/*
 *  EEL4746C - AVR Piano - Speaker Section
 *  speaker is connected to PD2 and ground
 *  15 buttons are connected to PD3-7, PC0-4, PB0-4
 *  the LCD Arduino UNO is connected to TX/RX (PD0/1)
 */

#include <avr/io.h>
#include <avr/interrupt.h>

#define F_CPU		16e6
#include <util/delay.h>

#define	T1_PRESCALAR	8
#define FREQ(f)		(16e6 / f / T1_PRESCALAR / 2)

#define HIGH(sn)	((sn >> 8) & 0xff)
#define LOW(sn)		(sn & 0xff)

#define P_RX		0
#define P_TX		1
#define P_SPKR		2

#define MARIO		50

unsigned short freqs[] = {
	// PD3-7
#if 0
	FREQ(100),
	FREQ(200),
	FREQ(250),
	FREQ(300),
	FREQ(350),
	// PB0-4
	FREQ(400),
#else
	FREQ(131),	// middle c
	FREQ(262),
	FREQ(110),
	FREQ(220),
	FREQ(117),
	FREQ(233),
#endif
	FREQ(500),
	FREQ(6000),
	FREQ(5000),
	FREQ(5500),
	// PC0-4
	FREQ(4000),
	FREQ(7250),
	FREQ(6500),
	FREQ(5750),
	FREQ(5000),
	FREQ(5000),
	FREQ(6000),
	FREQ(7000),
	FREQ(8000),
	FREQ(8000),
	FREQ(8000),
	FREQ(8000),
	FREQ(8000),

	// notes
	[MARIO] = FREQ(131),	// C3
	FREQ(262),	// C4
	FREQ(110),	// A2
	FREQ(220),	// A3
	FREQ(117),	// Bb2
	FREQ(233),	// Bb3

	FREQ(87),
	FREQ(175),
	FREQ(73),
	FREQ(147),
	FREQ(78),
	FREQ(156),

	FREQ(156),
	FREQ(147),
	FREQ(139),
	FREQ(131),
	FREQ(156),
	FREQ(147),
	FREQ(104),
	FREQ(98),
	FREQ(139),

	FREQ(156),
	FREQ(185),
	FREQ(175),
	FREQ(165),
	FREQ(233),
	FREQ(220),
	FREQ(208),
	FREQ(156),
	FREQ(123),
	FREQ(123),
	FREQ(110),
	FREQ(104),

	['"'] = FREQ(16000),

	[255] = 0	// used as a 'silent' note
};
unsigned char note = 0;
// 0 = buttons write note+cycles+\xff to UART
// 1 = buttons don't do anything, speaker reads note+cycles+\xff from UART
unsigned char mode = '0';

ISR (PCINT0_vect)
{
	// check if any button in the whole port is pressed
	for (unsigned char i = 0; i <= 5; i++) {
		if (PINB & (1 << i)) {
			note = i + 5;
			break;
		}
	}
}

ISR (PCINT1_vect)
{
	// check if any button in the whole port is pressed
	for (unsigned char i = 0; i <= 5; i++) {
		if (PINC & (1 << i)) {
			note = i + 10;
			break;
		}
	}
}

ISR (PCINT2_vect)
{
	// check if any button in the whole port is pressed
	for (unsigned char i = 3; i <= 7; i++) {
		if (PIND & (1 << i)) {
			note = i - 3;
			break;
		}
	}
}

void
usart_init(void)
{
	// 115200 bps, RX/TX enabled
	UBRR0 = 103;
	UCSR0B = (1 << RXEN0) | (1 << TXEN0);
	UCSR0C = (1 << UCSZ01) | (1 << UCSZ00);
}

void
usart_send(unsigned char c)
{
	while (!(UCSR0A & (1 << UDRE0)));
	UDR0 = c;
}

void
usart_send_str(const char *c)
{
	for (unsigned char i = 0; c[i] != '\0'; i++)
		usart_send(c[i]);
}

unsigned char
usart_read(void)
{
	while (!(UCSR0A & (1 << RXC0)));
	return UDR0;
}

void
playtone(void)
{
	// Prepare Timer/Counter
	TCNT1 = 1;
	OCR1A = freqs[note];
	TCCR1B |= 1 << CS11;

	// Monitor OutPut Compare Flag
	while ((TIFR1 & (1 << OCF1A)) == 0);

	// Toggles port For Speaker
	PORTD ^= 1 << P_SPKR;
	TIFR1 |= 1 << OCF1A;
	TCCR1B &= ~(1 << CS11);
}

void
play_note(unsigned char _note, unsigned short _cycles)
{
	note = _note;

	if (note != 255) {
		for (unsigned short i = 0; i < _cycles; i++)
			playtone();
	} else {
		// when note is 255, don't play anything for _cycles ms
		// Prepare Timer/Counter
		TCNT1 = 1;
		OCR1A = 16e3 * _cycles / T1_PRESCALAR;
		TCCR1B |= 1 << CS11;

		// Monitor OutPut Compare Flag
		while ((TIFR1 & (1 << OCF1A)) == 0);

		// Toggles port For Speaker
		PORTD ^= 1 << P_SPKR;
		TIFR1 |= 1 << OCF1A;
		TCCR1B &= ~(1 << CS11);
	}
}

int
main(void) 
{
	// Data Direction for Buttons, UART, Speaker
	DDRB = 0x00;
	DDRC = 0x00;
	DDRD = (1 << P_TX) | (1 << P_SPKR); 

	// Enabling Pin Change Interrupt for All Buttons
	PCMSK0 = 0b00011111;
	PCMSK1 = 0b00011111;
	PCMSK2 = 0b11111000;
	PCICR = (1 << PCIE0) | (1 << PCIE1) | (1 << PCIE2);

	TCCR1A = 0x00; // use timer1 CTC mode
	TCCR1B = 1 << WGM12; // already prescaled by 8 in table

	sei();

	usart_init();

	// Sends Square wave to the Speaker When a Button is Pressed
	unsigned short cycles = 0;
	unsigned char tmp = 0;
	for (unsigned char n = 0;; n = (n + 1) % 2) {
		if (UCSR0A & (1 << RXC0)) {
			mode = UDR0;
			PORTD &= ~(1 << P_SPKR);
			usart_send(mode);
		}
		// check if any buttons are pressed, otherwise don't play a note
		if (mode == '0' && ((PINB & PCMSK0) | (PINC & PCMSK1) | (PIND & PCMSK2)) == 0) {
			// if a button was released, then send note and cycles played
			if (cycles > 0) {
				usart_send(tmp);
				usart_send(HIGH(cycles));
				usart_send(LOW(cycles));
				usart_send(0xff);
				cycles = 0;
			}
			continue;
		}

		if (mode == '0') {
			tmp = note;

			playtone();

			cycles = (cycles + 1) % 0xffff;
		} else if (mode == '1') {
			note = usart_read();
			if (note >= 'Z') note -= '0';
			tmp = usart_read();
			cycles = tmp << 8;
			tmp = usart_read();
			cycles |= tmp;
			tmp = usart_read();

			// reset to default mode when an invalid note is read
			if (tmp != 'z' || note >= '|') {
				mode = '0';
				continue;
			}

			for (unsigned short i = 0; i < cycles; i++)
				playtone();
		} else if (mode == '2') {
			play_note(MARIO + 0, 131 * 0.3);
			play_note(MARIO + 1, 262 * 0.3);
			play_note(MARIO + 2, 110 * 0.3);
			play_note(MARIO + 3, 220 * 0.3);
			play_note(MARIO + 4, 117 * 0.3);
			play_note(MARIO + 5, 233 * 0.3);
			play_note(255, 1800);
			play_note(MARIO + 0, 131 * 0.3);
			play_note(MARIO + 1, 262 * 0.3);
			play_note(MARIO + 2, 110 * 0.3);
			play_note(MARIO + 3, 220 * 0.3);
			play_note(MARIO + 4, 117 * 0.3);
			play_note(MARIO + 5, 233 * 0.3);
			play_note(255, 1800);

			play_note(MARIO + 6, 87 * 0.3);
			play_note(MARIO + 7, 175 * 0.3);
			play_note(MARIO + 8, 73 * 0.3);
			play_note(MARIO + 9, 147 * 0.3);
			play_note(MARIO + 10, 78 * 0.3);
			play_note(MARIO + 11, 156 * 0.3);
			play_note(255, 1800);
			play_note(MARIO + 6, 87 * 0.3);
			play_note(MARIO + 7, 175 * 0.3);
			play_note(MARIO + 8, 73 * 0.3);
			play_note(MARIO + 9, 147 * 0.3);
			play_note(MARIO + 10, 78 * 0.3);
			play_note(MARIO + 11, 156 * 0.3);
			play_note(255, 1800);

			play_note(MARIO + 12, 156 * 0.3);
			play_note(255, 25);
			play_note(MARIO + 13, 147 * 0.3);
			play_note(255, 25);
			play_note(MARIO + 14, 139 * 0.3);
			play_note(255, 25);
			play_note(MARIO + 15, 131 * 0.6);
			play_note(255, 25);
			play_note(MARIO + 16, 156 * 0.3);
			play_note(255, 25);
			play_note(MARIO + 17, 147 * 0.6);
			play_note(255, 25);
			play_note(MARIO + 18, 104 * 0.6);
			play_note(255, 25);
			play_note(MARIO + 19, 98 * 0.6);
			play_note(255, 25);
			play_note(MARIO + 20, 139 * 0.6);

			play_note(MARIO + 21, 156 * 0.3);
			play_note(255, 25);
			play_note(MARIO + 22, 185 * 0.3);
			play_note(255, 25);
			play_note(MARIO + 23, 175 * 0.3);
			play_note(255, 25);
			play_note(MARIO + 24, 165 * 0.3);
			play_note(255, 25);
			play_note(MARIO + 25, 233 * 0.3);
			play_note(255, 25);
			play_note(MARIO + 26, 220 * 0.3);
			play_note(255, 25);
			play_note(MARIO + 27, 208 * 0.6);
			play_note(255, 25);
			play_note(MARIO + 28, 156 * 0.6);
			play_note(255, 25);
			play_note(MARIO + 29, 123 * 0.6);
			play_note(255, 25);
			play_note(MARIO + 30, 123 * 0.6);
			play_note(255, 25);
			play_note(MARIO + 31, 110 * 0.6);
			play_note(255, 25);
			play_note(MARIO + 32, 104 * 0.6);
			play_note(255, 25);

			play_note(255, 3600);
		}
	}
}