#include <stdio.h>
#include <unistd.h>
#include <poll.h>
#include <fcntl.h>
#define GPIO_DIR "/sys/class/gpio"
#define GPIO_NAME "gpio246"
#define GPIO_PATH GPIO_DIR "/" GPIO_NAME "/"
int main(void)
{
	int fd;
	int i;
	int ret;
	fd = open(GPIO_PATH "direction", O_RDWR);
	printf("fd=%d\n", fd);
	ret = write(fd, "in", 2);
	printf("write=%d\n", ret);
	close(fd);
	fd = open(GPIO_PATH "edge", O_RDWR);
	printf("fd=%d\n", fd);
//	ret=write(fd, "rising", 6);
	ret=write(fd, "falling", 7);
	printf("write=%d\n", ret);
	close(fd);
	for (i=0; i < 3; i++) {
		char val;
		struct pollfd pfd;
		fd = open(GPIO_PATH "value", O_RDWR);
		printf("fd=%d\n", fd);

		ret=read(fd, &val, 1);
		printf("read=%d val=%c\n", ret, val);
		printf("waiting for interrupt..."); fflush(stdout);
		pfd.fd = fd;
		pfd.events = POLLIN;
		pfd.revents = 0;
		ret = poll(&pfd, 1, -1);
		printf("poll=%d revent=0x%x\n", ret, pfd.revents);
		ret=lseek(fd, 0, SEEK_SET);
		printf("lseek=%d\n", ret);
		ret = read(fd, &val, 1);
		printf("read=%d val=%c\n", ret, val);
		close(fd);
		printf("OK (%c, %s)\n", val, val == '0' ? "Low" : "High");
		usleep(100000);
	}
	return 0;
}