buttontest.c

来自「linux下的矩阵式键盘驱动ppt教程与源码实例!」· C语言 代码 · 共 53 行

#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;
}