//	vim:ts=4
//
//	fl9999.c		2003.07.07 runner@protom.org
//
//	avr-gcc -mmcu=at90s8535 -Wa,-ahlms=fl9999.lst -o fl9999.elf fl9999.c
//	avr-objcopy -O ihex fl9999.elf fl9999.hex


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

#define	sleep()	({ asm volatile ("sleep" "\n"); })

static	uint16_t	counter;	// output data

uint8_t SEG[] = {
	0x3f,	// 0
	0x06,	// 1
	0x5b,	// 2
	0x4f,	// 3
	0x66,	// 4
	0x6d,	// 5
	0x7d,	// 6
	0x2f,	// 7
	0x7f,	// 8
	0x6f,	// 9
};

/*
 *	10MHz / 1024 / 256 = 38Hz
 */
SIGNAL(SIG_OVERFLOW0) {
	outp(SEG[(counter%10000)/1000], PORTA);
	outp(SEG[(counter%1000)/100], PORTB);
	outp(SEG[(counter%100)/10], PORTC);
	outp(SEG[counter%10], PORTD);
	counter++;
}

int main (void) {
	outp(0xff, DDRA);					// Set PORTA is OUTPUT Mode
	outp(0xff, DDRB);					// Set PORTB is OUTPUT Mode
	outp(0xff, DDRC);					// Set PORTC is OUTPUT Mode
	outp(0xff, DDRD);					// Set PORTD is OUTPUT Mode
	outp((1<<TOIE0), TIMSK);			// Timer#0 Interrupt ON
	outp((1<<CS02)|(1<<CS00), TCCR0);	// Timer#0 in Clock/1024
	outp((1<<SE), MCUCR);				// Enable SLEEP
	outp((1<<ACD), ACSR);				// PowerOff A/D Converter
	sei();								// Enable Interrupt

	counter = 0;

	for(;;) {
		sleep();
	}
}