icuSources/common/ucnv_ext.h

   1 // © 2016 and later: Unicode, Inc. and others.
   2 // License & terms of use: http://www.unicode.org/copyright.html
   3 /*
   4 ******************************************************************************
   5 *
   6 *   Copyright (C) 2003-2013, International Business Machines
   7 *   Corporation and others.  All Rights Reserved.
   8 *
   9 ******************************************************************************
  10 *   file name:  ucnv_ext.h
  11 *   encoding:   UTF-8
  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 #ifndef __UCNV_EXT_H__
  22 #define __UCNV_EXT_H__
  23
  24 #include "unicode/utypes.h"
  25
  26 #if !UCONFIG_NO_CONVERSION
  27
  28 #include "unicode/ucnv.h"
  29 #include "ucnv_cnv.h"
  30
  31 /*
  32  * See icuhtml/design/conversion/conversion_extensions.html
  33  *
  34  * Conversion extensions serve three purposes:
  35  * 1. They support m:n mappings.
  36  * 2. They support extension-only conversion files that are used together
  37  *    with the regular conversion data in base files.
  38  * 3. They support mappings with more complicated meta data,
  39  *    for example "good one-way" mappings (|4).
  40  *
  41  * A base file may contain an extension table (explicitly requested or
  42  * implicitly generated for m:n mappings), but its extension table is not
  43  * used when an extension-only file is used.
  44  *
  45  * It is an error if a base file contains any regular (not extension) mapping
  46  * from the same sequence as a mapping in the extension file
  47  * because the base mapping would hide the extension mapping.
  48  *
  49  *
  50  * Data for conversion extensions:
  51  *
  52  * One set of data structures per conversion direction (to/from Unicode).
  53  * The data structures are sorted by input units to allow for binary search.
  54  * Input sequences of more than one unit are handled like contraction tables
  55  * in collation:
  56  * The lookup value of a unit points to another table that is to be searched
  57  * for the next unit, recursively.
  58  *
  59  * For conversion from Unicode, the initial code point is looked up in
  60  * a 3-stage trie for speed,
  61  * with an additional table of unique results to save space.
  62  *
  63  * Long output strings are stored in separate arrays, with length and index
  64  * in the lookup tables.
  65  * Output results also include a flag distinguishing roundtrip from
  66  * (reverse) fallback mappings.
  67  *
  68  * Input Unicode strings must not begin or end with unpaired surrogates
  69  * to avoid problems with matches on parts of surrogate pairs.
  70  *
  71  * Mappings from multiple characters (code points or codepage state
  72  * table sequences) must be searched preferring the longest match.
  73  * For this to work and be efficient, the variable-width table must contain
  74  * all mappings that contain prefixes of the multiple characters.
  75  * If an extension table is built on top of a base table in another file
  76  * and a base table entry is a prefix of a multi-character mapping, then
  77  * this is an error.
  78  *
  79  *
  80  * Implementation note:
  81  *
  82  * Currently, the parser and several checks in the code limit the number
  83  * of UChars or bytes in a mapping to
  84  * UCNV_EXT_MAX_UCHARS and UCNV_EXT_MAX_BYTES, respectively,
  85  * which are output value limits in the data structure.
  86  *
  87  * For input, this is not strictly necessary - it is a hard limit only for the
  88  * buffers in UConverter that are used to store partial matches.
  89  *
  90  * Input sequences could otherwise be arbitrarily long if partial matches
  91  * need not be stored (i.e., if a sequence does not span several buffers with too
  92  * many units before the last buffer), although then results would differ
  93  * depending on whether partial matches exceed the limits or not,
  94  * which depends on the pattern of buffer sizes.
  95  *
  96  *
  97  * Data structure:
  98  *
  99  * int32_t indexes[>=32];
 100  *
 101  *   Array of indexes and lengths etc. The length of the array is at least 32.
 102  *   The actual length is stored in indexes[0] to be forward compatible.
 103  *
 104  *   Each index to another array is the number of bytes from indexes[].
 105  *   Each length of an array is the number of array base units in that array.
 106  *
 107  *   Some of the structures may not be present, in which case their indexes
 108  *   and lengths are 0.
 109  *
 110  *   Usage of indexes[i]:
 111  *   [0]  length of indexes[]
 112  *
 113  *   // to Unicode table
 114  *   [1]  index of toUTable[] (array of uint32_t)
 115  *   [2]  length of toUTable[]
 116  *   [3]  index of toUUChars[] (array of UChar)
 117  *   [4]  length of toUUChars[]
 118  *
 119  *   // from Unicode table, not for the initial code point
 120  *   [5]  index of fromUTableUChars[] (array of UChar)
 121  *   [6]  index of fromUTableValues[] (array of uint32_t)
 122  *   [7]  length of fromUTableUChars[] and fromUTableValues[]
 123  *   [8]  index of fromUBytes[] (array of char)
 124  *   [9]  length of fromUBytes[]
 125  *
 126  *   // from Unicode trie for initial-code point lookup
 127  *   [10] index of fromUStage12[] (combined array of uint16_t for stages 1 & 2)
 128  *   [11] length of stage 1 portion of fromUStage12[]
 129  *   [12] length of fromUStage12[]
 130  *   [13] index of fromUStage3[] (array of uint16_t indexes into fromUStage3b[])
 131  *   [14] length of fromUStage3[]
 132  *   [15] index of fromUStage3b[] (array of uint32_t like fromUTableValues[])
 133  *   [16] length of fromUStage3b[]
 134  *
 135  *   [17] Bit field containing numbers of bytes:
 136  *        31..24 reserved, 0
 137  *        23..16 maximum input bytes
 138  *        15.. 8 maximum output bytes
 139  *         7.. 0 maximum bytes per UChar
 140  *
 141  *   [18] Bit field containing numbers of UChars:
 142  *        31..24 reserved, 0
 143  *        23..16 maximum input UChars
 144  *        15.. 8 maximum output UChars
 145  *         7.. 0 maximum UChars per byte
 146  *
 147  *   [19] Bit field containing flags:
 148  *               (extension table unicodeMask)
 149  *         1     UCNV_HAS_SURROGATES flag for the extension table
 150  *         0     UCNV_HAS_SUPPLEMENTARY flag for the extension table
 151  *
 152  *   [20]..[30] reserved, 0
 153  *   [31] number of bytes for the entire extension structure
 154  *   [>31] reserved; there are indexes[0] indexes
 155  *
 156  *
 157  * uint32_t toUTable[];
 158  *
 159  *   Array of byte/value pairs for lookups for toUnicode conversion.
 160  *   The array is partitioned into sections like collation contraction tables.
 161  *   Each section contains one word with the number of following words and
 162  *   a default value for when the lookup in this section yields no match.
 163  *
 164  *   A section is sorted in ascending order of input bytes,
 165  *   allowing for fast linear or binary searches.
 166  *   The builder may store entries for a contiguous range of byte values
 167  *   (compare difference between the first and last one with count),
 168  *   which then allows for direct array access.
 169  *   The builder should always do this for the initial table section.
 170  *
 171  *   Entries may have 0 values, see below.
 172  *   No two entries in a section have the same byte values.
 173  *
 174  *   Each uint32_t contains an input byte value in bits 31..24 and the
 175  *   corresponding lookup value in bits 23..0.
 176  *   Interpret the value as follows:
 177  *     if(value==0) {
 178  *       no match, see below
 179  *     } else if(value<0x1f0000) {
 180  *       partial match - use value as index to the next toUTable section
 181  *       and match the next unit; (value indexes toUTable[value])
 182  *     } else {
 183  *       if(bit 23 set) {
 184  *         roundtrip;
 185  *       } else {
 186  *         fallback;
 187  *       }
 188  *       unset value bit 23;
 189  *       if(value<=0x2fffff) {
 190  *         (value-0x1f0000) is a code point; (BMP: value<=0x1fffff)
 191  *       } else {
 192  *         bits 17..0 (value&0x3ffff) is an index to
 193  *           the result UChars in toUUChars[]; (0 indexes toUUChars[0])
 194  *         length of the result=((value>>18)-12); (length=0..19)
 195  *       }
 196  *     }
 197  *
 198  *   The first word in a section contains the number of following words in the
 199  *   input byte position (bits 31..24, number=1..0xff).
 200  *   The value of the initial word is used when the current byte is not found
 201  *   in this section.
 202  *   If the value is not 0, then it represents a result as above.
 203  *   If the value is 0, then the search has to return a shorter match with an
 204  *   earlier default value as the result, or result in "unmappable" even for the
 205  *   initial bytes.
 206  *   If the value is 0 for the initial toUTable entry, then the initial byte
 207  *   does not start any mapping input.
 208  *
 209  *
 210  * UChar toUUChars[];
 211  *
 212  *   Contains toUnicode mapping results, stored as sequences of UChars.
 213  *   Indexes and lengths stored in the toUTable[].
 214  *
 215  *
 216  * UChar fromUTableUChars[];
 217  * uint32_t fromUTableValues[];
 218  *
 219  *   The fromUTable is split into two arrays, but works otherwise much like
 220  *   the toUTable. The array is partitioned into sections like collation
 221  *   contraction tables and toUTable.
 222  *   A row in the table consists of same-index entries in fromUTableUChars[]
 223  *   and fromUTableValues[].
 224  *
 225  *   Interpret a value as follows:
 226  *     if(value==0) {
 227  *       no match, see below
 228  *     } else if(value<=0xffffff) { (bits 31..24 are 0)
 229  *       partial match - use value as index to the next fromUTable section
 230  *       and match the next unit; (value indexes fromUTable[value])
 231  *     } else {
 232  *       if(value==0x80000001) {
 233  *         return no mapping, but request for <subchar1>;
 234  *       }
 235  *       if(bit 31 set) {
 236  *         roundtrip (|0);
 237  *       } else if(bit 30 set) {
 238  *         "good one-way" mapping (|4); -- new in ICU4C 51, _MBCSHeader.version 5.4/4.4
 239  *       } else {
 240  *         normal fallback (|1);
 241  *       }
 242  *       // bit 29 reserved, 0
 243  *       length=(value>>24)&0x1f; (bits 28..24)
 244  *       if(length==1..3) {
 245  *         bits 23..0 contain 1..3 bytes, padded with 00s on the left;
 246  *       } else {
 247  *         bits 23..0 (value&0xffffff) is an index to
 248  *           the result bytes in fromUBytes[]; (0 indexes fromUBytes[0])
 249  *       }
 250  *     }
 251  *
 252  *   The first pair in a section contains the number of following pairs in the
 253  *   UChar position (16 bits, number=1..0xffff).
 254  *   The value of the initial pair is used when the current UChar is not found
 255  *   in this section.
 256  *   If the value is not 0, then it represents a result as above.
 257  *   If the value is 0, then the search has to return a shorter match with an
 258  *   earlier default value as the result, or result in "unmappable" even for the
 259  *   initial UChars.
 260  *
 261  *   If the from Unicode trie is present, then the from Unicode search tables
 262  *   are not used for initial code points.
 263  *   In this case, the first entries (index 0) in the tables are not used
 264  *   (reserved, set to 0) because a value of 0 is used in trie results
 265  *   to indicate no mapping.
 266  *
 267  *
 268  * uint16_t fromUStage12[];
 269  *
 270  *   Stages 1 & 2 of a trie that maps an initial code point.
 271  *   Indexes in stage 1 are all offset by the length of stage 1 so that the
 272  *   same array pointer can be used for both stages.
 273  *   If (c>>10)>=(length of stage 1) then c does not start any mapping.
 274  *   Same bit distribution as for regular conversion tries.
 275  *
 276  *
 277  * uint16_t fromUStage3[];
 278  * uint32_t fromUStage3b[];
 279  *
 280  *   Stage 3 of the trie. The first array simply contains indexes to the second,
 281  *   which contains words in the same format as fromUTableValues[].
 282  *   Use a stage 3 granularity of 4, which allows for 256k stage 3 entries,
 283  *   and 16-bit entries in stage 3 allow for 64k stage 3b entries.
 284  *   The stage 3 granularity means that the stage 2 entry needs to be left-shifted.
 285  *
 286  *   Two arrays are used because it is expected that more than half of the stage 3
 287  *   entries will be zero. The 16-bit index stage 3 array saves space even
 288  *   considering storing a total of 6 bytes per non-zero entry in both arrays
 289  *   together.
 290  *   Using a stage 3 granularity of >1 diminishes the compactability in that stage
 291  *   but provides a larger effective addressing space in stage 2.
 292  *   All but the final result stage use 16-bit entries to save space.
 293  *
 294  *   fromUStage3b[] contains a zero for "no mapping" at its index 0,
 295  *   and may contain UCNV_EXT_FROM_U_SUBCHAR1 at index 1 for "<subchar1> SUB mapping"
 296  *   (i.e., "no mapping" with preference for <subchar1> rather than <subchar>),
 297  *   and all other items are unique non-zero results.
 298  *
 299  *   The default value of a fromUTableValues[] section that is referenced
 300  *   _directly_ from a fromUStage3b[] item may also be UCNV_EXT_FROM_U_SUBCHAR1,
 301  *   but this value must not occur anywhere else in fromUTableValues[]
 302  *   because "no mapping" is always a property of a single code point,
 303  *   never of multiple.
 304  *
 305  *
 306  * char fromUBytes[];
 307  *
 308  *   Contains fromUnicode mapping results, stored as sequences of chars.
 309  *   Indexes and lengths stored in the fromUTableValues[].
 310  */
 311 enum {
 312     UCNV_EXT_INDEXES_LENGTH,            /* 0 */
 313
 314     UCNV_EXT_TO_U_INDEX,                /* 1 */
 315     UCNV_EXT_TO_U_LENGTH,
 316     UCNV_EXT_TO_U_UCHARS_INDEX,
 317     UCNV_EXT_TO_U_UCHARS_LENGTH,
 318
 319     UCNV_EXT_FROM_U_UCHARS_INDEX,       /* 5 */
 320     UCNV_EXT_FROM_U_VALUES_INDEX,
 321     UCNV_EXT_FROM_U_LENGTH,
 322     UCNV_EXT_FROM_U_BYTES_INDEX,
 323     UCNV_EXT_FROM_U_BYTES_LENGTH,
 324
 325     UCNV_EXT_FROM_U_STAGE_12_INDEX,     /* 10 */
 326     UCNV_EXT_FROM_U_STAGE_1_LENGTH,
 327     UCNV_EXT_FROM_U_STAGE_12_LENGTH,
 328     UCNV_EXT_FROM_U_STAGE_3_INDEX,
 329     UCNV_EXT_FROM_U_STAGE_3_LENGTH,
 330     UCNV_EXT_FROM_U_STAGE_3B_INDEX,
 331     UCNV_EXT_FROM_U_STAGE_3B_LENGTH,
 332
 333     UCNV_EXT_COUNT_BYTES,               /* 17 */
 334     UCNV_EXT_COUNT_UCHARS,
 335     UCNV_EXT_FLAGS,
 336
 337     UCNV_EXT_RESERVED_INDEX,            /* 20, moves with additional indexes */
 338
 339     UCNV_EXT_SIZE=31,
 340     UCNV_EXT_INDEXES_MIN_LENGTH=32
 341 };
 342
 343 /* get the pointer to an extension array from indexes[index] */
 344 #define UCNV_EXT_ARRAY(indexes, index, itemType) \
 345     ((const itemType *)((const char *)(indexes)+(indexes)[index]))
 346
 347 #define UCNV_GET_MAX_BYTES_PER_UCHAR(indexes) \
 348     ((indexes)[UCNV_EXT_COUNT_BYTES]&0xff)
 349
 350 /* internal API ------------------------------------------------------------- */
 351
 352 U_CFUNC UBool
 353 ucnv_extInitialMatchToU(UConverter *cnv, const int32_t *cx,
 354                         int32_t firstLength,
 355                         const char **src, const char *srcLimit,
 356                         UChar **target, const UChar *targetLimit,
 357                         int32_t **offsets, int32_t srcIndex,
 358                         UBool flush,
 359                         UErrorCode *pErrorCode);
 360
 361 U_CFUNC UChar32
 362 ucnv_extSimpleMatchToU(const int32_t *cx,
 363                        const char *source, int32_t length,
 364                        UBool useFallback);
 365
 366 U_CFUNC void
 367 ucnv_extContinueMatchToU(UConverter *cnv,
 368                          UConverterToUnicodeArgs *pArgs, int32_t srcIndex,
 369                          UErrorCode *pErrorCode);
 370
 371
 372 U_CFUNC UBool
 373 ucnv_extInitialMatchFromU(UConverter *cnv, const int32_t *cx,
 374                           UChar32 cp,
 375                           const UChar **src, const UChar *srcLimit,
 376                           char **target, const char *targetLimit,
 377                           int32_t **offsets, int32_t srcIndex,
 378                           UBool flush,
 379                           UErrorCode *pErrorCode);
 380
 381 U_CFUNC int32_t
 382 ucnv_extSimpleMatchFromU(const int32_t *cx,
 383                          UChar32 cp, uint32_t *pValue,
 384                          UBool useFallback);
 385
 386 U_CFUNC void
 387 ucnv_extContinueMatchFromU(UConverter *cnv,
 388                            UConverterFromUnicodeArgs *pArgs, int32_t srcIndex,
 389                            UErrorCode *pErrorCode);
 390
 391 /*
 392  * Add code points and strings to the set according to the extension mappings.
 393  * Limitation on the UConverterSetFilter:
 394  * The filters currently assume that they are used with 1:1 mappings.
 395  * They only apply to single input code points, and then they pass through
 396  * only mappings with single-charset-code results.
 397  * For example, the Shift-JIS filter only works for 2-byte results and tests
 398  * that those 2 bytes are in the JIS X 0208 range of Shift-JIS.
 399  */
 400 U_CFUNC void
 401 ucnv_extGetUnicodeSet(const UConverterSharedData *sharedData,
 402                       const USetAdder *sa,
 403                       UConverterUnicodeSet which,
 404                       UConverterSetFilter filter,
 405                       UErrorCode *pErrorCode);
 406
 407 /* toUnicode helpers -------------------------------------------------------- */
 408
 409 #define UCNV_EXT_TO_U_BYTE_SHIFT 24
 410 #define UCNV_EXT_TO_U_VALUE_MASK 0xffffff
 411 #define UCNV_EXT_TO_U_MIN_CODE_POINT 0x1f0000
 412 #define UCNV_EXT_TO_U_MAX_CODE_POINT 0x2fffff
 413 #define UCNV_EXT_TO_U_ROUNDTRIP_FLAG ((uint32_t)1<<23)
 414 #define UCNV_EXT_TO_U_INDEX_MASK 0x3ffff
 415 #define UCNV_EXT_TO_U_LENGTH_SHIFT 18
 416 #define UCNV_EXT_TO_U_LENGTH_OFFSET 12
 417
 418 /* maximum number of indexed UChars */
 419 #define UCNV_EXT_MAX_UCHARS 19
 420
 421 #define UCNV_EXT_TO_U_MAKE_WORD(byte, value) (((uint32_t)(byte)<<UCNV_EXT_TO_U_BYTE_SHIFT)|(value))
 422
 423 #define UCNV_EXT_TO_U_GET_BYTE(word) ((word)>>UCNV_EXT_TO_U_BYTE_SHIFT)
 424 #define UCNV_EXT_TO_U_GET_VALUE(word) ((word)&UCNV_EXT_TO_U_VALUE_MASK)
 425
 426 #define UCNV_EXT_TO_U_IS_PARTIAL(value) ((value)<UCNV_EXT_TO_U_MIN_CODE_POINT)
 427 #define UCNV_EXT_TO_U_GET_PARTIAL_INDEX(value) (value)
 428
 429 #define UCNV_EXT_TO_U_IS_ROUNDTRIP(value) (((value)&UCNV_EXT_TO_U_ROUNDTRIP_FLAG)!=0)
 430 #define UCNV_EXT_TO_U_MASK_ROUNDTRIP(value) ((value)&~UCNV_EXT_TO_U_ROUNDTRIP_FLAG)
 431
 432 /* use after masking off the roundtrip flag */
 433 #define UCNV_EXT_TO_U_IS_CODE_POINT(value) ((value)<=UCNV_EXT_TO_U_MAX_CODE_POINT)
 434 #define UCNV_EXT_TO_U_GET_CODE_POINT(value) ((value)-UCNV_EXT_TO_U_MIN_CODE_POINT)
 435
 436 #define UCNV_EXT_TO_U_GET_INDEX(value) ((value)&UCNV_EXT_TO_U_INDEX_MASK)
 437 #define UCNV_EXT_TO_U_GET_LENGTH(value) (((value)>>UCNV_EXT_TO_U_LENGTH_SHIFT)-UCNV_EXT_TO_U_LENGTH_OFFSET)
 438
 439 /* fromUnicode helpers ------------------------------------------------------ */
 440
 441 /* most trie constants are shared with ucnvmbcs.h */
 442
 443 /* see similar utrie.h UTRIE_INDEX_SHIFT and UTRIE_DATA_GRANULARITY */
 444 #define UCNV_EXT_STAGE_2_LEFT_SHIFT 2
 445 #define UCNV_EXT_STAGE_3_GRANULARITY 4
 446
 447 /* trie access, returns the stage 3 value=index to stage 3b; s1Index=c>>10 */
 448 #define UCNV_EXT_FROM_U(stage12, stage3, s1Index, c) \
 449     (stage3)[ ((int32_t)(stage12)[ (stage12)[s1Index] +(((c)>>4)&0x3f) ]<<UCNV_EXT_STAGE_2_LEFT_SHIFT) +((c)&0xf) ]
 450
 451 #define UCNV_EXT_FROM_U_LENGTH_SHIFT 24
 452 #define UCNV_EXT_FROM_U_ROUNDTRIP_FLAG ((uint32_t)1<<31)
 453 #define UCNV_EXT_FROM_U_GOOD_ONE_WAY_FLAG 0x40000000
 454 #define UCNV_EXT_FROM_U_STATUS_MASK 0xc0000000
 455 #define UCNV_EXT_FROM_U_RESERVED_MASK 0x20000000
 456 #define UCNV_EXT_FROM_U_DATA_MASK 0xffffff
 457
 458 /* special value for "no mapping" to <subchar1> (impossible roundtrip to 0 bytes, value 01) */
 459 #define UCNV_EXT_FROM_U_SUBCHAR1 0x80000001
 460
 461 /* at most 3 bytes in the lower part of the value */
 462 #define UCNV_EXT_FROM_U_MAX_DIRECT_LENGTH 3
 463
 464 /* maximum number of indexed bytes */
 465 #define UCNV_EXT_MAX_BYTES 0x1f
 466
 467 #define UCNV_EXT_FROM_U_IS_PARTIAL(value) (((value)>>UCNV_EXT_FROM_U_LENGTH_SHIFT)==0)
 468 #define UCNV_EXT_FROM_U_GET_PARTIAL_INDEX(value) (value)
 469
 470 #define UCNV_EXT_FROM_U_IS_ROUNDTRIP(value) (((value)&UCNV_EXT_FROM_U_ROUNDTRIP_FLAG)!=0)
 471 #define UCNV_EXT_FROM_U_MASK_ROUNDTRIP(value) ((value)&~UCNV_EXT_FROM_U_ROUNDTRIP_FLAG)
 472
 473 /* get length; masks away all other bits */
 474 #define UCNV_EXT_FROM_U_GET_LENGTH(value) (int32_t)(((value)>>UCNV_EXT_FROM_U_LENGTH_SHIFT)&UCNV_EXT_MAX_BYTES)
 475
 476 /* get bytes or bytes index */
 477 #define UCNV_EXT_FROM_U_GET_DATA(value) ((value)&UCNV_EXT_FROM_U_DATA_MASK)
 478
 479 #endif
 480
 481 #endif