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Dogcows Code - chaz/yoink/blob - src/moof/ConvertUTF.c
2 * Copyright 2001-2004 Unicode, Inc.
6 * This source code is provided as is by Unicode, Inc. No claims are
7 * made as to fitness for any particular purpose. No warranties of any
8 * kind are expressed or implied. The recipient agrees to determine
9 * applicability of information provided. If this file has been
10 * purchased on magnetic or optical media from Unicode, Inc., the
11 * sole remedy for any claim will be exchange of defective media
12 * within 90 days of receipt.
14 * Limitations on Rights to Redistribute This Code
16 * Unicode, Inc. hereby grants the right to freely use the information
17 * supplied in this file in the creation of products supporting the
18 * Unicode Standard, and to make copies of this file in any form
19 * for internal or external distribution as long as this notice
23 /* ---------------------------------------------------------------------
25 Conversions between UTF32, UTF-16, and UTF-8. Source code file.
26 Author: Mark E. Davis, 1994.
27 Rev History: Rick McGowan, fixes & updates May 2001.
28 Sept 2001: fixed const & error conditions per
29 mods suggested by S. Parent & A. Lillich.
30 June 2002: Tim Dodd added detection and handling of incomplete
31 source sequences, enhanced error detection, added casts
32 to eliminate compiler warnings.
33 July 2003: slight mods to back out aggressive FFFE detection.
34 Jan 2004: updated switches in from-UTF8 conversions.
35 Oct 2004: updated to use UNI_MAX_LEGAL_UTF32 in UTF-32 conversions.
37 See the header file "ConvertUTF.h" for complete documentation.
39 ------------------------------------------------------------------------ */
42 #include "ConvertUTF.h"
47 static const int halfShift
= 10; /* used for shifting by 10 bits */
49 static const UTF32 halfBase
= 0x0010000UL
;
50 static const UTF32 halfMask
= 0x3FFUL
;
52 #define UNI_SUR_HIGH_START (UTF32)0xD800
53 #define UNI_SUR_HIGH_END (UTF32)0xDBFF
54 #define UNI_SUR_LOW_START (UTF32)0xDC00
55 #define UNI_SUR_LOW_END (UTF32)0xDFFF
59 /* --------------------------------------------------------------------- */
61 ConversionResult
ConvertUTF32toUTF16 (
62 const UTF32
** sourceStart
, const UTF32
* sourceEnd
,
63 UTF16
** targetStart
, UTF16
* targetEnd
, ConversionFlags flags
) {
64 ConversionResult result
= conversionOK
;
65 const UTF32
* source
= *sourceStart
;
66 UTF16
* target
= *targetStart
;
67 while (source
< sourceEnd
) {
69 if (target
>= targetEnd
) {
70 result
= targetExhausted
; break;
73 if (ch
<= UNI_MAX_BMP
) { /* Target is a character <= 0xFFFF */
74 /* UTF-16 surrogate values are illegal in UTF-32; 0xffff or 0xfffe are both reserved values */
75 if (ch
>= UNI_SUR_HIGH_START
&& ch
<= UNI_SUR_LOW_END
) {
76 if (flags
== strictConversion
) {
77 --source
; /* return to the illegal value itself */
78 result
= sourceIllegal
;
81 *target
++ = UNI_REPLACEMENT_CHAR
;
84 *target
++ = (UTF16
)ch
; /* normal case */
86 } else if (ch
> UNI_MAX_LEGAL_UTF32
) {
87 if (flags
== strictConversion
) {
88 result
= sourceIllegal
;
90 *target
++ = UNI_REPLACEMENT_CHAR
;
93 /* target is a character in range 0xFFFF - 0x10FFFF. */
94 if (target
+ 1 >= targetEnd
) {
95 --source
; /* Back up source pointer! */
96 result
= targetExhausted
; break;
99 *target
++ = (UTF16
)((ch
>> halfShift
) + UNI_SUR_HIGH_START
);
100 *target
++ = (UTF16
)((ch
& halfMask
) + UNI_SUR_LOW_START
);
103 *sourceStart
= source
;
104 *targetStart
= target
;
108 /* --------------------------------------------------------------------- */
110 ConversionResult
ConvertUTF16toUTF32 (
111 const UTF16
** sourceStart
, const UTF16
* sourceEnd
,
112 UTF32
** targetStart
, UTF32
* targetEnd
, ConversionFlags flags
) {
113 ConversionResult result
= conversionOK
;
114 const UTF16
* source
= *sourceStart
;
115 UTF32
* target
= *targetStart
;
117 while (source
< sourceEnd
) {
118 const UTF16
* oldSource
= source
; /* In case we have to back up because of target overflow. */
120 /* If we have a surrogate pair, convert to UTF32 first. */
121 if (ch
>= UNI_SUR_HIGH_START
&& ch
<= UNI_SUR_HIGH_END
) {
122 /* If the 16 bits following the high surrogate are in the source buffer... */
123 if (source
< sourceEnd
) {
125 /* If it's a low surrogate, convert to UTF32. */
126 if (ch2
>= UNI_SUR_LOW_START
&& ch2
<= UNI_SUR_LOW_END
) {
127 ch
= ((ch
- UNI_SUR_HIGH_START
) << halfShift
)
128 + (ch2
- UNI_SUR_LOW_START
) + halfBase
;
130 } else if (flags
== strictConversion
) { /* it's an unpaired high surrogate */
131 --source
; /* return to the illegal value itself */
132 result
= sourceIllegal
;
135 } else { /* We don't have the 16 bits following the high surrogate. */
136 --source
; /* return to the high surrogate */
137 result
= sourceExhausted
;
140 } else if (flags
== strictConversion
) {
141 /* UTF-16 surrogate values are illegal in UTF-32 */
142 if (ch
>= UNI_SUR_LOW_START
&& ch
<= UNI_SUR_LOW_END
) {
143 --source
; /* return to the illegal value itself */
144 result
= sourceIllegal
;
148 if (target
>= targetEnd
) {
149 source
= oldSource
; /* Back up source pointer! */
150 result
= targetExhausted
; break;
154 *sourceStart
= source
;
155 *targetStart
= target
;
157 if (result
== sourceIllegal
) {
158 fprintf(stderr
, "ConvertUTF16toUTF32 illegal seq 0x%04x,%04x\n", ch
, ch2
);
165 /* --------------------------------------------------------------------- */
168 * Index into the table below with the first byte of a UTF-8 sequence to
169 * get the number of trailing bytes that are supposed to follow it.
170 * Note that *legal* UTF-8 values can't have 4 or 5-bytes. The table is
171 * left as-is for anyone who may want to do such conversion, which was
172 * allowed in earlier algorithms.
174 static const char trailingBytesForUTF8
[256] = {
175 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
176 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
177 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
178 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
179 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
180 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
181 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
182 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, 3,3,3,3,3,3,3,3,4,4,4,4,5,5,5,5
186 * Magic values subtracted from a buffer value during UTF8 conversion.
187 * This table contains as many values as there might be trailing bytes
188 * in a UTF-8 sequence.
190 static const UTF32 offsetsFromUTF8
[6] = { 0x00000000UL
, 0x00003080UL
, 0x000E2080UL
,
191 0x03C82080UL
, 0xFA082080UL
, 0x82082080UL
};
194 * Once the bits are split out into bytes of UTF-8, this is a mask OR-ed
195 * into the first byte, depending on how many bytes follow. There are
196 * as many entries in this table as there are UTF-8 sequence types.
197 * (I.e., one byte sequence, two byte... etc.). Remember that sequencs
198 * for *legal* UTF-8 will be 4 or fewer bytes total.
200 static const UTF8 firstByteMark
[7] = { 0x00, 0x00, 0xC0, 0xE0, 0xF0, 0xF8, 0xFC };
202 /* --------------------------------------------------------------------- */
204 /* The interface converts a whole buffer to avoid function-call overhead.
205 * Constants have been gathered. Loops & conditionals have been removed as
206 * much as possible for efficiency, in favor of drop-through switches.
207 * (See "Note A" at the bottom of the file for equivalent code.)
208 * If your compiler supports it, the "isLegalUTF8" call can be turned
209 * into an inline function.
212 /* --------------------------------------------------------------------- */
214 ConversionResult
ConvertUTF16toUTF8 (
215 const UTF16
** sourceStart
, const UTF16
* sourceEnd
,
216 UTF8
** targetStart
, UTF8
* targetEnd
, ConversionFlags flags
) {
217 ConversionResult result
= conversionOK
;
218 const UTF16
* source
= *sourceStart
;
219 UTF8
* target
= *targetStart
;
220 while (source
< sourceEnd
) {
222 unsigned short bytesToWrite
= 0;
223 const UTF32 byteMask
= 0xBF;
224 const UTF32 byteMark
= 0x80;
225 const UTF16
* oldSource
= source
; /* In case we have to back up because of target overflow. */
227 /* If we have a surrogate pair, convert to UTF32 first. */
228 if (ch
>= UNI_SUR_HIGH_START
&& ch
<= UNI_SUR_HIGH_END
) {
229 /* If the 16 bits following the high surrogate are in the source buffer... */
230 if (source
< sourceEnd
) {
232 /* If it's a low surrogate, convert to UTF32. */
233 if (ch2
>= UNI_SUR_LOW_START
&& ch2
<= UNI_SUR_LOW_END
) {
234 ch
= ((ch
- UNI_SUR_HIGH_START
) << halfShift
)
235 + (ch2
- UNI_SUR_LOW_START
) + halfBase
;
237 } else if (flags
== strictConversion
) { /* it's an unpaired high surrogate */
238 --source
; /* return to the illegal value itself */
239 result
= sourceIllegal
;
242 } else { /* We don't have the 16 bits following the high surrogate. */
243 --source
; /* return to the high surrogate */
244 result
= sourceExhausted
;
247 } else if (flags
== strictConversion
) {
248 /* UTF-16 surrogate values are illegal in UTF-32 */
249 if (ch
>= UNI_SUR_LOW_START
&& ch
<= UNI_SUR_LOW_END
) {
250 --source
; /* return to the illegal value itself */
251 result
= sourceIllegal
;
255 /* Figure out how many bytes the result will require */
256 if (ch
< (UTF32
)0x80) { bytesToWrite
= 1;
257 } else if (ch
< (UTF32
)0x800) { bytesToWrite
= 2;
258 } else if (ch
< (UTF32
)0x10000) { bytesToWrite
= 3;
259 } else if (ch
< (UTF32
)0x110000) { bytesToWrite
= 4;
260 } else { bytesToWrite
= 3;
261 ch
= UNI_REPLACEMENT_CHAR
;
264 target
+= bytesToWrite
;
265 if (target
> targetEnd
) {
266 source
= oldSource
; /* Back up source pointer! */
267 target
-= bytesToWrite
; result
= targetExhausted
; break;
269 switch (bytesToWrite
) { /* note: everything falls through. */
270 case 4: *--target
= (UTF8
)((ch
| byteMark
) & byteMask
); ch
>>= 6;
271 case 3: *--target
= (UTF8
)((ch
| byteMark
) & byteMask
); ch
>>= 6;
272 case 2: *--target
= (UTF8
)((ch
| byteMark
) & byteMask
); ch
>>= 6;
273 case 1: *--target
= (UTF8
)(ch
| firstByteMark
[bytesToWrite
]);
275 target
+= bytesToWrite
;
277 *sourceStart
= source
;
278 *targetStart
= target
;
282 /* --------------------------------------------------------------------- */
285 * Utility routine to tell whether a sequence of bytes is legal UTF-8.
286 * This must be called with the length pre-determined by the first byte.
287 * If not calling this from ConvertUTF8to*, then the length can be set by:
288 * length = trailingBytesForUTF8[*source]+1;
289 * and the sequence is illegal right away if there aren't that many bytes
291 * If presented with a length > 4, this returns false. The Unicode
292 * definition of UTF-8 goes up to 4-byte sequences.
295 static bool isLegalUTF8(const UTF8
*source
, int length
) {
297 const UTF8
*srcptr
= source
+length
;
299 default: return false;
300 /* Everything else falls through when "true"... */
301 case 4: if ((a
= (*--srcptr
)) < 0x80 || a
> 0xBF) return false;
302 case 3: if ((a
= (*--srcptr
)) < 0x80 || a
> 0xBF) return false;
303 case 2: if ((a
= (*--srcptr
)) > 0xBF) return false;
306 /* no fall-through in this inner switch */
307 case 0xE0: if (a
< 0xA0) return false; break;
308 case 0xED: if (a
> 0x9F) return false; break;
309 case 0xF0: if (a
< 0x90) return false; break;
310 case 0xF4: if (a
> 0x8F) return false; break;
311 default: if (a
< 0x80) return false;
314 case 1: if (*source
>= 0x80 && *source
< 0xC2) return false;
316 if (*source
> 0xF4) return false;
320 /* --------------------------------------------------------------------- */
323 * Exported function to return whether a UTF-8 sequence is legal or not.
324 * This is not used here; it's just exported.
326 bool isLegalUTF8Sequence(const UTF8
*source
, const UTF8
*sourceEnd
) {
327 int length
= trailingBytesForUTF8
[*source
]+1;
328 if (source
+length
> sourceEnd
) {
331 return isLegalUTF8(source
, length
);
334 /* --------------------------------------------------------------------- */
336 ConversionResult
ConvertUTF8toUTF16 (
337 const UTF8
** sourceStart
, const UTF8
* sourceEnd
,
338 UTF16
** targetStart
, UTF16
* targetEnd
, ConversionFlags flags
) {
339 ConversionResult result
= conversionOK
;
340 const UTF8
* source
= *sourceStart
;
341 UTF16
* target
= *targetStart
;
342 while (source
< sourceEnd
) {
344 unsigned short extraBytesToRead
= trailingBytesForUTF8
[*source
];
345 if (source
+ extraBytesToRead
>= sourceEnd
) {
346 result
= sourceExhausted
; break;
348 /* Do this check whether lenient or strict */
349 if (! isLegalUTF8(source
, extraBytesToRead
+1)) {
350 result
= sourceIllegal
;
354 * The cases all fall through. See "Note A" below.
356 switch (extraBytesToRead
) {
357 case 5: ch
+= *source
++; ch
<<= 6; /* remember, illegal UTF-8 */
358 case 4: ch
+= *source
++; ch
<<= 6; /* remember, illegal UTF-8 */
359 case 3: ch
+= *source
++; ch
<<= 6;
360 case 2: ch
+= *source
++; ch
<<= 6;
361 case 1: ch
+= *source
++; ch
<<= 6;
362 case 0: ch
+= *source
++;
364 ch
-= offsetsFromUTF8
[extraBytesToRead
];
366 if (target
>= targetEnd
) {
367 source
-= (extraBytesToRead
+1); /* Back up source pointer! */
368 result
= targetExhausted
; break;
370 if (ch
<= UNI_MAX_BMP
) { /* Target is a character <= 0xFFFF */
371 /* UTF-16 surrogate values are illegal in UTF-32 */
372 if (ch
>= UNI_SUR_HIGH_START
&& ch
<= UNI_SUR_LOW_END
) {
373 if (flags
== strictConversion
) {
374 source
-= (extraBytesToRead
+1); /* return to the illegal value itself */
375 result
= sourceIllegal
;
378 *target
++ = UNI_REPLACEMENT_CHAR
;
381 *target
++ = (UTF16
)ch
; /* normal case */
383 } else if (ch
> UNI_MAX_UTF16
) {
384 if (flags
== strictConversion
) {
385 result
= sourceIllegal
;
386 source
-= (extraBytesToRead
+1); /* return to the start */
387 break; /* Bail out; shouldn't continue */
389 *target
++ = UNI_REPLACEMENT_CHAR
;
392 /* target is a character in range 0xFFFF - 0x10FFFF. */
393 if (target
+ 1 >= targetEnd
) {
394 source
-= (extraBytesToRead
+1); /* Back up source pointer! */
395 result
= targetExhausted
; break;
398 *target
++ = (UTF16
)((ch
>> halfShift
) + UNI_SUR_HIGH_START
);
399 *target
++ = (UTF16
)((ch
& halfMask
) + UNI_SUR_LOW_START
);
402 *sourceStart
= source
;
403 *targetStart
= target
;
407 /* --------------------------------------------------------------------- */
409 ConversionResult
ConvertUTF32toUTF8 (
410 const UTF32
** sourceStart
, const UTF32
* sourceEnd
,
411 UTF8
** targetStart
, UTF8
* targetEnd
, ConversionFlags flags
) {
412 ConversionResult result
= conversionOK
;
413 const UTF32
* source
= *sourceStart
;
414 UTF8
* target
= *targetStart
;
415 while (source
< sourceEnd
) {
417 unsigned short bytesToWrite
= 0;
418 const UTF32 byteMask
= 0xBF;
419 const UTF32 byteMark
= 0x80;
421 if (flags
== strictConversion
) {
422 /* UTF-16 surrogate values are illegal in UTF-32 */
423 if (ch
>= UNI_SUR_HIGH_START
&& ch
<= UNI_SUR_LOW_END
) {
424 --source
; /* return to the illegal value itself */
425 result
= sourceIllegal
;
430 * Figure out how many bytes the result will require. Turn any
431 * illegally large UTF32 things (> Plane 17) into replacement chars.
433 if (ch
< (UTF32
)0x80) { bytesToWrite
= 1;
434 } else if (ch
< (UTF32
)0x800) { bytesToWrite
= 2;
435 } else if (ch
< (UTF32
)0x10000) { bytesToWrite
= 3;
436 } else if (ch
<= UNI_MAX_LEGAL_UTF32
) { bytesToWrite
= 4;
437 } else { bytesToWrite
= 3;
438 ch
= UNI_REPLACEMENT_CHAR
;
439 result
= sourceIllegal
;
442 target
+= bytesToWrite
;
443 if (target
> targetEnd
) {
444 --source
; /* Back up source pointer! */
445 target
-= bytesToWrite
; result
= targetExhausted
; break;
447 switch (bytesToWrite
) { /* note: everything falls through. */
448 case 4: *--target
= (UTF8
)((ch
| byteMark
) & byteMask
); ch
>>= 6;
449 case 3: *--target
= (UTF8
)((ch
| byteMark
) & byteMask
); ch
>>= 6;
450 case 2: *--target
= (UTF8
)((ch
| byteMark
) & byteMask
); ch
>>= 6;
451 case 1: *--target
= (UTF8
) (ch
| firstByteMark
[bytesToWrite
]);
453 target
+= bytesToWrite
;
455 *sourceStart
= source
;
456 *targetStart
= target
;
460 /* --------------------------------------------------------------------- */
462 ConversionResult
ConvertUTF8toUTF32 (
463 const UTF8
** sourceStart
, const UTF8
* sourceEnd
,
464 UTF32
** targetStart
, UTF32
* targetEnd
, ConversionFlags flags
) {
465 ConversionResult result
= conversionOK
;
466 const UTF8
* source
= *sourceStart
;
467 UTF32
* target
= *targetStart
;
468 while (source
< sourceEnd
) {
470 unsigned short extraBytesToRead
= trailingBytesForUTF8
[*source
];
471 if (source
+ extraBytesToRead
>= sourceEnd
) {
472 result
= sourceExhausted
; break;
474 /* Do this check whether lenient or strict */
475 if (! isLegalUTF8(source
, extraBytesToRead
+1)) {
476 result
= sourceIllegal
;
480 * The cases all fall through. See "Note A" below.
482 switch (extraBytesToRead
) {
483 case 5: ch
+= *source
++; ch
<<= 6;
484 case 4: ch
+= *source
++; ch
<<= 6;
485 case 3: ch
+= *source
++; ch
<<= 6;
486 case 2: ch
+= *source
++; ch
<<= 6;
487 case 1: ch
+= *source
++; ch
<<= 6;
488 case 0: ch
+= *source
++;
490 ch
-= offsetsFromUTF8
[extraBytesToRead
];
492 if (target
>= targetEnd
) {
493 source
-= (extraBytesToRead
+1); /* Back up the source pointer! */
494 result
= targetExhausted
; break;
496 if (ch
<= UNI_MAX_LEGAL_UTF32
) {
498 * UTF-16 surrogate values are illegal in UTF-32, and anything
499 * over Plane 17 (> 0x10FFFF) is illegal.
501 if (ch
>= UNI_SUR_HIGH_START
&& ch
<= UNI_SUR_LOW_END
) {
502 if (flags
== strictConversion
) {
503 source
-= (extraBytesToRead
+1); /* return to the illegal value itself */
504 result
= sourceIllegal
;
507 *target
++ = UNI_REPLACEMENT_CHAR
;
512 } else { /* i.e., ch > UNI_MAX_LEGAL_UTF32 */
513 result
= sourceIllegal
;
514 *target
++ = UNI_REPLACEMENT_CHAR
;
517 *sourceStart
= source
;
518 *targetStart
= target
;
522 /* ---------------------------------------------------------------------
525 The fall-through switches in UTF-8 reading code save a
526 temp variable, some decrements & conditionals. The switches
527 are equivalent to the following loop:
529 int tmpBytesToRead = extraBytesToRead+1;
533 if (tmpBytesToRead) ch <<= 6;
534 } while (tmpBytesToRead > 0);
536 In UTF-8 writing code, the switches on "bytesToWrite" are
537 similarly unrolled loops.
539 --------------------------------------------------------------------- */
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