/* inv.c	Programa que emula uma calculadora
			Atividae 2 MC 404   1º Sem 2011
			Prof Célio G
			Atualizado em: 16 Maio 2011
***************************************************************************************************/

#include <avr/io.h>
#include <avr/pgmspace.h>
#include <util/delay.h>			// biblioteca para tratar dados na area de programa
//#define _BV(bit) (1<< (bit))
unsigned char temp;
//unsigned char lcdinput;
int strlen(char *);  // somente para o compilador não emitir warnings!
char message1[] PROGMEM= "Press any key(1-16)"; // define uma cadeia C na área de programa
char message2[] PROGMEM = "You pressed key:";	
char message3[] PROGMEM = "Comando recebido:";
char message4[] PROGMEM = "Caracteres demais";
char buf[20] __attribute__((section("*.noinit")));  // __attribute__((section("*.noinit"))); // qdo não queremos inicializar variavel global;
char * p=buf;

#define TDELAY 1			// Obs: _delay_loop_2(1000) delays 4ms on a 1 MHz CPU
#define ENABLE 0
#define RS 1
#define RW 2
void lcd_busy(){
	PORTC |= _BV(RW);
	PORTC &= ~_BV(RS);
	DDRD= 0xff;
	DDRD= 0x00;
	PORTD= 0x00;
    while (1){
		PORTC |= _BV(ENABLE);
		temp= PORTC;
		PORTC &= ~_BV(ENABLE);
		if (bit_is_clear(temp,7)) break;
	}
	DDRD= 0xff;
}

void lcd_cmd(char lcdinput){
	PORTC &= ~(_BV(RS) | _BV(RW));
	//PORTC &= ~(_BV(RW));
	PORTC |= _BV(ENABLE);
	PORTD= lcdinput;
	PORTC &= ~(_BV(ENABLE));
}
 
void lcd_write(char lcdinput){
	//PORTC |= _BV(RS);
	PORTC &= ~(_BV(RW)); 
	PORTC  |= (_BV(ENABLE) | _BV(RS));
	PORTD= lcdinput;
	PORTC &=  ~_BV(ENABLE);
}
void writemsg(char * msg){
	char * getbyte= msg;
	while(1){
		temp= pgm_read_byte(getbyte++);
		if (!temp) break;
		lcd_write(temp);
		lcd_busy();
	}
}
void writemsgram(char * msg){
	char * p= msg;
	while(*p !=0){
		lcd_write(*p++);
		lcd_busy();
	}
}
void lcdinit(){
	DDRD= 0xff;
	DDRC=0xff;
	lcd_cmd(0x38);   // 8 bit mode 2 line LCD, blink cursor default
	lcd_busy();
	lcd_cmd(1);		// clear screen
	lcd_busy();
	lcd_cmd(2);		// cursor home command
	lcd_busy();
}
void delay(int val){
	//_delay_ms(20);
	_delay_loop_2(val);	
	}

unsigned char check_keys(){
while (1){
	PINB= 0xff;
	delay(TDELAY);
	PORTB= 0b11101111;   //col1
	delay(TDELAY*1500);	// para contotnar bug de seleção na col 3
	if (bit_is_clear(PINB,PB0))	return ('1');
	else if (bit_is_clear(PINB,PB1)) return ('4');
	else if (bit_is_clear(PINB,PB2)) return ('7');
	else if (bit_is_clear(PINB,PB3)) return ('C');
	PORTB= 0b11011111;   //col2
	delay(TDELAY);
	if (bit_is_clear(PINB,PB0))	return ('2');
	else if (bit_is_clear(PINB,PB1)) return ('5');
	else if (bit_is_clear(PINB,PB2)) return ('8');
	else if (bit_is_clear(PINB,PB3)) return ('0');
	PORTB= 0b10111111;   //col3
	delay(TDELAY);
	if (bit_is_clear(PINB,PB0))	return ('3');
	else if (bit_is_clear(PINB,PB1)) return ('6');
	else if (bit_is_clear(PINB,PB2)) return ('9');
	else if (bit_is_clear(PINB,PB3)) return ('E');
	PORTB= 0b01111111;   //col4
	delay(TDELAY);
	if (bit_is_clear(PINB,PB0))	return ('A');
	else if (bit_is_clear(PINB,PB1)) return ('S');
	else if (bit_is_clear(PINB,PB2)) return ('M');
	else if (bit_is_clear(PINB,PB3)) return ('D');
	}
}
int store (char key){		//armazena caracter no buffer buf
	if (p==buf+20) return 0;
	if (key== 'E'){
		*p=0;    //insira terminador de cadeia
		return 2;
	}
	*p++= key;		// armazena caracter digitado
	return 1;
}
int main(){
	unsigned char key, res;
	p=buf;
	lcdinit();
	DDRB= 0b11110000;
	PORTB= 0b00001111;
	writemsg(message1);
    while(1){
		lcd_cmd(0xc0);  // go to beginning of 2nd line
		lcd_busy();
		key= check_keys();
		writemsg(message2);
		lcd_write (key);
		res= store(key);
		if (res==1) continue;
		lcd_cmd(1);  // clear screen, go to beginning of 1st line
		lcd_busy();
		if (res==2) {
			writemsg(message3);
			lcd_cmd(0xc0);
			lcd_busy();
			writemsgram(buf);
        }
		else if (res == 0){
			writemsg(message4);
		}
		p=buf;
	}

}