1// © 2016 and later: Unicode, Inc. and others.
2// License & terms of use: http://www.unicode.org/copyright.html#License
3/*
4*******************************************************************************
5* Copyright (C) 2010-2015, International Business Machines
6* Corporation and others.  All Rights Reserved.
7*******************************************************************************
8* Collation.java, ported from collation.h/.cpp
9*
10* C++ version created on: 2010oct27
11* created by: Markus W. Scherer
12*/
13
14package com.ibm.icu.impl.coll;
15
16/**
17 * Collation v2 basic definitions and static helper functions.
18 *
19 * Data structures except for expansion tables store 32-bit CEs which are
20 * either specials (see tags below) or are compact forms of 64-bit CEs.
21 */
22public final class Collation {
23    /** UChar32 U_SENTINEL.
24     * TODO: Create a common, public constant?
25     */
26    public static final int SENTINEL_CP = -1;
27
28    // ICU4C compare() API returns enum UCollationResult values (with UCOL_ prefix).
29    // ICU4J just returns int. We use these constants for ease of porting.
30    public static final int LESS = -1;
31    public static final int EQUAL = 0;
32    public static final int GREATER = 1;
33
34    // Special sort key bytes for all levels.
35    public static final int TERMINATOR_BYTE = 0;
36    public static final int LEVEL_SEPARATOR_BYTE = 1;
37
38    /** The secondary/tertiary lower limit for tailoring before any root elements. */
39    static final int BEFORE_WEIGHT16 = 0x100;
40
41    /**
42     * Merge-sort-key separator.
43     * Same as the unique primary and identical-level weights of U+FFFE.
44     * Must not be used as primary compression low terminator.
45     * Otherwise usable.
46     */
47    public static final int MERGE_SEPARATOR_BYTE = 2;
48    public static final long MERGE_SEPARATOR_PRIMARY = 0x02000000;  // U+FFFE
49    static final int MERGE_SEPARATOR_CE32 = 0x02000505;  // U+FFFE
50
51    /**
52     * Primary compression low terminator, must be greater than MERGE_SEPARATOR_BYTE.
53     * Reserved value in primary second byte if the lead byte is compressible.
54     * Otherwise usable in all CE weight bytes.
55     */
56    public static final int PRIMARY_COMPRESSION_LOW_BYTE = 3;
57    /**
58     * Primary compression high terminator.
59     * Reserved value in primary second byte if the lead byte is compressible.
60     * Otherwise usable in all CE weight bytes.
61     */
62    public static final int PRIMARY_COMPRESSION_HIGH_BYTE = 0xff;
63
64    /** Default secondary/tertiary weight lead byte. */
65    static final int COMMON_BYTE = 5;
66    public static final int COMMON_WEIGHT16 = 0x0500;
67    /** Middle 16 bits of a CE with a common secondary weight. */
68    static final int COMMON_SECONDARY_CE = 0x05000000;
69    /** Lower 16 bits of a CE with a common tertiary weight. */
70    static final int COMMON_TERTIARY_CE = 0x0500;
71    /** Lower 32 bits of a CE with common secondary and tertiary weights. */
72    public static final int COMMON_SEC_AND_TER_CE = 0x05000500;
73
74    static final int SECONDARY_MASK = 0xffff0000;
75    public static final int CASE_MASK = 0xc000;
76    static final int SECONDARY_AND_CASE_MASK = SECONDARY_MASK | CASE_MASK;
77    /** Only the 2*6 bits for the pure tertiary weight. */
78    public static final int ONLY_TERTIARY_MASK = 0x3f3f;
79    /** Only the secondary & tertiary bits; no case, no quaternary. */
80    static final int ONLY_SEC_TER_MASK = SECONDARY_MASK | ONLY_TERTIARY_MASK;
81    /** Case bits and tertiary bits. */
82    static final int CASE_AND_TERTIARY_MASK = CASE_MASK | ONLY_TERTIARY_MASK;
83    public static final int QUATERNARY_MASK = 0xc0;
84    /** Case bits and quaternary bits. */
85    public static final int CASE_AND_QUATERNARY_MASK = CASE_MASK | QUATERNARY_MASK;
86
87    static final int UNASSIGNED_IMPLICIT_BYTE = 0xfe;  // compressible
88    /**
89     * First unassigned: AlphabeticIndex overflow boundary.
90     * We want a 3-byte primary so that it fits into the root elements table.
91     *
92     * This 3-byte primary will not collide with
93     * any unassigned-implicit 4-byte primaries because
94     * the first few hundred Unicode code points all have real mappings.
95     */
96    static final long FIRST_UNASSIGNED_PRIMARY = 0xfe040200L;
97
98    static final int TRAIL_WEIGHT_BYTE = 0xff;  // not compressible
99    static final long FIRST_TRAILING_PRIMARY = 0xff020200L;  // [first trailing]
100    public static final long MAX_PRIMARY = 0xffff0000L;  // U+FFFF
101    static final int MAX_REGULAR_CE32 = 0xffff0505;  // U+FFFF
102
103    // CE32 value for U+FFFD as well as illegal UTF-8 byte sequences (which behave like U+FFFD).
104    // We use the third-highest primary weight for U+FFFD (as in UCA 6.3+).
105    public static final long FFFD_PRIMARY = MAX_PRIMARY - 0x20000;
106    static final int FFFD_CE32 = MAX_REGULAR_CE32 - 0x20000;
107
108    /**
109     * A CE32 is special if its low byte is this or greater.
110     * Impossible case bits 11 mark special CE32s.
111     * This value itself is used to indicate a fallback to the base collator.
112     */
113    static final int SPECIAL_CE32_LOW_BYTE = 0xc0;
114    static final int FALLBACK_CE32 = SPECIAL_CE32_LOW_BYTE;
115    /**
116     * Low byte of a long-primary special CE32.
117     */
118    static final int LONG_PRIMARY_CE32_LOW_BYTE = 0xc1;  // SPECIAL_CE32_LOW_BYTE | LONG_PRIMARY_TAG
119
120    static final int UNASSIGNED_CE32 = 0xffffffff;  // Compute an unassigned-implicit CE.
121
122    static final int NO_CE32 = 1;
123
124    /** No CE: End of input. Only used in runtime code, not stored in data. */
125    static final long NO_CE_PRIMARY = 1;  // not a left-adjusted weight
126    static final int NO_CE_WEIGHT16 = 0x0100;  // weight of LEVEL_SEPARATOR_BYTE
127    public static final long NO_CE = 0x101000100L;  // NO_CE_PRIMARY, NO_CE_WEIGHT16, NO_CE_WEIGHT16
128
129    /** Sort key levels. */
130
131    /** Unspecified level. */
132    public static final int NO_LEVEL = 0;
133    public static final int PRIMARY_LEVEL = 1;
134    public static final int SECONDARY_LEVEL = 2;
135    public static final int CASE_LEVEL = 3;
136    public static final int TERTIARY_LEVEL = 4;
137    public static final int QUATERNARY_LEVEL = 5;
138    public static final int IDENTICAL_LEVEL = 6;
139    /** Beyond sort key bytes. */
140    public static final int ZERO_LEVEL = 7;
141
142    /**
143     * Sort key level flags: xx_FLAG = 1 << xx_LEVEL.
144     * In Java, use enum Level with flag() getters, or use EnumSet rather than hand-made bit sets.
145     */
146    static final int NO_LEVEL_FLAG = 1;
147    static final int PRIMARY_LEVEL_FLAG = 2;
148    static final int SECONDARY_LEVEL_FLAG = 4;
149    static final int CASE_LEVEL_FLAG = 8;
150    static final int TERTIARY_LEVEL_FLAG = 0x10;
151    static final int QUATERNARY_LEVEL_FLAG = 0x20;
152    static final int IDENTICAL_LEVEL_FLAG = 0x40;
153    static final int ZERO_LEVEL_FLAG = 0x80;
154
155    /**
156     * Special-CE32 tags, from bits 3..0 of a special 32-bit CE.
157     * Bits 31..8 are available for tag-specific data.
158     * Bits  5..4: Reserved. May be used in the future to indicate lccc!=0 and tccc!=0.
159     */
160
161    /**
162     * Fall back to the base collator.
163     * This is the tag value in SPECIAL_CE32_LOW_BYTE and FALLBACK_CE32.
164     * Bits 31..8: Unused, 0.
165     */
166    static final int FALLBACK_TAG = 0;
167    /**
168     * Long-primary CE with COMMON_SEC_AND_TER_CE.
169     * Bits 31..8: Three-byte primary.
170     */
171    static final int LONG_PRIMARY_TAG = 1;
172    /**
173     * Long-secondary CE with zero primary.
174     * Bits 31..16: Secondary weight.
175     * Bits 15.. 8: Tertiary weight.
176     */
177    static final int LONG_SECONDARY_TAG = 2;
178    /**
179     * Unused.
180     * May be used in the future for single-byte secondary CEs (SHORT_SECONDARY_TAG),
181     * storing the secondary in bits 31..24, the ccc in bits 23..16,
182     * and the tertiary in bits 15..8.
183     */
184    static final int RESERVED_TAG_3 = 3;
185    /**
186     * Latin mini expansions of two simple CEs [pp, 05, tt] [00, ss, 05].
187     * Bits 31..24: Single-byte primary weight pp of the first CE.
188     * Bits 23..16: Tertiary weight tt of the first CE.
189     * Bits 15.. 8: Secondary weight ss of the second CE.
190     */
191    static final int LATIN_EXPANSION_TAG = 4;
192    /**
193     * Points to one or more simple/long-primary/long-secondary 32-bit CE32s.
194     * Bits 31..13: Index into int table.
195     * Bits 12.. 8: Length=1..31.
196     */
197    static final int EXPANSION32_TAG = 5;
198    /**
199     * Points to one or more 64-bit CEs.
200     * Bits 31..13: Index into CE table.
201     * Bits 12.. 8: Length=1..31.
202     */
203    static final int EXPANSION_TAG = 6;
204    /**
205     * Builder data, used only in the CollationDataBuilder, not in runtime data.
206     *
207     * If bit 8 is 0: Builder context, points to a list of context-sensitive mappings.
208     * Bits 31..13: Index to the builder's list of ConditionalCE32 for this character.
209     * Bits 12.. 9: Unused, 0.
210     *
211     * If bit 8 is 1 (IS_BUILDER_JAMO_CE32): Builder-only jamoCE32 value.
212     * The builder fetches the Jamo CE32 from the trie.
213     * Bits 31..13: Jamo code point.
214     * Bits 12.. 9: Unused, 0.
215     */
216    static final int BUILDER_DATA_TAG = 7;
217    /**
218     * Points to prefix trie.
219     * Bits 31..13: Index into prefix/contraction data.
220     * Bits 12.. 8: Unused, 0.
221     */
222    static final int PREFIX_TAG = 8;
223    /**
224     * Points to contraction data.
225     * Bits 31..13: Index into prefix/contraction data.
226     * Bits 12..11: Unused, 0.
227     * Bit      10: CONTRACT_TRAILING_CCC flag.
228     * Bit       9: CONTRACT_NEXT_CCC flag.
229     * Bit       8: CONTRACT_SINGLE_CP_NO_MATCH flag.
230     */
231    static final int CONTRACTION_TAG = 9;
232    /**
233     * Decimal digit.
234     * Bits 31..13: Index into int table for non-numeric-collation CE32.
235     * Bit      12: Unused, 0.
236     * Bits 11.. 8: Digit value 0..9.
237     */
238    static final int DIGIT_TAG = 10;
239    /**
240     * Tag for U+0000, for moving the NUL-termination handling
241     * from the regular fastpath into specials-handling code.
242     * Bits 31..8: Unused, 0.
243     */
244    static final int U0000_TAG = 11;
245    /**
246     * Tag for a Hangul syllable.
247     * Bits 31..9: Unused, 0.
248     * Bit      8: HANGUL_NO_SPECIAL_JAMO flag.
249     */
250    static final int HANGUL_TAG = 12;
251    /**
252     * Tag for a lead surrogate code unit.
253     * Optional optimization for UTF-16 string processing.
254     * Bits 31..10: Unused, 0.
255     *       9.. 8: =0: All associated supplementary code points are unassigned-implict.
256     *              =1: All associated supplementary code points fall back to the base data.
257     *              else: (Normally 2) Look up the data for the supplementary code point.
258     */
259    static final int LEAD_SURROGATE_TAG = 13;
260    /**
261     * Tag for CEs with primary weights in code point order.
262     * Bits 31..13: Index into CE table, for one data "CE".
263     * Bits 12.. 8: Unused, 0.
264     *
265     * This data "CE" has the following bit fields:
266     * Bits 63..32: Three-byte primary pppppp00.
267     *      31.. 8: Start/base code point of the in-order range.
268     *           7: Flag isCompressible primary.
269     *       6.. 0: Per-code point primary-weight increment.
270     */
271    static final int OFFSET_TAG = 14;
272    /**
273     * Implicit CE tag. Compute an unassigned-implicit CE.
274     * All bits are set (UNASSIGNED_CE32=0xffffffff).
275     */
276    static final int IMPLICIT_TAG = 15;
277
278    static boolean isAssignedCE32(int ce32) {
279        return ce32 != FALLBACK_CE32 && ce32 != UNASSIGNED_CE32;
280    }
281
282    /**
283     * We limit the number of CEs in an expansion
284     * so that we can use a small number of length bits in the data structure,
285     * and so that an implementation can copy CEs at runtime without growing a destination buffer.
286     */
287    static final int MAX_EXPANSION_LENGTH = 31;
288    static final int MAX_INDEX = 0x7ffff;
289
290    /**
291     * Set if there is no match for the single (no-suffix) character itself.
292     * This is only possible if there is a prefix.
293     * In this case, discontiguous contraction matching cannot add combining marks
294     * starting from an empty suffix.
295     * The default CE32 is used anyway if there is no suffix match.
296     */
297    static final int CONTRACT_SINGLE_CP_NO_MATCH = 0x100;
298    /** Set if the first character of every contraction suffix has lccc!=0. */
299    static final int CONTRACT_NEXT_CCC = 0x200;
300    /** Set if any contraction suffix ends with lccc!=0. */
301    static final int CONTRACT_TRAILING_CCC = 0x400;
302
303    /** For HANGUL_TAG: None of its Jamo CE32s isSpecialCE32(). */
304    static final int HANGUL_NO_SPECIAL_JAMO = 0x100;
305
306    static final int LEAD_ALL_UNASSIGNED = 0;
307    static final int LEAD_ALL_FALLBACK = 0x100;
308    static final int LEAD_MIXED = 0x200;
309    static final int LEAD_TYPE_MASK = 0x300;
310
311    static int makeLongPrimaryCE32(long p) { return (int)(p | LONG_PRIMARY_CE32_LOW_BYTE); }
312
313    /** Turns the long-primary CE32 into a primary weight pppppp00. */
314    static long primaryFromLongPrimaryCE32(int ce32) {
315        return (long)ce32 & 0xffffff00L;
316    }
317    static long ceFromLongPrimaryCE32(int ce32) {
318        return ((long)(ce32 & 0xffffff00) << 32) | COMMON_SEC_AND_TER_CE;
319    }
320
321    static int makeLongSecondaryCE32(int lower32) {
322        return lower32 | SPECIAL_CE32_LOW_BYTE | LONG_SECONDARY_TAG;
323    }
324    static long ceFromLongSecondaryCE32(int ce32) {
325        return (long)ce32 & 0xffffff00L;
326    }
327
328    /** Makes a special CE32 with tag, index and length. */
329    static int makeCE32FromTagIndexAndLength(int tag, int index, int length) {
330        return (index << 13) | (length << 8) | SPECIAL_CE32_LOW_BYTE | tag;
331    }
332    /** Makes a special CE32 with only tag and index. */
333    static int makeCE32FromTagAndIndex(int tag, int index) {
334        return (index << 13) | SPECIAL_CE32_LOW_BYTE | tag;
335    }
336
337    static boolean isSpecialCE32(int ce32) {
338        return (ce32 & 0xff) >= SPECIAL_CE32_LOW_BYTE;
339    }
340
341    static int tagFromCE32(int ce32) {
342        return ce32 & 0xf;
343    }
344
345    static boolean hasCE32Tag(int ce32, int tag) {
346        return isSpecialCE32(ce32) && tagFromCE32(ce32) == tag;
347    }
348
349    static boolean isLongPrimaryCE32(int ce32) {
350        return hasCE32Tag(ce32, LONG_PRIMARY_TAG);
351    }
352
353    static boolean isSimpleOrLongCE32(int ce32) {
354        return !isSpecialCE32(ce32) ||
355                tagFromCE32(ce32) == LONG_PRIMARY_TAG ||
356                tagFromCE32(ce32) == LONG_SECONDARY_TAG;
357    }
358
359    /**
360     * @return true if the ce32 yields one or more CEs without further data lookups
361     */
362    static boolean isSelfContainedCE32(int ce32) {
363        return !isSpecialCE32(ce32) ||
364                tagFromCE32(ce32) == LONG_PRIMARY_TAG ||
365                tagFromCE32(ce32) == LONG_SECONDARY_TAG ||
366                tagFromCE32(ce32) == LATIN_EXPANSION_TAG;
367    }
368
369    static boolean isPrefixCE32(int ce32) {
370        return hasCE32Tag(ce32, PREFIX_TAG);
371    }
372
373    static boolean isContractionCE32(int ce32) {
374        return hasCE32Tag(ce32, CONTRACTION_TAG);
375    }
376
377    static boolean ce32HasContext(int ce32) {
378        return isSpecialCE32(ce32) &&
379                (tagFromCE32(ce32) == PREFIX_TAG ||
380                tagFromCE32(ce32) == CONTRACTION_TAG);
381    }
382
383    /**
384     * Get the first of the two Latin-expansion CEs encoded in ce32.
385     * @see LATIN_EXPANSION_TAG
386     */
387    static long latinCE0FromCE32(int ce32) {
388        return ((long)(ce32 & 0xff000000) << 32) | COMMON_SECONDARY_CE | ((ce32 & 0xff0000) >> 8);
389    }
390
391    /**
392     * Get the second of the two Latin-expansion CEs encoded in ce32.
393     * @see LATIN_EXPANSION_TAG
394     */
395    static long latinCE1FromCE32(int ce32) {
396        return (((long)ce32 & 0xff00) << 16) | COMMON_TERTIARY_CE;
397    }
398
399    /**
400     * Returns the data index from a special CE32.
401     */
402    static int indexFromCE32(int ce32) {
403        return ce32 >>> 13;
404    }
405
406    /**
407     * Returns the data length from a ce32.
408     */
409    static int lengthFromCE32(int ce32) {
410        return (ce32 >> 8) & 31;
411    }
412
413    /**
414     * Returns the digit value from a DIGIT_TAG ce32.
415     */
416    static char digitFromCE32(int ce32) {
417        return (char)((ce32 >> 8) & 0xf);
418    }
419
420    /** Returns a 64-bit CE from a simple CE32 (not special). */
421    static long ceFromSimpleCE32(int ce32) {
422        // normal form ppppsstt -> pppp0000ss00tt00
423        assert (ce32 & 0xff) < SPECIAL_CE32_LOW_BYTE;
424        return ((long)(ce32 & 0xffff0000) << 32) | ((long)(ce32 & 0xff00) << 16) | ((ce32 & 0xff) << 8);
425    }
426
427    /** Returns a 64-bit CE from a simple/long-primary/long-secondary CE32. */
428    static long ceFromCE32(int ce32) {
429        int tertiary = ce32 & 0xff;
430        if(tertiary < SPECIAL_CE32_LOW_BYTE) {
431            // normal form ppppsstt -> pppp0000ss00tt00
432            return ((long)(ce32 & 0xffff0000) << 32) | ((long)(ce32 & 0xff00) << 16) | (tertiary << 8);
433        } else {
434            ce32 -= tertiary;
435            if((tertiary & 0xf) == LONG_PRIMARY_TAG) {
436                // long-primary form ppppppC1 -> pppppp00050000500
437                return ((long)ce32 << 32) | COMMON_SEC_AND_TER_CE;
438            } else {
439                // long-secondary form ssssttC2 -> 00000000sssstt00
440                assert (tertiary & 0xf) == LONG_SECONDARY_TAG;
441                return ce32 & 0xffffffffL;
442            }
443        }
444    }
445
446    /** Creates a CE from a primary weight. */
447    public static long makeCE(long p) {
448        return (p << 32) | COMMON_SEC_AND_TER_CE;
449    }
450    /**
451     * Creates a CE from a primary weight,
452     * 16-bit secondary/tertiary weights, and a 2-bit quaternary.
453     */
454    static long makeCE(long p, int s, int t, int q) {
455        return (p << 32) | ((long)s << 16) | t | (q << 6);
456    }
457
458    /**
459     * Increments a 2-byte primary by a code point offset.
460     */
461    public static long incTwoBytePrimaryByOffset(long basePrimary, boolean isCompressible,
462                                              int offset) {
463        // Extract the second byte, minus the minimum byte value,
464        // plus the offset, modulo the number of usable byte values, plus the minimum.
465        // Reserve the PRIMARY_COMPRESSION_LOW_BYTE and high byte if necessary.
466        long primary;
467        if(isCompressible) {
468            offset += ((int)(basePrimary >> 16) & 0xff) - 4;
469            primary = ((offset % 251) + 4) << 16;
470            offset /= 251;
471        } else {
472            offset += ((int)(basePrimary >> 16) & 0xff) - 2;
473            primary = ((offset % 254) + 2) << 16;
474            offset /= 254;
475        }
476        // First byte, assume no further overflow.
477        return primary | ((basePrimary & 0xff000000L) + ((long)offset << 24));
478    }
479
480    /**
481     * Increments a 3-byte primary by a code point offset.
482     */
483    public static long incThreeBytePrimaryByOffset(long basePrimary, boolean isCompressible,
484                                                int offset) {
485        // Extract the third byte, minus the minimum byte value,
486        // plus the offset, modulo the number of usable byte values, plus the minimum.
487        offset += ((int)(basePrimary >> 8) & 0xff) - 2;
488        long primary = ((offset % 254) + 2) << 8;
489        offset /= 254;
490        // Same with the second byte,
491        // but reserve the PRIMARY_COMPRESSION_LOW_BYTE and high byte if necessary.
492        if(isCompressible) {
493            offset += ((int)(basePrimary >> 16) & 0xff) - 4;
494            primary |= ((offset % 251) + 4) << 16;
495            offset /= 251;
496        } else {
497            offset += ((int)(basePrimary >> 16) & 0xff) - 2;
498            primary |= ((offset % 254) + 2) << 16;
499            offset /= 254;
500        }
501        // First byte, assume no further overflow.
502        return primary | ((basePrimary & 0xff000000L) + ((long)offset << 24));
503    }
504
505    /**
506     * Decrements a 2-byte primary by one range step (1..0x7f).
507     */
508    static long decTwoBytePrimaryByOneStep(long basePrimary, boolean isCompressible, int step) {
509        // Extract the second byte, minus the minimum byte value,
510        // minus the step, modulo the number of usable byte values, plus the minimum.
511        // Reserve the PRIMARY_COMPRESSION_LOW_BYTE and high byte if necessary.
512        // Assume no further underflow for the first byte.
513        assert(0 < step && step <= 0x7f);
514        int byte2 = ((int)(basePrimary >> 16) & 0xff) - step;
515        if(isCompressible) {
516            if(byte2 < 4) {
517                byte2 += 251;
518                basePrimary -= 0x1000000;
519            }
520        } else {
521            if(byte2 < 2) {
522                byte2 += 254;
523                basePrimary -= 0x1000000;
524            }
525        }
526        return (basePrimary & 0xff000000L) | (byte2 << 16);
527    }
528
529    /**
530     * Decrements a 3-byte primary by one range step (1..0x7f).
531     */
532    static long decThreeBytePrimaryByOneStep(long basePrimary, boolean isCompressible, int step) {
533        // Extract the third byte, minus the minimum byte value,
534        // minus the step, modulo the number of usable byte values, plus the minimum.
535        assert(0 < step && step <= 0x7f);
536        int byte3 = ((int)(basePrimary >> 8) & 0xff) - step;
537        if(byte3 >= 2) {
538            return (basePrimary & 0xffff0000L) | (byte3 << 8);
539        }
540        byte3 += 254;
541        // Same with the second byte,
542        // but reserve the PRIMARY_COMPRESSION_LOW_BYTE and high byte if necessary.
543        int byte2 = ((int)(basePrimary >> 16) & 0xff) - 1;
544        if(isCompressible) {
545            if(byte2 < 4) {
546                byte2 = 0xfe;
547                basePrimary -= 0x1000000;
548            }
549        } else {
550            if(byte2 < 2) {
551                byte2 = 0xff;
552                basePrimary -= 0x1000000;
553            }
554        }
555        // First byte, assume no further underflow.
556        return (basePrimary & 0xff000000L) | (byte2 << 16) | (byte3 << 8);
557    }
558
559    /**
560     * Computes a 3-byte primary for c's OFFSET_TAG data "CE".
561     */
562    static long getThreeBytePrimaryForOffsetData(int c, long dataCE) {
563        long p = dataCE >>> 32;  // three-byte primary pppppp00
564        int lower32 = (int)dataCE;  // base code point b & step s: bbbbbbss (bit 7: isCompressible)
565        int offset = (c - (lower32 >> 8)) * (lower32 & 0x7f);  // delta * increment
566        boolean isCompressible = (lower32 & 0x80) != 0;
567        return Collation.incThreeBytePrimaryByOffset(p, isCompressible, offset);
568    }
569
570    /**
571     * Returns the unassigned-character implicit primary weight for any valid code point c.
572     */
573    static long unassignedPrimaryFromCodePoint(int c) {
574        // Create a gap before U+0000. Use c=-1 for [first unassigned].
575        ++c;
576        // Fourth byte: 18 values, every 14th byte value (gap of 13).
577        long primary = 2 + (c % 18) * 14;
578        c /= 18;
579        // Third byte: 254 values.
580        primary |= (2 + (c % 254)) << 8;
581        c /= 254;
582        // Second byte: 251 values 04..FE excluding the primary compression bytes.
583        primary |= (4 + (c % 251)) << 16;
584        // One lead byte covers all code points (c < 0x1182B4 = 1*251*254*18).
585        return primary | ((long)UNASSIGNED_IMPLICIT_BYTE << 24);
586    }
587
588    static long unassignedCEFromCodePoint(int c) {
589        return makeCE(unassignedPrimaryFromCodePoint(c));
590    }
591
592    // private Collation()  // No instantiation.
593}
594