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 */
311enum {
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
352U_CFUNC UBool
353ucnv_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
361U_CFUNC UChar32
362ucnv_extSimpleMatchToU(const int32_t *cx,
363 const char *source, int32_t length,
364 UBool useFallback);
365
366U_CFUNC void
367ucnv_extContinueMatchToU(UConverter *cnv,
368 UConverterToUnicodeArgs *pArgs, int32_t srcIndex,
369 UErrorCode *pErrorCode);
370
371
372U_CFUNC UBool
373ucnv_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
381U_CFUNC int32_t
382ucnv_extSimpleMatchFromU(const int32_t *cx,
383 UChar32 cp, uint32_t *pValue,
384 UBool useFallback);
385
386U_CFUNC void
387ucnv_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 */
400U_CFUNC void
401ucnv_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
482