ref: e5894dcceaedeaf7d4f5537dd306170b1b6d4814
dir: /sys/src/libc/port/utfrrune.c/
#include <u.h>
#include <libc.h>
char*
utfrrune(char *s, long c)
{
long c1;
Rune r;
char *s1;
if(c < Runesync) /* not part of utf sequence */
return strrchr(s, c);
s1 = 0;
for(;;) {
c1 = *(uchar*)s;
if(c1 < Runeself) { /* one byte rune */
if(c1 == 0)
return s1;
if(c1 == c)
s1 = s;
s++;
continue;
}
c1 = chartorune(&r, s);
if(r == c)
s1 = s;
s += c1;
}
}