1// © 2016 and later: Unicode, Inc. and others.
2// License & terms of use: http://www.unicode.org/copyright.html
3/*
4 **********************************************************************
5 * Copyright (C) 2005-2013, 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 "csrucode.h"
15#include "csmatch.h"
16
17U_NAMESPACE_BEGIN
18
19CharsetRecog_Unicode::~CharsetRecog_Unicode()
20{
21 // nothing to do
22}
23
24CharsetRecog_UTF_16_BE::~CharsetRecog_UTF_16_BE()
25{
26 // nothing to do
27}
28
29const char *CharsetRecog_UTF_16_BE::getName() const
30{
31 return "UTF-16BE";
32}
33
34// UTF-16 confidence calculation. Very simple minded, but better than nothing.
35// Any 8 bit non-control characters bump the confidence up. These have a zero high byte,
36// and are very likely to be UTF-16, although they could also be part of a UTF-32 code.
37// NULs are a contra-indication, they will appear commonly if the actual encoding is UTF-32.
38// NULs should be rare in actual text.
39
40static int32_t adjustConfidence(UChar codeUnit, int32_t confidence) {
41 if (codeUnit == 0) {
42 confidence -= 10;
43 } else if ((codeUnit >= 0x20 && codeUnit <= 0xff) || codeUnit == 0x0a) {
44 confidence += 10;
45 }
46 if (confidence < 0) {
47 confidence = 0;
48 } else if (confidence > 100) {
49 confidence = 100;
50 }
51 return confidence;
52}
53
54
55UBool CharsetRecog_UTF_16_BE::match(InputText* textIn, CharsetMatch *results) const
56{
57 const uint8_t *input = textIn->fRawInput;
58 int32_t confidence = 10;
59 int32_t length = textIn->fRawLength;
60
61 int32_t bytesToCheck = (length > 30) ? 30 : length;
62 for (int32_t charIndex=0; charIndex<bytesToCheck-1; charIndex+=2) {
63 UChar codeUnit = (input[charIndex] << 8) | input[charIndex + 1];
64 if (charIndex == 0 && codeUnit == 0xFEFF) {
65 confidence = 100;
66 break;
67 }
68 confidence = adjustConfidence(codeUnit, confidence);
69 if (confidence == 0 || confidence == 100) {
70 break;
71 }
72 }
73 if (bytesToCheck < 4 && confidence < 100) {
74 confidence = 0;
75 }
76 results->set(textIn, this, confidence);
77 return (confidence > 0);
78}
79
80CharsetRecog_UTF_16_LE::~CharsetRecog_UTF_16_LE()
81{
82 // nothing to do
83}
84
85const char *CharsetRecog_UTF_16_LE::getName() const
86{
87 return "UTF-16LE";
88}
89
90UBool CharsetRecog_UTF_16_LE::match(InputText* textIn, CharsetMatch *results) const
91{
92 const uint8_t *input = textIn->fRawInput;
93 int32_t confidence = 10;
94 int32_t length = textIn->fRawLength;
95
96 int32_t bytesToCheck = (length > 30) ? 30 : length;
97 for (int32_t charIndex=0; charIndex<bytesToCheck-1; charIndex+=2) {
98 UChar codeUnit = input[charIndex] | (input[charIndex + 1] << 8);
99 if (charIndex == 0 && codeUnit == 0xFEFF) {
100 confidence = 100; // UTF-16 BOM
101 if (length >= 4 && input[2] == 0 && input[3] == 0) {
102 confidence = 0; // UTF-32 BOM
103 }
104 break;
105 }
106 confidence = adjustConfidence(codeUnit, confidence);
107 if (confidence == 0 || confidence == 100) {
108 break;
109 }
110 }
111 if (bytesToCheck < 4 && confidence < 100) {
112 confidence = 0;
113 }
114 results->set(textIn, this, confidence);
115 return (confidence > 0);
116}
117
118CharsetRecog_UTF_32::~CharsetRecog_UTF_32()
119{
120 // nothing to do
121}
122
123UBool CharsetRecog_UTF_32::match(InputText* textIn, CharsetMatch *results) const
124{
125 const uint8_t *input = textIn->fRawInput;
126 int32_t limit = (textIn->fRawLength / 4) * 4;
127 int32_t numValid = 0;
128 int32_t numInvalid = 0;
129 bool hasBOM = FALSE;
130 int32_t confidence = 0;
131
132 if (limit > 0 && getChar(input, 0) == 0x0000FEFFUL) {
133 hasBOM = TRUE;
134 }
135
136 for(int32_t i = 0; i < limit; i += 4) {
137 int32_t ch = getChar(input, i);
138
139 if (ch < 0 || ch >= 0x10FFFF || (ch >= 0xD800 && ch <= 0xDFFF)) {
140 numInvalid += 1;
141 } else {
142 numValid += 1;
143 }
144 }
145
146
147 // Cook up some sort of confidence score, based on presense of a BOM
148 // and the existence of valid and/or invalid multi-byte sequences.
149 if (hasBOM && numInvalid==0) {
150 confidence = 100;
151 } else if (hasBOM && numValid > numInvalid*10) {
152 confidence = 80;
153 } else if (numValid > 3 && numInvalid == 0) {
154 confidence = 100;
155 } else if (numValid > 0 && numInvalid == 0) {
156 confidence = 80;
157 } else if (numValid > numInvalid*10) {
158 // Probably corruput UTF-32BE data. Valid sequences aren't likely by chance.
159 confidence = 25;
160 }
161
162 results->set(textIn, this, confidence);
163 return (confidence > 0);
164}
165
166CharsetRecog_UTF_32_BE::~CharsetRecog_UTF_32_BE()
167{
168 // nothing to do
169}
170
171const char *CharsetRecog_UTF_32_BE::getName() const
172{
173 return "UTF-32BE";
174}
175
176int32_t CharsetRecog_UTF_32_BE::getChar(const uint8_t *input, int32_t index) const
177{
178 return input[index + 0] << 24 | input[index + 1] << 16 |
179 input[index + 2] << 8 | input[index + 3];
180}
181
182CharsetRecog_UTF_32_LE::~CharsetRecog_UTF_32_LE()
183{
184 // nothing to do
185}
186
187const char *CharsetRecog_UTF_32_LE::getName() const
188{
189 return "UTF-32LE";
190}
191
192int32_t CharsetRecog_UTF_32_LE::getChar(const uint8_t *input, int32_t index) const
193{
194 return input[index + 3] << 24 | input[index + 2] << 16 |
195 input[index + 1] << 8 | input[index + 0];
196}
197
198U_NAMESPACE_END
199#endif
200
201