utfrune.c - 9base - revived minimalist port of Plan 9 userland to Unix
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       utfrune.c (1184B)
       ---
            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 utfrune(char *s, long c)
           21 {
           22         long c1;
           23         Rune r;
           24         int n;
           25 
           26         if(c < Runesync)                /* not part of utf sequence */
           27                 return strchr(s, c);
           28 
           29         for(;;) {
           30                 c1 = *(uchar*)s;
           31                 if(c1 < Runeself) {        /* one byte rune */
           32                         if(c1 == 0)
           33                                 return 0;
           34                         if(c1 == c)
           35                                 return s;
           36                         s++;
           37                         continue;
           38                 }
           39                 n = chartorune(&r, s);
           40                 if(r == c)
           41                         return s;
           42                 s += n;
           43         }
           44 }