#include <reg51.h>    
#include <stdio.h>   
#define    SIZE_OF_KEYBD_MENU    20
unsigned  DummyJob=0;
unsigned  DspUserInfo=0;
unsigned  DspServiceInfo=0;
unsigned  DspVoltInfo=0;
unsigned  DspCurrInfo=0;
unsigned  DspFreqInfo=0;
unsigned  DspCableInfo=0;
unsigned  DspSetVoltLevel=0;
unsigned  KeyFuncIndex=0;

void    (*KeyFuncPtr)();                    //按鍵功能指針

typedef struct
{
   unsigned char    KeyStateIndex;    //當前狀態索引號
   unsigned char    KeyDnState;      //按下"向下"鍵時轉向的狀態索引號
   unsigned char    KeyUpState;      //按下"向上"鍵時轉向的狀態索引號
   unsigned char    KeyCrState;        //按下"回車"鍵時轉向的狀態索引號
    void    (*CurrentOperate)();    //當前狀態應該執行的功能操作
}    KbdTabStruct;

KbdTabStruct  code  KeyTab[SIZE_OF_KEYBD_MENU]=
{
    { 0, 0, 0, 1,(&DummyJob)},          //頂層
    
    { 1, 2, 0, 3,(&DspUserInfo)},        //第二層
    { 2, 1, 1, 9,(&DspServiceInfo)},      //第二層
    
    { 3, 0, 0, 1,(&DspVoltInfo)},     //第三層>>DspUserInfo的展開
    { 4, 0, 0, 1,(&DspCurrInfo)},     //第三層>>DspUserInfo的展開
    { 5, 0, 0, 1,(&DspFreqInfo)},     //第三層>>DspUserInfo的展開
    { 6, 0, 0, 1,(&DspCableInfo)},    //第三層>>DspUserInfo的展開
//...........
{ 9, 0, 0, 1,(&DspSetVoltLevel)}      //第三層>>DspServiceInfo的展開
//..........
};

void    GetKeyInput(void)
{unsigned char    KeyValue;
    KeyValue=P1&0x07;             //去掉高5位
//    delay(50000);
    switch(KeyValue)
    {
        case    1:                 //回車鍵,找出新的菜單狀態編號
        {
            KeyFuncIndex=KeyTab[KeyFuncIndex].KeyCrState;
            break;
        }
        case    2:              //向上鍵,找出新的菜單狀態編號
        {
            KeyFuncIndex=KeyTab[KeyFuncIndex].KeyUpState;
            break;
        }
        case    4:             //向下鍵,找出新的菜單狀態編號
        {
            KeyFuncIndex=KeyTab[KeyFuncIndex].KeyDnState;
            break;
        }
        default:                //按鍵錯誤的處理
//......
        break;
    }
    KeyFuncPtr=KeyTab[KeyFuncIndex].CurrentOperate;
    (*KeyFuncPtr)();//
}