1// © 2016 and later: Unicode, Inc. and others.
2// License & terms of use: http://www.unicode.org/copyright.html
3/*
4 **********************************************************************
5 * Copyright (C) 2005-2016, International Business Machines
6 * Corporation and others. All Rights Reserved.
7 **********************************************************************
8 */
9
10#include "unicode/utypes.h"
11
12#if !UCONFIG_NO_CONVERSION
13
14#include "cmemory.h"
15#include "cstring.h"
16
17#include "csr2022.h"
18#include "csmatch.h"
19
20U_NAMESPACE_BEGIN
21
22/**
23 * Matching function shared among the 2022 detectors JP, CN and KR
24 * Counts up the number of legal and unrecognized escape sequences in
25 * the sample of text, and computes a score based on the total number &
26 * the proportion that fit the encoding.
27 *
28 *
29 * @param text the byte buffer containing text to analyse
30 * @param textLen the size of the text in the byte.
31 * @param escapeSequences the byte escape sequences to test for.
32 * @return match quality, in the range of 0-100.
33 */
34int32_t CharsetRecog_2022::match_2022(const uint8_t *text, int32_t textLen, const uint8_t escapeSequences[][5], int32_t escapeSequences_length) const
35{
36 int32_t i, j;
37 int32_t escN;
38 int32_t hits = 0;
39 int32_t misses = 0;
40 int32_t shifts = 0;
41 int32_t quality;
42
43 i = 0;
44 while(i < textLen) {
45 if(text[i] == 0x1B) {
46 escN = 0;
47 while(escN < escapeSequences_length) {
48 const uint8_t *seq = escapeSequences[escN];
49 int32_t seq_length = (int32_t)uprv_strlen((const char *) seq);
50
51 if (textLen-i >= seq_length) {
52 j = 1;
53 while(j < seq_length) {
54 if(seq[j] != text[i+j]) {
55 goto checkEscapes;
56 }
57
58 j += 1;
59 }
60
61 hits += 1;
62 i += seq_length-1;
63 goto scanInput;
64 }
65 // else we ran out of string to compare this time.
66checkEscapes:
67 escN += 1;
68 }
69
70 misses += 1;
71 }
72
73 if( text[i]== 0x0e || text[i] == 0x0f){
74 shifts += 1;
75 }
76
77scanInput:
78 i += 1;
79 }
80
81 if (hits == 0) {
82 return 0;
83 }
84
85 //
86 // Initial quality is based on relative proportion of recongized vs.
87 // unrecognized escape sequences.
88 // All good: quality = 100;
89 // half or less good: quality = 0;
90 // linear inbetween.
91 quality = (100*hits - 100*misses) / (hits + misses);
92
93 // Back off quality if there were too few escape sequences seen.
94 // Include shifts in this computation, so that KR does not get penalized
95 // for having only a single Escape sequence, but many shifts.
96 if (hits+shifts < 5) {
97 quality -= (5-(hits+shifts))*10;
98 }
99
100 if (quality < 0) {
101 quality = 0;
102 }
103
104 return quality;
105}
106
107
108static const uint8_t escapeSequences_2022JP[][5] = {
109 {0x1b, 0x24, 0x28, 0x43, 0x00}, // KS X 1001:1992
110 {0x1b, 0x24, 0x28, 0x44, 0x00}, // JIS X 212-1990
111 {0x1b, 0x24, 0x40, 0x00, 0x00}, // JIS C 6226-1978
112 {0x1b, 0x24, 0x41, 0x00, 0x00}, // GB 2312-80
113 {0x1b, 0x24, 0x42, 0x00, 0x00}, // JIS X 208-1983
114 {0x1b, 0x26, 0x40, 0x00, 0x00}, // JIS X 208 1990, 1997
115 {0x1b, 0x28, 0x42, 0x00, 0x00}, // ASCII
116 {0x1b, 0x28, 0x48, 0x00, 0x00}, // JIS-Roman
117 {0x1b, 0x28, 0x49, 0x00, 0x00}, // Half-width katakana
118 {0x1b, 0x28, 0x4a, 0x00, 0x00}, // JIS-Roman
119 {0x1b, 0x2e, 0x41, 0x00, 0x00}, // ISO 8859-1
120 {0x1b, 0x2e, 0x46, 0x00, 0x00} // ISO 8859-7
121};
122
123#if !UCONFIG_ONLY_HTML_CONVERSION
124static const uint8_t escapeSequences_2022KR[][5] = {
125 {0x1b, 0x24, 0x29, 0x43, 0x00}
126};
127
128static const uint8_t escapeSequences_2022CN[][5] = {
129 {0x1b, 0x24, 0x29, 0x41, 0x00}, // GB 2312-80
130 {0x1b, 0x24, 0x29, 0x47, 0x00}, // CNS 11643-1992 Plane 1
131 {0x1b, 0x24, 0x2A, 0x48, 0x00}, // CNS 11643-1992 Plane 2
132 {0x1b, 0x24, 0x29, 0x45, 0x00}, // ISO-IR-165
133 {0x1b, 0x24, 0x2B, 0x49, 0x00}, // CNS 11643-1992 Plane 3
134 {0x1b, 0x24, 0x2B, 0x4A, 0x00}, // CNS 11643-1992 Plane 4
135 {0x1b, 0x24, 0x2B, 0x4B, 0x00}, // CNS 11643-1992 Plane 5
136 {0x1b, 0x24, 0x2B, 0x4C, 0x00}, // CNS 11643-1992 Plane 6
137 {0x1b, 0x24, 0x2B, 0x4D, 0x00}, // CNS 11643-1992 Plane 7
138 {0x1b, 0x4e, 0x00, 0x00, 0x00}, // SS2
139 {0x1b, 0x4f, 0x00, 0x00, 0x00}, // SS3
140};
141#endif
142
143CharsetRecog_2022JP::~CharsetRecog_2022JP() {}
144
145const char *CharsetRecog_2022JP::getName() const {
146 return "ISO-2022-JP";
147}
148
149UBool CharsetRecog_2022JP::match(InputText *textIn, CharsetMatch *results) const {
150 int32_t confidence = match_2022(textIn->fInputBytes,
151 textIn->fInputLen,
152 escapeSequences_2022JP,
153 UPRV_LENGTHOF(escapeSequences_2022JP));
154 results->set(textIn, this, confidence);
155 return (confidence > 0);
156}
157
158#if !UCONFIG_ONLY_HTML_CONVERSION
159CharsetRecog_2022KR::~CharsetRecog_2022KR() {}
160
161const char *CharsetRecog_2022KR::getName() const {
162 return "ISO-2022-KR";
163}
164
165UBool CharsetRecog_2022KR::match(InputText *textIn, CharsetMatch *results) const {
166 int32_t confidence = match_2022(textIn->fInputBytes,
167 textIn->fInputLen,
168 escapeSequences_2022KR,
169 UPRV_LENGTHOF(escapeSequences_2022KR));
170 results->set(textIn, this, confidence);
171 return (confidence > 0);
172}
173
174CharsetRecog_2022CN::~CharsetRecog_2022CN() {}
175
176const char *CharsetRecog_2022CN::getName() const {
177 return "ISO-2022-CN";
178}
179
180UBool CharsetRecog_2022CN::match(InputText *textIn, CharsetMatch *results) const {
181 int32_t confidence = match_2022(textIn->fInputBytes,
182 textIn->fInputLen,
183 escapeSequences_2022CN,
184 UPRV_LENGTHOF(escapeSequences_2022CN));
185 results->set(textIn, this, confidence);
186 return (confidence > 0);
187}
188#endif
189
190CharsetRecog_2022::~CharsetRecog_2022() {
191 // nothing to do
192}
193
194U_NAMESPACE_END
195#endif
196