#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define MSEC 1000

#define LED_OFF   fputs("7,1", led)
#define LED_ON    fputs("7,2", led)
#define LED_BLINK fputs("7,3", led)

void randblink(FILE* led);

main()
{
	FILE* f_led;

	f_led = fopen("/var/led", "w");
	setvbuf(f_led, NULL, _IONBF, BUFSIZ);

	randblink(f_led);

	return 0;
}

void randblink(FILE* led)
{
	int r;

	srand(time(NULL));
	while (1) {
		r = 1+(int) (3.0*rand()/(RAND_MAX+1.0));
		switch (r) {
			case 1:
				LED_OFF;
				break;
			case 2:
				LED_ON;
				break;
			case 3:
				LED_BLINK;
				break;
		}
		usleep(1+(int) (100.0*MSEC*rand()/(RAND_MAX+1.0)));

	}
}