2个I/O实现6个按键的程序代码

2个I/O实现6个按键的程序代码
sbit IO1=P1^0;
sbit IO2=P1^1;
uchar keybuf,keydat;
bit bkeyok;

void delay_us(unsigned int n)
{
while(--n);
}

void delay_ms(unsigned int n)
{
do
{
delay_us(1000);
}
while(--n);
}

bit scan_key(void)
{
uchar tempkey;
IO1=1;IO2=1;
if(!IO1)
{
if (!IO2)
tempkey=3;
else
tempkey=2;
}
else
{
if (!IO2)
tempkey=1;
else
{
IO1=0;
if (!IO2)
{
IO1=1;IO2=0;
if (!IO1)
tempkey=4;
else
tempkey=6;
}
else
{
IO1=1;IO2=0;
if (!IO1)
tempkey=5;
else
tempkey=0;
}

}
}
IO1=1;IO2=1;
if((keybuf !=0) && (keybuf == tempkey))
{
bkeyok=1;
keydat=tempkey;
}
keybuf=tempkey;
return(bkeyok);
}

uchar read_key(void)
{
bkeyok=0;
return(keydat);
}

void doanything(uchar key)//按键处理;
{
}

void main(void)
{
while(1)
{
if(scan_key())
doanything(read_key());
delay_ms(10);
}
}