读取RTC时间

读取RTC时间

冷胜魁(Seaquester)
[e-mail]
2009-11-18

一段简单的代码演示如何使用RTC driver提供的接口读取RTC 时间，并与系统时间做比较。


 

#include <stdio.h>
#include <stdlib.h>
#include <linux/rtc.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <time.h>


int main(void)
{
        int fd, retval;
        struct rtc_time rtc_tm;
        time_t timep;
        struct tm *p;

        fd = open("/dev/rtc", O_RDONLY);
        if (fd == -1) {
                perror("/dev/rtc");
                exit(errno);
        }

        /* Read the RTC time/date */
        retval = ioctl(fd, RTC_RD_TIME, &rtc_tm);
        if (retval == -1) {
                perror("ioctl");
                exit(errno);
        }
        close(fd);

        fprintf(stderr, "RTC date/time: %d/%d/%d %02d:%02d:%02d\n",
                rtc_tm.tm_mday, rtc_tm.tm_mon + 1, rtc_tm.tm_year + 1900,
                rtc_tm.tm_hour, rtc_tm.tm_min, rtc_tm.tm_sec);

        time(&timep);
        p = gmtime(&timep);
        fprintf(stderr, "OS date/time(UTC): %d/%d/%d %02d:%02d:%02d\n",
                p->tm_mday, p->tm_mon + 1, p->tm_year + 1900,
                p->tm_hour, p->tm_min, p->tm_sec);
        
        p = localtime(&timep);
        fprintf(stderr, "OS date/time(Local): %d/%d/%d %02d:%02d:%02d\n",
                p->tm_mday, p->tm_mon + 1, p->tm_year + 1900,
                p->tm_hour, p->tm_min, p->tm_sec);
  
        return 0;
}