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1 office 1 /**
2 * @file Utf16Decoder.h
3 * @author Ambroz Bizjak <ambrop7@gmail.com>
4 *
5 * @section LICENSE
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the author nor the
15 * names of its contributors may be used to endorse or promote products
16 * derived from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
20 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
21 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
22 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
23 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
24 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
25 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
27 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29  
30 #ifndef BADVPN_UTF16DECODER_H
31 #define BADVPN_UTF16DECODER_H
32  
33 #include <stdint.h>
34  
35 #include <misc/debug.h>
36  
37 /**
38 * Decodes UTF-16 data into Unicode characters.
39 */
40 typedef struct {
41 int cont;
42 uint32_t ch;
43 } Utf16Decoder;
44  
45 /**
46 * Initializes the UTF-16 decoder.
47 *
48 * @param o the object
49 */
50 static void Utf16Decoder_Init (Utf16Decoder *o);
51  
52 /**
53 * Inputs a 16-bit value to the decoder.
54 *
55 * @param o the object
56 * @param b 16-bit value to input
57 * @param out_ch will receive a Unicode character if this function returns 1.
58 * If written, the character will be in the range 0 - 0x10FFFF,
59 * excluding the surrogate range 0xD800 - 0xDFFF.
60 * @return 1 if a Unicode character has been written to *out_ch, 0 if not
61 */
62 static int Utf16Decoder_Input (Utf16Decoder *o, uint16_t b, uint32_t *out_ch);
63  
64 void Utf16Decoder_Init (Utf16Decoder *o)
65 {
66 o->cont = 0;
67 }
68  
69 int Utf16Decoder_Input (Utf16Decoder *o, uint16_t b, uint32_t *out_ch)
70 {
71 // high surrogate
72 if (b >= UINT16_C(0xD800) && b <= UINT16_C(0xDBFF)) {
73 // set continuation state
74 o->cont = 1;
75  
76 // add high bits
77 o->ch = (uint32_t)(b - UINT16_C(0xD800)) << 10;
78  
79 return 0;
80 }
81  
82 // low surrogate
83 if (b >= UINT16_C(0xDC00) && b <= UINT16_C(0xDFFF)) {
84 // check continuation
85 if (!o->cont) {
86 return 0;
87 }
88  
89 // add low bits
90 o->ch |= (b - UINT16_C(0xDC00));
91  
92 // reset state
93 o->cont = 0;
94  
95 // don't report surrogates
96 if (o->ch >= UINT32_C(0xD800) && o->ch <= UINT32_C(0xDFFF)) {
97 return 0;
98 }
99  
100 // return character
101 *out_ch = o->ch;
102 return 1;
103 }
104  
105 // reset state
106 o->cont = 0;
107  
108 // return character
109 *out_ch = b;
110 return 1;
111 }
112  
113 #endif