Hiển thị số 00-99 lên led 7 thanh đôi

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#include <REGX52.H>
sbit led1 = P3^0;
sbit led2 = P3^1;
void delay_ms(unsigned int ms)
{
unsigned int x,y;
for(x=0;x<ms;x++)
for(y=0;y<=125;y++);
}
void delay_us(int time)
{
while(time--);
}
unsigned char seg7[]={0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90};
void sang(int n)
{
int c,dv,i;
c=n/10;
dv=n%10;
for(i=0;i<50;i++)
{
P2=seg7[c];
led1=1;led2=0;
delay_us(100);

P2=0xff;
delay_us(100);

P2=seg7[dv];
led2=1;led1=0;
delay_us(100);

P2=0xff;
delay_us(100);
}

}


void main()
{
int a;
while(1)
{
for(a=0;a<99;a++)
{
sang(a);
}
}
}