1/* 2******************************************************************************* 3* Copyright (C) 2001-2014, International Business Machines 4* Corporation and others. All Rights Reserved. 5******************************************************************************* 6* file name: bocsu.cpp 7* encoding: US-ASCII 8* tab size: 8 (not used) 9* indentation:4 10* 11* Author: Markus W. Scherer 12* 13* Modification history: 14* 05/18/2001 weiv Made into separate module 15*/ 16 17 18#include "unicode/utypes.h" 19 20#if !UCONFIG_NO_COLLATION 21 22#include "unicode/bytestream.h" 23#include "unicode/utf16.h" 24#include "bocsu.h" 25 26/* 27 * encode one difference value -0x10ffff..+0x10ffff in 1..4 bytes, 28 * preserving lexical order 29 */ 30static uint8_t * 31u_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)); 43 p+=3; 44 } else { 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); 50 *p=SLOPE_MAX; 51 p+=4; 52 } 53 } else { 54 int32_t m; 55 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); 66 p+=3; 67 } else { 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); 74 *p=SLOPE_MIN; 75 p+=4; 76 } 77 } 78 return p; 79} 80 81/* 82 * Encode the code points of a string as 83 * a sequence of byte-encoded differences (slope detection), 84 * preserving lexical order. 85 * 86 * Optimize the difference-taking for runs of Unicode text within 87 * small scripts: 88 * 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. 92 * 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. 97 */ 98U_CFUNC UChar32 99u_writeIdenticalLevelRun(UChar32 prev, const UChar *s, int32_t length, icu::ByteSink &sink) { 100 char scratch[64]; 101 int32_t capacity; 102 103 int32_t i=0; 104 while(i<length) { 105 char *buffer=sink.GetAppendBuffer(1, length*2, scratch, (int32_t)sizeof(scratch), &capacity); 106 uint8_t *p; 107 // We must have capacity>=SLOPE_MAX_BYTES in case u_writeDiff() writes that much, 108 // but we do not want to force the sink.GetAppendBuffer() to allocate 109 // for a large min_capacity because we might actually only write one byte. 110 if(capacity<16) { 111 buffer=scratch; 112 capacity=(int32_t)sizeof(scratch); 113 } 114 p=reinterpret_cast<uint8_t *>(buffer); 115 uint8_t *lastSafe=p+capacity-SLOPE_MAX_BYTES; 116 while(i<length && p<=lastSafe) { 117 if(prev<0x4e00 || prev>=0xa000) { 118 prev=(prev&~0x7f)-SLOPE_REACH_NEG_1; 119 } else { 120 /* 121 * Unihan U+4e00..U+9fa5: 122 * double-bytes down from the upper end 123 */ 124 prev=0x9fff-SLOPE_REACH_POS_2; 125 } 126 127 UChar32 c; 128 U16_NEXT(s, i, length, c); 129 if(c==0xfffe) { 130 *p++=2; // merge separator 131 prev=0; 132 } else { 133 p=u_writeDiff(c-prev, p); 134 prev=c; 135 } 136 } 137 sink.Append(buffer, (int32_t)(p-reinterpret_cast<uint8_t *>(buffer))); 138 } 139 return prev; 140} 141 142#endif /* #if !UCONFIG_NO_COLLATION */ 143