int
PerlIO_fast_gets(PerlIO *f)
{
    if (PerlIOValid(f) && (PerlIOBase(f)->flags & PERLIO_F_FASTGETS)) {
         const PerlIO_funcs * const tab = PerlIOBase(f)->tab;

         if (tab)
              return (tab->Set_ptrcnt != NULL);
         SETERRNO(EINVAL, LIB_INVARG);
    }
    else
         SETERRNO(EBADF, SS_IVCHAN);

    return 0;
}