transport.py 文件源码

def read(self, timeout):
        if self.tty is not None:
            self.tty.timeout = max(timeout/1E3, 0.05)
            frame = bytearray(self.tty.read(6))
            if frame is None or len(frame) == 0:
                raise IOError(errno.ETIMEDOUT, os.strerror(errno.ETIMEDOUT))
            if frame.startswith(b"\x00\x00\xff\x00\xff\x00"):
                log.log(logging.DEBUG-1, "<<< %s", str(frame).encode("hex"))
                return frame
            LEN = frame[3]
            if LEN == 0xFF:
                frame += self.tty.read(3)
                LEN = frame[5] << 8 | frame[6]
            frame += self.tty.read(LEN + 1)
            log.log(logging.DEBUG-1, "<<< %s", hexlify(frame))
            return frame