#include "key.h"


struct	{
	unsigned char old_key_a,new_key_a;
	unsigned char old_key_b,new_key_b;
	unsigned char old_key_c,new_key_c;
	unsigned char old_key_d,new_key_d;
}key_state;

unsigned char SCAN_KEY(void){
	key_state.new_key_a=KEY_A;
	if(key_state.new_key_a!=key_state.old_key_a){
		key_state.old_key_a=key_state.new_key_a;
		if(KEY_A)return  1;
		else return  2;
	}
	key_state.new_key_b=KEY_B;
	if(key_state.new_key_b!=key_state.old_key_b) {
		key_state.old_key_b=key_state.new_key_b;
		if(KEY_B)return  3;
		else return  4;
	}
	key_state.new_key_c=KEY_C;
	if(key_state.new_key_c!=key_state.old_key_c) {
		key_state.old_key_c=key_state.new_key_c;
		if(KEY_C)return  5;
		else return  6;
	}
	key_state.new_key_d=KEY_D;	
	if(key_state.new_key_d!=key_state.old_key_d) {
		key_state.old_key_d=key_state.new_key_d;
		if(KEY_D)return  7;
		else return  8;
	}
	return 0;	  
}