内核定时机制API之mktime

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
static inline unsigned long mktime(const unsigned int year,
			const unsigned int mon, const unsigned int day,
			const unsigned int hour, const unsigned int min,
			const unsigned int sec)
这个函数用于返回形参表示的时间到1970年的秒数
其源码分析如下：
static inline unsigned long mktime(const unsigned int year,
			const unsigned int mon, const unsigned int day,
			const unsigned int hour, const unsigned int min,
			const unsigned int sec)
{
	return mktime64(year, mon, day, hour, min, sec);
}
直接调用mktime64
time64_t mktime64(const unsigned int year0, const unsigned int mon0,
		const unsigned int day, const unsigned int hour,
		const unsigned int min, const unsigned int sec)
{
	unsigned int mon = mon0, year = year0;

	/* 1..12 -> 11,12,1..10 */
	if (0 >= (int) (mon -= 2)) {
		mon += 12;	/* Puts Feb last since it has leap day */
		year -= 1;
	}

	return ((((time64_t)
		  (year/4 - year/100 + year/400 + 367*mon/12 + day) +
		  year*365 - 719499
	    )*24 + hour /* now have hours - midnight tomorrow handled here */
	  )*60 + min /* now have minutes */
	)*60 + sec; /* finally seconds */
}
程序比较简单就是用形参时间减去1970年表示时间得到的秒数.