regex.c:2580
static void
insert_op(op, there, current_end)
     int op;
     char *there, *current_end;
{
  register char *pfrom = current_end;		/* Copy from here...  */
  register char *pto = current_end + 1;		/* ...to here.  */

  while (pfrom != there)			       
    *--pto = *--pfrom;

  there[0] = (char)op;
}
