#include<reg52.h>
#define unchar unsigned char
#define unint unsigned int
sbit rs=P2^0;
sbit rw=P2^1;
sbit en=P2^2;
sbit busy=P0^7;
char i,flag,fuhao;
unchar num,temp;
long  a,b,c;
unchar code table[]={7,8,9,0,//內部運算用
					 4,5,6,0,
					 1,2,3,0,
					 0,0,0,0};
unchar code table1[]={7,8,9,0x2f-0x30,//顯示用7，8，9，/
					  4,5,6,0x2a-0x30,//4,5,6,*
					  1,2,3,0x2d-0x30,//1,2,3,-
					   0x01-0x30,0,0x3d-0x30,0x2b-0x30};//ON/C,0,=,+
void delay(unchar z)
{
	unchar x,y;
	for(x=z;x>0;x--)
		for(y=110;y>0;y--);
}
void checkbusy()
{	
	while(busy==1)//P0^7最高位為1為忙，0為閑
	{	
		P0=0xff;
		rs=0;
		rw=1;
		en=0;//禁止讀寫
		delay(20);		
		en=1;		
	}
}

void write_com(unchar com)
{
	rs=0;
	rw=0;
	en=0;
	checkbusy();
	P0=com;
	delay(5);
	en=1;
	delay(5);
	en=0;
}
void write_date(unchar date)
{ 
	rs=1;
	rw=0;
	en=0;
	checkbusy();
	P0=date;
	delay(5);
	en=1;
	delay(5);
	en=0;	
}
void init()
{		
	write_com(0x38);
	delay(50);
	write_com(0x0c);//開顯示關光標和閃爍
	delay(50);
	write_com(0x06);//地址向后移
	delay(50);
	write_com(0x80);//初始地址
	write_com(0x01);//清屏
	delay(50);
	i=0;flag=0;//賦初值
	fuhao=0;a=0;b=0;c=0;
	
	
}
void lcd_clean()//清屏
{
	write_com(0x01);
	delay(20);
}
void keyscan()
{
	
	P1=0xfe;
	temp=P1;
	temp=temp&0xf0;
	if(temp!=0xf0)
		 {		delay(10);
				temp=P1;
				temp=temp&0xf0;
				if(temp!=0xf0)
				{
					temp=P1;
					switch(temp)
						{
							case 0xee:num=0; break;
							case 0xde:num=1; break;
							case 0xbe:num=2; break;
							case 0x7e:num=3; break;													
						}												
				}
			while(P1!=0xfe);
		if(num==0||num==1||num==2)
		 {           
			if(flag==0)
				a=a*10+table[num];//a是在沒按符號鍵之前輸入的值
			if(flag==1)
				b=b*10+table[num];//b是按符號鍵后輸入的值		
		 }
	 	if(num==3)//"/"鍵
			{	
				flag=1;
				fuhao=4;//"/"
			}
		i=table1[num];//顯示的值
		write_date(0x30+i);//十六進制表示的ASC碼		
	}
		P1=0xfd;
		temp=P1;
		temp=temp&0xf0;
		if(temp!=0xf0)				
		  {		delay(5);
				temp=P1;
				temp=temp&0xf0;
				if(temp!=0xf0)
				{
					temp=P1;
					switch(temp)
						{
							case 0xed:num=4; break;
							case 0xdd:num=5; break;
							case 0xbd:num=6; break;
							case 0x7d:num=7; break;												
						}													
				}
			while(P1!=0xfd);
			if(num==4||num==5||num==6) 
				{
					if(flag==0)
						a=a*10+table[num];
					else
						b=b*10+table[num];
				}
		if(num==7)//"*"
				{
					flag=1;
					fuhao=3;
				}
			i=table1[num];
			write_date(0x30+i);		 		
		  }
			P1=0xfb;
			temp=P1;
			temp=temp&0xf0;
			if(temp!=0xf0)				
		  	{	delay(5);
				temp=P1;
				temp=temp&0xf0;
				if(temp!=0xf0)
				{
					temp=P1;
					switch(temp)
						{
							case 0xeb:num=8; break;
							case 0xdb:num=9; break;
							case 0xbb:num=10; break;
							case 0x7b:num=11; break;												
						}											
				}
		while(P1!=0xfb);
			if(num==8||num==9||num==10)
			{
				if(flag==0)
					{a=a*10+table[num];}
				else
					{b=b*10+table[num];}
			}
			if(num==11)//"-"
			{
				flag=1;
				fuhao=2;
			} 
			i=table1[num];
			write_date(0x30+i);					
		   }
			P1=0xf7;
			temp=P1;
			temp=temp&0xf0;
			if(temp!=0xf0)				
		  	{	delay(5);
				temp=P1;
				temp=temp&0xf0;
				if(temp!=0xf0)
				{
					temp=P1;
					switch(temp)
						{
							case 0xe7:num=12; break;
							case 0xd7:num=13; break;
							case 0xb7:num=14; break;
							case 0x77:num=15; break;							
							
						}										
				}
		while(P1!=0xf7);//松手檢測，沒有松手則保持顯示的狀態					   
		  switch(num)
			{
				case 12:{	
							lcd_clean();
						 	a=0;b=0;flag=0;
							fuhao=0;
						} break;
				case 13:{	
							if(flag==0)
								{
									a=a*10;write_date(0x30);
								}
							else
							{
								b=b*10;
								write_date(0x30);
							}
						} break;												 
				case 14:{
							if(fuhao==1)
							{	
							  write_com(0x80+0x0f);
							  lcd_clean();//重新定位后再清屏
							  write_com(0x04);									
							  c=a+b;										
								while(c!=0)
									{
										write_date(0x30+c%10);
										c=c/10;
									}
									write_date(0x3d);//寫"="
									a=0;b=0;flag=0;fuhao=0;//清0
								}
						else if(fuhao==2)
								{	
									write_com(0x80+0x0f);
									lcd_clean();
									write_com(0x04);
									if(a-b>0)
										c=a-b;
									else
										c=b-a;
									while(c!=0)
										{
											write_date(0x30+c%10);												
											c=c/10;
										}
									if(a-b<0)
									write_date(0x2d);//"-"
									write_date(0x3d);
									a=0;b=0;flag=0;fuhao=0;
								}
							else if(fuhao==3)
								{
								  write_com(0x80+0x0f);
								  lcd_clean();
								  write_com(0x04);
								  c=a*b;
									while(c!=0)
										{
										    write_date(0x30+c%10);								
											c=c/10;
										}
									write_date(0x3d);
									a=0;b=0;flag=0;fuhao=0;
								}
						else if(fuhao==4)
							{
								write_com(0x80+0x0f);
								lcd_clean();
								 write_com(0x04);
								i=0;
								c=(long)(((float)a/b)*1000);//化整后再加小數點							
								while(c!=0)
								{
								   write_date(0x30+c%10);
									c=c/10;		i++;
								if(i==3)
								write_date(0x2e);//加小數點"."
								}
								if(a/b<=0)
									write_date(0x30);
									write_date(0x3d);
									a=0;b=0;flag=0;fuhao=0;
							}
							
						}	break;
			case 15:{	
						i=table1[num];
						write_date(0x30+i);//"+"
						flag=1;fuhao=1;
					} break;
				
			}
   		}						
}

 void main()
{	
	init();
	while(1)
		{
			keyscan();
		}
}