utfrune.c (1192B) 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
20char* utfrune(char* s, long c) {
21 long c1;
22 Rune r;
23 int n;
24
25 if (c < Runesync) /* not part of utf sequence */
26 return strchr(s, c);
27
28 for (;;) {
29 c1 = *(uchar*) s;
30 if (c1 < Runeself) { /* one byte rune */
31 if (c1 == 0)
32 return 0;
33 if (c1 == c)
34 return s;
35 s++;
36 continue;
37 }
38 n = chartorune(&r, s);
39 if (r == c)
40 return s;
41 s += n;
42 }
43}