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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 ANY
     11  * 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 "utf.h"
     17 #include "utfdef.h"
     18 
     19 const
     20 char*
     21 utfrrune(const char *s, Rune c)
     22 {
     23 	long c1;
     24 	Rune r;
     25 	const char *s1;
     26 
     27 	if(c < Runesync)		/* not part of utf sequence */
     28 		return strrchr(s, c);
     29 
     30 	s1 = 0;
     31 	for(;;) {
     32 		c1 = *(uchar*)s;
     33 		if(c1 < Runeself) {	/* one byte rune */
     34 			if(c1 == 0)
     35 				return s1;
     36 			if(c1 == c)
     37 				s1 = s;
     38 			s++;
     39 			continue;
     40 		}
     41 		c1 = chartorune(&r, s);
     42 		if(r == c)
     43 			s1 = s;
     44 		s += c1;
     45 	}
     46 	return 0;
     47 }
     48