CC1101的硬件BUG？

simpliciti上面的源码

    /*
    *  Read the RXBYTES register from the radio.
    *  Bit description of RXBYTES register:
    *    bit 7     - RXFIFO_OVERFLOW, set if receive overflow occurred
    *    bits 6:0  - NUM_BYTES, number of bytes in receive FIFO
    *
    *  Due a chip bug, the RXBYTES register must read the same value twice
    *  in a row to guarantee an accurate value.
    */
    {
        uint8_t rxBytesVerify;
        
        rxBytesVerify = mrfiSpiReadReg( RXBYTES );

        do
        {
            rxBytes = rxBytesVerify;
            rxBytesVerify = mrfiSpiReadReg( RXBYTES );
        }
        while (rxBytes != rxBytesVerify);
    }

事实上我以前读RxByte读取一次，还是稳定的！不知道为什么这段代码要读两次？

还有个问题，按照常理，接收触发一次都应该清洗一次RXFIFO，（SFRX）。但协议栈接收中断居然没有？