/****************************************************************************
 * keyer.c
 * (c) 2007 Michael Wichmann
 * 
 * This code is under the MIT-License
 *
 ****************************************************************************/

#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/sleep.h>
#include <avr/eeprom.h>
#include <inttypes.h>

// shorthand for a nop operation
#define nop() asm volatile("nop" ::)

// define our ports and pins we will be using
#define PORTINP		PORTB
#define PININP		PINB
#define nDOT		PORTB0
#define nDASH		PORTB1
#define nBUT1		PORTB2
#define nBUT2		PORTB3

#define PORTOUT		PORTA
#define DDROUT		DDRA
#define nLED		PORTA0
#define nKEY		PORTA1

// some shorthands
#define ledon()		PORTOUT |= _BV(nLED)
#define ledoff()	PORTOUT &= ~_BV(nLED)
//#define keydown()	DDROUT  |= _BV(nKEY)
//#define keyup()		DDROUT	&= ~_BV(nKEY)
#define keydown()	PORTOUT |= _BV(nKEY)
#define keyup()		PORTOUT &= ~_BV(nKEY)

#define TMRCLKSRC	(_BV(CS12))
#define timeroff()	TCCR1B &= ~TMRCLKSRC
#define timeron()	TCCR1B |= TMRCLKSRC


// timing issues
#define FOSC		1000000
// counts per msec
#define CNTSPERMSEC (FOSC/256)/1000

// forward declarations
void calcspeed();
void delay(uint16_t n);

#define SEND_DOT	1
#define SEND_DASH	2
#define SEND_PAUSE	3
void send(uint8_t ch);



// global variables


// 
uint8_t EEMEM eeSpeed = 20;
uint8_t  gSpeed;
uint16_t gDotLength;
uint16_t gDashLength;
//uint16_t gIntraSignPauseLength = 234;
#define gIntraSignPauseLength gDotLength

// blink?
uint8_t bBlink = 1;

// state variables for dot/dash paddles
// declare volatile to be able to change within isr()
volatile uint8_t gDot = 0;
volatile uint8_t gDash = 0;
volatile uint8_t gBut1 = 0;
volatile uint8_t gBut2 = 0;

#define BUF_EMPTY		0
#define BUF_DOT			1
#define BUF_DASH		2

#define BUFSTAT_IDLE	5
#define BUFSTAT_PLAYING	3
#define BUFSTAT_PAUSE	4

uint8_t buf[2];
uint8_t bufstat;




// PCINT interrupt vector
ISR(PCINT_vect) {
	// setup initial state of pininp... dot,dash,buttons are in unpressed status
	// and are therefore pulled up by internal pullup therefor pinstatus is one
	static uint8_t oldval = _BV(nBUT1)|_BV(nDOT)|_BV(nDASH);
	// get current value of ports register
	uint8_t val = PININP;

	// button one changed
	if ((val^oldval)&_BV(nBUT1)) {
		// button released
		if (val&_BV(nBUT1)) {	
			gBut1 = 0;
		}
		// button depressed
		else {
			gBut1 = 1;
		} 
	}

	// button two changed
	if ((val^oldval)&_BV(nBUT2)) {
		// button released
		if (val&_BV(nBUT2)) {
			gBut2 = 0;
			keyup();
		}
		// button depressed
		else {
			gBut2 = 1;
		}
	}
	
	// dot lever changed
	if ((val^oldval)&_BV(nDOT)) {
		// dot lever released
		if (val&_BV(nDOT)) {
			gDot = 0;
		}
		// dot lever depressed
		else {
			gDot = 1;
		}
	}

	// dash lever changed
	if ((val^oldval)&_BV(nDASH)) {
		// dash lever released
		if (val&_BV(nDASH)) {
			gDash = 0;
		}
		// dash lever depressed
		else {
			gDash = 1;
		}
	}

	
	// save the current value so next time we know exactly what pin has changed
	oldval = val;
}



ISR(TIMER1_COMPA_vect) {
	timeroff();
	if (bufstat == BUFSTAT_PLAYING) {
		keyup();
		ledoff();
		// pause
		OCR1A = gIntraSignPauseLength;

		bufstat = BUFSTAT_PAUSE;
		
		timeron();
	}
	else if (bufstat == BUFSTAT_PAUSE) {
		buf[0] = buf[1];
		buf[1] = BUF_EMPTY;
		bufstat = BUFSTAT_IDLE;
	}
}




void delay(uint16_t n) {
	for (uint16_t i=0; i<n; i++) {
		for (uint8_t j=0; j<64; j++) {
			nop();
		}
	}
}


void send(uint8_t ch) {
	keydown();
	if (bBlink) ledon();
	// start timer
	if (ch == SEND_DOT) OCR1A = gDotLength;
	if (ch == SEND_DASH) OCR1A = gDashLength;
	timeron();
}


void calcspeed() {
	// dotlength[msec] = 1200/Speed[wpm]
	gDotLength = (307/gSpeed) * (FOSC/65536);
	gDashLength = 3*gDotLength;
}



int main() {
	// this is the output pin
	DDROUT = _BV(nLED);
	// OBSOLETE:
	// keyer is keyed by switching between input and output.
	// input->then hiz, output->gnd
	//DDROUT &= ~_BV(nKEY); // is used to switch
	
	// NOW: 
	// use BC547 or BS170 as switch therefore do the same as with led
	DDROUT |= _BV(nKEY);
	
	// reset led and key
	PORTOUT &= ~_BV(nLED);
	PORTOUT &= ~_BV(nKEY); 

	// activate internal pullup
	PORTINP = _BV(nDOT)|_BV(nDASH)|_BV(nBUT1)|_BV(nBUT2);

	// pc int enable
	PCMSK = _BV(nDOT)|_BV(nDASH)|_BV(nBUT1)|_BV(nBUT2);
	GIMSK |= _BV(PCIE);

	// setup timer/counter1
	// select timer mode
	TCCR1B = _BV(WGM12);
	// timer output compare interrupt
	TIMSK |= _BV(OCIE1A);


	// init buffer
	buf[0] = BUF_EMPTY;
	buf[1] = BUF_EMPTY;
	bufstat = BUFSTAT_IDLE;

	// set the sleep mode
	set_sleep_mode(SLEEP_MODE_IDLE);

	// calculate speeds
	gSpeed = eeprom_read_byte(&eeSpeed);
	if ((gSpeed < 10) || (gSpeed > 30)) gSpeed = 20;
	calcspeed();


	// allow interrupts
	sei();

	// enter the loop
	while(1) {
		// go to sleep
		sleep_mode();
		
		// woke up, so some interrupt must have happened

		// check paddle and fill buffer
		if ((gDot || gDash) && (!(gBut1 || gBut2))) {
			if (buf[0] == BUF_EMPTY) {
				if (gDot == 1) {
					buf[0] = BUF_DOT;
				}
				else {
					buf[0] = BUF_DASH;
				}
			}
			else if (buf[1] == BUF_EMPTY) {
				if ((buf[0] == BUF_DOT) && (gDash == 1)) {
					buf[1] = BUF_DASH;
				}
				else if ((buf[0] == BUF_DASH ) && (gDot == 1)) {
					buf[1] = BUF_DOT;
				}
			}
		}

		// button pressed
		if (gBut1 && (buf[0] == BUF_EMPTY)) {
			if (gDot) {
				gSpeed -= 1;
				calcspeed();
				buf[0] = BUF_DOT;
				buf[1] = BUF_DASH;
				if (gSpeed==20) buf[1] = BUF_DOT;
			}
			else if (gDash) {
				gSpeed += 1;
				calcspeed();
				buf[0] = BUF_DOT;
				buf[1] = BUF_DASH;
				if (gSpeed==20) buf[1] = BUF_DOT;
			}
			if (gSpeed < 10) {
				gSpeed = 10;
				calcspeed();
			} 
			else if (gSpeed > 30) {
				gSpeed = 30;
				calcspeed();
			}
			
			if (eeprom_read_byte(&eeSpeed) != gSpeed) {
				eeprom_write_byte(&eeSpeed, gSpeed);
			}
						
		}

		// button2 pressed ... output tune carrier
		if (gBut2) {
			keydown();
		}


		// empty the buffer
		if (bufstat == BUFSTAT_IDLE) {
			if (buf[0] == BUF_DOT) {
				bufstat = BUFSTAT_PLAYING;
				send(SEND_DOT);
			} 
			else if (buf[0] == BUF_DASH) {
				bufstat = BUFSTAT_PLAYING;
				send(SEND_DASH);
			}
		}

	}


	return 0;
}