#include<reg52.h>
#define		uchar	unsigned	char
#define		uint	unsigned	int

void	delay(uint	i);
uint keyb(void);
main()
{char i=0;
SCON=0x80;
PCON=0X00;
TI=0;

 
for(;;i++)
{SBUF=keyb();while(TI==0);TI=0;delay(1000);} 
}

void	delay(uint	i)
{unsigned	int	j;
for(;i>0;i--)
for(j=100;j>0;j--);}


uint keyb(void)
{unsigned int a,b=0,c,jzhi,f=0,i=0,dma[]={0,0,0,0,0,0,0,3,0,0,0,2,0,1,0};
 int yw[]={0x7f,0xbf,0xdf,0xef};a=0x7f;
 for(;;)
{P2=a;a=P2;b=a;c=a;
  a=a&0x0f;
  if(a==0x0f) {i++;a=yw[i];if(i==4) {i=0;a=0x7f;}}
  else break;} 
  b=b>>4;f=c&0x0f;
  jzhi=dma[b]*4+dma[f];
  return jzhi;}