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1 // © 2016 and later: Unicode, Inc. and others.
2 // License & terms of use: http://www.unicode.org/copyright.html
3 /*
4 *******************************************************************************
5 * Copyright (C) 2012-2015, International Business Machines
6 * Corporation and others.  All Rights Reserved.
7 *******************************************************************************
8 * collationkeys.cpp
9 *
10 * created on: 2012sep02
11 * created by: Markus W. Scherer
12 */
13 
14 #include "unicode/utypes.h"
15 
16 #if !UCONFIG_NO_COLLATION
17 
18 #include "unicode/bytestream.h"
19 #include "collation.h"
20 #include "collationiterator.h"
21 #include "collationkeys.h"
22 #include "collationsettings.h"
23 #include "uassert.h"
24 
25 U_NAMESPACE_BEGIN
26 
~SortKeyByteSink()27 SortKeyByteSink::~SortKeyByteSink() {}
28 
29 void
Append(const char * bytes,int32_t n)30 SortKeyByteSink::Append(const char *bytes, int32_t n) {
31     if (n <= 0 || bytes == NULL) {
32         return;
33     }
34     if (ignore_ > 0) {
35         int32_t ignoreRest = ignore_ - n;
36         if (ignoreRest >= 0) {
37             ignore_ = ignoreRest;
38             return;
39         } else {
40             bytes += ignore_;
41             n = -ignoreRest;
42             ignore_ = 0;
43         }
44     }
45     int32_t length = appended_;
46     appended_ += n;
47     if ((buffer_ + length) == bytes) {
48         return;  // the caller used GetAppendBuffer() and wrote the bytes already
49     }
50     int32_t available = capacity_ - length;
51     if (n <= available) {
52         uprv_memcpy(buffer_ + length, bytes, n);
53     } else {
54         AppendBeyondCapacity(bytes, n, length);
55     }
56 }
57 
58 char *
GetAppendBuffer(int32_t min_capacity,int32_t desired_capacity_hint,char * scratch,int32_t scratch_capacity,int32_t * result_capacity)59 SortKeyByteSink::GetAppendBuffer(int32_t min_capacity,
60                                  int32_t desired_capacity_hint,
61                                  char *scratch,
62                                  int32_t scratch_capacity,
63                                  int32_t *result_capacity) {
64     if (min_capacity < 1 || scratch_capacity < min_capacity) {
65         *result_capacity = 0;
66         return NULL;
67     }
68     if (ignore_ > 0) {
69         // Do not write ignored bytes right at the end of the buffer.
70         *result_capacity = scratch_capacity;
71         return scratch;
72     }
73     int32_t available = capacity_ - appended_;
74     if (available >= min_capacity) {
75         *result_capacity = available;
76         return buffer_ + appended_;
77     } else if (Resize(desired_capacity_hint, appended_)) {
78         *result_capacity = capacity_ - appended_;
79         return buffer_ + appended_;
80     } else {
81         *result_capacity = scratch_capacity;
82         return scratch;
83     }
84 }
85 
86 namespace {
87 
88 /**
89  * uint8_t byte buffer, similar to CharString but simpler.
90  */
91 class SortKeyLevel : public UMemory {
92 public:
SortKeyLevel()93     SortKeyLevel() : len(0), ok(TRUE) {}
~SortKeyLevel()94     ~SortKeyLevel() {}
95 
96     /** @return FALSE if memory allocation failed */
isOk() const97     UBool isOk() const { return ok; }
isEmpty() const98     UBool isEmpty() const { return len == 0; }
length() const99     int32_t length() const { return len; }
data() const100     const uint8_t *data() const { return buffer.getAlias(); }
operator [](int32_t index) const101     uint8_t operator[](int32_t index) const { return buffer[index]; }
102 
data()103     uint8_t *data() { return buffer.getAlias(); }
104 
105     void appendByte(uint32_t b);
106     void appendWeight16(uint32_t w);
107     void appendWeight32(uint32_t w);
108     void appendReverseWeight16(uint32_t w);
109 
110     /** Appends all but the last byte to the sink. The last byte should be the 01 terminator. */
appendTo(ByteSink & sink) const111     void appendTo(ByteSink &sink) const {
112         U_ASSERT(len > 0 && buffer[len - 1] == 1);
113         sink.Append(reinterpret_cast<const char *>(buffer.getAlias()), len - 1);
114     }
115 
116 private:
117     MaybeStackArray<uint8_t, 40> buffer;
118     int32_t len;
119     UBool ok;
120 
121     UBool ensureCapacity(int32_t appendCapacity);
122 
123     SortKeyLevel(const SortKeyLevel &other); // forbid copying of this class
124     SortKeyLevel &operator=(const SortKeyLevel &other); // forbid copying of this class
125 };
126 
appendByte(uint32_t b)127 void SortKeyLevel::appendByte(uint32_t b) {
128     if(len < buffer.getCapacity() || ensureCapacity(1)) {
129         buffer[len++] = (uint8_t)b;
130     }
131 }
132 
133 void
appendWeight16(uint32_t w)134 SortKeyLevel::appendWeight16(uint32_t w) {
135     U_ASSERT((w & 0xffff) != 0);
136     uint8_t b0 = (uint8_t)(w >> 8);
137     uint8_t b1 = (uint8_t)w;
138     int32_t appendLength = (b1 == 0) ? 1 : 2;
139     if((len + appendLength) <= buffer.getCapacity() || ensureCapacity(appendLength)) {
140         buffer[len++] = b0;
141         if(b1 != 0) {
142             buffer[len++] = b1;
143         }
144     }
145 }
146 
147 void
appendWeight32(uint32_t w)148 SortKeyLevel::appendWeight32(uint32_t w) {
149     U_ASSERT(w != 0);
150     uint8_t bytes[4] = { (uint8_t)(w >> 24), (uint8_t)(w >> 16), (uint8_t)(w >> 8), (uint8_t)w };
151     int32_t appendLength = (bytes[1] == 0) ? 1 : (bytes[2] == 0) ? 2 : (bytes[3] == 0) ? 3 : 4;
152     if((len + appendLength) <= buffer.getCapacity() || ensureCapacity(appendLength)) {
153         buffer[len++] = bytes[0];
154         if(bytes[1] != 0) {
155             buffer[len++] = bytes[1];
156             if(bytes[2] != 0) {
157                 buffer[len++] = bytes[2];
158                 if(bytes[3] != 0) {
159                     buffer[len++] = bytes[3];
160                 }
161             }
162         }
163     }
164 }
165 
166 void
appendReverseWeight16(uint32_t w)167 SortKeyLevel::appendReverseWeight16(uint32_t w) {
168     U_ASSERT((w & 0xffff) != 0);
169     uint8_t b0 = (uint8_t)(w >> 8);
170     uint8_t b1 = (uint8_t)w;
171     int32_t appendLength = (b1 == 0) ? 1 : 2;
172     if((len + appendLength) <= buffer.getCapacity() || ensureCapacity(appendLength)) {
173         if(b1 == 0) {
174             buffer[len++] = b0;
175         } else {
176             buffer[len] = b1;
177             buffer[len + 1] = b0;
178             len += 2;
179         }
180     }
181 }
182 
ensureCapacity(int32_t appendCapacity)183 UBool SortKeyLevel::ensureCapacity(int32_t appendCapacity) {
184     if(!ok) {
185         return FALSE;
186     }
187     int32_t newCapacity = 2 * buffer.getCapacity();
188     int32_t altCapacity = len + 2 * appendCapacity;
189     if (newCapacity < altCapacity) {
190         newCapacity = altCapacity;
191     }
192     if (newCapacity < 200) {
193         newCapacity = 200;
194     }
195     if(buffer.resize(newCapacity, len)==NULL) {
196         return ok = FALSE;
197     }
198     return TRUE;
199 }
200 
201 }  // namespace
202 
~LevelCallback()203 CollationKeys::LevelCallback::~LevelCallback() {}
204 
205 UBool
needToWrite(Collation::Level)206 CollationKeys::LevelCallback::needToWrite(Collation::Level /*level*/) { return TRUE; }
207 
208 /**
209  * Map from collation strength (UColAttributeValue)
210  * to a mask of Collation::Level bits up to that strength,
211  * excluding the CASE_LEVEL which is independent of the strength,
212  * and excluding IDENTICAL_LEVEL which this function does not write.
213  */
214 static const uint32_t levelMasks[UCOL_STRENGTH_LIMIT] = {
215     2,          // UCOL_PRIMARY -> PRIMARY_LEVEL
216     6,          // UCOL_SECONDARY -> up to SECONDARY_LEVEL
217     0x16,       // UCOL_TERTIARY -> up to TERTIARY_LEVEL
218     0x36,       // UCOL_QUATERNARY -> up to QUATERNARY_LEVEL
219     0, 0, 0, 0,
220     0, 0, 0, 0,
221     0, 0, 0,
222     0x36        // UCOL_IDENTICAL -> up to QUATERNARY_LEVEL
223 };
224 
225 void
writeSortKeyUpToQuaternary(CollationIterator & iter,const UBool * compressibleBytes,const CollationSettings & settings,SortKeyByteSink & sink,Collation::Level minLevel,LevelCallback & callback,UBool preflight,UErrorCode & errorCode)226 CollationKeys::writeSortKeyUpToQuaternary(CollationIterator &iter,
227                                           const UBool *compressibleBytes,
228                                           const CollationSettings &settings,
229                                           SortKeyByteSink &sink,
230                                           Collation::Level minLevel, LevelCallback &callback,
231                                           UBool preflight, UErrorCode &errorCode) {
232     if(U_FAILURE(errorCode)) { return; }
233 
234     int32_t options = settings.options;
235     // Set of levels to process and write.
236     uint32_t levels = levelMasks[CollationSettings::getStrength(options)];
237     if((options & CollationSettings::CASE_LEVEL) != 0) {
238         levels |= Collation::CASE_LEVEL_FLAG;
239     }
240     // Minus the levels below minLevel.
241     levels &= ~(((uint32_t)1 << minLevel) - 1);
242     if(levels == 0) { return; }
243 
244     uint32_t variableTop;
245     if((options & CollationSettings::ALTERNATE_MASK) == 0) {
246         variableTop = 0;
247     } else {
248         // +1 so that we can use "<" and primary ignorables test out early.
249         variableTop = settings.variableTop + 1;
250     }
251 
252     uint32_t tertiaryMask = CollationSettings::getTertiaryMask(options);
253 
254     SortKeyLevel cases;
255     SortKeyLevel secondaries;
256     SortKeyLevel tertiaries;
257     SortKeyLevel quaternaries;
258 
259     uint32_t prevReorderedPrimary = 0;  // 0==no compression
260     int32_t commonCases = 0;
261     int32_t commonSecondaries = 0;
262     int32_t commonTertiaries = 0;
263     int32_t commonQuaternaries = 0;
264 
265     uint32_t prevSecondary = 0;
266     int32_t secSegmentStart = 0;
267 
268     for(;;) {
269         // No need to keep all CEs in the buffer when we write a sort key.
270         iter.clearCEsIfNoneRemaining();
271         int64_t ce = iter.nextCE(errorCode);
272         uint32_t p = (uint32_t)(ce >> 32);
273         if(p < variableTop && p > Collation::MERGE_SEPARATOR_PRIMARY) {
274             // Variable CE, shift it to quaternary level.
275             // Ignore all following primary ignorables, and shift further variable CEs.
276             if(commonQuaternaries != 0) {
277                 --commonQuaternaries;
278                 while(commonQuaternaries >= QUAT_COMMON_MAX_COUNT) {
279                     quaternaries.appendByte(QUAT_COMMON_MIDDLE);
280                     commonQuaternaries -= QUAT_COMMON_MAX_COUNT;
281                 }
282                 // Shifted primary weights are lower than the common weight.
283                 quaternaries.appendByte(QUAT_COMMON_LOW + commonQuaternaries);
284                 commonQuaternaries = 0;
285             }
286             do {
287                 if((levels & Collation::QUATERNARY_LEVEL_FLAG) != 0) {
288                     if(settings.hasReordering()) {
289                         p = settings.reorder(p);
290                     }
291                     if((p >> 24) >= QUAT_SHIFTED_LIMIT_BYTE) {
292                         // Prevent shifted primary lead bytes from
293                         // overlapping with the common compression range.
294                         quaternaries.appendByte(QUAT_SHIFTED_LIMIT_BYTE);
295                     }
296                     quaternaries.appendWeight32(p);
297                 }
298                 do {
299                     ce = iter.nextCE(errorCode);
300                     p = (uint32_t)(ce >> 32);
301                 } while(p == 0);
302             } while(p < variableTop && p > Collation::MERGE_SEPARATOR_PRIMARY);
303         }
304         // ce could be primary ignorable, or NO_CE, or the merge separator,
305         // or a regular primary CE, but it is not variable.
306         // If ce==NO_CE, then write nothing for the primary level but
307         // terminate compression on all levels and then exit the loop.
308         if(p > Collation::NO_CE_PRIMARY && (levels & Collation::PRIMARY_LEVEL_FLAG) != 0) {
309             // Test the un-reordered primary for compressibility.
310             UBool isCompressible = compressibleBytes[p >> 24];
311             if(settings.hasReordering()) {
312                 p = settings.reorder(p);
313             }
314             uint32_t p1 = p >> 24;
315             if(!isCompressible || p1 != (prevReorderedPrimary >> 24)) {
316                 if(prevReorderedPrimary != 0) {
317                     if(p < prevReorderedPrimary) {
318                         // No primary compression terminator
319                         // at the end of the level or merged segment.
320                         if(p1 > Collation::MERGE_SEPARATOR_BYTE) {
321                             sink.Append(Collation::PRIMARY_COMPRESSION_LOW_BYTE);
322                         }
323                     } else {
324                         sink.Append(Collation::PRIMARY_COMPRESSION_HIGH_BYTE);
325                     }
326                 }
327                 sink.Append(p1);
328                 if(isCompressible) {
329                     prevReorderedPrimary = p;
330                 } else {
331                     prevReorderedPrimary = 0;
332                 }
333             }
334             char p2 = (char)(p >> 16);
335             if(p2 != 0) {
336                 char buffer[3] = { p2, (char)(p >> 8), (char)p };
337                 sink.Append(buffer, (buffer[1] == 0) ? 1 : (buffer[2] == 0) ? 2 : 3);
338             }
339             // Optimization for internalNextSortKeyPart():
340             // When the primary level overflows we can stop because we need not
341             // calculate (preflight) the whole sort key length.
342             if(!preflight && sink.Overflowed()) {
343                 if(U_SUCCESS(errorCode) && !sink.IsOk()) {
344                     errorCode = U_MEMORY_ALLOCATION_ERROR;
345                 }
346                 return;
347             }
348         }
349 
350         uint32_t lower32 = (uint32_t)ce;
351         if(lower32 == 0) { continue; }  // completely ignorable, no secondary/case/tertiary/quaternary
352 
353         if((levels & Collation::SECONDARY_LEVEL_FLAG) != 0) {
354             uint32_t s = lower32 >> 16;
355             if(s == 0) {
356                 // secondary ignorable
357             } else if(s == Collation::COMMON_WEIGHT16 &&
358                     ((options & CollationSettings::BACKWARD_SECONDARY) == 0 ||
359                         p != Collation::MERGE_SEPARATOR_PRIMARY)) {
360                 // s is a common secondary weight, and
361                 // backwards-secondary is off or the ce is not the merge separator.
362                 ++commonSecondaries;
363             } else if((options & CollationSettings::BACKWARD_SECONDARY) == 0) {
364                 if(commonSecondaries != 0) {
365                     --commonSecondaries;
366                     while(commonSecondaries >= SEC_COMMON_MAX_COUNT) {
367                         secondaries.appendByte(SEC_COMMON_MIDDLE);
368                         commonSecondaries -= SEC_COMMON_MAX_COUNT;
369                     }
370                     uint32_t b;
371                     if(s < Collation::COMMON_WEIGHT16) {
372                         b = SEC_COMMON_LOW + commonSecondaries;
373                     } else {
374                         b = SEC_COMMON_HIGH - commonSecondaries;
375                     }
376                     secondaries.appendByte(b);
377                     commonSecondaries = 0;
378                 }
379                 secondaries.appendWeight16(s);
380             } else {
381                 if(commonSecondaries != 0) {
382                     --commonSecondaries;
383                     // Append reverse weights. The level will be re-reversed later.
384                     int32_t remainder = commonSecondaries % SEC_COMMON_MAX_COUNT;
385                     uint32_t b;
386                     if(prevSecondary < Collation::COMMON_WEIGHT16) {
387                         b = SEC_COMMON_LOW + remainder;
388                     } else {
389                         b = SEC_COMMON_HIGH - remainder;
390                     }
391                     secondaries.appendByte(b);
392                     commonSecondaries -= remainder;
393                     // commonSecondaries is now a multiple of SEC_COMMON_MAX_COUNT.
394                     while(commonSecondaries > 0) {  // same as >= SEC_COMMON_MAX_COUNT
395                         secondaries.appendByte(SEC_COMMON_MIDDLE);
396                         commonSecondaries -= SEC_COMMON_MAX_COUNT;
397                     }
398                     // commonSecondaries == 0
399                 }
400                 if(0 < p && p <= Collation::MERGE_SEPARATOR_PRIMARY) {
401                     // The backwards secondary level compares secondary weights backwards
402                     // within segments separated by the merge separator (U+FFFE).
403                     uint8_t *secs = secondaries.data();
404                     int32_t last = secondaries.length() - 1;
405                     if(secSegmentStart < last) {
406                         uint8_t *q = secs + secSegmentStart;
407                         uint8_t *r = secs + last;
408                         do {
409                             uint8_t b = *q;
410                             *q++ = *r;
411                             *r-- = b;
412                         } while(q < r);
413                     }
414                     secondaries.appendByte(p == Collation::NO_CE_PRIMARY ?
415                         Collation::LEVEL_SEPARATOR_BYTE : Collation::MERGE_SEPARATOR_BYTE);
416                     prevSecondary = 0;
417                     secSegmentStart = secondaries.length();
418                 } else {
419                     secondaries.appendReverseWeight16(s);
420                     prevSecondary = s;
421                 }
422             }
423         }
424 
425         if((levels & Collation::CASE_LEVEL_FLAG) != 0) {
426             if((CollationSettings::getStrength(options) == UCOL_PRIMARY) ?
427                     p == 0 : lower32 <= 0xffff) {
428                 // Primary+caseLevel: Ignore case level weights of primary ignorables.
429                 // Otherwise: Ignore case level weights of secondary ignorables.
430                 // For details see the comments in the CollationCompare class.
431             } else {
432                 uint32_t c = (lower32 >> 8) & 0xff;  // case bits & tertiary lead byte
433                 U_ASSERT((c & 0xc0) != 0xc0);
434                 if((c & 0xc0) == 0 && c > Collation::LEVEL_SEPARATOR_BYTE) {
435                     ++commonCases;
436                 } else {
437                     if((options & CollationSettings::UPPER_FIRST) == 0) {
438                         // lowerFirst: Compress common weights to nibbles 1..7..13, mixed=14, upper=15.
439                         // If there are only common (=lowest) weights in the whole level,
440                         // then we need not write anything.
441                         // Level length differences are handled already on the next-higher level.
442                         if(commonCases != 0 &&
443                                 (c > Collation::LEVEL_SEPARATOR_BYTE || !cases.isEmpty())) {
444                             --commonCases;
445                             while(commonCases >= CASE_LOWER_FIRST_COMMON_MAX_COUNT) {
446                                 cases.appendByte(CASE_LOWER_FIRST_COMMON_MIDDLE << 4);
447                                 commonCases -= CASE_LOWER_FIRST_COMMON_MAX_COUNT;
448                             }
449                             uint32_t b;
450                             if(c <= Collation::LEVEL_SEPARATOR_BYTE) {
451                                 b = CASE_LOWER_FIRST_COMMON_LOW + commonCases;
452                             } else {
453                                 b = CASE_LOWER_FIRST_COMMON_HIGH - commonCases;
454                             }
455                             cases.appendByte(b << 4);
456                             commonCases = 0;
457                         }
458                         if(c > Collation::LEVEL_SEPARATOR_BYTE) {
459                             c = (CASE_LOWER_FIRST_COMMON_HIGH + (c >> 6)) << 4;  // 14 or 15
460                         }
461                     } else {
462                         // upperFirst: Compress common weights to nibbles 3..15, mixed=2, upper=1.
463                         // The compressed common case weights only go up from the "low" value
464                         // because with upperFirst the common weight is the highest one.
465                         if(commonCases != 0) {
466                             --commonCases;
467                             while(commonCases >= CASE_UPPER_FIRST_COMMON_MAX_COUNT) {
468                                 cases.appendByte(CASE_UPPER_FIRST_COMMON_LOW << 4);
469                                 commonCases -= CASE_UPPER_FIRST_COMMON_MAX_COUNT;
470                             }
471                             cases.appendByte((CASE_UPPER_FIRST_COMMON_LOW + commonCases) << 4);
472                             commonCases = 0;
473                         }
474                         if(c > Collation::LEVEL_SEPARATOR_BYTE) {
475                             c = (CASE_UPPER_FIRST_COMMON_LOW - (c >> 6)) << 4;  // 2 or 1
476                         }
477                     }
478                     // c is a separator byte 01,
479                     // or a left-shifted nibble 0x10, 0x20, ... 0xf0.
480                     cases.appendByte(c);
481                 }
482             }
483         }
484 
485         if((levels & Collation::TERTIARY_LEVEL_FLAG) != 0) {
486             uint32_t t = lower32 & tertiaryMask;
487             U_ASSERT((lower32 & 0xc000) != 0xc000);
488             if(t == Collation::COMMON_WEIGHT16) {
489                 ++commonTertiaries;
490             } else if((tertiaryMask & 0x8000) == 0) {
491                 // Tertiary weights without case bits.
492                 // Move lead bytes 06..3F to C6..FF for a large common-weight range.
493                 if(commonTertiaries != 0) {
494                     --commonTertiaries;
495                     while(commonTertiaries >= TER_ONLY_COMMON_MAX_COUNT) {
496                         tertiaries.appendByte(TER_ONLY_COMMON_MIDDLE);
497                         commonTertiaries -= TER_ONLY_COMMON_MAX_COUNT;
498                     }
499                     uint32_t b;
500                     if(t < Collation::COMMON_WEIGHT16) {
501                         b = TER_ONLY_COMMON_LOW + commonTertiaries;
502                     } else {
503                         b = TER_ONLY_COMMON_HIGH - commonTertiaries;
504                     }
505                     tertiaries.appendByte(b);
506                     commonTertiaries = 0;
507                 }
508                 if(t > Collation::COMMON_WEIGHT16) { t += 0xc000; }
509                 tertiaries.appendWeight16(t);
510             } else if((options & CollationSettings::UPPER_FIRST) == 0) {
511                 // Tertiary weights with caseFirst=lowerFirst.
512                 // Move lead bytes 06..BF to 46..FF for the common-weight range.
513                 if(commonTertiaries != 0) {
514                     --commonTertiaries;
515                     while(commonTertiaries >= TER_LOWER_FIRST_COMMON_MAX_COUNT) {
516                         tertiaries.appendByte(TER_LOWER_FIRST_COMMON_MIDDLE);
517                         commonTertiaries -= TER_LOWER_FIRST_COMMON_MAX_COUNT;
518                     }
519                     uint32_t b;
520                     if(t < Collation::COMMON_WEIGHT16) {
521                         b = TER_LOWER_FIRST_COMMON_LOW + commonTertiaries;
522                     } else {
523                         b = TER_LOWER_FIRST_COMMON_HIGH - commonTertiaries;
524                     }
525                     tertiaries.appendByte(b);
526                     commonTertiaries = 0;
527                 }
528                 if(t > Collation::COMMON_WEIGHT16) { t += 0x4000; }
529                 tertiaries.appendWeight16(t);
530             } else {
531                 // Tertiary weights with caseFirst=upperFirst.
532                 // Do not change the artificial uppercase weight of a tertiary CE (0.0.ut),
533                 // to keep tertiary CEs well-formed.
534                 // Their case+tertiary weights must be greater than those of
535                 // primary and secondary CEs.
536                 //
537                 // Separator         01 -> 01      (unchanged)
538                 // Lowercase     02..04 -> 82..84  (includes uncased)
539                 // Common weight     05 -> 85..C5  (common-weight compression range)
540                 // Lowercase     06..3F -> C6..FF
541                 // Mixed case    42..7F -> 42..7F
542                 // Uppercase     82..BF -> 02..3F
543                 // Tertiary CE   86..BF -> C6..FF
544                 if(t <= Collation::NO_CE_WEIGHT16) {
545                     // Keep separators unchanged.
546                 } else if(lower32 > 0xffff) {
547                     // Invert case bits of primary & secondary CEs.
548                     t ^= 0xc000;
549                     if(t < (TER_UPPER_FIRST_COMMON_HIGH << 8)) {
550                         t -= 0x4000;
551                     }
552                 } else {
553                     // Keep uppercase bits of tertiary CEs.
554                     U_ASSERT(0x8600 <= t && t <= 0xbfff);
555                     t += 0x4000;
556                 }
557                 if(commonTertiaries != 0) {
558                     --commonTertiaries;
559                     while(commonTertiaries >= TER_UPPER_FIRST_COMMON_MAX_COUNT) {
560                         tertiaries.appendByte(TER_UPPER_FIRST_COMMON_MIDDLE);
561                         commonTertiaries -= TER_UPPER_FIRST_COMMON_MAX_COUNT;
562                     }
563                     uint32_t b;
564                     if(t < (TER_UPPER_FIRST_COMMON_LOW << 8)) {
565                         b = TER_UPPER_FIRST_COMMON_LOW + commonTertiaries;
566                     } else {
567                         b = TER_UPPER_FIRST_COMMON_HIGH - commonTertiaries;
568                     }
569                     tertiaries.appendByte(b);
570                     commonTertiaries = 0;
571                 }
572                 tertiaries.appendWeight16(t);
573             }
574         }
575 
576         if((levels & Collation::QUATERNARY_LEVEL_FLAG) != 0) {
577             uint32_t q = lower32 & 0xffff;
578             if((q & 0xc0) == 0 && q > Collation::NO_CE_WEIGHT16) {
579                 ++commonQuaternaries;
580             } else if(q == Collation::NO_CE_WEIGHT16 &&
581                     (options & CollationSettings::ALTERNATE_MASK) == 0 &&
582                     quaternaries.isEmpty()) {
583                 // If alternate=non-ignorable and there are only common quaternary weights,
584                 // then we need not write anything.
585                 // The only weights greater than the merge separator and less than the common weight
586                 // are shifted primary weights, which are not generated for alternate=non-ignorable.
587                 // There are also exactly as many quaternary weights as tertiary weights,
588                 // so level length differences are handled already on tertiary level.
589                 // Any above-common quaternary weight will compare greater regardless.
590                 quaternaries.appendByte(Collation::LEVEL_SEPARATOR_BYTE);
591             } else {
592                 if(q == Collation::NO_CE_WEIGHT16) {
593                     q = Collation::LEVEL_SEPARATOR_BYTE;
594                 } else {
595                     q = 0xfc + ((q >> 6) & 3);
596                 }
597                 if(commonQuaternaries != 0) {
598                     --commonQuaternaries;
599                     while(commonQuaternaries >= QUAT_COMMON_MAX_COUNT) {
600                         quaternaries.appendByte(QUAT_COMMON_MIDDLE);
601                         commonQuaternaries -= QUAT_COMMON_MAX_COUNT;
602                     }
603                     uint32_t b;
604                     if(q < QUAT_COMMON_LOW) {
605                         b = QUAT_COMMON_LOW + commonQuaternaries;
606                     } else {
607                         b = QUAT_COMMON_HIGH - commonQuaternaries;
608                     }
609                     quaternaries.appendByte(b);
610                     commonQuaternaries = 0;
611                 }
612                 quaternaries.appendByte(q);
613             }
614         }
615 
616         if((lower32 >> 24) == Collation::LEVEL_SEPARATOR_BYTE) { break; }  // ce == NO_CE
617     }
618 
619     if(U_FAILURE(errorCode)) { return; }
620 
621     // Append the beyond-primary levels.
622     UBool ok = TRUE;
623     if((levels & Collation::SECONDARY_LEVEL_FLAG) != 0) {
624         if(!callback.needToWrite(Collation::SECONDARY_LEVEL)) { return; }
625         ok &= secondaries.isOk();
626         sink.Append(Collation::LEVEL_SEPARATOR_BYTE);
627         secondaries.appendTo(sink);
628     }
629 
630     if((levels & Collation::CASE_LEVEL_FLAG) != 0) {
631         if(!callback.needToWrite(Collation::CASE_LEVEL)) { return; }
632         ok &= cases.isOk();
633         sink.Append(Collation::LEVEL_SEPARATOR_BYTE);
634         // Write pairs of nibbles as bytes, except separator bytes as themselves.
635         int32_t length = cases.length() - 1;  // Ignore the trailing NO_CE.
636         uint8_t b = 0;
637         for(int32_t i = 0; i < length; ++i) {
638             uint8_t c = (uint8_t)cases[i];
639             U_ASSERT((c & 0xf) == 0 && c != 0);
640             if(b == 0) {
641                 b = c;
642             } else {
643                 sink.Append(b | (c >> 4));
644                 b = 0;
645             }
646         }
647         if(b != 0) {
648             sink.Append(b);
649         }
650     }
651 
652     if((levels & Collation::TERTIARY_LEVEL_FLAG) != 0) {
653         if(!callback.needToWrite(Collation::TERTIARY_LEVEL)) { return; }
654         ok &= tertiaries.isOk();
655         sink.Append(Collation::LEVEL_SEPARATOR_BYTE);
656         tertiaries.appendTo(sink);
657     }
658 
659     if((levels & Collation::QUATERNARY_LEVEL_FLAG) != 0) {
660         if(!callback.needToWrite(Collation::QUATERNARY_LEVEL)) { return; }
661         ok &= quaternaries.isOk();
662         sink.Append(Collation::LEVEL_SEPARATOR_BYTE);
663         quaternaries.appendTo(sink);
664     }
665 
666     if(!ok || !sink.IsOk()) {
667         errorCode = U_MEMORY_ALLOCATION_ERROR;
668     }
669 }
670 
671 U_NAMESPACE_END
672 
673 #endif  // !UCONFIG_NO_COLLATION
674