rune.c (4071B) download
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 "plan9.h"
15#include "utf.h"
16
17#include <stdarg.h>
18#include <string.h>
19
20enum {
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
46int chartorune(Rune* rune, char* str) {
47 int c, c1, c2, c3;
48 long l;
49
50 /*
51 * one character sequence
52 * 00000-0007F => T1
53 */
54 c = *(uchar*) str;
55 if (c < Tx) {
56 *rune = c;
57 return 1;
58 }
59
60 /*
61 * two character sequence
62 * 0080-07FF => T2 Tx
63 */
64 c1 = *(uchar*) (str + 1) ^ Tx;
65 if (c1 & Testx)
66 goto bad;
67 if (c < T3) {
68 if (c < T2)
69 goto bad;
70 l = ((c << Bitx) | c1) & Rune2;
71 if (l <= Rune1)
72 goto bad;
73 *rune = l;
74 return 2;
75 }
76
77 /*
78 * three character sequence
79 * 0800-FFFF => T3 Tx Tx
80 */
81 c2 = *(uchar*) (str + 2) ^ Tx;
82 if (c2 & Testx)
83 goto bad;
84 if (c < T4) {
85 l = ((((c << Bitx) | c1) << Bitx) | c2) & Rune3;
86 if (l <= Rune2)
87 goto bad;
88 *rune = l;
89 return 3;
90 }
91
92 /*
93 * four character sequence
94 * 10000-10FFFF => T4 Tx Tx Tx
95 */
96 if (UTFmax >= 4) {
97 c3 = *(uchar*) (str + 3) ^ Tx;
98 if (c3 & Testx)
99 goto bad;
100 if (c < T5) {
101 l = ((((((c << Bitx) | c1) << Bitx) | c2) << Bitx) | c3) & Rune4;
102 if (l <= Rune3)
103 goto bad;
104 if (l > Runemax)
105 goto bad;
106 *rune = l;
107 return 4;
108 }
109 }
110
111 /*
112 * bad decoding
113 */
114bad:
115 *rune = Bad;
116 return 1;
117}
118
119int runetochar(char* str, Rune* rune) {
120 long c;
121
122 /*
123 * one character sequence
124 * 00000-0007F => 00-7F
125 */
126 c = *rune;
127 if (c <= Rune1) {
128 str[0] = c;
129 return 1;
130 }
131
132 /*
133 * two character sequence
134 * 00080-007FF => T2 Tx
135 */
136 if (c <= Rune2) {
137 str[0] = T2 | (c >> 1 * Bitx);
138 str[1] = Tx | (c & Maskx);
139 return 2;
140 }
141
142 /*
143 * three character sequence
144 * 00800-0FFFF => T3 Tx Tx
145 */
146 if (c > Runemax)
147 c = Runeerror;
148 if (c <= Rune3) {
149 str[0] = T3 | (c >> 2 * Bitx);
150 str[1] = Tx | ((c >> 1 * Bitx) & Maskx);
151 str[2] = Tx | (c & Maskx);
152 return 3;
153 }
154
155 /*
156 * four character sequence
157 * 010000-1FFFFF => T4 Tx Tx Tx
158 */
159 str[0] = T4 | (c >> 3 * Bitx);
160 str[1] = Tx | ((c >> 2 * Bitx) & Maskx);
161 str[2] = Tx | ((c >> 1 * Bitx) & Maskx);
162 str[3] = Tx | (c & Maskx);
163 return 4;
164}
165
166int runelen(long c) {
167 Rune rune;
168 char str[10];
169
170 rune = c;
171 return runetochar(str, &rune);
172}
173
174int runenlen(Rune* r, int nrune) {
175 int nb, c;
176
177 nb = 0;
178 while (nrune--) {
179 c = *r++;
180 if (c <= Rune1)
181 nb++;
182 else if (c <= Rune2)
183 nb += 2;
184 else if (c <= Rune3 || c > Runemax)
185 nb += 3;
186 else
187 nb += 4;
188 }
189 return nb;
190}
191
192int fullrune(char* str, int n) {
193 int c;
194
195 if (n <= 0)
196 return 0;
197 c = *(uchar*) str;
198 if (c < Tx)
199 return 1;
200 if (c < T3)
201 return n >= 2;
202 if (UTFmax == 3 || c < T4)
203 return n >= 3;
204 return n >= 4;
205}