ref: c309f466eff33a331f9a8d8c8b18cfe613c1d3f4
dir: /sys/src/libc/port/memchr.c/
#include <u.h>
#include <libc.h>
void*
memchr(void *ap, int c, usize n)
{
uchar *sp;
sp = ap;
c &= 0xFF;
while(n > 0) {
if(*sp++ == c)
return sp-1;
n--;
}
return 0;
}