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1 /*
2 ******************************************************************************
3 *
4 *   Copyright (C) 2000-2007, 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 4.3 optionally modifies the fromUnicode data structures
64  * slightly and optionally adds a table for conversion to MBCS (non-SBCS)
65  * charsets.
66  *
67  * The modifications are to make the data utf8Friendly. Not every 4.3 file
68  * file contains utf8Friendly data.
69  * It is utf8Friendly if _MBCSHeader.version[2]!=0.
70  * In this case, the data structures are utf8Friendly up to the code point
71  *   maxFastUChar=((_MBCSHeader.version[2]<<8)|0xff)
72  *
73  * A utf8Friendly file has fromUnicode stage 3 entries for code points up to
74  * maxFastUChar allocated in blocks of 64 for indexing with the 6 bits from
75  * a UTF-8 trail byte. ASCII is allocated linearly with 128 contiguous entries.
76  *
77  * In addition, a utf8Friendly MBCS file contains an additional
78  *   uint16_t mbcsIndex[(maxFastUChar+1)>>6];
79  * which replaces the stage 1 and 2 tables for indexing with bits from the
80  * UTF-8 lead byte and middle trail byte. Unlike the older MBCS stage 2 table,
81  * the mbcsIndex does not contain roundtrip flags. Therefore, all fallbacks
82  * from code points up to maxFastUChar (and roundtrips to 0x00) are moved to
83  * the extension data structure. This also allows for faster roundtrip
84  * conversion from UTF-16.
85  *
86  * SBCS files do not contain an additional sbcsIndex[] array because the
87  * proportional size increase would be noticeable, but the runtime
88  * code builds one for the code point range for which the runtime conversion
89  * code is optimized.
90  *
91  * For SBCS, maxFastUChar should be at least U+0FFF. The initial makeconv
92  * implementation sets it to U+1FFF. Because the sbcsIndex is not stored in
93  * the file, a larger maxFastUChar only affects stage 3 block allocation size
94  * and is free in empty blocks. (Larger blocks with sparse contents cause larger
95  * files.) U+1FFF includes almost all of the small scripts.
96  * U+0FFF covers UTF-8 two-byte sequences and three-byte sequences starting with
97  * 0xe0. This includes most scripts with legacy SBCS charsets.
98  * The initial runtime implementation using 4.3 files only builds an sbcsIndex
99  * for code points up to U+0FFF.
100  *
101  * For MBCS, maxFastUChar should be at least U+D7FF (=initial value).
102  * This boundary is convenient because practically all of the commonly used
103  * characters are below it, and because it is the boundary to surrogate
104  * code points, above which special handling is necessary anyway.
105  * (Surrogate pair assembly for UTF-16, validity checking for UTF-8.)
106  *
107  * maxFastUChar could be up to U+FFFF to cover the whole BMP, which could be
108  * useful especially for conversion from UTF-8 when the input can be assumed
109  * to be valid, because the surrogate range would then not have to be
110  * checked.
111  * (With maxFastUChar=0xffff, makeconv would have to check for mbcsIndex value
112  * overflow because with the all-unassigned block 0 and nearly full mappings
113  * from the BMP it is theoretically possible that an index into stage 3
114  * exceeds 16 bits.)
115  *
116  * _MBCSHeader.version 4.2 adds an optional conversion extension data structure.
117  * If it is present, then an ICU version reading header versions 4.0 or 4.1
118  * will be able to use the base table and ignore the extension.
119  *
120  * The unicodeMask in the static data is part of the base table data structure.
121  * Especially, the UCNV_HAS_SUPPLEMENTARY flag determines the length of the
122  * fromUnicode stage 1 array.
123  * The static data unicodeMask refers only to the base table's properties if
124  * a base table is included.
125  * In an extension-only file, the static data unicodeMask is 0.
126  * The extension data indexes have a separate field with the unicodeMask flags.
127  *
128  * MBCS-style data structure following the static data.
129  * Offsets are counted in bytes from the beginning of the MBCS header structure.
130  * Details about usage in comments in ucnvmbcs.c.
131  *
132  * struct _MBCSHeader (see the definition in this header file below)
133  * contains 32-bit fields as follows:
134  * 8 values:
135  *  0   uint8_t[4]  MBCS version in UVersionInfo format (currently 4.3.x.0)
136  *  1   uint32_t    countStates
137  *  2   uint32_t    countToUFallbacks
138  *  3   uint32_t    offsetToUCodeUnits
139  *  4   uint32_t    offsetFromUTable
140  *  5   uint32_t    offsetFromUBytes
141  *  6   uint32_t    flags, bits:
142  *                      31.. 8 offsetExtension -- _MBCSHeader.version 4.2 (ICU 2.8) and higher
143  *                                                0 for older versions and if
144  *                                                there is not extension structure
145  *                       7.. 0 outputType
146  *  7   uint32_t    fromUBytesLength -- _MBCSHeader.version 4.1 (ICU 2.4) and higher
147  *                  counts bytes in fromUBytes[]
148  *
149  * New and required in version 5:
150  *  8   uint32_t    options, bits:
151  *                      31..16 reserved for flags that can be added without breaking
152  *                                 backward compatibility
153  *                      15.. 6 reserved for flags whose addition will break
154  *                                 backward compatibility
155  *                           6 MBCS_OPT_FROM_U -- if set,
156  *                                 then most of the fromUnicode data is omitted;
157  *                                 fullStage2Length is present and the missing
158  *                                 bottom part of stage 2 must be reconstituted from
159  *                                 the toUnicode data;
160  *                                 stage 3 is missing completely as well;
161  *                                 not used for SBCS tables
162  *                       5.. 0 length of the _MBCSHeader (number of uint32_t)
163  *
164  * New and optional in version 5:
165  *  9   uint32_t    fullStage2Length: used if MBCS_OPT_FROM_U is set
166  *                                 specifies the full length of stage 2
167  *                                 including the omitted part
168  *
169  * if(outputType==MBCS_OUTPUT_EXT_ONLY) {
170  *     -- base table name for extension-only table
171  *     char baseTableName[variable]; -- with NUL plus padding for 4-alignment
172  *
173  *     -- all _MBCSHeader fields except for version and flags are 0
174  * } else {
175  *     -- normal base table with optional extension
176  *
177  *     int32_t stateTable[countStates][256];
178  *
179  *     struct _MBCSToUFallback { (fallbacks are sorted by offset)
180  *         uint32_t offset;
181  *         UChar32 codePoint;
182  *     } toUFallbacks[countToUFallbacks];
183  *
184  *     uint16_t unicodeCodeUnits[(offsetFromUTable-offsetToUCodeUnits)/2];
185  *                  (padded to an even number of units)
186  *
187  *     -- stage 1 tables
188  *     if(staticData.unicodeMask&UCNV_HAS_SUPPLEMENTARY) {
189  *         -- stage 1 table for all of Unicode
190  *         uint16_t fromUTable[0x440]; (32-bit-aligned)
191  *     } else {
192  *         -- BMP-only tables have a smaller stage 1 table
193  *         uint16_t fromUTable[0x40]; (32-bit-aligned)
194  *     }
195  *
196  *     -- stage 2 tables
197  *        length determined by top of stage 1 and bottom of stage 3 tables
198  *     if(outputType==MBCS_OUTPUT_1) {
199  *         -- SBCS: pure indexes
200  *         uint16_t stage 2 indexes[?];
201  *     } else {
202  *         -- DBCS, MBCS, EBCDIC_STATEFUL, ...: roundtrip flags and indexes
203  *         uint32_t stage 2 flags and indexes[?];
204  *         if(options&MBCS_OPT_NO_FROM_U) {
205  *             stage 2 really has length fullStage2Length
206  *             and the omitted lower part must be reconstituted from
207  *             the toUnicode data
208  *         }
209  *     }
210  *
211  *     -- stage 3 tables with byte results
212  *     if(outputType==MBCS_OUTPUT_1) {
213  *         -- SBCS: each 16-bit result contains flags and the result byte, see ucnvmbcs.c
214  *         uint16_t fromUBytes[fromUBytesLength/2];
215  *     } else if(!(options&MBCS_OPT_NO_FROM_U)) {
216  *         -- DBCS, MBCS, EBCDIC_STATEFUL, ... 2/3/4 bytes result, see ucnvmbcs.c
217  *         uint8_t fromUBytes[fromUBytesLength]; or
218  *         uint16_t fromUBytes[fromUBytesLength/2]; or
219  *         uint32_t fromUBytes[fromUBytesLength/4];
220  *     } else {
221  *         fromUBytes[] must be reconstituted from the toUnicode data
222  *     }
223  *
224  *     -- optional utf8Friendly mbcsIndex -- _MBCSHeader.version 4.3 (ICU 3.8) and higher
225  *     if(outputType!=MBCS_OUTPUT_1 &&
226  *        _MBCSHeader.version[1]>=3 &&
227  *        (maxFastUChar=_MBCSHeader.version[2])!=0
228  *     ) {
229  *         maxFastUChar=(maxFastUChar<<8)|0xff;
230  *         uint16_t mbcsIndex[(maxFastUChar+1)>>6];
231  *     }
232  * }
233  *
234  * -- extension table, details see ucnv_ext.h
235  * int32_t indexes[>=32]; ...
236  */
237 
238 /* MBCS converter data and state -------------------------------------------- */
239 
240 enum {
241     MBCS_MAX_STATE_COUNT=128
242 };
243 
244 /**
245  * MBCS action codes for conversions to Unicode.
246  * These values are in bits 23..20 of the state table entries.
247  */
248 enum {
249     MBCS_STATE_VALID_DIRECT_16,
250     MBCS_STATE_VALID_DIRECT_20,
251 
252     MBCS_STATE_FALLBACK_DIRECT_16,
253     MBCS_STATE_FALLBACK_DIRECT_20,
254 
255     MBCS_STATE_VALID_16,
256     MBCS_STATE_VALID_16_PAIR,
257 
258     MBCS_STATE_UNASSIGNED,
259     MBCS_STATE_ILLEGAL,
260 
261     MBCS_STATE_CHANGE_ONLY
262 };
263 
264 /* Macros for state table entries */
265 #define MBCS_ENTRY_TRANSITION(state, offset) (int32_t)(((int32_t)(state)<<24L)|(offset))
266 #define MBCS_ENTRY_TRANSITION_SET_OFFSET(entry, offset) (int32_t)(((entry)&0xff000000)|(offset))
267 #define MBCS_ENTRY_TRANSITION_ADD_OFFSET(entry, offset) (int32_t)((entry)+(offset))
268 
269 #define MBCS_ENTRY_FINAL(state, action, value) (int32_t)(0x80000000|((int32_t)(state)<<24L)|((action)<<20L)|(value))
270 #define MBCS_ENTRY_SET_FINAL(entry) (int32_t)((entry)|0x80000000)
271 #define MBCS_ENTRY_FINAL_SET_ACTION(entry, action) (int32_t)(((entry)&0xff0fffff)|((int32_t)(action)<<20L))
272 #define MBCS_ENTRY_FINAL_SET_VALUE(entry, value) (int32_t)(((entry)&0xfff00000)|(value))
273 #define MBCS_ENTRY_FINAL_SET_ACTION_VALUE(entry, action, value) (int32_t)(((entry)&0xff000000)|((int32_t)(action)<<20L)|(value))
274 
275 #define MBCS_ENTRY_SET_STATE(entry, state) (int32_t)(((entry)&0x80ffffff)|((int32_t)(state)<<24L))
276 
277 #define MBCS_ENTRY_STATE(entry) (((entry)>>24)&0x7f)
278 
279 #define MBCS_ENTRY_IS_TRANSITION(entry) ((entry)>=0)
280 #define MBCS_ENTRY_IS_FINAL(entry) ((entry)<0)
281 
282 #define MBCS_ENTRY_TRANSITION_STATE(entry) ((entry)>>24)
283 #define MBCS_ENTRY_TRANSITION_OFFSET(entry) ((entry)&0xffffff)
284 
285 #define MBCS_ENTRY_FINAL_STATE(entry) (((entry)>>24)&0x7f)
286 #define MBCS_ENTRY_FINAL_IS_VALID_DIRECT_16(entry) ((entry)<(int32_t)0x80100000)
287 #define MBCS_ENTRY_FINAL_ACTION(entry) (((entry)>>20)&0xf)
288 #define MBCS_ENTRY_FINAL_VALUE(entry) ((entry)&0xfffff)
289 #define MBCS_ENTRY_FINAL_VALUE_16(entry) (uint16_t)(entry)
290 
291 #define IS_ASCII_ROUNDTRIP(b, asciiRoundtrips) (((asciiRoundtrips) & (1<<((b)>>2)))!=0)
292 
293 /* single-byte fromUnicode: get the 16-bit result word */
294 #define MBCS_SINGLE_RESULT_FROM_U(table, results, c) (results)[ (table)[ (table)[(c)>>10] +(((c)>>4)&0x3f) ] +((c)&0xf) ]
295 
296 /* single-byte fromUnicode using the sbcsIndex */
297 #define SBCS_RESULT_FROM_LOW_BMP(table, results, c) (results)[ (table)[(c)>>6] +((c)&0x3f) ]
298 
299 /* single-byte fromUTF8 using the sbcsIndex; l and t must be masked externally; can be l=0 and t<=0x7f */
300 #define SBCS_RESULT_FROM_UTF8(table, results, l, t) (results)[ (table)[l] +(t) ]
301 
302 /* multi-byte fromUnicode: get the 32-bit stage 2 entry */
303 #define MBCS_STAGE_2_FROM_U(table, c) ((const uint32_t *)(table))[ (table)[(c)>>10] +(((c)>>4)&0x3f) ]
304 #define MBCS_FROM_U_IS_ROUNDTRIP(stage2Entry, c) ( ((stage2Entry) & ((uint32_t)1<< (16+((c)&0xf)) )) !=0)
305 
306 #define MBCS_VALUE_2_FROM_STAGE_2(bytes, stage2Entry, c) ((uint16_t *)(bytes))[16*(uint32_t)(uint16_t)(stage2Entry)+((c)&0xf)]
307 #define MBCS_VALUE_4_FROM_STAGE_2(bytes, stage2Entry, c) ((uint32_t *)(bytes))[16*(uint32_t)(uint16_t)(stage2Entry)+((c)&0xf)]
308 
309 #define MBCS_POINTER_3_FROM_STAGE_2(bytes, stage2Entry, c) ((bytes)+(16*(uint32_t)(uint16_t)(stage2Entry)+((c)&0xf))*3)
310 
311 /* double-byte fromUnicode using the mbcsIndex */
312 #define DBCS_RESULT_FROM_MOST_BMP(table, results, c) (results)[ (table)[(c)>>6] +((c)&0x3f) ]
313 
314 /* double-byte fromUTF8 using the mbcsIndex; l and t1 combined into lt1; lt1 and t2 must be masked externally */
315 #define DBCS_RESULT_FROM_UTF8(table, results, lt1, t2) (results)[ (table)[lt1] +(t2) ]
316 
317 
318 /**
319  * MBCS output types for conversions from Unicode.
320  * These per-converter types determine the storage method in stage 3 of the lookup table,
321  * mostly how many bytes are stored per entry.
322  */
323 enum {
324     MBCS_OUTPUT_1,          /* 0 */
325     MBCS_OUTPUT_2,          /* 1 */
326     MBCS_OUTPUT_3,          /* 2 */
327     MBCS_OUTPUT_4,          /* 3 */
328 
329     MBCS_OUTPUT_3_EUC=8,    /* 8 */
330     MBCS_OUTPUT_4_EUC,      /* 9 */
331 
332     MBCS_OUTPUT_2_SISO=12,  /* c */
333     MBCS_OUTPUT_2_HZ,       /* d */
334 
335     MBCS_OUTPUT_EXT_ONLY,   /* e */
336 
337     MBCS_OUTPUT_COUNT,
338 
339     MBCS_OUTPUT_DBCS_ONLY=0xdb  /* runtime-only type for DBCS-only handling of SISO tables */
340 };
341 
342 /**
343  * Fallbacks to Unicode are stored outside the normal state table and code point structures
344  * in a vector of items of this type. They are sorted by offset.
345  */
346 typedef struct {
347     uint32_t offset;
348     UChar32 codePoint;
349 } _MBCSToUFallback;
350 
351 /** Constants for fast and UTF-8-friendly conversion. */
352 enum {
353     SBCS_FAST_MAX=0x0fff,               /* maximum code point with UTF-8-friendly SBCS runtime code, see makeconv SBCS_UTF8_MAX */
354     SBCS_FAST_LIMIT=SBCS_FAST_MAX+1,    /* =0x1000 */
355     MBCS_FAST_MAX=0xd7ff,               /* maximum code point with UTF-8-friendly MBCS runtime code, see makeconv MBCS_UTF8_MAX */
356     MBCS_FAST_LIMIT=MBCS_FAST_MAX+1     /* =0xd800 */
357 };
358 
359 /**
360  * This is the MBCS part of the UConverterTable union (a runtime data structure).
361  * It keeps all the per-converter data and points into the loaded mapping tables.
362  *
363  * utf8Friendly data structures added with _MBCSHeader.version 4.3
364  */
365 typedef struct UConverterMBCSTable {
366     /* toUnicode */
367     uint8_t countStates, dbcsOnlyState, stateTableOwned;
368     uint32_t countToUFallbacks;
369 
370     const int32_t (*stateTable)/*[countStates]*/[256];
371     int32_t (*swapLFNLStateTable)/*[countStates]*/[256]; /* for swaplfnl */
372     const uint16_t *unicodeCodeUnits/*[countUnicodeResults]*/;
373     const _MBCSToUFallback *toUFallbacks;
374 
375     /* fromUnicode */
376     const uint16_t *fromUnicodeTable;
377     const uint16_t *mbcsIndex;              /* for fast conversion from most of BMP to MBCS (utf8Friendly data) */
378     uint16_t sbcsIndex[SBCS_FAST_LIMIT>>6]; /* for fast conversion from low BMP to SBCS (utf8Friendly data) */
379     const uint8_t *fromUnicodeBytes;
380     uint8_t *swapLFNLFromUnicodeBytes;      /* for swaplfnl */
381     uint32_t fromUBytesLength;
382     uint8_t outputType, unicodeMask;
383     UBool utf8Friendly;                     /* for utf8Friendly data */
384     UChar maxFastUChar;                     /* for utf8Friendly data */
385 
386     /* roundtrips */
387     uint32_t asciiRoundtrips;
388 
389     /* reconstituted data that was omitted from the .cnv file */
390     uint8_t *reconstitutedData;
391 
392     /* converter name for swaplfnl */
393     char *swapLFNLName;
394 
395     /* extension data */
396     struct UConverterSharedData *baseSharedData;
397     const int32_t *extIndexes;
398 } UConverterMBCSTable;
399 
400 enum {
401     MBCS_OPT_LENGTH_MASK=0x3f,
402     MBCS_OPT_NO_FROM_U=0x40,
403     /*
404      * If any of the following options bits are set,
405      * then the file must be rejected.
406      */
407     MBCS_OPT_INCOMPATIBLE_MASK=0xffc0,
408     /*
409      * Remove bits from this mask as more options are recognized
410      * by all implementations that use this constant.
411      */
412     MBCS_OPT_UNKNOWN_INCOMPATIBLE_MASK=0xff80
413 };
414 
415 enum {
416     MBCS_HEADER_V4_LENGTH=8,
417     MBCS_HEADER_V5_MIN_LENGTH=9
418 };
419 
420 /**
421  * MBCS data header. See data format description above.
422  */
423 typedef struct {
424     UVersionInfo version;
425     uint32_t countStates,
426              countToUFallbacks,
427              offsetToUCodeUnits,
428              offsetFromUTable,
429              offsetFromUBytes,
430              flags,
431              fromUBytesLength;
432 
433     /* new and required in version 5 */
434     uint32_t options;
435 
436     /* new and optional in version 5; used if options&MBCS_OPT_NO_FROM_U */
437     uint32_t fullStage2Length;  /* number of 32-bit units */
438 } _MBCSHeader;
439 
440 /*
441  * This is a simple version of _MBCSGetNextUChar() that is used
442  * by other converter implementations.
443  * It only returns an "assigned" result if it consumes the entire input.
444  * It does not use state from the converter, nor error codes.
445  * It does not handle the EBCDIC swaplfnl option (set in UConverter).
446  * It handles conversion extensions but not GB 18030.
447  *
448  * Return value:
449  * U+fffe   unassigned
450  * U+ffff   illegal
451  * otherwise the Unicode code point
452  */
453 U_CFUNC UChar32
454 ucnv_MBCSSimpleGetNextUChar(UConverterSharedData *sharedData,
455                         const char *source, int32_t length,
456                         UBool useFallback);
457 
458 /**
459  * This version of _MBCSSimpleGetNextUChar() is optimized for single-byte, single-state codepages.
460  * It does not handle the EBCDIC swaplfnl option (set in UConverter).
461  * It does not handle conversion extensions (_extToU()).
462  */
463 U_CFUNC UChar32
464 ucnv_MBCSSingleSimpleGetNextUChar(UConverterSharedData *sharedData,
465                               uint8_t b, UBool useFallback);
466 
467 /**
468  * This macro version of _MBCSSingleSimpleGetNextUChar() gets a code point from a byte.
469  * It works for single-byte, single-state codepages that only map
470  * to and from BMP code points, and it always
471  * returns fallback values.
472  */
473 #define _MBCS_SINGLE_SIMPLE_GET_NEXT_BMP(sharedData, b) \
474     (UChar)MBCS_ENTRY_FINAL_VALUE_16((sharedData)->mbcs.stateTable[0][(uint8_t)(b)])
475 
476 /**
477  * This is an internal function that allows other converter implementations
478  * to check whether a byte is a lead byte.
479  */
480 U_CFUNC UBool
481 ucnv_MBCSIsLeadByte(UConverterSharedData *sharedData, char byte);
482 
483 /** This is a macro version of _MBCSIsLeadByte(). */
484 #define _MBCS_IS_LEAD_BYTE(sharedData, byte) \
485     (UBool)MBCS_ENTRY_IS_TRANSITION((sharedData)->mbcs.stateTable[0][(uint8_t)(byte)])
486 
487 /*
488  * This is another simple conversion function for internal use by other
489  * conversion implementations.
490  * It does not use the converter state nor call callbacks.
491  * It does not handle the EBCDIC swaplfnl option (set in UConverter).
492  * It handles conversion extensions but not GB 18030.
493  *
494  * It converts one single Unicode code point into codepage bytes, encoded
495  * as one 32-bit value. The function returns the number of bytes in *pValue:
496  * 1..4 the number of bytes in *pValue
497  * 0    unassigned (*pValue undefined)
498  * -1   illegal (currently not used, *pValue undefined)
499  *
500  * *pValue will contain the resulting bytes with the last byte in bits 7..0,
501  * the second to last byte in bits 15..8, etc.
502  * Currently, the function assumes but does not check that 0<=c<=0x10ffff.
503  */
504 U_CFUNC int32_t
505 ucnv_MBCSFromUChar32(UConverterSharedData *sharedData,
506                  UChar32 c, uint32_t *pValue,
507                  UBool useFallback);
508 
509 /**
510  * This version of _MBCSFromUChar32() is optimized for single-byte codepages.
511  * It does not handle the EBCDIC swaplfnl option (set in UConverter).
512  *
513  * It returns the codepage byte for the code point, or -1 if it is unassigned.
514  */
515 U_CFUNC int32_t
516 ucnv_MBCSSingleFromUChar32(UConverterSharedData *sharedData,
517                        UChar32 c,
518                        UBool useFallback);
519 
520 /**
521  * SBCS, DBCS, and EBCDIC_STATEFUL are replaced by MBCS, but
522  * we cheat a little about the type, returning the old types if appropriate.
523  */
524 U_CFUNC UConverterType
525 ucnv_MBCSGetType(const UConverter* converter);
526 
527 U_CFUNC void
528 ucnv_MBCSFromUnicodeWithOffsets(UConverterFromUnicodeArgs *pArgs,
529                             UErrorCode *pErrorCode);
530 U_CFUNC void
531 ucnv_MBCSToUnicodeWithOffsets(UConverterToUnicodeArgs *pArgs,
532                           UErrorCode *pErrorCode);
533 
534 /*
535  * Internal function returning a UnicodeSet for toUnicode() conversion.
536  * Currently only used for ISO-2022-CN, and only handles roundtrip mappings.
537  * In the future, if we add support for fallback sets, this function
538  * needs to be updated.
539  * Handles extensions.
540  * Does not empty the set first.
541  */
542 U_CFUNC void
543 ucnv_MBCSGetUnicodeSetForUnicode(const UConverterSharedData *sharedData,
544                                  const USetAdder *sa,
545                                  UConverterUnicodeSet which,
546                                  UErrorCode *pErrorCode);
547 
548 /*
549  * Same as ucnv_MBCSGetUnicodeSetForUnicode() but
550  * the set can be filtered by encoding scheme.
551  * Used by stateful converters which share regular conversion tables
552  * but only use a subset of their mappings.
553  */
554 U_CFUNC void
555 ucnv_MBCSGetFilteredUnicodeSetForUnicode(const UConverterSharedData *sharedData,
556                                          const USetAdder *sa,
557                                          UConverterUnicodeSet which,
558                                          UConverterSetFilter filter,
559                                          UErrorCode *pErrorCode);
560 
561 #endif
562 
563 #endif
564