1 /* 2 ********************************************************************** 3 * Copyright (C) 2005-2012, International Business Machines 4 * Corporation and others. All Rights Reserved. 5 ********************************************************************** 6 */ 7 8 #include "unicode/utypes.h" 9 10 #if !UCONFIG_NO_CONVERSION 11 12 #include "cstring.h" 13 14 #include "csr2022.h" 15 #include "csmatch.h" 16 17 U_NAMESPACE_BEGIN 18 19 #define ARRAY_SIZE(array) (sizeof array / sizeof array[0]) 20 21 /** 22 * Matching function shared among the 2022 detectors JP, CN and KR 23 * Counts up the number of legal and unrecognized escape sequences in 24 * the sample of text, and computes a score based on the total number & 25 * the proportion that fit the encoding. 26 * 27 * 28 * @param text the byte buffer containing text to analyse 29 * @param textLen the size of the text in the byte. 30 * @param escapeSequences the byte escape sequences to test for. 31 * @return match quality, in the range of 0-100. 32 */ 33 int32_t CharsetRecog_2022::match_2022(const uint8_t *text, int32_t textLen, const uint8_t escapeSequences[][5], int32_t escapeSequences_length) const 34 { 35 int32_t i, j; 36 int32_t escN; 37 int32_t hits = 0; 38 int32_t misses = 0; 39 int32_t shifts = 0; 40 int32_t quality; 41 42 i = 0; 43 while(i < textLen) { 44 if(text[i] == 0x1B) { 45 escN = 0; 46 while(escN < escapeSequences_length) { 47 const uint8_t *seq = escapeSequences[escN]; 48 int32_t seq_length = (int32_t)uprv_strlen((const char *) seq); 49 50 if (textLen-i >= seq_length) { 51 j = 1; 52 while(j < seq_length) { 53 if(seq[j] != text[i+j]) { 54 goto checkEscapes; 55 } 56 57 j += 1; 58 } 59 60 hits += 1; 61 i += seq_length-1; 62 goto scanInput; 63 } 64 // else we ran out of string to compare this time. 65 checkEscapes: 66 escN += 1; 67 } 68 69 misses += 1; 70 } 71 72 if( text[i]== 0x0e || text[i] == 0x0f){ 73 shifts += 1; 74 } 75 76 scanInput: 77 i += 1; 78 } 79 80 if (hits == 0) { 81 return 0; 82 } 83 84 // 85 // Initial quality is based on relative proportion of recongized vs. 86 // unrecognized escape sequences. 87 // All good: quality = 100; 88 // half or less good: quality = 0; 89 // linear inbetween. 90 quality = (100*hits - 100*misses) / (hits + misses); 91 92 // Back off quality if there were too few escape sequences seen. 93 // Include shifts in this computation, so that KR does not get penalized 94 // for having only a single Escape sequence, but many shifts. 95 if (hits+shifts < 5) { 96 quality -= (5-(hits+shifts))*10; 97 } 98 99 if (quality < 0) { 100 quality = 0; 101 } 102 103 return quality; 104 } 105 106 107 static const uint8_t escapeSequences_2022JP[][5] = { 108 {0x1b, 0x24, 0x28, 0x43, 0x00}, // KS X 1001:1992 109 {0x1b, 0x24, 0x28, 0x44, 0x00}, // JIS X 212-1990 110 {0x1b, 0x24, 0x40, 0x00, 0x00}, // JIS C 6226-1978 111 {0x1b, 0x24, 0x41, 0x00, 0x00}, // GB 2312-80 112 {0x1b, 0x24, 0x42, 0x00, 0x00}, // JIS X 208-1983 113 {0x1b, 0x26, 0x40, 0x00, 0x00}, // JIS X 208 1990, 1997 114 {0x1b, 0x28, 0x42, 0x00, 0x00}, // ASCII 115 {0x1b, 0x28, 0x48, 0x00, 0x00}, // JIS-Roman 116 {0x1b, 0x28, 0x49, 0x00, 0x00}, // Half-width katakana 117 {0x1b, 0x28, 0x4a, 0x00, 0x00}, // JIS-Roman 118 {0x1b, 0x2e, 0x41, 0x00, 0x00}, // ISO 8859-1 119 {0x1b, 0x2e, 0x46, 0x00, 0x00} // ISO 8859-7 120 }; 121 122 static const uint8_t escapeSequences_2022KR[][5] = { 123 {0x1b, 0x24, 0x29, 0x43, 0x00} 124 }; 125 126 static const uint8_t escapeSequences_2022CN[][5] = { 127 {0x1b, 0x24, 0x29, 0x41, 0x00}, // GB 2312-80 128 {0x1b, 0x24, 0x29, 0x47, 0x00}, // CNS 11643-1992 Plane 1 129 {0x1b, 0x24, 0x2A, 0x48, 0x00}, // CNS 11643-1992 Plane 2 130 {0x1b, 0x24, 0x29, 0x45, 0x00}, // ISO-IR-165 131 {0x1b, 0x24, 0x2B, 0x49, 0x00}, // CNS 11643-1992 Plane 3 132 {0x1b, 0x24, 0x2B, 0x4A, 0x00}, // CNS 11643-1992 Plane 4 133 {0x1b, 0x24, 0x2B, 0x4B, 0x00}, // CNS 11643-1992 Plane 5 134 {0x1b, 0x24, 0x2B, 0x4C, 0x00}, // CNS 11643-1992 Plane 6 135 {0x1b, 0x24, 0x2B, 0x4D, 0x00}, // CNS 11643-1992 Plane 7 136 {0x1b, 0x4e, 0x00, 0x00, 0x00}, // SS2 137 {0x1b, 0x4f, 0x00, 0x00, 0x00}, // SS3 138 }; 139 140 CharsetRecog_2022JP::~CharsetRecog_2022JP() {} 141 142 const char *CharsetRecog_2022JP::getName() const { 143 return "ISO-2022-JP"; 144 } 145 146 UBool CharsetRecog_2022JP::match(InputText *textIn, CharsetMatch *results) const { 147 int32_t confidence = match_2022(textIn->fInputBytes, 148 textIn->fInputLen, 149 escapeSequences_2022JP, 150 ARRAY_SIZE(escapeSequences_2022JP)); 151 results->set(textIn, this, confidence); 152 return (confidence > 0); 153 } 154 155 CharsetRecog_2022KR::~CharsetRecog_2022KR() {} 156 157 const char *CharsetRecog_2022KR::getName() const { 158 return "ISO-2022-KR"; 159 } 160 161 UBool CharsetRecog_2022KR::match(InputText *textIn, CharsetMatch *results) const { 162 int32_t confidence = match_2022(textIn->fInputBytes, 163 textIn->fInputLen, 164 escapeSequences_2022KR, 165 ARRAY_SIZE(escapeSequences_2022KR)); 166 results->set(textIn, this, confidence); 167 return (confidence > 0); 168 } 169 170 CharsetRecog_2022CN::~CharsetRecog_2022CN() {} 171 172 const char *CharsetRecog_2022CN::getName() const { 173 return "ISO-2022-CN"; 174 } 175 176 UBool CharsetRecog_2022CN::match(InputText *textIn, CharsetMatch *results) const { 177 int32_t confidence = match_2022(textIn->fInputBytes, 178 textIn->fInputLen, 179 escapeSequences_2022CN, 180 ARRAY_SIZE(escapeSequences_2022CN)); 181 results->set(textIn, this, confidence); 182 return (confidence > 0); 183 } 184 185 CharsetRecog_2022::~CharsetRecog_2022() { 186 // nothing to do 187 } 188 189 U_NAMESPACE_END 190 #endif 191
