ParagonIE_Sodium_Core_Ristretto255::fe_iszero( ParagonIE_Sodium_Core_Curve25519_Fe $f ): int

43    public static function fe_iszero(ParagonIE_Sodium_Core_Curve25519_Fe $f)44    {45        static $zero;46        if ($zero === null) {47            $zero = str_repeat("\x00", 32);48        }49        /** @var string $zero */50        $str = self::fe_tobytes($f);51 52        $d = 0;53        for ($i = 0; $i < 32; ++$i) {54            $d |= self::chrToInt($str[$i]);55        }56        return (($d - 1) >> 31) & 1;57    }