ref: c8ea1cd8d7df5c044cf3ac0f29914721093ec0a9
dir: /sys/src/libc/port/memchr.c/
#include <u.h>
#include <libc.h>
void*
memchr(void *ap, int c, ulong n)
{
uchar *sp;
sp = ap;
c &= 0xFF;
while(n > 0) {
if(*sp++ == c)
return sp-1;
n--;
}
return 0;
}