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 */
match_2022(const uint8_t * text,int32_t textLen,const uint8_t escapeSequences[][5],int32_t escapeSequences_length)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
getName() const139 const char *CharsetRecog_2022JP::getName() const
140 {
141 return "ISO-2022-JP";
142 }
143
match(InputText * textIn)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
getName() const149 const char *CharsetRecog_2022KR::getName() const
150 {
151 return "ISO-2022-KR";
152 }
153
match(InputText * textIn)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
getName() const159 const char *CharsetRecog_2022CN::getName() const
160 {
161 return "ISO-2022-CN";
162 }
163
match(InputText * textIn)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
~CharsetRecog_2022()169 CharsetRecog_2022::~CharsetRecog_2022()
170 {
171 // nothing to do
172 }
173
174 U_NAMESPACE_END
175 #endif
176