1 /* 2 ********************************************************************** 3 * Copyright (C) 2005-2009, 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 16 U_NAMESPACE_BEGIN 17 18 #define ARRAY_SIZE(array) (sizeof array / sizeof array[0]) 19 20 /** 21 * Matching function shared among the 2022 detectors JP, CN and KR 22 * Counts up the number of legal an unrecognized escape sequences in 23 * the sample of text, and computes a score based on the total number & 24 * the proportion that fit the encoding. 25 * 26 * 27 * @param text the byte buffer containing text to analyse 28 * @param textLen the size of the text in the byte. 29 * @param escapeSequences the byte escape sequences to test for. 30 * @return match quality, in the range of 0-100. 31 */ 32 int32_t CharsetRecog_2022::match_2022(const uint8_t *text, int32_t textLen, const uint8_t escapeSequences[][5], int32_t escapeSequences_length) 33 { 34 int32_t i, j; 35 int32_t escN; 36 int32_t hits = 0; 37 int32_t misses = 0; 38 int32_t shifts = 0; 39 int32_t quality; 40 41 i = 0; 42 while(i < textLen) { 43 if(text[i] == 0x1B) { 44 escN = 0; 45 while(escN < escapeSequences_length) { 46 const uint8_t *seq = escapeSequences[escN]; 47 int32_t seq_length = (int32_t)uprv_strlen((const char *) seq); 48 49 if (textLen-i >= seq_length) { 50 j = 1; 51 while(j < seq_length) { 52 if(seq[j] != text[i+j]) { 53 goto checkEscapes; 54 } 55 56 j += 1; 57 } 58 59 hits += 1; 60 i += seq_length-1; 61 goto scanInput; 62 } 63 // else we ran out of string to compare this time. 64 checkEscapes: 65 escN += 1; 66 } 67 68 misses += 1; 69 } 70 71 if( text[i]== 0x0e || text[i] == 0x0f){ 72 shifts += 1; 73 } 74 75 scanInput: 76 i += 1; 77 } 78 79 if (hits == 0) { 80 return 0; 81 } 82 83 // 84 // Initial quality is based on relative proportion of recongized vs. 85 // unrecognized escape sequences. 86 // All good: quality = 100; 87 // half or less good: quality = 0; 88 // linear inbetween. 89 quality = (100*hits - 100*misses) / (hits + misses); 90 91 // Back off quality if there were too few escape sequences seen. 92 // Include shifts in this computation, so that KR does not get penalized 93 // for having only a single Escape sequence, but many shifts. 94 if (hits+shifts < 5) { 95 quality -= (5-(hits+shifts))*10; 96 } 97 98 if (quality < 0) { 99 quality = 0; 100 } 101 102 return quality; 103 } 104 105 106 static const uint8_t escapeSequences_2022JP[][5] = { 107 {0x1b, 0x24, 0x28, 0x43, 0x00}, // KS X 1001:1992 108 {0x1b, 0x24, 0x28, 0x44, 0x00}, // JIS X 212-1990 109 {0x1b, 0x24, 0x40, 0x00, 0x00}, // JIS C 6226-1978 110 {0x1b, 0x24, 0x41, 0x00, 0x00}, // GB 2312-80 111 {0x1b, 0x24, 0x42, 0x00, 0x00}, // JIS X 208-1983 112 {0x1b, 0x26, 0x40, 0x00, 0x00}, // JIS X 208 1990, 1997 113 {0x1b, 0x28, 0x42, 0x00, 0x00}, // ASCII 114 {0x1b, 0x28, 0x48, 0x00, 0x00}, // JIS-Roman 115 {0x1b, 0x28, 0x49, 0x00, 0x00}, // Half-width katakana 116 {0x1b, 0x28, 0x4a, 0x00, 0x00}, // JIS-Roman 117 {0x1b, 0x2e, 0x41, 0x00, 0x00}, // ISO 8859-1 118 {0x1b, 0x2e, 0x46, 0x00, 0x00} // ISO 8859-7 119 }; 120 121 static const uint8_t escapeSequences_2022KR[][5] = { 122 {0x1b, 0x24, 0x29, 0x43, 0x00} 123 }; 124 125 static const uint8_t escapeSequences_2022CN[][5] = { 126 {0x1b, 0x24, 0x29, 0x41, 0x00}, // GB 2312-80 127 {0x1b, 0x24, 0x29, 0x47, 0x00}, // CNS 11643-1992 Plane 1 128 {0x1b, 0x24, 0x2A, 0x48, 0x00}, // CNS 11643-1992 Plane 2 129 {0x1b, 0x24, 0x29, 0x45, 0x00}, // ISO-IR-165 130 {0x1b, 0x24, 0x2B, 0x49, 0x00}, // CNS 11643-1992 Plane 3 131 {0x1b, 0x24, 0x2B, 0x4A, 0x00}, // CNS 11643-1992 Plane 4 132 {0x1b, 0x24, 0x2B, 0x4B, 0x00}, // CNS 11643-1992 Plane 5 133 {0x1b, 0x24, 0x2B, 0x4C, 0x00}, // CNS 11643-1992 Plane 6 134 {0x1b, 0x24, 0x2B, 0x4D, 0x00}, // CNS 11643-1992 Plane 7 135 {0x1b, 0x4e, 0x00, 0x00, 0x00}, // SS2 136 {0x1b, 0x4f, 0x00, 0x00, 0x00}, // SS3 137 }; 138 139 const char *CharsetRecog_2022JP::getName() const 140 { 141 return "ISO-2022-JP"; 142 } 143 144 int32_t CharsetRecog_2022JP::match(InputText *textIn) 145 { 146 return match_2022(textIn->fInputBytes, textIn->fInputLen, escapeSequences_2022JP, ARRAY_SIZE(escapeSequences_2022JP)); 147 } 148 149 const char *CharsetRecog_2022KR::getName() const 150 { 151 return "ISO-2022-KR"; 152 } 153 154 int32_t CharsetRecog_2022KR::match(InputText *textIn) 155 { 156 return match_2022(textIn->fInputBytes, textIn->fInputLen, escapeSequences_2022KR, ARRAY_SIZE(escapeSequences_2022KR)); 157 } 158 159 const char *CharsetRecog_2022CN::getName() const 160 { 161 return "ISO-2022-CN"; 162 } 163 164 int32_t CharsetRecog_2022CN::match(InputText *textIn) 165 { 166 return match_2022(textIn->fInputBytes, textIn->fInputLen, escapeSequences_2022CN, ARRAY_SIZE(escapeSequences_2022CN)); 167 } 168 169 CharsetRecog_2022::~CharsetRecog_2022() 170 { 171 // nothing to do 172 } 173 174 U_NAMESPACE_END 175 #endif 176
