請問，用四個獨立按鍵來制作簡易密碼鎖C語言程序該怎麽編寫

#include<reg51.h>

#define uchar unsigned char

uchar mima[4]={1,2,3,4};

uchar keymm[4]={0,0,0,0};

sbit key1=P1^0;

sbit key2=P1^1;

sbit key3=P1^2;

sbit key4=P1^3;

sbit led=P1^4;

bit flag=0;

void delay(uchar a)

{

uchar i;

while(a--)for(i=0;i<120;i++);

}

main()

{

uchar i;

led=1;

while(1)

{

if(key1==0)

{

while(key1==0);

keymm[0]++;

keymm[0]%=10;

}

if(key2==0)

{

while(key2==0);

keymm[1]++;

keymm[1]%=10;

}

if(key3==0)

{

while(key3==0);

keymm[2]++;

keymm[2]%=10;

}

if(key4==0)

{

while(key4==0);

keymm[3]++;

keymm[3]%=10;

}

for(i=0;i<4;i++)

{

if(keymm[i]!=mima[i])break;

if(i==3)flag=1;

}

if(flag)

{

i=10;

while(i--)

{

led=~led;

delay(100);

}

flag=0;

}

}

}