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 char*
20 utfrrune(char *s, long c)
21 {
22 	long c1;
23 	Rune r;
24 	char *s1;
25 
26 	if(c < Runesync)		/* not part of utf sequence */
27 		return strrchr(s, c);
28 
29 	s1 = 0;
30 	for(;;) {
31 		c1 = *(uchar*)s;
32 		if(c1 < Runeself) {	/* one byte rune */
33 			if(c1 == 0)
34 				return s1;
35 			if(c1 == c)
36 				s1 = s;
37 			s++;
38 			continue;
39 		}
40 		c1 = chartorune(&r, s);
41 		if(r == c)
42 			s1 = s;
43 		s += c1;
44 	}
45 }