1 /*
2 **********************************************************************
3 * Copyright (C) 2005-2015, 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 */
match_2022(const uint8_t * text,int32_t textLen,const uint8_t escapeSequences[][5],int32_t escapeSequences_length) const33 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 #if !UCONFIG_ONLY_HTML_CONVERSION
123 static const uint8_t escapeSequences_2022KR[][5] = {
124 {0x1b, 0x24, 0x29, 0x43, 0x00}
125 };
126
127 static const uint8_t escapeSequences_2022CN[][5] = {
128 {0x1b, 0x24, 0x29, 0x41, 0x00}, // GB 2312-80
129 {0x1b, 0x24, 0x29, 0x47, 0x00}, // CNS 11643-1992 Plane 1
130 {0x1b, 0x24, 0x2A, 0x48, 0x00}, // CNS 11643-1992 Plane 2
131 {0x1b, 0x24, 0x29, 0x45, 0x00}, // ISO-IR-165
132 {0x1b, 0x24, 0x2B, 0x49, 0x00}, // CNS 11643-1992 Plane 3
133 {0x1b, 0x24, 0x2B, 0x4A, 0x00}, // CNS 11643-1992 Plane 4
134 {0x1b, 0x24, 0x2B, 0x4B, 0x00}, // CNS 11643-1992 Plane 5
135 {0x1b, 0x24, 0x2B, 0x4C, 0x00}, // CNS 11643-1992 Plane 6
136 {0x1b, 0x24, 0x2B, 0x4D, 0x00}, // CNS 11643-1992 Plane 7
137 {0x1b, 0x4e, 0x00, 0x00, 0x00}, // SS2
138 {0x1b, 0x4f, 0x00, 0x00, 0x00}, // SS3
139 };
140 #endif
141
~CharsetRecog_2022JP()142 CharsetRecog_2022JP::~CharsetRecog_2022JP() {}
143
getName() const144 const char *CharsetRecog_2022JP::getName() const {
145 return "ISO-2022-JP";
146 }
147
match(InputText * textIn,CharsetMatch * results) const148 UBool CharsetRecog_2022JP::match(InputText *textIn, CharsetMatch *results) const {
149 int32_t confidence = match_2022(textIn->fInputBytes,
150 textIn->fInputLen,
151 escapeSequences_2022JP,
152 ARRAY_SIZE(escapeSequences_2022JP));
153 results->set(textIn, this, confidence);
154 return (confidence > 0);
155 }
156
157 #if !UCONFIG_ONLY_HTML_CONVERSION
~CharsetRecog_2022KR()158 CharsetRecog_2022KR::~CharsetRecog_2022KR() {}
159
getName() const160 const char *CharsetRecog_2022KR::getName() const {
161 return "ISO-2022-KR";
162 }
163
match(InputText * textIn,CharsetMatch * results) const164 UBool CharsetRecog_2022KR::match(InputText *textIn, CharsetMatch *results) const {
165 int32_t confidence = match_2022(textIn->fInputBytes,
166 textIn->fInputLen,
167 escapeSequences_2022KR,
168 ARRAY_SIZE(escapeSequences_2022KR));
169 results->set(textIn, this, confidence);
170 return (confidence > 0);
171 }
172
~CharsetRecog_2022CN()173 CharsetRecog_2022CN::~CharsetRecog_2022CN() {}
174
getName() const175 const char *CharsetRecog_2022CN::getName() const {
176 return "ISO-2022-CN";
177 }
178
match(InputText * textIn,CharsetMatch * results) const179 UBool CharsetRecog_2022CN::match(InputText *textIn, CharsetMatch *results) const {
180 int32_t confidence = match_2022(textIn->fInputBytes,
181 textIn->fInputLen,
182 escapeSequences_2022CN,
183 ARRAY_SIZE(escapeSequences_2022CN));
184 results->set(textIn, this, confidence);
185 return (confidence > 0);
186 }
187 #endif
188
~CharsetRecog_2022()189 CharsetRecog_2022::~CharsetRecog_2022() {
190 // nothing to do
191 }
192
193 U_NAMESPACE_END
194 #endif
195