long kernel_mktime(struct tm * tm){
long res; int year;
year = tm->tm_year - 70;/* magic offsets (y+1) needed to get leapyears right.*/
res = YEAR*year + DAY*((year+1)/4);
res += month[tm->tm_mon];/* and (y+2) here. If it wasn't a leap-year, we have to adjust */
if (tm->tm_mon>1 && ((year+2)%4))
res -= DAY; res += DAY*(tm->tm_mday-1);
res += HOUR*tm->tm_hour;
res += MINUTE*tm->tm_min;
res += tm->tm_sec;
return res;
}
本文详细解析了longkernel_mktime函数的实现原理及过程。该函数通过计算年份、月份、日期、小时、分钟和秒数来获取时间戳。特别地,文章关注于如何正确处理闰年,并解释了为什么需要特定的偏移量来确保计算准确。
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