#include<port.h>
#include"var_extern.h"
#include<intrins.h>
//p1=row
//p2=col
bdata unsigned char row_no,col_no;
sbit col_no0=col_no^0;
bit debounce=1;
void delay(unsigned int itime)
{
 	int i,j;
	for(i=0;i<1275;i++)
	{
		for(j=0;j<itime;j++){}
	}
}
//this function for checking which column is low
void col_check()
{
 	unsigned char i;
	for(i=0;i<8;i++)
	{
	 	if(col_no0==0)
		{
		 	break;
		}
		col_no=col_no>>1;
	}
	col_no=i;
}
//this function for scaning keypad
unsigned char key_scan()
{
 	unsigned char temp,i,key=100;
	col=0xff;					  //make colmn high
	row=0x00;					  //make row low
	while(col==0xff)		//loop untile any column will be low(means untill any key is pressed)
	{
	}
	temp=col;//value of col is stored for debounce check
	delay(50);//debounce delay
	while(col==0xff) //loop untile any column will be low(means untill any key is pressed)
	{
	}
	if(temp!=col)//if key is same then this row and column will find
	{
	 	debounce=0;
		key=100;
		ACK=0;
		return key;
	}
	else
	{
	 	while(col==0xff)// this routine for debounce check
		{
		}
		temp=col;
		delay(1);
		while(col==0xff)
		{
		}
		if(temp!=col)
		{
	 		debounce=0;
			key=100;
			return key;
		}else
		{
	
			temp=0xfe;		  //make first row will low
			for(i=0;i<8;i++)
			{
			 	row=_crol_(temp,i);	//shift row by value of i
				if(col!=0xff)		//check any column is low or not
				{					//if yes then read value of column port
				 	col_no=col;
					col_check();	//check which column is being low
					key=key_matrix[i][col_no];	 //put value of row and column in matrix and receive key
					col=0xff;
					row=0x00;
					while(col!=0xff)
					{
					}
					return key;
					
				}
			}
		}
	}
	
}
void keypad_init()
{
 	col=0xff;
	row=0x00;
}