PTR_DIFF
if (nbt_len>PTR_DIFF(maxbuf,data))
return(PTR_DIFF(s,s0)+1);
int l = PTR_DIFF(p,fmt);
printf("%.*s",(int)PTR_DIFF(maxbuf,buf),unistr(buf, &len));
*buf,(int)PTR_DIFF(maxbuf,buf));
printf("%.*s",(int)PTR_DIFF(maxbuf,buf+1),unistr(buf+1, &len));
name_type = name_extract(startbuf,PTR_DIFF(buf,startbuf),maxbuf,
int len = PTR_DIFF(maxbuf,buf);