/* *      Buttons Example for Matrix V * *      Copyright (C) 2004 capbily - friendly-arm *	capbily@hotmail.com */#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <sys/ioctl.h>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <sys/select.h>#include <sys/time.h>#include <errno.h>int main(void){	int buttons_fd;	int key_value;	buttons_fd = open("/dev/buttons", 0);	if (buttons_fd < 0) {		perror("open device buttons");		exit(1);	}	for (;;) {		fd_set rds;		int ret;		FD_ZERO(&rds);		FD_SET(buttons_fd, &rds);		ret = select(buttons_fd + 1, &rds, NULL, NULL, NULL);		if (ret < 0) {			perror("select");			exit(1);		}		if (ret == 0) {			printf("Timeout.\n");		} else if (FD_ISSET(buttons_fd, &rds)) {			int ret = read(buttons_fd, &key_value, sizeof key_value);			if (ret != sizeof key_value) {				if (errno != EAGAIN)					perror("read buttons\n");				continue;			} else {				printf("buttons_value: %d\n", key_value);			}						}	}	close(buttons_fd);	return 0;}