keil中怎么用结构，联合定义位变量？我在ARM中这么定义正确吗？ typedef union _MAC_FRAME_CONTROL
{
    WORD_VAL word;
    struct _MAC_FRAME_CONTROL_bits
    {
        unsigned char FrameType :3;
        unsigned char SecurityEnabled :1;
        unsigned char FramePending :1;
        unsigned char ACKRequest :1;
        unsigned char IntraPAN :1;
        unsigned char :1;
        unsigned char :1;
        unsigned char :1;
        unsigned char DstAddrMode :2;
        unsigned char :1;
        unsigned char :1;
        unsigned char SrcAddrMode :2;
    } bits;
} MAC_FRAME_CONTROL; 此帖出自小平头技术问答