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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