1 /*
2 * The authors of this software are Rob Pike and Ken Thompson.
3 * Copyright (c) 2002 by Lucent Technologies.
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose without fee is hereby granted, provided that this entire notice
6 * is included in all copies of any software which is or includes a copy
7 * or modification of this software and in all copies of the supporting
8 * documentation for such software.
9 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
10 * WARRANTY. IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE
11 * ANY REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
12 * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
13 */
14 #include <stdarg.h>
15 #include <string.h>
16 #include "plan9.h"
17 #include "utf.h"
18
19 enum
20 {
21 Bit1 = 7,
22 Bitx = 6,
23 Bit2 = 5,
24 Bit3 = 4,
25 Bit4 = 3,
26
27 T1 = ((1<<(Bit1+1))-1) ^ 0xFF, /* 0000 0000 */
28 Tx = ((1<<(Bitx+1))-1) ^ 0xFF, /* 1000 0000 */
29 T2 = ((1<<(Bit2+1))-1) ^ 0xFF, /* 1100 0000 */
30 T3 = ((1<<(Bit3+1))-1) ^ 0xFF, /* 1110 0000 */
31 T4 = ((1<<(Bit4+1))-1) ^ 0xFF, /* 1111 0000 */
32
33 Rune1 = (1<<(Bit1+0*Bitx))-1, /* 0000 0000 0111 1111 */
34 Rune2 = (1<<(Bit2+1*Bitx))-1, /* 0000 0111 1111 1111 */
35 Rune3 = (1<<(Bit3+2*Bitx))-1, /* 1111 1111 1111 1111 */
36
37 Maskx = (1<<Bitx)-1, /* 0011 1111 */
38 Testx = Maskx ^ 0xFF, /* 1100 0000 */
39
40 Bad = Runeerror,
41 };
42
43 int
chartorune(Rune * rune,const char * str)44 chartorune(Rune *rune, const char *str)
45 {
46 int c, c1, c2;
47 long l;
48
49 /*
50 * one character sequence
51 * 00000-0007F => T1
52 */
53 c = *(uchar*)str;
54 if(c < Tx) {
55 *rune = c;
56 return 1;
57 }
58
59 /*
60 * two character sequence
61 * 0080-07FF => T2 Tx
62 */
63 c1 = *(uchar*)(str+1) ^ Tx;
64 if(c1 & Testx)
65 goto bad;
66 if(c < T3) {
67 if(c < T2)
68 goto bad;
69 l = ((c << Bitx) | c1) & Rune2;
70 if(l <= Rune1)
71 goto bad;
72 *rune = l;
73 return 2;
74 }
75
76 /*
77 * three character sequence
78 * 0800-FFFF => T3 Tx Tx
79 */
80 c2 = *(uchar*)(str+2) ^ Tx;
81 if(c2 & Testx)
82 goto bad;
83 if(c < T4) {
84 l = ((((c << Bitx) | c1) << Bitx) | c2) & Rune3;
85 if(l <= Rune2)
86 goto bad;
87 *rune = l;
88 return 3;
89 }
90
91 /*
92 * bad decoding
93 */
94 bad:
95 *rune = Bad;
96 return 1;
97 }
98
99 int
runetochar(char * str,const Rune * rune)100 runetochar(char *str, const Rune *rune)
101 {
102 long c;
103
104 /*
105 * one character sequence
106 * 00000-0007F => 00-7F
107 */
108 c = *rune;
109 if(c <= Rune1) {
110 str[0] = c;
111 return 1;
112 }
113
114 /*
115 * two character sequence
116 * 0080-07FF => T2 Tx
117 */
118 if(c <= Rune2) {
119 str[0] = T2 | (c >> 1*Bitx);
120 str[1] = Tx | (c & Maskx);
121 return 2;
122 }
123
124 /*
125 * three character sequence
126 * 0800-FFFF => T3 Tx Tx
127 */
128 str[0] = T3 | (c >> 2*Bitx);
129 str[1] = Tx | ((c >> 1*Bitx) & Maskx);
130 str[2] = Tx | (c & Maskx);
131 return 3;
132 }
133
134 int
runelen(Rune c)135 runelen(Rune c)
136 {
137 char str[10];
138
139 return runetochar(str, &c);
140 }
141
142 int
runenlen(const Rune * r,int nrune)143 runenlen(const Rune *r, int nrune)
144 {
145 int nb, c;
146
147 nb = 0;
148 while(nrune--) {
149 c = *r++;
150 if(c <= Rune1)
151 nb++;
152 else
153 if(c <= Rune2)
154 nb += 2;
155 else
156 nb += 3;
157 }
158 return nb;
159 }
160
161 int
fullrune(const char * str,int n)162 fullrune(const char *str, int n)
163 {
164 int c;
165
166 if(n > 0) {
167 c = *(uchar*)str;
168 if(c < Tx)
169 return 1;
170 if(n > 1)
171 if(c < T3 || n > 2)
172 return 1;
173 }
174 return 0;
175 }
176