rune.c - 9base - revived minimalist port of Plan 9 userland to Unix
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rune.c (3963B)
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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 Bit5 = 2,
27
28 T1 = ((1<<(Bit1+1))-1) ^ 0xFF, /* 0000 0000 */
29 Tx = ((1<<(Bitx+1))-1) ^ 0xFF, /* 1000 0000 */
30 T2 = ((1<<(Bit2+1))-1) ^ 0xFF, /* 1100 0000 */
31 T3 = ((1<<(Bit3+1))-1) ^ 0xFF, /* 1110 0000 */
32 T4 = ((1<<(Bit4+1))-1) ^ 0xFF, /* 1111 0000 */
33 T5 = ((1<<(Bit5+1))-1) ^ 0xFF, /* 1111 1000 */
34
35 Rune1 = (1<<(Bit1+0*Bitx))-1, /* 0000 0000 0000 0000 0111 1111 */
36 Rune2 = (1<<(Bit2+1*Bitx))-1, /* 0000 0000 0000 0111 1111 1111 */
37 Rune3 = (1<<(Bit3+2*Bitx))-1, /* 0000 0000 1111 1111 1111 1111 */
38 Rune4 = (1<<(Bit4+3*Bitx))-1, /* 0011 1111 1111 1111 1111 1111 */
39
40 Maskx = (1<<Bitx)-1, /* 0011 1111 */
41 Testx = Maskx ^ 0xFF, /* 1100 0000 */
42
43 Bad = Runeerror
44 };
45
46 int
47 chartorune(Rune *rune, char *str)
48 {
49 int c, c1, c2, c3;
50 long l;
51
52 /*
53 * one character sequence
54 * 00000-0007F => T1
55 */
56 c = *(uchar*)str;
57 if(c < Tx) {
58 *rune = c;
59 return 1;
60 }
61
62 /*
63 * two character sequence
64 * 0080-07FF => T2 Tx
65 */
66 c1 = *(uchar*)(str+1) ^ Tx;
67 if(c1 & Testx)
68 goto bad;
69 if(c < T3) {
70 if(c < T2)
71 goto bad;
72 l = ((c << Bitx) | c1) & Rune2;
73 if(l <= Rune1)
74 goto bad;
75 *rune = l;
76 return 2;
77 }
78
79 /*
80 * three character sequence
81 * 0800-FFFF => T3 Tx Tx
82 */
83 c2 = *(uchar*)(str+2) ^ Tx;
84 if(c2 & Testx)
85 goto bad;
86 if(c < T4) {
87 l = ((((c << Bitx) | c1) << Bitx) | c2) & Rune3;
88 if(l <= Rune2)
89 goto bad;
90 *rune = l;
91 return 3;
92 }
93
94 /*
95 * four character sequence
96 * 10000-10FFFF => T4 Tx Tx Tx
97 */
98 if(UTFmax >= 4) {
99 c3 = *(uchar*)(str+3) ^ Tx;
100 if(c3 & Testx)
101 goto bad;
102 if(c < T5) {
103 l = ((((((c << Bitx) | c1) << Bitx) | c2) << Bitx) | c3) & Rune4;
104 if(l <= Rune3)
105 goto bad;
106 if(l > Runemax)
107 goto bad;
108 *rune = l;
109 return 4;
110 }
111 }
112
113 /*
114 * bad decoding
115 */
116 bad:
117 *rune = Bad;
118 return 1;
119 }
120
121 int
122 runetochar(char *str, Rune *rune)
123 {
124 long c;
125
126 /*
127 * one character sequence
128 * 00000-0007F => 00-7F
129 */
130 c = *rune;
131 if(c <= Rune1) {
132 str[0] = c;
133 return 1;
134 }
135
136 /*
137 * two character sequence
138 * 00080-007FF => T2 Tx
139 */
140 if(c <= Rune2) {
141 str[0] = T2 | (c >> 1*Bitx);
142 str[1] = Tx | (c & Maskx);
143 return 2;
144 }
145
146 /*
147 * three character sequence
148 * 00800-0FFFF => T3 Tx Tx
149 */
150 if(c > Runemax)
151 c = Runeerror;
152 if(c <= Rune3) {
153 str[0] = T3 | (c >> 2*Bitx);
154 str[1] = Tx | ((c >> 1*Bitx) & Maskx);
155 str[2] = Tx | (c & Maskx);
156 return 3;
157 }
158
159 /*
160 * four character sequence
161 * 010000-1FFFFF => T4 Tx Tx Tx
162 */
163 str[0] = T4 | (c >> 3*Bitx);
164 str[1] = Tx | ((c >> 2*Bitx) & Maskx);
165 str[2] = Tx | ((c >> 1*Bitx) & Maskx);
166 str[3] = Tx | (c & Maskx);
167 return 4;
168 }
169
170 int
171 runelen(long c)
172 {
173 Rune rune;
174 char str[10];
175
176 rune = c;
177 return runetochar(str, &rune);
178 }
179
180 int
181 runenlen(Rune *r, int nrune)
182 {
183 int nb, c;
184
185 nb = 0;
186 while(nrune--) {
187 c = *r++;
188 if(c <= Rune1)
189 nb++;
190 else
191 if(c <= Rune2)
192 nb += 2;
193 else
194 if(c <= Rune3 || c > Runemax)
195 nb += 3;
196 else
197 nb += 4;
198 }
199 return nb;
200 }
201
202 int
203 fullrune(char *str, int n)
204 {
205 int c;
206
207 if(n <= 0)
208 return 0;
209 c = *(uchar*)str;
210 if(c < Tx)
211 return 1;
212 if(c < T3)
213 return n >= 2;
214 if(UTFmax == 3 || c < T4)
215 return n >= 3;
216 return n >= 4;
217 }