ucnv_lmb.c revision c69afcec261fc345fda8daf46f0ea6b4351dc777
1/*
2**********************************************************************
3*   Copyright (C) 2000-2007, International Business Machines
4*   Corporation and others.  All Rights Reserved.
5**********************************************************************
6*   file name:  ucnv_lmb.cpp
7*   encoding:   US-ASCII
8*   tab size:   4 (not used)
9*   indentation:4
10*
11*   created on: 2000feb09
12*   created by: Brendan Murray
13*   extensively hacked up by: Jim Snyder-Grant
14*
15* Modification History:
16*
17*   Date        Name             Description
18*
19*   06/20/2000  helena           OS/400 port changes; mostly typecast.
20*   06/27/2000  Jim Snyder-Grant Deal with partial characters and small buffers.
21*                                Add comments to document LMBCS format and implementation
22*                                restructured order & breakdown of functions
23*   06/28/2000  helena           Major rewrite for the callback API changes.
24*/
25
26#include "unicode/utypes.h"
27
28#if !UCONFIG_NO_CONVERSION && !UCONFIG_NO_LEGACY_CONVERSION
29
30#include "unicode/ucnv_err.h"
31#include "unicode/ucnv.h"
32#include "unicode/uset.h"
33#include "cmemory.h"
34#include "cstring.h"
35#include "uassert.h"
36#include "ucnv_imp.h"
37#include "ucnv_bld.h"
38#include "ucnv_cnv.h"
39
40#define LENGTHOF(array) (int32_t)(sizeof(array)/sizeof((array)[0]))
41
42/*
43  LMBCS
44
45  (Lotus Multi-Byte Character Set)
46
47  LMBCS was invented in the late 1980's and is primarily used in Lotus Notes
48  databases and in Lotus 1-2-3 files. Programmers who work with the APIs
49  into these products will sometimes need to deal with strings in this format.
50
51  The code in this file provides an implementation for an ICU converter of
52  LMBCS to and from Unicode.
53
54  Since the LMBCS character set is only sparsely documented in existing
55  printed or online material, we have added  extensive annotation to this
56  file to serve as a guide to understanding LMBCS.
57
58  LMBCS was originally designed with these four sometimes-competing design goals:
59
60  -Provide encodings for the characters in 12 existing national standards
61   (plus a few other characters)
62  -Minimal memory footprint
63  -Maximal speed of conversion into the existing national character sets
64  -No need to track a changing state as you interpret a string.
65
66
67  All of the national character sets LMBCS was trying to encode are 'ANSI'
68  based, in that the bytes from 0x20 - 0x7F are almost exactly the
69  same common Latin unaccented characters and symbols in all character sets.
70
71  So, in order to help meet the speed & memory design goals, the common ANSI
72  bytes from 0x20-0x7F are represented by the same single-byte values in LMBCS.
73
74  The general LMBCS code unit is from 1-3 bytes. We can describe the 3 bytes as
75  follows:
76
77  [G] D1 [D2]
78
79  That is, a sometimes-optional 'group' byte, followed by 1 and sometimes 2
80  data bytes. The maximum size of a LMBCS chjaracter is 3 bytes:
81*/
82#define ULMBCS_CHARSIZE_MAX      3
83/*
84  The single-byte values from 0x20 to 0x7F are examples of single D1 bytes.
85  We often have to figure out if byte values are below or above this, so we
86  use the ANSI nomenclature 'C0' and 'C1' to refer to the range of control
87  characters just above & below the common lower-ANSI  range */
88#define ULMBCS_C0END           0x1F
89#define ULMBCS_C1START         0x80
90/*
91  Since LMBCS is always dealing in byte units. we create a local type here for
92  dealing with these units of LMBCS code units:
93
94*/
95typedef uint8_t ulmbcs_byte_t;
96
97/*
98   Most of the values less than 0x20 are reserved in LMBCS to announce
99   which national  character standard is being used for the 'D' bytes.
100   In the comments we show the common name and the IBM character-set ID
101   for these character-set announcers:
102*/
103
104#define ULMBCS_GRP_L1         0x01   /* Latin-1    :ibm-850  */
105#define ULMBCS_GRP_GR         0x02   /* Greek      :ibm-851  */
106#define ULMBCS_GRP_HE         0x03   /* Hebrew     :ibm-1255 */
107#define ULMBCS_GRP_AR         0x04   /* Arabic     :ibm-1256 */
108#define ULMBCS_GRP_RU         0x05   /* Cyrillic   :ibm-1251 */
109#define ULMBCS_GRP_L2         0x06   /* Latin-2    :ibm-852  */
110#define ULMBCS_GRP_TR         0x08   /* Turkish    :ibm-1254 */
111#define ULMBCS_GRP_TH         0x0B   /* Thai       :ibm-874  */
112#define ULMBCS_GRP_JA         0x10   /* Japanese   :ibm-943  */
113#define ULMBCS_GRP_KO         0x11   /* Korean     :ibm-1261 */
114#define ULMBCS_GRP_TW         0x12   /* Chinese SC :ibm-950  */
115#define ULMBCS_GRP_CN         0x13   /* Chinese TC :ibm-1386 */
116
117/*
118   So, the beginning of understanding LMBCS is that IF the first byte of a LMBCS
119   character is one of those 12 values, you can interpret the remaining bytes of
120   that character as coming from one of those character sets. Since the lower
121   ANSI bytes already are represented in single bytes, using one of the character
122   set announcers is used to announce a character that starts with a byte of
123   0x80 or greater.
124
125   The character sets are  arranged so that the single byte sets all appear
126   before the multi-byte character sets. When we need to tell whether a
127   group byte is for a single byte char set or not we use this define: */
128
129#define ULMBCS_DOUBLEOPTGROUP_START  0x10
130
131/*
132However, to fully understand LMBCS, you must also understand a series of
133exceptions & optimizations made in service of the design goals.
134
135First, those of you who are character set mavens may have noticed that
136the 'double-byte' character sets are actually multi-byte character sets
137that can have 1 or two bytes, even in the upper-ascii range. To force
138each group byte to introduce a fixed-width encoding (to make it faster to
139count characters), we use a convention of doubling up on the group byte
140to introduce any single-byte character > 0x80 in an otherwise double-byte
141character set. So, for example, the LMBCS sequence x10 x10 xAE is the
142same as '0xAE' in the Japanese code page 943.
143
144Next, you will notice that the list of group bytes has some gaps.
145These are used in various ways.
146
147We reserve a few special single byte values for common control
148characters. These are in the same place as their ANSI eqivalents for speed.
149*/
150
151#define ULMBCS_HT    0x09   /* Fixed control char - Horizontal Tab */
152#define ULMBCS_LF    0x0A   /* Fixed control char - Line Feed */
153#define ULMBCS_CR    0x0D   /* Fixed control char - Carriage Return */
154
155/* Then, 1-2-3 reserved a special single-byte character to put at the
156beginning of internal 'system' range names: */
157
158#define ULMBCS_123SYSTEMRANGE  0x19
159
160/* Then we needed a place to put all the other ansi control characters
161that must be moved to different values because LMBCS reserves those
162values for other purposes. To represent the control characters, we start
163with a first byte of 0xF & add the control chaarcter value as the
164second byte */
165#define ULMBCS_GRP_CTRL       0x0F
166
167/* For the C0 controls (less than 0x20), we add 0x20 to preserve the
168useful doctrine that any byte less than 0x20 in a LMBCS char must be
169the first byte of a character:*/
170#define ULMBCS_CTRLOFFSET      0x20
171
172/*
173Where to put the characters that aren't part of any of the 12 national
174character sets? The first thing that was done, in the earlier years of
175LMBCS, was to use up the spaces of the form
176
177  [G] D1,
178
179 where  'G' was one of the single-byte character groups, and
180 D1 was less than 0x80. These sequences are gathered together
181 into a Lotus-invented doublebyte character set to represent a
182 lot of stray values. Internally, in this implementation, we track this
183 as group '0', as a place to tuck this exceptions list.*/
184
185#define ULMBCS_GRP_EXCEPT     0x00
186/*
187 Finally, as the durability and usefulness of UNICODE became clear,
188 LOTUS added a new group 0x14 to hold Unicode values not otherwise
189 represented in LMBCS: */
190#define ULMBCS_GRP_UNICODE    0x14
191/* The two bytes appearing after a 0x14 are intrepreted as UFT-16 BE
192(Big-Endian) characters. The exception comes when the UTF16
193representation would have a zero as the second byte. In that case,
194'F6' is used in its place, and the bytes are swapped. (This prevents
195LMBCS from encoding any Unicode values of the form U+F6xx, but that's OK:
1960xF6xx is in the middle of the Private Use Area.)*/
197#define ULMBCS_UNICOMPATZERO   0xF6
198
199/* It is also useful in our code to have a constant for the size of
200a LMBCS char that holds a literal Unicode value */
201#define ULMBCS_UNICODE_SIZE      3
202
203/*
204To squish the LMBCS representations down even further, and to make
205translations even faster,sometimes the optimization group byte can be dropped
206from a LMBCS character. This is decided on a process-by-process basis. The
207group byte that is dropped is called the 'optimization group'.
208
209For Notes, the optimzation group is always 0x1.*/
210#define ULMBCS_DEFAULTOPTGROUP 0x1
211/* For 1-2-3 files, the optimzation group is stored in the header of the 1-2-3
212file.
213
214 In any case, when using ICU, you either pass in the
215optimization group as part of the name of the converter (LMBCS-1, LMBCS-2,
216etc.). Using plain 'LMBCS' as the name of the converter will give you
217LMBCS-1.
218
219
220*** Implementation strategy ***
221
222
223Because of the extensive use of other character sets, the LMBCS converter
224keeps a mapping between optimization groups and IBM character sets, so that
225ICU converters can be created and used as needed. */
226
227/* As you can see, even though any byte below 0x20 could be an optimization
228byte, only those at 0x13 or below can map to an actual converter. To limit
229some loops and searches, we define a value for that last group converter:*/
230
231#define ULMBCS_GRP_LAST       0x13   /* last LMBCS group that has a converter */
232
233static const char * const OptGroupByteToCPName[ULMBCS_GRP_LAST + 1] = {
234   /* 0x0000 */ "lmb-excp", /* internal home for the LOTUS exceptions list */
235   /* 0x0001 */ "ibm-850",
236   /* 0x0002 */ "ibm-851",
237   /* 0x0003 */ "windows-1255",
238   /* 0x0004 */ "windows-1256",
239   /* 0x0005 */ "windows-1251",
240   /* 0x0006 */ "ibm-852",
241   /* 0x0007 */ NULL,      /* Unused */
242   /* 0x0008 */ "windows-1254",
243   /* 0x0009 */ NULL,      /* Control char HT */
244   /* 0x000A */ NULL,      /* Control char LF */
245   /* 0x000B */ "windows-874",
246   /* 0x000C */ NULL,      /* Unused */
247   /* 0x000D */ NULL,      /* Control char CR */
248   /* 0x000E */ NULL,      /* Unused */
249   /* 0x000F */ NULL,      /* Control chars: 0x0F20 + C0/C1 character: algorithmic */
250   /* 0x0010 */ "windows-932",
251   /* 0x0011 */ "windows-949",
252   /* 0x0012 */ "windows-950",
253   /* 0x0013 */ "windows-936"
254
255   /* The rest are null, including the 0x0014 Unicode compatibility region
256   and 0x0019, the 1-2-3 system range control char */
257};
258
259
260/* That's approximately all the data that's needed for translating
261  LMBCS to Unicode.
262
263
264However, to translate Unicode to LMBCS, we need some more support.
265
266That's because there are often more than one possible mappings from a Unicode
267code point back into LMBCS. The first thing we do is look up into a table
268to figure out if there are more than one possible mappings. This table,
269arranged by Unicode values (including ranges) either lists which group
270to use, or says that it could go into one or more of the SBCS sets, or
271into one or more of the DBCS sets.  (If the character exists in both DBCS &
272SBCS, the table will place it in the SBCS sets, to make the LMBCS code point
273length as small as possible. Here's the two special markers we use to indicate
274ambiguous mappings: */
275
276#define ULMBCS_AMBIGUOUS_SBCS   0x80   /* could fit in more than one
277                                          LMBCS sbcs native encoding
278                                          (example: most accented latin) */
279#define ULMBCS_AMBIGUOUS_MBCS   0x81   /* could fit in more than one
280                                          LMBCS mbcs native encoding
281                                          (example: Unihan) */
282
283/* And here's a simple way to see if a group falls in an appropriate range */
284#define ULMBCS_AMBIGUOUS_MATCH(agroup, xgroup) \
285                  ((((agroup) == ULMBCS_AMBIGUOUS_SBCS) && \
286                  (xgroup) < ULMBCS_DOUBLEOPTGROUP_START) || \
287                  (((agroup) == ULMBCS_AMBIGUOUS_MBCS) && \
288                  (xgroup) >= ULMBCS_DOUBLEOPTGROUP_START))
289
290
291/* The table & some code to use it: */
292
293
294static const struct _UniLMBCSGrpMap
295{
296   const UChar uniStartRange;
297   const UChar uniEndRange;
298   const ulmbcs_byte_t  GrpType;
299} UniLMBCSGrpMap[]
300=
301{
302
303   {0x0001, 0x001F,  ULMBCS_GRP_CTRL},
304   {0x0080, 0x009F,  ULMBCS_GRP_CTRL},
305   {0x00A0, 0x01CD,  ULMBCS_AMBIGUOUS_SBCS},
306   {0x01CE, 0x01CE,  ULMBCS_GRP_TW },
307   {0x01CF, 0x02B9,  ULMBCS_AMBIGUOUS_SBCS},
308   {0x02BA, 0x02BA,  ULMBCS_GRP_CN},
309   {0x02BC, 0x02C8,  ULMBCS_AMBIGUOUS_SBCS},
310   {0x02C9, 0x02D0,  ULMBCS_AMBIGUOUS_MBCS},
311   {0x02D8, 0x02DD,  ULMBCS_AMBIGUOUS_SBCS},
312   {0x0384, 0x03CE,  ULMBCS_AMBIGUOUS_SBCS},
313   {0x0400, 0x044E,  ULMBCS_GRP_RU},
314   {0x044F, 0x044F,  ULMBCS_AMBIGUOUS_MBCS},
315   {0x0450, 0x0491,  ULMBCS_GRP_RU},
316   {0x05B0, 0x05F2,  ULMBCS_GRP_HE},
317   {0x060C, 0x06AF,  ULMBCS_GRP_AR},
318   {0x0E01, 0x0E5B,  ULMBCS_GRP_TH},
319   {0x200C, 0x200F,  ULMBCS_AMBIGUOUS_SBCS},
320   {0x2010, 0x2010,  ULMBCS_AMBIGUOUS_MBCS},
321   {0x2013, 0x2015,  ULMBCS_AMBIGUOUS_SBCS},
322   {0x2016, 0x2016,  ULMBCS_AMBIGUOUS_MBCS},
323   {0x2017, 0x2024,  ULMBCS_AMBIGUOUS_SBCS},
324   {0x2025, 0x2025,  ULMBCS_AMBIGUOUS_MBCS},
325   {0x2026, 0x2026,  ULMBCS_AMBIGUOUS_SBCS},
326   {0x2027, 0x2027,  ULMBCS_GRP_CN},
327   {0x2030, 0x2033,  ULMBCS_AMBIGUOUS_SBCS},
328   {0x2035, 0x2035,  ULMBCS_AMBIGUOUS_MBCS},
329   {0x2039, 0x203A,  ULMBCS_AMBIGUOUS_SBCS},
330   {0x203B, 0x203B,  ULMBCS_AMBIGUOUS_MBCS},
331   {0x2074, 0x2074,  ULMBCS_GRP_KO},
332   {0x207F, 0x207F,  ULMBCS_GRP_EXCEPT},
333   {0x2081, 0x2084,  ULMBCS_GRP_KO},
334   {0x20A4, 0x20AC,  ULMBCS_AMBIGUOUS_SBCS},
335   {0x2103, 0x2109,  ULMBCS_AMBIGUOUS_MBCS},
336   {0x2111, 0x2126,  ULMBCS_AMBIGUOUS_SBCS},
337   {0x212B, 0x212B,  ULMBCS_AMBIGUOUS_MBCS},
338   {0x2135, 0x2135,  ULMBCS_AMBIGUOUS_SBCS},
339   {0x2153, 0x2154,  ULMBCS_GRP_KO},
340   {0x215B, 0x215E,  ULMBCS_GRP_EXCEPT},
341   {0x2160, 0x2179,  ULMBCS_AMBIGUOUS_MBCS},
342   {0x2190, 0x2195,  ULMBCS_GRP_EXCEPT},
343   {0x2196, 0x2199,  ULMBCS_AMBIGUOUS_MBCS},
344   {0x21A8, 0x21A8,  ULMBCS_GRP_EXCEPT},
345   {0x21B8, 0x21B9,  ULMBCS_GRP_CN},
346   {0x21D0, 0x21D5,  ULMBCS_GRP_EXCEPT},
347   {0x21E7, 0x21E7,  ULMBCS_GRP_CN},
348   {0x2200, 0x220B,  ULMBCS_GRP_EXCEPT},
349   {0x220F, 0x2215,  ULMBCS_AMBIGUOUS_MBCS},
350   {0x2219, 0x2220,  ULMBCS_GRP_EXCEPT},
351   {0x2223, 0x2228,  ULMBCS_AMBIGUOUS_MBCS},
352   {0x2229, 0x222B,  ULMBCS_GRP_EXCEPT},
353   {0x222C, 0x223D,  ULMBCS_AMBIGUOUS_MBCS},
354   {0x2245, 0x2248,  ULMBCS_GRP_EXCEPT},
355   {0x224C, 0x224C,  ULMBCS_GRP_TW},
356   {0x2252, 0x2252,  ULMBCS_AMBIGUOUS_MBCS},
357   {0x2260, 0x2265,  ULMBCS_GRP_EXCEPT},
358   {0x2266, 0x226F,  ULMBCS_AMBIGUOUS_MBCS},
359   {0x2282, 0x2297,  ULMBCS_GRP_EXCEPT},
360   {0x2299, 0x22BF,  ULMBCS_AMBIGUOUS_MBCS},
361   {0x22C0, 0x22C0,  ULMBCS_GRP_EXCEPT},
362   {0x2310, 0x2310,  ULMBCS_GRP_EXCEPT},
363   {0x2312, 0x2312,  ULMBCS_AMBIGUOUS_MBCS},
364   {0x2318, 0x2321,  ULMBCS_GRP_EXCEPT},
365   {0x2318, 0x2321,  ULMBCS_GRP_CN},
366   {0x2460, 0x24E9,  ULMBCS_AMBIGUOUS_MBCS},
367   {0x2500, 0x2500,  ULMBCS_AMBIGUOUS_SBCS},
368   {0x2501, 0x2501,  ULMBCS_AMBIGUOUS_MBCS},
369   {0x2502, 0x2502,  ULMBCS_AMBIGUOUS_SBCS},
370   {0x2503, 0x2503,  ULMBCS_AMBIGUOUS_MBCS},
371   {0x2504, 0x2505,  ULMBCS_GRP_TW},
372   {0x2506, 0x2665,  ULMBCS_AMBIGUOUS_MBCS},
373   {0x2666, 0x2666,  ULMBCS_GRP_EXCEPT},
374   {0x2666, 0x2666,  ULMBCS_GRP_EXCEPT},
375   {0x2667, 0x2E7F,  ULMBCS_AMBIGUOUS_SBCS},
376   {0x2E80, 0xF861,  ULMBCS_AMBIGUOUS_MBCS},
377   {0xF862, 0xF8FF,  ULMBCS_GRP_EXCEPT},
378   {0xF900, 0xFA2D,  ULMBCS_AMBIGUOUS_MBCS},
379   {0xFB00, 0xFEFF,  ULMBCS_AMBIGUOUS_SBCS},
380   {0xFF01, 0xFFEE,  ULMBCS_AMBIGUOUS_MBCS},
381   {0xFFFF, 0xFFFF,  ULMBCS_GRP_UNICODE}
382};
383
384static ulmbcs_byte_t
385FindLMBCSUniRange(UChar uniChar)
386{
387   const struct _UniLMBCSGrpMap * pTable = UniLMBCSGrpMap;
388
389   while (uniChar > pTable->uniEndRange)
390   {
391      pTable++;
392   }
393
394   if (uniChar >= pTable->uniStartRange)
395   {
396      return pTable->GrpType;
397   }
398   return ULMBCS_GRP_UNICODE;
399}
400
401/*
402We also ask the creator of a converter to send in a preferred locale
403that we can use in resolving ambiguous mappings. They send the locale
404in as a string, and we map it, if possible, to one of the
405LMBCS groups. We use this table, and the associated code, to
406do the lookup: */
407
408/**************************************************
409  This table maps locale ID's to LMBCS opt groups.
410  The default return is group 0x01. Note that for
411  performance reasons, the table is sorted in
412  increasing alphabetic order, with the notable
413  exception of zhTW. This is to force the check
414  for Traditonal Chinese before dropping back to
415  Simplified.
416
417  Note too that the Latin-1 groups have been
418  commented out because it's the default, and
419  this shortens the table, allowing a serial
420  search to go quickly.
421 *************************************************/
422
423static const struct _LocaleLMBCSGrpMap
424{
425   const char    *LocaleID;
426   const ulmbcs_byte_t OptGroup;
427} LocaleLMBCSGrpMap[] =
428{
429    {"ar", ULMBCS_GRP_AR},
430    {"be", ULMBCS_GRP_RU},
431    {"bg", ULMBCS_GRP_L2},
432   /* {"ca", ULMBCS_GRP_L1}, */
433    {"cs", ULMBCS_GRP_L2},
434   /* {"da", ULMBCS_GRP_L1}, */
435   /* {"de", ULMBCS_GRP_L1}, */
436    {"el", ULMBCS_GRP_GR},
437   /* {"en", ULMBCS_GRP_L1}, */
438   /* {"es", ULMBCS_GRP_L1}, */
439   /* {"et", ULMBCS_GRP_L1}, */
440   /* {"fi", ULMBCS_GRP_L1}, */
441   /* {"fr", ULMBCS_GRP_L1}, */
442    {"he", ULMBCS_GRP_HE},
443    {"hu", ULMBCS_GRP_L2},
444   /* {"is", ULMBCS_GRP_L1}, */
445   /* {"it", ULMBCS_GRP_L1}, */
446    {"iw", ULMBCS_GRP_HE},
447    {"ja", ULMBCS_GRP_JA},
448    {"ko", ULMBCS_GRP_KO},
449   /* {"lt", ULMBCS_GRP_L1}, */
450   /* {"lv", ULMBCS_GRP_L1}, */
451    {"mk", ULMBCS_GRP_RU},
452   /* {"nl", ULMBCS_GRP_L1}, */
453   /* {"no", ULMBCS_GRP_L1}, */
454    {"pl", ULMBCS_GRP_L2},
455   /* {"pt", ULMBCS_GRP_L1}, */
456    {"ro", ULMBCS_GRP_L2},
457    {"ru", ULMBCS_GRP_RU},
458    {"sh", ULMBCS_GRP_L2},
459    {"sk", ULMBCS_GRP_L2},
460    {"sl", ULMBCS_GRP_L2},
461    {"sq", ULMBCS_GRP_L2},
462    {"sr", ULMBCS_GRP_RU},
463   /* {"sv", ULMBCS_GRP_L1}, */
464    {"th", ULMBCS_GRP_TH},
465    {"tr", ULMBCS_GRP_TR},
466    {"uk", ULMBCS_GRP_RU},
467   /* {"vi", ULMBCS_GRP_L1}, */
468    {"zhTW", ULMBCS_GRP_TW},
469    {"zh", ULMBCS_GRP_CN},
470    {NULL, ULMBCS_GRP_L1}
471};
472
473
474static ulmbcs_byte_t
475FindLMBCSLocale(const char *LocaleID)
476{
477   const struct _LocaleLMBCSGrpMap *pTable = LocaleLMBCSGrpMap;
478
479   if ((!LocaleID) || (!*LocaleID))
480   {
481      return 0;
482   }
483
484   while (pTable->LocaleID)
485   {
486      if (*pTable->LocaleID == *LocaleID) /* Check only first char for speed */
487      {
488         /* First char matches - check whole name, for entry-length */
489         if (uprv_strncmp(pTable->LocaleID, LocaleID, strlen(pTable->LocaleID)) == 0)
490            return pTable->OptGroup;
491      }
492      else
493      if (*pTable->LocaleID > *LocaleID) /* Sorted alphabetically - exit */
494         break;
495      pTable++;
496   }
497   return ULMBCS_GRP_L1;
498}
499
500
501/*
502  Before we get to the main body of code, here's how we hook up to the rest
503  of ICU. ICU converters are required to define a structure that includes
504  some function pointers, and some common data, in the style of a C++
505  vtable. There is also room in there for converter-specific data. LMBCS
506  uses that converter-specific data to keep track of the 12 subconverters
507  we use, the optimization group, and the group (if any) that matches the
508  locale. We have one structure instantiated for each of the 12 possible
509  optimization groups. To avoid typos & to avoid boring the reader, we
510  put the declarations of these structures and functions into macros. To see
511  the definitions of these structures, see unicode\ucnv_bld.h
512*/
513
514typedef struct
515  {
516    UConverterSharedData *OptGrpConverter[ULMBCS_GRP_LAST+1];    /* Converter per Opt. grp. */
517    uint8_t    OptGroup;                  /* default Opt. grp. for this LMBCS session */
518    uint8_t    localeConverterIndex;      /* reasonable locale match for index */
519  }
520UConverterDataLMBCS;
521
522
523#define DECLARE_LMBCS_DATA(n) \
524static const UConverterImpl _LMBCSImpl##n={\
525    UCNV_LMBCS_##n,\
526    NULL,NULL,\
527    _LMBCSOpen##n,\
528    _LMBCSClose,\
529    NULL,\
530    _LMBCSToUnicodeWithOffsets,\
531    _LMBCSToUnicodeWithOffsets,\
532    _LMBCSFromUnicode,\
533    _LMBCSFromUnicode,\
534    NULL,\
535    NULL,\
536    NULL,\
537    NULL,\
538    _LMBCSSafeClone,\
539    ucnv_getCompleteUnicodeSet\
540};\
541static const UConverterStaticData _LMBCSStaticData##n={\
542  sizeof(UConverterStaticData),\
543 "LMBCS-"  #n,\
544    0, UCNV_IBM, UCNV_LMBCS_##n, 1, 3,\
545    { 0x3f, 0, 0, 0 },1,FALSE,FALSE,0,0,{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0} \
546};\
547const UConverterSharedData _LMBCSData##n={\
548    sizeof(UConverterSharedData), ~((uint32_t) 0),\
549    NULL, NULL, &_LMBCSStaticData##n, FALSE, &_LMBCSImpl##n, \
550    0 \
551};
552
553 /* The only function we needed to duplicate 12 times was the 'open'
554function, which will do basically the same thing except set a  different
555optimization group. So, we put the common stuff into a worker function,
556and set up another macro to stamp out the 12 open functions:*/
557#define DEFINE_LMBCS_OPEN(n) \
558static void \
559   _LMBCSOpen##n(UConverter*  _this,const char* name,const char* locale,uint32_t options,UErrorCode*  err) \
560{ _LMBCSOpenWorker(_this, name,locale,options, err, n);}
561
562
563
564/* Here's the open worker & the common close function */
565static void
566_LMBCSOpenWorker(UConverter*  _this,
567                       const char*  name,
568                       const char*  locale,
569                       uint32_t options,
570                       UErrorCode*  err,
571                       ulmbcs_byte_t OptGroup
572                       )
573{
574    UConverterDataLMBCS * extraInfo = (UConverterDataLMBCS*)uprv_malloc (sizeof (UConverterDataLMBCS));
575    if(extraInfo != NULL)
576    {
577        ulmbcs_byte_t i;
578
579        uprv_memset(extraInfo, 0, sizeof(UConverterDataLMBCS));
580
581        for (i=0; i <= ULMBCS_GRP_LAST && U_SUCCESS(*err); i++)
582        {
583            if(OptGroupByteToCPName[i] != NULL) {
584                extraInfo->OptGrpConverter[i] = ucnv_loadSharedData(OptGroupByteToCPName[i], NULL, err);
585            }
586        }
587
588        if(U_SUCCESS(*err)) {
589            extraInfo->OptGroup = OptGroup;
590            extraInfo->localeConverterIndex = FindLMBCSLocale(locale);
591        } else {
592            /* one of the subconverters could not be loaded, unload the previous ones */
593            while(i > 0) {
594                if(extraInfo->OptGrpConverter[--i] != NULL) {
595                    ucnv_unloadSharedDataIfReady(extraInfo->OptGrpConverter[i]);
596                    extraInfo->OptGrpConverter[i] = NULL;
597                }
598            }
599        }
600   }
601   else
602   {
603       *err = U_MEMORY_ALLOCATION_ERROR;
604   }
605   _this->extraInfo = extraInfo;
606}
607
608static void
609_LMBCSClose(UConverter *   _this)
610{
611    if (_this->extraInfo != NULL)
612    {
613        ulmbcs_byte_t Ix;
614        UConverterDataLMBCS * extraInfo = (UConverterDataLMBCS *) _this->extraInfo;
615
616        for (Ix=0; Ix <= ULMBCS_GRP_LAST; Ix++)
617        {
618           if (extraInfo->OptGrpConverter[Ix] != NULL)
619              ucnv_unloadSharedDataIfReady(extraInfo->OptGrpConverter[Ix]);
620        }
621        if (!_this->isExtraLocal) {
622            uprv_free (_this->extraInfo);
623        }
624    }
625}
626
627typedef struct LMBCSClone {
628    UConverter cnv;
629    UConverterDataLMBCS lmbcs;
630} LMBCSClone;
631
632static UConverter *
633_LMBCSSafeClone(const UConverter *cnv,
634                void *stackBuffer,
635                int32_t *pBufferSize,
636                UErrorCode *status) {
637    LMBCSClone *newLMBCS;
638    UConverterDataLMBCS *extraInfo;
639    int32_t i;
640
641    if(*pBufferSize<=0) {
642        *pBufferSize=(int32_t)sizeof(LMBCSClone);
643        return NULL;
644    }
645
646    extraInfo=(UConverterDataLMBCS *)cnv->extraInfo;
647    newLMBCS=(LMBCSClone *)stackBuffer;
648
649    /* ucnv.c/ucnv_safeClone() copied the main UConverter already */
650
651    uprv_memcpy(&newLMBCS->lmbcs, extraInfo, sizeof(UConverterDataLMBCS));
652
653    /* share the subconverters */
654    for(i = 0; i <= ULMBCS_GRP_LAST; ++i) {
655        if(extraInfo->OptGrpConverter[i] != NULL) {
656            ucnv_incrementRefCount(extraInfo->OptGrpConverter[i]);
657        }
658    }
659
660    newLMBCS->cnv.extraInfo = &newLMBCS->lmbcs;
661    newLMBCS->cnv.isExtraLocal = TRUE;
662    return &newLMBCS->cnv;
663}
664
665/*
666 * There used to be a _LMBCSGetUnicodeSet() function here (up to svn revision 20117)
667 * which added all code points except for U+F6xx
668 * because those cannot be represented in the Unicode group.
669 * However, it turns out that windows-950 has roundtrips for all of U+F6xx
670 * which means that LMBCS can convert all Unicode code points after all.
671 * We now simply use ucnv_getCompleteUnicodeSet().
672 */
673
674/*
675   Here's the basic helper function that we use when converting from
676   Unicode to LMBCS, and we suspect that a Unicode character will fit into
677   one of the 12 groups. The return value is the number of bytes written
678   starting at pStartLMBCS (if any).
679*/
680
681static size_t
682LMBCSConversionWorker (
683   UConverterDataLMBCS * extraInfo,    /* subconverters, opt & locale groups */
684   ulmbcs_byte_t group,                /* The group to try */
685   ulmbcs_byte_t  * pStartLMBCS,              /* where to put the results */
686   UChar * pUniChar,                   /* The input unicode character */
687   ulmbcs_byte_t * lastConverterIndex, /* output: track last successful group used */
688   UBool * groups_tried                /* output: track any unsuccessful groups */
689)
690{
691   ulmbcs_byte_t  * pLMBCS = pStartLMBCS;
692   UConverterSharedData * xcnv = extraInfo->OptGrpConverter[group];
693
694   int bytesConverted;
695   uint32_t value;
696   ulmbcs_byte_t firstByte;
697
698   U_ASSERT(xcnv);
699   U_ASSERT(group<ULMBCS_GRP_UNICODE);
700
701   bytesConverted = ucnv_MBCSFromUChar32(xcnv, *pUniChar, &value, FALSE);
702
703   /* get the first result byte */
704   if(bytesConverted > 0) {
705      firstByte = (ulmbcs_byte_t)(value >> ((bytesConverted - 1) * 8));
706   } else {
707      /* most common failure mode is an unassigned character */
708      groups_tried[group] = TRUE;
709      return 0;
710   }
711
712   *lastConverterIndex = group;
713
714   /* All initial byte values in lower ascii range should have been caught by now,
715      except with the exception group.
716    */
717   U_ASSERT((firstByte <= ULMBCS_C0END) || (firstByte >= ULMBCS_C1START) || (group == ULMBCS_GRP_EXCEPT));
718
719   /* use converted data: first write 0, 1 or two group bytes */
720   if (group != ULMBCS_GRP_EXCEPT && extraInfo->OptGroup != group)
721   {
722      *pLMBCS++ = group;
723      if (bytesConverted == 1 && group >= ULMBCS_DOUBLEOPTGROUP_START)
724      {
725         *pLMBCS++ = group;
726      }
727   }
728
729  /* don't emit control chars */
730   if ( bytesConverted == 1 && firstByte < 0x20 )
731      return 0;
732
733
734   /* then move over the converted data */
735   switch(bytesConverted)
736   {
737   case 4:
738      *pLMBCS++ = (ulmbcs_byte_t)(value >> 24);
739   case 3:
740      *pLMBCS++ = (ulmbcs_byte_t)(value >> 16);
741   case 2:
742      *pLMBCS++ = (ulmbcs_byte_t)(value >> 8);
743   case 1:
744      *pLMBCS++ = (ulmbcs_byte_t)value;
745   default:
746      /* will never occur */
747      break;
748   }
749
750   return (pLMBCS - pStartLMBCS);
751}
752
753
754/* This is a much simpler version of above, when we
755know we are writing LMBCS using the Unicode group
756*/
757static size_t
758LMBCSConvertUni(ulmbcs_byte_t * pLMBCS, UChar uniChar)
759{
760     /* encode into LMBCS Unicode range */
761   uint8_t LowCh =   (uint8_t)(uniChar & 0x00FF);
762   uint8_t HighCh  = (uint8_t)(uniChar >> 8);
763
764   *pLMBCS++ = ULMBCS_GRP_UNICODE;
765
766   if (LowCh == 0)
767   {
768      *pLMBCS++ = ULMBCS_UNICOMPATZERO;
769      *pLMBCS++ = HighCh;
770   }
771   else
772   {
773      *pLMBCS++ = HighCh;
774      *pLMBCS++ = LowCh;
775   }
776   return ULMBCS_UNICODE_SIZE;
777}
778
779
780
781/* The main Unicode to LMBCS conversion function */
782static void
783_LMBCSFromUnicode(UConverterFromUnicodeArgs*     args,
784                  UErrorCode*     err)
785{
786   ulmbcs_byte_t lastConverterIndex = 0;
787   UChar uniChar;
788   ulmbcs_byte_t  LMBCS[ULMBCS_CHARSIZE_MAX];
789   ulmbcs_byte_t  * pLMBCS;
790   int bytes_written;
791   UBool groups_tried[ULMBCS_GRP_LAST+1];
792   UConverterDataLMBCS * extraInfo = (UConverterDataLMBCS *) args->converter->extraInfo;
793   int sourceIndex = 0;
794
795
796   /* Basic strategy: attempt to fill in local LMBCS 1-char buffer.(LMBCS)
797      If that succeeds, see if it will all fit into the target & copy it over
798      if it does.
799
800      We try conversions in the following order:
801
802      1. Single-byte ascii & special fixed control chars (&null)
803      2. Look up group in table & try that (could be
804            A) Unicode group
805            B) control group,
806            C) national encoding,
807               or ambiguous SBCS or MBCS group (on to step 4...)
808
809      3. If its ambiguous, try this order:
810         A) The optimization group
811         B) The locale group
812         C) The last group that succeeded with this string.
813         D) every other group that's relevent (single or double)
814         E) If its single-byte ambiguous, try the exceptions group
815
816      4. And as a grand fallback: Unicode
817   */
818
819   while (args->source < args->sourceLimit && !U_FAILURE(*err))
820   {
821      if (args->target >= args->targetLimit)
822      {
823         *err = U_BUFFER_OVERFLOW_ERROR;
824         break;
825      }
826      uniChar = *(args->source);
827      bytes_written = 0;
828      pLMBCS = LMBCS;
829
830      /* check cases in rough order of how common they are, for speed */
831
832      /* single byte matches: strategy 1 */
833
834      if (((uniChar > ULMBCS_C0END) && (uniChar < ULMBCS_C1START)) ||
835          uniChar == 0 || uniChar == ULMBCS_HT || uniChar == ULMBCS_CR ||
836          uniChar == ULMBCS_LF || uniChar == ULMBCS_123SYSTEMRANGE
837          )
838      {
839         *pLMBCS++ = (ulmbcs_byte_t ) uniChar;
840         bytes_written = 1;
841      }
842
843
844      if (!bytes_written)
845      {
846         /* Check by UNICODE range (Strategy 2) */
847         ulmbcs_byte_t group = FindLMBCSUniRange(uniChar);
848
849         if (group == ULMBCS_GRP_UNICODE)  /* (Strategy 2A) */
850         {
851            pLMBCS += LMBCSConvertUni(pLMBCS,uniChar);
852
853            bytes_written = pLMBCS - LMBCS;
854         }
855         else if (group == ULMBCS_GRP_CTRL)  /* (Strategy 2B) */
856         {
857            /* Handle control characters here */
858            if (uniChar <= ULMBCS_C0END)
859            {
860               *pLMBCS++ = ULMBCS_GRP_CTRL;
861               *pLMBCS++ = (ulmbcs_byte_t)(ULMBCS_CTRLOFFSET + uniChar);
862            }
863            else if (uniChar >= ULMBCS_C1START && uniChar <= ULMBCS_C1START + ULMBCS_CTRLOFFSET)
864            {
865               *pLMBCS++ = ULMBCS_GRP_CTRL;
866               *pLMBCS++ = (ulmbcs_byte_t ) (uniChar & 0x00FF);
867            }
868            bytes_written = pLMBCS - LMBCS;
869         }
870         else if (group < ULMBCS_GRP_UNICODE)  /* (Strategy 2C) */
871         {
872            /* a specific converter has been identified - use it */
873            bytes_written = LMBCSConversionWorker (
874                              extraInfo, group, pLMBCS, &uniChar,
875                              &lastConverterIndex, groups_tried);
876         }
877         if (!bytes_written)    /* the ambiguous group cases  (Strategy 3) */
878         {
879            uprv_memset(groups_tried, 0, sizeof(groups_tried));
880
881         /* check for non-default optimization group (Strategy 3A )*/
882            if (extraInfo->OptGroup != 1
883                  && ULMBCS_AMBIGUOUS_MATCH(group, extraInfo->OptGroup))
884            {
885               bytes_written = LMBCSConversionWorker (extraInfo,
886                  extraInfo->OptGroup, pLMBCS, &uniChar,
887                  &lastConverterIndex, groups_tried);
888            }
889            /* check for locale optimization group (Strategy 3B) */
890            if (!bytes_written
891               && (extraInfo->localeConverterIndex)
892               && (ULMBCS_AMBIGUOUS_MATCH(group, extraInfo->localeConverterIndex)))
893               {
894                  bytes_written = LMBCSConversionWorker (extraInfo,
895                     extraInfo->localeConverterIndex, pLMBCS, &uniChar,
896                     &lastConverterIndex, groups_tried);
897               }
898            /* check for last optimization group used for this string (Strategy 3C) */
899            if (!bytes_written
900                && (lastConverterIndex)
901               && (ULMBCS_AMBIGUOUS_MATCH(group, lastConverterIndex)))
902               {
903                  bytes_written = LMBCSConversionWorker (extraInfo,
904                     lastConverterIndex, pLMBCS, &uniChar,
905                     &lastConverterIndex, groups_tried);
906
907               }
908            if (!bytes_written)
909            {
910               /* just check every possible matching converter (Strategy 3D) */
911               ulmbcs_byte_t grp_start;
912               ulmbcs_byte_t grp_end;
913               ulmbcs_byte_t grp_ix;
914               grp_start = (ulmbcs_byte_t)((group == ULMBCS_AMBIGUOUS_MBCS)
915                        ? ULMBCS_DOUBLEOPTGROUP_START
916                        :  ULMBCS_GRP_L1);
917               grp_end = (ulmbcs_byte_t)((group == ULMBCS_AMBIGUOUS_MBCS)
918                        ? ULMBCS_GRP_LAST
919                        :  ULMBCS_GRP_TH);
920               for (grp_ix = grp_start;
921                   grp_ix <= grp_end && !bytes_written;
922                    grp_ix++)
923               {
924                  if (extraInfo->OptGrpConverter [grp_ix] && !groups_tried [grp_ix])
925                  {
926                     bytes_written = LMBCSConversionWorker (extraInfo,
927                       grp_ix, pLMBCS, &uniChar,
928                       &lastConverterIndex, groups_tried);
929                  }
930               }
931                /* a final conversion fallback to the exceptions group if its likely
932                     to be single byte  (Strategy 3E) */
933               if (!bytes_written && grp_start == ULMBCS_GRP_L1)
934               {
935                  bytes_written = LMBCSConversionWorker (extraInfo,
936                     ULMBCS_GRP_EXCEPT, pLMBCS, &uniChar,
937                     &lastConverterIndex, groups_tried);
938               }
939            }
940            /* all of our other strategies failed. Fallback to Unicode. (Strategy 4)*/
941            if (!bytes_written)
942            {
943
944               pLMBCS += LMBCSConvertUni(pLMBCS, uniChar);
945               bytes_written = pLMBCS - LMBCS;
946            }
947         }
948      }
949
950      /* we have a translation. increment source and write as much as posible to target */
951      args->source++;
952      pLMBCS = LMBCS;
953      while (args->target < args->targetLimit && bytes_written--)
954      {
955         *(args->target)++ = *pLMBCS++;
956         if (args->offsets)
957         {
958            *(args->offsets)++ = sourceIndex;
959         }
960      }
961      sourceIndex++;
962      if (bytes_written > 0)
963      {
964         /* write any bytes that didn't fit in target to the error buffer,
965            common code will move this to target if we get called back with
966            enough target room
967         */
968         uint8_t * pErrorBuffer = args->converter->charErrorBuffer;
969         *err = U_BUFFER_OVERFLOW_ERROR;
970         args->converter->charErrorBufferLength = (int8_t)bytes_written;
971         while (bytes_written--)
972         {
973            *pErrorBuffer++ = *pLMBCS++;
974         }
975      }
976   }
977}
978
979
980/* Now, the Unicode from LMBCS section */
981
982
983/* A function to call when we are looking at the Unicode group byte in LMBCS */
984static UChar
985GetUniFromLMBCSUni(char const ** ppLMBCSin)  /* Called with LMBCS-style Unicode byte stream */
986{
987   uint8_t  HighCh = *(*ppLMBCSin)++;  /* Big-endian Unicode in LMBCS compatibility group*/
988   uint8_t  LowCh  = *(*ppLMBCSin)++;
989
990   if (HighCh == ULMBCS_UNICOMPATZERO )
991   {
992      HighCh = LowCh;
993      LowCh = 0; /* zero-byte in LSB special character */
994   }
995   return (UChar)((HighCh << 8) | LowCh);
996}
997
998
999
1000/* CHECK_SOURCE_LIMIT: Helper macro to verify that there are at least'index'
1001   bytes left in source up to  sourceLimit.Errors appropriately if not.
1002   If we reach the limit, then update the source pointer to there to consume
1003   all input as required by ICU converter semantics.
1004*/
1005
1006#define CHECK_SOURCE_LIMIT(index) \
1007     if (args->source+index > args->sourceLimit){\
1008         *err = U_TRUNCATED_CHAR_FOUND;\
1009         args->source = args->sourceLimit;\
1010         return 0xffff;}
1011
1012/* Return the Unicode representation for the current LMBCS character */
1013
1014static UChar32
1015_LMBCSGetNextUCharWorker(UConverterToUnicodeArgs*   args,
1016                         UErrorCode*   err)
1017{
1018    UChar32 uniChar = 0;    /* an output UNICODE char */
1019    ulmbcs_byte_t   CurByte; /* A byte from the input stream */
1020
1021    /* error check */
1022    if (args->source >= args->sourceLimit)
1023    {
1024        *err = U_ILLEGAL_ARGUMENT_ERROR;
1025        return 0xffff;
1026    }
1027    /* Grab first byte & save address for error recovery */
1028    CurByte = *((ulmbcs_byte_t  *) (args->source++));
1029
1030    /*
1031    * at entry of each if clause:
1032    * 1. 'CurByte' points at the first byte of a LMBCS character
1033    * 2. '*source'points to the next byte of the source stream after 'CurByte'
1034    *
1035    * the job of each if clause is:
1036    * 1. set '*source' to point at the beginning of next char (nop if LMBCS char is only 1 byte)
1037    * 2. set 'uniChar' up with the right Unicode value, or set 'err' appropriately
1038    */
1039
1040    /* First lets check the simple fixed values. */
1041
1042    if(((CurByte > ULMBCS_C0END) && (CurByte < ULMBCS_C1START)) /* ascii range */
1043    ||  (CurByte == 0)
1044    ||  CurByte == ULMBCS_HT || CurByte == ULMBCS_CR
1045    ||  CurByte == ULMBCS_LF || CurByte == ULMBCS_123SYSTEMRANGE)
1046    {
1047        uniChar = CurByte;
1048    }
1049    else
1050    {
1051        UConverterDataLMBCS * extraInfo;
1052        ulmbcs_byte_t group;
1053        UConverterSharedData *cnv;
1054
1055        if (CurByte == ULMBCS_GRP_CTRL)  /* Control character group - no opt group update */
1056        {
1057            ulmbcs_byte_t  C0C1byte;
1058            CHECK_SOURCE_LIMIT(1);
1059            C0C1byte = *(args->source)++;
1060            uniChar = (C0C1byte < ULMBCS_C1START) ? C0C1byte - ULMBCS_CTRLOFFSET : C0C1byte;
1061        }
1062        else
1063        if (CurByte == ULMBCS_GRP_UNICODE) /* Unicode compatibility group: BigEndian UTF16 */
1064        {
1065            CHECK_SOURCE_LIMIT(2);
1066
1067            /* don't check for error indicators fffe/ffff below */
1068            return GetUniFromLMBCSUni(&(args->source));
1069        }
1070        else if (CurByte <= ULMBCS_CTRLOFFSET)
1071        {
1072            group = CurByte;                   /* group byte is in the source */
1073            extraInfo = (UConverterDataLMBCS *) args->converter->extraInfo;
1074            if (group > ULMBCS_GRP_LAST || (cnv = extraInfo->OptGrpConverter[group]) == NULL)
1075            {
1076                /* this is not a valid group byte - no converter*/
1077                *err = U_INVALID_CHAR_FOUND;
1078            }
1079            else if (group >= ULMBCS_DOUBLEOPTGROUP_START)    /* double byte conversion */
1080            {
1081
1082                CHECK_SOURCE_LIMIT(2);
1083
1084                /* check for LMBCS doubled-group-byte case */
1085                if (*args->source == group) {
1086                    /* single byte */
1087                    ++args->source;
1088                    uniChar = ucnv_MBCSSimpleGetNextUChar(cnv, args->source, 1, FALSE);
1089                    ++args->source;
1090                } else {
1091                    /* double byte */
1092                    uniChar = ucnv_MBCSSimpleGetNextUChar(cnv, args->source, 2, FALSE);
1093                    args->source += 2;
1094                }
1095            }
1096            else {                                  /* single byte conversion */
1097                CHECK_SOURCE_LIMIT(1);
1098                CurByte = *(args->source)++;
1099
1100                if (CurByte >= ULMBCS_C1START)
1101                {
1102                    uniChar = _MBCS_SINGLE_SIMPLE_GET_NEXT_BMP(cnv, CurByte);
1103                }
1104                else
1105                {
1106                    /* The non-optimizable oddballs where there is an explicit byte
1107                    * AND the second byte is not in the upper ascii range
1108                    */
1109                    char bytes[2];
1110
1111                    extraInfo = (UConverterDataLMBCS *) args->converter->extraInfo;
1112                    cnv = extraInfo->OptGrpConverter [ULMBCS_GRP_EXCEPT];
1113
1114                    /* Lookup value must include opt group */
1115                    bytes[0] = group;
1116                    bytes[1] = CurByte;
1117                    uniChar = ucnv_MBCSSimpleGetNextUChar(cnv, bytes, 2, FALSE);
1118                }
1119            }
1120        }
1121        else if (CurByte >= ULMBCS_C1START) /* group byte is implicit */
1122        {
1123            extraInfo = (UConverterDataLMBCS *) args->converter->extraInfo;
1124            group = extraInfo->OptGroup;
1125            cnv = extraInfo->OptGrpConverter[group];
1126            if (group >= ULMBCS_DOUBLEOPTGROUP_START)    /* double byte conversion */
1127            {
1128                if (!ucnv_MBCSIsLeadByte(cnv, CurByte))
1129                {
1130                    CHECK_SOURCE_LIMIT(0);
1131
1132                    /* let the MBCS conversion consume CurByte again */
1133                    uniChar = ucnv_MBCSSimpleGetNextUChar(cnv, args->source - 1, 1, FALSE);
1134                }
1135                else
1136                {
1137                    CHECK_SOURCE_LIMIT(1);
1138                    /* let the MBCS conversion consume CurByte again */
1139                    uniChar = ucnv_MBCSSimpleGetNextUChar(cnv, args->source - 1, 2, FALSE);
1140                    ++args->source;
1141                }
1142            }
1143            else                                   /* single byte conversion */
1144            {
1145                uniChar = _MBCS_SINGLE_SIMPLE_GET_NEXT_BMP(cnv, CurByte);
1146            }
1147        }
1148    }
1149    return uniChar;
1150}
1151
1152
1153/* The exported function that converts lmbcs to one or more
1154   UChars - currently UTF-16
1155*/
1156static void
1157_LMBCSToUnicodeWithOffsets(UConverterToUnicodeArgs*    args,
1158                     UErrorCode*    err)
1159{
1160   char LMBCS [ULMBCS_CHARSIZE_MAX];
1161   UChar uniChar;    /* one output UNICODE char */
1162   const char * saveSource; /* beginning of current code point */
1163   const char * pStartLMBCS = args->source;  /* beginning of whole string */
1164   const char * errSource = NULL; /* pointer to actual input in case an error occurs */
1165   int8_t savebytes = 0;
1166
1167   /* Process from source to limit, or until error */
1168   while (U_SUCCESS(*err) && args->sourceLimit > args->source && args->targetLimit > args->target)
1169   {
1170      saveSource = args->source; /* beginning of current code point */
1171
1172      if (args->converter->toULength) /* reassemble char from previous call */
1173      {
1174        const char *saveSourceLimit;
1175        size_t size_old = args->converter->toULength;
1176
1177         /* limit from source is either remainder of temp buffer, or user limit on source */
1178        size_t size_new_maybe_1 = sizeof(LMBCS) - size_old;
1179        size_t size_new_maybe_2 = args->sourceLimit - args->source;
1180        size_t size_new = (size_new_maybe_1 < size_new_maybe_2) ? size_new_maybe_1 : size_new_maybe_2;
1181
1182
1183        uprv_memcpy(LMBCS, args->converter->toUBytes, size_old);
1184        uprv_memcpy(LMBCS + size_old, args->source, size_new);
1185        saveSourceLimit = args->sourceLimit;
1186        args->source = errSource = LMBCS;
1187        args->sourceLimit = LMBCS+size_old+size_new;
1188        savebytes = (int8_t)(size_old+size_new);
1189        uniChar = (UChar) _LMBCSGetNextUCharWorker(args, err);
1190        args->source = saveSource + ((args->source - LMBCS) - size_old);
1191        args->sourceLimit = saveSourceLimit;
1192
1193        if (*err == U_TRUNCATED_CHAR_FOUND)
1194        {
1195            /* evil special case: source buffers so small a char spans more than 2 buffers */
1196            args->converter->toULength = savebytes;
1197            uprv_memcpy(args->converter->toUBytes, LMBCS, savebytes);
1198            args->source = args->sourceLimit;
1199            *err = U_ZERO_ERROR;
1200            return;
1201         }
1202         else
1203         {
1204            /* clear the partial-char marker */
1205            args->converter->toULength = 0;
1206         }
1207      }
1208      else
1209      {
1210         errSource = saveSource;
1211         uniChar = (UChar) _LMBCSGetNextUCharWorker(args, err);
1212         savebytes = (int8_t)(args->source - saveSource);
1213      }
1214      if (U_SUCCESS(*err))
1215      {
1216         if (uniChar < 0xfffe)
1217         {
1218            *(args->target)++ = uniChar;
1219            if(args->offsets)
1220            {
1221               *(args->offsets)++ = saveSource - pStartLMBCS;
1222            }
1223         }
1224         else if (uniChar == 0xfffe)
1225         {
1226            *err = U_INVALID_CHAR_FOUND;
1227         }
1228         else /* if (uniChar == 0xffff) */
1229         {
1230            *err = U_ILLEGAL_CHAR_FOUND;
1231         }
1232      }
1233   }
1234   /* if target ran out before source, return U_BUFFER_OVERFLOW_ERROR */
1235   if (U_SUCCESS(*err) && args->sourceLimit > args->source && args->targetLimit <= args->target)
1236   {
1237      *err = U_BUFFER_OVERFLOW_ERROR;
1238   }
1239   else if (U_FAILURE(*err))
1240   {
1241      /* If character incomplete or unmappable/illegal, store it in toUBytes[] */
1242      args->converter->toULength = savebytes;
1243      if (savebytes > 0) {
1244         uprv_memcpy(args->converter->toUBytes, errSource, savebytes);
1245      }
1246      if (*err == U_TRUNCATED_CHAR_FOUND) {
1247         *err = U_ZERO_ERROR;
1248      }
1249   }
1250}
1251
1252/* And now, the macroized declarations of data & functions: */
1253DEFINE_LMBCS_OPEN(1)
1254DEFINE_LMBCS_OPEN(2)
1255DEFINE_LMBCS_OPEN(3)
1256DEFINE_LMBCS_OPEN(4)
1257DEFINE_LMBCS_OPEN(5)
1258DEFINE_LMBCS_OPEN(6)
1259DEFINE_LMBCS_OPEN(8)
1260DEFINE_LMBCS_OPEN(11)
1261DEFINE_LMBCS_OPEN(16)
1262DEFINE_LMBCS_OPEN(17)
1263DEFINE_LMBCS_OPEN(18)
1264DEFINE_LMBCS_OPEN(19)
1265
1266
1267DECLARE_LMBCS_DATA(1)
1268DECLARE_LMBCS_DATA(2)
1269DECLARE_LMBCS_DATA(3)
1270DECLARE_LMBCS_DATA(4)
1271DECLARE_LMBCS_DATA(5)
1272DECLARE_LMBCS_DATA(6)
1273DECLARE_LMBCS_DATA(8)
1274DECLARE_LMBCS_DATA(11)
1275DECLARE_LMBCS_DATA(16)
1276DECLARE_LMBCS_DATA(17)
1277DECLARE_LMBCS_DATA(18)
1278DECLARE_LMBCS_DATA(19)
1279
1280#endif /* #if !UCONFIG_NO_LEGACY_CONVERSION */
1281