2 *******************************************************************************
3 * Copyright (C) 2001-2011, International Business Machines
4 * Corporation and others. All Rights Reserved.
5 *******************************************************************************
8 * tab size: 8 (not used)
11 * Author: Markus W. Scherer
13 * Modification history:
14 * 05/18/2001 weiv Made into separate module
18 #include "unicode/utypes.h"
20 #if !UCONFIG_NO_COLLATION
22 #include "unicode/bytestream.h"
23 #include "unicode/utf16.h"
27 * encode one difference value -0x10ffff..+0x10ffff in 1..3 bytes,
28 * preserving lexical order
31 u_writeDiff(int32_t diff, uint8_t *p) {
32 if(diff>=SLOPE_REACH_NEG_1) {
33 if(diff<=SLOPE_REACH_POS_1) {
34 *p++=(uint8_t)(SLOPE_MIDDLE+diff);
35 } else if(diff<=SLOPE_REACH_POS_2) {
36 *p++=(uint8_t)(SLOPE_START_POS_2+(diff/SLOPE_TAIL_COUNT));
37 *p++=(uint8_t)(SLOPE_MIN+diff%SLOPE_TAIL_COUNT);
38 } else if(diff<=SLOPE_REACH_POS_3) {
39 p[2]=(uint8_t)(SLOPE_MIN+diff%SLOPE_TAIL_COUNT);
40 diff/=SLOPE_TAIL_COUNT;
41 p[1]=(uint8_t)(SLOPE_MIN+diff%SLOPE_TAIL_COUNT);
42 *p=(uint8_t)(SLOPE_START_POS_3+(diff/SLOPE_TAIL_COUNT));
45 p[3]=(uint8_t)(SLOPE_MIN+diff%SLOPE_TAIL_COUNT);
46 diff/=SLOPE_TAIL_COUNT;
47 p[2]=(uint8_t)(SLOPE_MIN+diff%SLOPE_TAIL_COUNT);
48 diff/=SLOPE_TAIL_COUNT;
49 p[1]=(uint8_t)(SLOPE_MIN+diff%SLOPE_TAIL_COUNT);
56 if(diff>=SLOPE_REACH_NEG_2) {
57 NEGDIVMOD(diff, SLOPE_TAIL_COUNT, m);
58 *p++=(uint8_t)(SLOPE_START_NEG_2+diff);
59 *p++=(uint8_t)(SLOPE_MIN+m);
60 } else if(diff>=SLOPE_REACH_NEG_3) {
61 NEGDIVMOD(diff, SLOPE_TAIL_COUNT, m);
62 p[2]=(uint8_t)(SLOPE_MIN+m);
63 NEGDIVMOD(diff, SLOPE_TAIL_COUNT, m);
64 p[1]=(uint8_t)(SLOPE_MIN+m);
65 *p=(uint8_t)(SLOPE_START_NEG_3+diff);
68 NEGDIVMOD(diff, SLOPE_TAIL_COUNT, m);
69 p[3]=(uint8_t)(SLOPE_MIN+m);
70 NEGDIVMOD(diff, SLOPE_TAIL_COUNT, m);
71 p[2]=(uint8_t)(SLOPE_MIN+m);
72 NEGDIVMOD(diff, SLOPE_TAIL_COUNT, m);
73 p[1]=(uint8_t)(SLOPE_MIN+m);
82 * Encode the code points of a string as
83 * a sequence of byte-encoded differences (slope detection),
84 * preserving lexical order.
86 * Optimize the difference-taking for runs of Unicode text within
89 * Most small scripts are allocated within aligned 128-blocks of Unicode
90 * code points. Lexical order is preserved if "prev" is always moved
91 * into the middle of such a block.
93 * Additionally, "prev" is moved from anywhere in the Unihan
94 * area into the middle of that area.
95 * Note that the identical-level run in a sort key is generated from
96 * NFD text - there are never Hangul characters included.
99 u_writeIdenticalLevelRun(const UChar *s, int32_t length, icu::ByteSink &sink) {
106 char *buffer=sink.GetAppendBuffer(1, length*2, scratch, (int32_t)sizeof(scratch), &capacity);
108 // We must have capacity>=SLOPE_MAX_BYTES in case u_writeDiff() writes that much,
109 // but we do not want to force the sink.GetAppendBuffer() to allocate
110 // for a large min_capacity because we might actually only write one byte.
113 capacity=(int32_t)sizeof(scratch);
115 p=reinterpret_cast<uint8_t *>(buffer);
116 uint8_t *lastSafe=p+capacity-SLOPE_MAX_BYTES;
117 while(i<length && p<=lastSafe) {
118 if(prev<0x4e00 || prev>=0xa000) {
119 prev=(prev&~0x7f)-SLOPE_REACH_NEG_1;
122 * Unihan U+4e00..U+9fa5:
123 * double-bytes down from the upper end
125 prev=0x9fff-SLOPE_REACH_POS_2;
129 U16_NEXT(s, i, length, c);
130 p=u_writeDiff(c-prev, p);
133 sink.Append(buffer, (int32_t)(p-reinterpret_cast<uint8_t *>(buffer)));
138 u_writeIdenticalLevelRunTwoChars(UChar32 first, UChar32 second, uint8_t *p) {
140 if(first<0x4e00 || first>=0xa000) {
141 first=(first&~0x7f)-SLOPE_REACH_NEG_1;
144 * Unihan U+4e00..U+9fa5:
145 * double-bytes down from the upper end
147 first=0x9fff-SLOPE_REACH_POS_2;
150 p=u_writeDiff(second-first, p);
151 return (int32_t)(p-p0);
154 #endif /* #if !UCONFIG_NO_COLLATION */