharedData,
    978                             const int32_t *cx,
    979                             const USetAdder *sa,
    980                             UConverterUnicodeSet which,
    981                             int32_t minLength,
    982                             UChar32 firstCP,
    983                             UChar s[UCNV_EXT_MAX_UCHARS], int32_t length,
    984                             int32_t sectionIndex,
    985                             UErrorCode *pErrorCode) {
    986     const UChar *fromUSectionUChars;
    987     const uint32_t *fromUSectionValues;
    988 
    989     uint32_t value;
    990     int32_t i, count;
    991 
    992     fromUSectionUChars=UCNV_EXT_ARRAY(cx, UCNV_EXT_FROM_U_UCHARS_INDEX, UChar)+sectionIndex;
    993     fromUSectionValues=UCNV_EXT_ARRAY(cx, UCNV_EXT_FROM_U_VALUES_INDEX, uint32_t)+sectionIndex;
    994 
    995     /* read first pair of the section */
    996     count=*fromUSectionUChars++;
    997     value=*fromUSectionValues++;
    998 
    999     if(extSetUseMapping(which, minLength, value)) {
   1000         if(length==U16_LENGTH(firstCP)) {
   1001             /* add the initial code point */
   1002             sa->add(sa->set, firstCP);
   1003         } else {
   1004             /* add the string so far */
   1005             sa->addString(sa->set, s, length);
   1006         }
   1007     }
   1008 
   1009     for(i=0; i<count; ++i) {
   1010         /* append this code unit and recurse or add the string */
   1011         s[length]=fromUSectionUChars[i];
   1012         value=fromUSectionValues[i];
   1013 
   1014         if(value==0) {
   1015             /* no mapping, do nothing */
   1016         } else if(UCNV_EXT_FROM_U_IS_PARTIAL(value)) {
   1017             ucnv_extGetUnicodeSetString(
   1018                 sharedData, cx, sa, which, minLength,
   1019                 firstCP, s, length+1,
   1020                 (int32_t)UCNV_EXT_FROM_U_GET_PARTIAL_INDEX(value),
   1021                 pErrorCode);
   1022         } else if(extSetUseMapping(which, minLength, value)) {
   1023             sa->addString(sa->set, s, length+1);
   1024         }
   1025     }
   1026 }
   1027 
   1028 U_CFUNC void
   1029 ucnv_extGetUnicodeSet(const UConverterSharedData *sharedData,
   1030                       const USetAdder *sa,
   1031                       UConverterUnicodeSet which,
   1032                       UConverterSetFilter filter,
   1033                       UErrorCode *pErrorCode) {
   1034     const int32_t *cx;
   1035     const uint16_t *stage12, *stage3, *ps2, *ps3;
   1036     const uint32_t *stage3b;
   1037 
   1038     uint32_t value;
   1039     int32_t st1, stage1Length, st2, st3, minLength;
   1040 
   1041     UChar s[UCNV_EXT_MAX_UCHARS];
   1042     UChar32 c;
   1043     int32_t length;
   1044 
   1045     cx=sharedData->mbcs.extIndexes;
   1046     if(cx==NULL) {
   1047         return;
   1048     }
   1049 
   1050     stage12=UCNV_EXT_ARRAY(cx, UCNV_EXT_FROM_U_STAGE_12_INDEX, uint16_t);
   1051     stage3=UCNV_EXT_ARRAY(cx, UCNV_EXT_FROM_U_STAGE_3_INDEX, uint16_t);
   1052     stage3b=UCNV_EXT_ARRAY(cx, UCNV_EXT_FROM_U_STAGE_3B_INDEX, uint32_t);
   1053 
   1054     stage1Length=cx[UCNV_EXT_FROM_U_STAGE_1_LENGTH];
   1055 
   1056     /* enumerate the from-Unicode trie table */
   1057     c=0; /* keep track of the current code point while enumerating */
   1058 
   1059     if(filter==UCNV_SET_FILTER_2022_CN) {
   1060         minLength=3;
   1061     } else if( sharedData->mbcs.outputType==MBCS_OUTPUT_DBCS_ONLY ||
   1062                filter!=UCNV_SET_FILTER_NONE
   1063     ) {
   1064         /* DBCS-only, ignore single-byte results */
   1065         minLength=2;
   1066     } else {
   1067         minLength=1;
   1068     }
   1069 
   1070     /*
   1071      * the trie enumeration is almost the same as
   1072      * in MBCSGetUnicodeSet() for MBCS_OUTPUT_1
   1073      */
   1074     for(st1=0; st1<stage1Length; ++st1) {
   1075         st2=stage12[st1];
   1076         if(st2>stage1Length) {
   1077             ps2=stage12+st2;
   1078             for(st2=0; st2<64; ++st2) {
   1079                 if((st3=(int32_t)ps2[st2]<<UCNV_EXT_STAGE_2_LEFT_SHIFT)!=0) {
   1080                     /* read the stage 3 block */
   1081                     ps3=stage3+st3;
   1082 
   1083                     do {
   1084                         value=stage3b[*ps3++];
   1085                         if(value==0) {
   1086                             /* no mapping, do nothing */
   1087                         } else if(UCNV_EXT_FROM_U_IS_PARTIAL(value)) {
   1088                             // Recurse for partial results.
   1089                             length=0;
   1090                             U16_APPEND_UNSAFE(s, length, c);
   1091                             ucnv_extGetUnicodeSetString(
   1092                                 sharedData, cx, sa, which, minLength,
   1093                                 c, s, length,
   1094                                 (int32_t)UCNV_EXT_FROM_U_GET_PARTIAL_INDEX(value),
   1095                                 pErrorCode);
   1096                         } else if(extSetUseMapping(which, minLength, value)) {
   1097                             switch(filter) {
   1098                             case UCNV_SET_FILTER_2022_CN:
   1099                                 if(!(UCNV_EXT_FROM_U_GET_LENGTH(value)==3 && UCNV_EXT_FROM_U_GET_DATA(value)<=0x82ffff)) {
   1100                                     continue;
   1101                                 }
   1102                                 break;
   1103                             case UCNV_SET_FILTER_SJIS:
   1104                                 if(!(UCNV_EXT_FROM_U_GET_LENGTH(value)==2 && (value=UCNV_EXT_FROM_U_GET_DATA(value))>=0x8140 && value<=0xeffc)) {
   1105                                     continue;
   1106                                 }
   1107                                 break;
   1108                             case UCNV_SET_FILTER_GR94DBCS:
   1109                                 if(!(UCNV_EXT_FROM_U_GET_LENGTH(value)==2 &&
   1110                                      (uint16_t)((value=UCNV_EXT_FROM_U_GET_DATA(value))-0xa1a1)<=(0xfefe - 0xa1a1) &&
   1111                                      (uint8_t)(value-0xa1)<=(0xfe - 0xa1))) {
   1112                                     continue;
   1113                                 }
   1114                                 break;
   1115                             case UCNV_SET_FILTER_HZ:
   1116                                 if(!(UCNV_EXT_FROM_U_GET_LENGTH(value)==2 &&
   1117                                      (uint16_t)((value=UCNV_EXT_FROM_U_GET_DATA(value))-0xa1a1)<=(0xfdfe - 0xa1a1) &&
   1118                                      (uint8_t)(value-0xa1)<=(0xfe - 0xa1))) {
   1119                                     continue;
   1120                                 }
   1121                                 break;
   1122                             default:
   1123                                 /*
   1124                                  * UCNV_SET_FILTER_NONE,
   1125                                  * or UCNV_SET_FILTER_DBCS_ONLY which is handled via minLength
   1126                                  */
   1127                                 break;
   1128                             }
   1129                             sa->add(sa->set, c);
   1130                         }
   1131                     } while((++c&0xf)!=0);
   1132                 } else {
   1133                     c+=16; /* empty stage 3 block */
   1134                 }
   1135             }
   1136         } else {
   1137             c+=1024; /* empty stage 2 block */
   1138         }
   1139     }
   1140 }
   1141 
   1142 #endif /* #if !UCONFIG_NO_LEGACY_CONVERSION */
   1143