1 /*
2 ******************************************************************************
3 *
4 *   Copyright (C) 2000-2013, International Business Machines
5 *   Corporation and others.  All Rights Reserved.
6 *
7 ******************************************************************************
8 *   file name:  ucnvmbcs.h
9 *   encoding:   US-ASCII
10 *   tab size:   8 (not used)
11 *   indentation:4
12 *
13 *   created on: 2000jul07
14 *   created by: Markus W. Scherer
15 */
16 
17 #ifndef __UCNVMBCS_H__
18 #define __UCNVMBCS_H__
19 
20 #include "unicode/utypes.h"
21 
22 #if !UCONFIG_NO_CONVERSION
23 
24 #include "unicode/ucnv.h"
25 #include "ucnv_cnv.h"
26 #include "ucnv_ext.h"
27 
28 /**
29  * ICU conversion (.cnv) data file structure, following the usual UDataInfo
30  * header.
31  *
32  * Format version: 6.2
33  *
34  * struct UConverterStaticData -- struct containing the converter name, IBM CCSID,
35  *                                min/max bytes per character, etc.
36  *                                see ucnv_bld.h
37  *
38  * --------------------
39  *
40  * The static data is followed by conversionType-specific data structures.
41  * At the moment, there are only variations of MBCS converters. They all have
42  * the same toUnicode structures, while the fromUnicode structures for SBCS
43  * differ from those for other MBCS-style converters.
44  *
45  * _MBCSHeader.version 5 is optional and not backward-compatible
46  * (as usual for changes in the major version field).
47  *
48  * Versions 5.m work like versions 4.m except:
49  * - The _MBCSHeader has variable length (and is always longer than in version 4).
50  *   See the struct _MBCSHeader further description below.
51  * - There is a set of flags which indicate further incompatible changes.
52  *   (Reader code must reject the file if it does not recognize them all.)
53  * - In particular, one of these flags indicates that most of the fromUnicode
54  *   data is missing and must be reconstituted from the toUnicode data
55  *   and from the utf8Friendly mbcsIndex at load time.
56  *   (This only works with a utf8Friendly table.)
57  *   In this case, makeconv may increase maxFastUChar automatically to U+FFFF.
58  *
59  * The first of these versions is 5.3, which is like 4.3 except for the differences above.
60  *
61  * When possible, makeconv continues to generate version 4.m files.
62  *
63  * _MBCSHeader.version 5.4/4.4 supports "good one-way" mappings (|4)
64  * in the extension tables (fromUTableValues bit 30). See ucnv_ext.h for details.
65  *
66  * _MBCSHeader.version 4.3 optionally modifies the fromUnicode data structures
67  * slightly and optionally adds a table for conversion to MBCS (non-SBCS)
68  * charsets.
69  *
70  * The modifications are to make the data utf8Friendly. Not every 4.3 file
71  * file contains utf8Friendly data.
72  * It is utf8Friendly if _MBCSHeader.version[2]!=0.
73  * In this case, the data structures are utf8Friendly up to the code point
74  *   maxFastUChar=((_MBCSHeader.version[2]<<8)|0xff)
75  *
76  * A utf8Friendly file has fromUnicode stage 3 entries for code points up to
77  * maxFastUChar allocated in blocks of 64 for indexing with the 6 bits from
78  * a UTF-8 trail byte. ASCII is allocated linearly with 128 contiguous entries.
79  *
80  * In addition, a utf8Friendly MBCS file contains an additional
81  *   uint16_t mbcsIndex[(maxFastUChar+1)>>6];
82  * which replaces the stage 1 and 2 tables for indexing with bits from the
83  * UTF-8 lead byte and middle trail byte. Unlike the older MBCS stage 2 table,
84  * the mbcsIndex does not contain roundtrip flags. Therefore, all fallbacks
85  * from code points up to maxFastUChar (and roundtrips to 0x00) are moved to
86  * the extension data structure. This also allows for faster roundtrip
87  * conversion from UTF-16.
88  *
89  * SBCS files do not contain an additional sbcsIndex[] array because the
90  * proportional size increase would be noticeable, but the runtime
91  * code builds one for the code point range for which the runtime conversion
92  * code is optimized.
93  *
94  * For SBCS, maxFastUChar should be at least U+0FFF. The initial makeconv
95  * implementation sets it to U+1FFF. Because the sbcsIndex is not stored in
96  * the file, a larger maxFastUChar only affects stage 3 block allocation size
97  * and is free in empty blocks. (Larger blocks with sparse contents cause larger
98  * files.) U+1FFF includes almost all of the small scripts.
99  * U+0FFF covers UTF-8 two-byte sequences and three-byte sequences starting with
100  * 0xe0. This includes most scripts with legacy SBCS charsets.
101  * The initial runtime implementation using 4.3 files only builds an sbcsIndex
102  * for code points up to U+0FFF.
103  *
104  * For MBCS, maxFastUChar should be at least U+D7FF (=initial value).
105  * This boundary is convenient because practically all of the commonly used
106  * characters are below it, and because it is the boundary to surrogate
107  * code points, above which special handling is necessary anyway.
108  * (Surrogate pair assembly for UTF-16, validity checking for UTF-8.)
109  *
110  * maxFastUChar could be up to U+FFFF to cover the whole BMP, which could be
111  * useful especially for conversion from UTF-8 when the input can be assumed
112  * to be valid, because the surrogate range would then not have to be
113  * checked.
114  * (With maxFastUChar=0xffff, makeconv would have to check for mbcsIndex value
115  * overflow because with the all-unassigned block 0 and nearly full mappings
116  * from the BMP it is theoretically possible that an index into stage 3
117  * exceeds 16 bits.)
118  *
119  * _MBCSHeader.version 4.2 adds an optional conversion extension data structure.
120  * If it is present, then an ICU version reading header versions 4.0 or 4.1
121  * will be able to use the base table and ignore the extension.
122  *
123  * The unicodeMask in the static data is part of the base table data structure.
124  * Especially, the UCNV_HAS_SUPPLEMENTARY flag determines the length of the
125  * fromUnicode stage 1 array.
126  * The static data unicodeMask refers only to the base table's properties if
127  * a base table is included.
128  * In an extension-only file, the static data unicodeMask is 0.
129  * The extension data indexes have a separate field with the unicodeMask flags.
130  *
131  * MBCS-style data structure following the static data.
132  * Offsets are counted in bytes from the beginning of the MBCS header structure.
133  * Details about usage in comments in ucnvmbcs.c.
134  *
135  * struct _MBCSHeader (see the definition in this header file below)
136  * contains 32-bit fields as follows:
137  * 8 values:
138  *  0   uint8_t[4]  MBCS version in UVersionInfo format (currently 4.3.x.0)
139  *  1   uint32_t    countStates
140  *  2   uint32_t    countToUFallbacks
141  *  3   uint32_t    offsetToUCodeUnits
142  *  4   uint32_t    offsetFromUTable
143  *  5   uint32_t    offsetFromUBytes
144  *  6   uint32_t    flags, bits:
145  *                      31.. 8 offsetExtension -- _MBCSHeader.version 4.2 (ICU 2.8) and higher
146  *                                                0 for older versions and if
147  *                                                there is not extension structure
148  *                       7.. 0 outputType
149  *  7   uint32_t    fromUBytesLength -- _MBCSHeader.version 4.1 (ICU 2.4) and higher
150  *                  counts bytes in fromUBytes[]
151  *
152  * New and required in version 5:
153  *  8   uint32_t    options, bits:
154  *                      31..16 reserved for flags that can be added without breaking
155  *                                 backward compatibility
156  *                      15.. 6 reserved for flags whose addition will break
157  *                                 backward compatibility
158  *                           6 MBCS_OPT_FROM_U -- if set,
159  *                                 then most of the fromUnicode data is omitted;
160  *                                 fullStage2Length is present and the missing
161  *                                 bottom part of stage 2 must be reconstituted from
162  *                                 the toUnicode data;
163  *                                 stage 3 is missing completely as well;
164  *                                 not used for SBCS tables
165  *                       5.. 0 length of the _MBCSHeader (number of uint32_t)
166  *
167  * New and optional in version 5:
168  *  9   uint32_t    fullStage2Length: used if MBCS_OPT_FROM_U is set
169  *                                 specifies the full length of stage 2
170  *                                 including the omitted part
171  *
172  * if(outputType==MBCS_OUTPUT_EXT_ONLY) {
173  *     -- base table name for extension-only table
174  *     char baseTableName[variable]; -- with NUL plus padding for 4-alignment
175  *
176  *     -- all _MBCSHeader fields except for version and flags are 0
177  * } else {
178  *     -- normal base table with optional extension
179  *
180  *     int32_t stateTable[countStates][256];
181  *
182  *     struct _MBCSToUFallback { (fallbacks are sorted by offset)
183  *         uint32_t offset;
184  *         UChar32 codePoint;
185  *     } toUFallbacks[countToUFallbacks];
186  *
187  *     uint16_t unicodeCodeUnits[(offsetFromUTable-offsetToUCodeUnits)/2];
188  *                  (padded to an even number of units)
189  *
190  *     -- stage 1 tables
191  *     if(staticData.unicodeMask&UCNV_HAS_SUPPLEMENTARY) {
192  *         -- stage 1 table for all of Unicode
193  *         uint16_t fromUTable[0x440]; (32-bit-aligned)
194  *     } else {
195  *         -- BMP-only tables have a smaller stage 1 table
196  *         uint16_t fromUTable[0x40]; (32-bit-aligned)
197  *     }
198  *
199  *     -- stage 2 tables
200  *        length determined by top of stage 1 and bottom of stage 3 tables
201  *     if(outputType==MBCS_OUTPUT_1) {
202  *         -- SBCS: pure indexes
203  *         uint16_t stage 2 indexes[?];
204  *     } else {
205  *         -- DBCS, MBCS, EBCDIC_STATEFUL, ...: roundtrip flags and indexes
206  *         uint32_t stage 2 flags and indexes[?];
207  *         if(options&MBCS_OPT_NO_FROM_U) {
208  *             stage 2 really has length fullStage2Length
209  *             and the omitted lower part must be reconstituted from
210  *             the toUnicode data
211  *         }
212  *     }
213  *
214  *     -- stage 3 tables with byte results
215  *     if(outputType==MBCS_OUTPUT_1) {
216  *         -- SBCS: each 16-bit result contains flags and the result byte, see ucnvmbcs.c
217  *         uint16_t fromUBytes[fromUBytesLength/2];
218  *     } else if(!(options&MBCS_OPT_NO_FROM_U)) {
219  *         -- DBCS, MBCS, EBCDIC_STATEFUL, ... 2/3/4 bytes result, see ucnvmbcs.c
220  *         uint8_t fromUBytes[fromUBytesLength]; or
221  *         uint16_t fromUBytes[fromUBytesLength/2]; or
222  *         uint32_t fromUBytes[fromUBytesLength/4];
223  *     } else {
224  *         fromUBytes[] must be reconstituted from the toUnicode data
225  *     }
226  *
227  *     -- optional utf8Friendly mbcsIndex -- _MBCSHeader.version 4.3 (ICU 3.8) and higher
228  *     if(outputType!=MBCS_OUTPUT_1 &&
229  *        _MBCSHeader.version[1]>=3 &&
230  *        (maxFastUChar=_MBCSHeader.version[2])!=0
231  *     ) {
232  *         maxFastUChar=(maxFastUChar<<8)|0xff;
233  *         uint16_t mbcsIndex[(maxFastUChar+1)>>6];
234  *     }
235  * }
236  *
237  * -- extension table, details see ucnv_ext.h
238  * int32_t indexes[>=32]; ...
239  */
240 
241 /* MBCS converter data and state -------------------------------------------- */
242 
243 enum {
244     MBCS_MAX_STATE_COUNT=128
245 };
246 
247 /**
248  * MBCS action codes for conversions to Unicode.
249  * These values are in bits 23..20 of the state table entries.
250  */
251 enum {
252     MBCS_STATE_VALID_DIRECT_16,
253     MBCS_STATE_VALID_DIRECT_20,
254 
255     MBCS_STATE_FALLBACK_DIRECT_16,
256     MBCS_STATE_FALLBACK_DIRECT_20,
257 
258     MBCS_STATE_VALID_16,
259     MBCS_STATE_VALID_16_PAIR,
260 
261     MBCS_STATE_UNASSIGNED,
262     MBCS_STATE_ILLEGAL,
263 
264     MBCS_STATE_CHANGE_ONLY
265 };
266 
267 /* Macros for state table entries */
268 #define MBCS_ENTRY_TRANSITION(state, offset) (int32_t)(((int32_t)(state)<<24L)|(offset))
269 #define MBCS_ENTRY_TRANSITION_SET_OFFSET(entry, offset) (int32_t)(((entry)&0xff000000)|(offset))
270 #define MBCS_ENTRY_TRANSITION_ADD_OFFSET(entry, offset) (int32_t)((entry)+(offset))
271 
272 #define MBCS_ENTRY_FINAL(state, action, value) (int32_t)(0x80000000|((int32_t)(state)<<24L)|((action)<<20L)|(value))
273 #define MBCS_ENTRY_SET_FINAL(entry) (int32_t)((entry)|0x80000000)
274 #define MBCS_ENTRY_FINAL_SET_ACTION(entry, action) (int32_t)(((entry)&0xff0fffff)|((int32_t)(action)<<20L))
275 #define MBCS_ENTRY_FINAL_SET_VALUE(entry, value) (int32_t)(((entry)&0xfff00000)|(value))
276 #define MBCS_ENTRY_FINAL_SET_ACTION_VALUE(entry, action, value) (int32_t)(((entry)&0xff000000)|((int32_t)(action)<<20L)|(value))
277 
278 #define MBCS_ENTRY_SET_STATE(entry, state) (int32_t)(((entry)&0x80ffffff)|((int32_t)(state)<<24L))
279 
280 #define MBCS_ENTRY_STATE(entry) ((((uint32_t)entry)>>24)&0x7f)
281 
282 #define MBCS_ENTRY_IS_TRANSITION(entry) ((entry)>=0)
283 #define MBCS_ENTRY_IS_FINAL(entry) ((entry)<0)
284 
285 #define MBCS_ENTRY_TRANSITION_STATE(entry) (((uint32_t)entry)>>24)
286 #define MBCS_ENTRY_TRANSITION_OFFSET(entry) ((entry)&0xffffff)
287 
288 #define MBCS_ENTRY_FINAL_STATE(entry) ((((uint32_t)entry)>>24)&0x7f)
289 #define MBCS_ENTRY_FINAL_IS_VALID_DIRECT_16(entry) ((entry)<(int32_t)0x80100000)
290 #define MBCS_ENTRY_FINAL_ACTION(entry) ((((uint32_t)entry)>>20)&0xf)
291 #define MBCS_ENTRY_FINAL_VALUE(entry) ((entry)&0xfffff)
292 #define MBCS_ENTRY_FINAL_VALUE_16(entry) (uint16_t)(entry)
293 
294 #define IS_ASCII_ROUNDTRIP(b, asciiRoundtrips) (((asciiRoundtrips) & (1<<((b)>>2)))!=0)
295 
296 /* single-byte fromUnicode: get the 16-bit result word */
297 #define MBCS_SINGLE_RESULT_FROM_U(table, results, c) (results)[ (table)[ (table)[(c)>>10] +(((c)>>4)&0x3f) ] +((c)&0xf) ]
298 
299 /* single-byte fromUnicode using the sbcsIndex */
300 #define SBCS_RESULT_FROM_LOW_BMP(table, results, c) (results)[ (table)[(c)>>6] +((c)&0x3f) ]
301 
302 /* single-byte fromUTF8 using the sbcsIndex; l and t must be masked externally; can be l=0 and t<=0x7f */
303 #define SBCS_RESULT_FROM_UTF8(table, results, l, t) (results)[ (table)[l] +(t) ]
304 
305 /* multi-byte fromUnicode: get the 32-bit stage 2 entry */
306 #define MBCS_STAGE_2_FROM_U(table, c) ((const uint32_t *)(table))[ (table)[(c)>>10] +(((c)>>4)&0x3f) ]
307 #define MBCS_FROM_U_IS_ROUNDTRIP(stage2Entry, c) ( ((stage2Entry) & ((uint32_t)1<< (16+((c)&0xf)) )) !=0)
308 
309 #define MBCS_VALUE_2_FROM_STAGE_2(bytes, stage2Entry, c) ((uint16_t *)(bytes))[16*(uint32_t)(uint16_t)(stage2Entry)+((c)&0xf)]
310 #define MBCS_VALUE_4_FROM_STAGE_2(bytes, stage2Entry, c) ((uint32_t *)(bytes))[16*(uint32_t)(uint16_t)(stage2Entry)+((c)&0xf)]
311 
312 #define MBCS_POINTER_3_FROM_STAGE_2(bytes, stage2Entry, c) ((bytes)+(16*(uint32_t)(uint16_t)(stage2Entry)+((c)&0xf))*3)
313 
314 /* double-byte fromUnicode using the mbcsIndex */
315 #define DBCS_RESULT_FROM_MOST_BMP(table, results, c) (results)[ (table)[(c)>>6] +((c)&0x3f) ]
316 
317 /* double-byte fromUTF8 using the mbcsIndex; l and t1 combined into lt1; lt1 and t2 must be masked externally */
318 #define DBCS_RESULT_FROM_UTF8(table, results, lt1, t2) (results)[ (table)[lt1] +(t2) ]
319 
320 
321 /**
322  * MBCS output types for conversions from Unicode.
323  * These per-converter types determine the storage method in stage 3 of the lookup table,
324  * mostly how many bytes are stored per entry.
325  */
326 enum {
327     MBCS_OUTPUT_1,          /* 0 */
328     MBCS_OUTPUT_2,          /* 1 */
329     MBCS_OUTPUT_3,          /* 2 */
330     MBCS_OUTPUT_4,          /* 3 */
331 
332     MBCS_OUTPUT_3_EUC=8,    /* 8 */
333     MBCS_OUTPUT_4_EUC,      /* 9 */
334 
335     MBCS_OUTPUT_2_SISO=12,  /* c */
336     MBCS_OUTPUT_2_HZ,       /* d */
337 
338     MBCS_OUTPUT_EXT_ONLY,   /* e */
339 
340     MBCS_OUTPUT_COUNT,
341 
342     MBCS_OUTPUT_DBCS_ONLY=0xdb  /* runtime-only type for DBCS-only handling of SISO tables */
343 };
344 
345 /**
346  * Fallbacks to Unicode are stored outside the normal state table and code point structures
347  * in a vector of items of this type. They are sorted by offset.
348  */
349 typedef struct {
350     uint32_t offset;
351     UChar32 codePoint;
352 } _MBCSToUFallback;
353 
354 /** Constants for fast and UTF-8-friendly conversion. */
355 enum {
356     SBCS_FAST_MAX=0x0fff,               /* maximum code point with UTF-8-friendly SBCS runtime code, see makeconv SBCS_UTF8_MAX */
357     SBCS_FAST_LIMIT=SBCS_FAST_MAX+1,    /* =0x1000 */
358     MBCS_FAST_MAX=0xd7ff,               /* maximum code point with UTF-8-friendly MBCS runtime code, see makeconv MBCS_UTF8_MAX */
359     MBCS_FAST_LIMIT=MBCS_FAST_MAX+1     /* =0xd800 */
360 };
361 
362 /**
363  * This is the MBCS part of the UConverterTable union (a runtime data structure).
364  * It keeps all the per-converter data and points into the loaded mapping tables.
365  *
366  * utf8Friendly data structures added with _MBCSHeader.version 4.3
367  */
368 typedef struct UConverterMBCSTable {
369     /* toUnicode */
370     uint8_t countStates, dbcsOnlyState, stateTableOwned;
371     uint32_t countToUFallbacks;
372 
373     const int32_t (*stateTable)/*[countStates]*/[256];
374     int32_t (*swapLFNLStateTable)/*[countStates]*/[256]; /* for swaplfnl */
375     const uint16_t *unicodeCodeUnits/*[countUnicodeResults]*/;
376     const _MBCSToUFallback *toUFallbacks;
377 
378     /* fromUnicode */
379     const uint16_t *fromUnicodeTable;
380     const uint16_t *mbcsIndex;              /* for fast conversion from most of BMP to MBCS (utf8Friendly data) */
381     uint16_t sbcsIndex[SBCS_FAST_LIMIT>>6]; /* for fast conversion from low BMP to SBCS (utf8Friendly data) */
382     const uint8_t *fromUnicodeBytes;
383     uint8_t *swapLFNLFromUnicodeBytes;      /* for swaplfnl */
384     uint32_t fromUBytesLength;
385     uint8_t outputType, unicodeMask;
386     UBool utf8Friendly;                     /* for utf8Friendly data */
387     UChar maxFastUChar;                     /* for utf8Friendly data */
388 
389     /* roundtrips */
390     uint32_t asciiRoundtrips;
391 
392     /* reconstituted data that was omitted from the .cnv file */
393     uint8_t *reconstitutedData;
394 
395     /* converter name for swaplfnl */
396     char *swapLFNLName;
397 
398     /* extension data */
399     struct UConverterSharedData *baseSharedData;
400     const int32_t *extIndexes;
401 } UConverterMBCSTable;
402 
403 #define UCNV_MBCS_TABLE_INITIALIZER { \
404     /* toUnicode */ \
405     0, 0, 0, \
406     0, \
407      \
408     NULL, \
409     NULL, \
410     NULL, \
411     NULL, \
412      \
413     /* fromUnicode */ \
414     NULL, \
415     NULL, \
416     { 0 }, \
417     NULL, \
418     NULL, \
419     0, \
420     0, 0, \
421     FALSE, \
422     0, \
423      \
424     /* roundtrips */ \
425     0, \
426      \
427     /* reconstituted data that was omitted from the .cnv file */ \
428     NULL, \
429      \
430     /* converter name for swaplfnl */ \
431     NULL, \
432      \
433     /* extension data */ \
434     NULL, \
435     NULL \
436 }
437 
438 enum {
439     MBCS_OPT_LENGTH_MASK=0x3f,
440     MBCS_OPT_NO_FROM_U=0x40,
441     /*
442      * If any of the following options bits are set,
443      * then the file must be rejected.
444      */
445     MBCS_OPT_INCOMPATIBLE_MASK=0xffc0,
446     /*
447      * Remove bits from this mask as more options are recognized
448      * by all implementations that use this constant.
449      */
450     MBCS_OPT_UNKNOWN_INCOMPATIBLE_MASK=0xff80
451 };
452 
453 enum {
454     MBCS_HEADER_V4_LENGTH=8,
455     MBCS_HEADER_V5_MIN_LENGTH=9
456 };
457 
458 /**
459  * MBCS data header. See data format description above.
460  */
461 typedef struct {
462     UVersionInfo version;
463     uint32_t countStates,
464              countToUFallbacks,
465              offsetToUCodeUnits,
466              offsetFromUTable,
467              offsetFromUBytes,
468              flags,
469              fromUBytesLength;
470 
471     /* new and required in version 5 */
472     uint32_t options;
473 
474     /* new and optional in version 5; used if options&MBCS_OPT_NO_FROM_U */
475     uint32_t fullStage2Length;  /* number of 32-bit units */
476 } _MBCSHeader;
477 
478 #define UCNV_MBCS_HEADER_INITIALIZER { { 0 },  0, 0, 0, 0, 0, 0, 0,  0,  0 }
479 
480 /*
481  * This is a simple version of _MBCSGetNextUChar() that is used
482  * by other converter implementations.
483  * It only returns an "assigned" result if it consumes the entire input.
484  * It does not use state from the converter, nor error codes.
485  * It does not handle the EBCDIC swaplfnl option (set in UConverter).
486  * It handles conversion extensions but not GB 18030.
487  *
488  * Return value:
489  * U+fffe   unassigned
490  * U+ffff   illegal
491  * otherwise the Unicode code point
492  */
493 U_CFUNC UChar32
494 ucnv_MBCSSimpleGetNextUChar(UConverterSharedData *sharedData,
495                         const char *source, int32_t length,
496                         UBool useFallback);
497 
498 /**
499  * This version of _MBCSSimpleGetNextUChar() is optimized for single-byte, single-state codepages.
500  * It does not handle the EBCDIC swaplfnl option (set in UConverter).
501  * It does not handle conversion extensions (_extToU()).
502  */
503 U_CFUNC UChar32
504 ucnv_MBCSSingleSimpleGetNextUChar(UConverterSharedData *sharedData,
505                               uint8_t b, UBool useFallback);
506 
507 /**
508  * This macro version of _MBCSSingleSimpleGetNextUChar() gets a code point from a byte.
509  * It works for single-byte, single-state codepages that only map
510  * to and from BMP code points, and it always
511  * returns fallback values.
512  */
513 #define _MBCS_SINGLE_SIMPLE_GET_NEXT_BMP(sharedData, b) \
514     (UChar)MBCS_ENTRY_FINAL_VALUE_16((sharedData)->mbcs.stateTable[0][(uint8_t)(b)])
515 
516 /**
517  * This is an internal function that allows other converter implementations
518  * to check whether a byte is a lead byte.
519  */
520 U_CFUNC UBool
521 ucnv_MBCSIsLeadByte(UConverterSharedData *sharedData, char byte);
522 
523 /** This is a macro version of _MBCSIsLeadByte(). */
524 #define _MBCS_IS_LEAD_BYTE(sharedData, byte) \
525     (UBool)MBCS_ENTRY_IS_TRANSITION((sharedData)->mbcs.stateTable[0][(uint8_t)(byte)])
526 
527 /*
528  * This is another simple conversion function for internal use by other
529  * conversion implementations.
530  * It does not use the converter state nor call callbacks.
531  * It does not handle the EBCDIC swaplfnl option (set in UConverter).
532  * It handles conversion extensions but not GB 18030.
533  *
534  * It converts one single Unicode code point into codepage bytes, encoded
535  * as one 32-bit value. The function returns the number of bytes in *pValue:
536  * 1..4 the number of bytes in *pValue
537  * 0    unassigned (*pValue undefined)
538  * -1   illegal (currently not used, *pValue undefined)
539  *
540  * *pValue will contain the resulting bytes with the last byte in bits 7..0,
541  * the second to last byte in bits 15..8, etc.
542  * Currently, the function assumes but does not check that 0<=c<=0x10ffff.
543  */
544 U_CFUNC int32_t
545 ucnv_MBCSFromUChar32(UConverterSharedData *sharedData,
546                  UChar32 c, uint32_t *pValue,
547                  UBool useFallback);
548 
549 /**
550  * This version of _MBCSFromUChar32() is optimized for single-byte codepages.
551  * It does not handle the EBCDIC swaplfnl option (set in UConverter).
552  *
553  * It returns the codepage byte for the code point, or -1 if it is unassigned.
554  */
555 U_CFUNC int32_t
556 ucnv_MBCSSingleFromUChar32(UConverterSharedData *sharedData,
557                        UChar32 c,
558                        UBool useFallback);
559 
560 /**
561  * SBCS, DBCS, and EBCDIC_STATEFUL are replaced by MBCS, but
562  * we cheat a little about the type, returning the old types if appropriate.
563  */
564 U_CFUNC UConverterType
565 ucnv_MBCSGetType(const UConverter* converter);
566 
567 U_CFUNC void
568 ucnv_MBCSFromUnicodeWithOffsets(UConverterFromUnicodeArgs *pArgs,
569                             UErrorCode *pErrorCode);
570 U_CFUNC void
571 ucnv_MBCSToUnicodeWithOffsets(UConverterToUnicodeArgs *pArgs,
572                           UErrorCode *pErrorCode);
573 
574 /*
575  * Internal function returning a UnicodeSet for toUnicode() conversion.
576  * Currently only used for ISO-2022-CN, and only handles roundtrip mappings.
577  * In the future, if we add support for fallback sets, this function
578  * needs to be updated.
579  * Handles extensions.
580  * Does not empty the set first.
581  */
582 U_CFUNC void
583 ucnv_MBCSGetUnicodeSetForUnicode(const UConverterSharedData *sharedData,
584                                  const USetAdder *sa,
585                                  UConverterUnicodeSet which,
586                                  UErrorCode *pErrorCode);
587 
588 /*
589  * Same as ucnv_MBCSGetUnicodeSetForUnicode() but
590  * the set can be filtered by encoding scheme.
591  * Used by stateful converters which share regular conversion tables
592  * but only use a subset of their mappings.
593  */
594 U_CFUNC void
595 ucnv_MBCSGetFilteredUnicodeSetForUnicode(const UConverterSharedData *sharedData,
596                                          const USetAdder *sa,
597                                          UConverterUnicodeSet which,
598                                          UConverterSetFilter filter,
599                                          UErrorCode *pErrorCode);
600 
601 #endif
602 
603 #endif
604