1. 根目录:
2. include
3. uapi
4. linux
5. time.h

#ifndef _UAPI_LINUX_TIME_H
#define _UAPI_LINUX_TIME_H

#include <linux/types.h>


#ifndef _STRUCT_TIMESPEC
#define _STRUCT_TIMESPEC
struct timespec {
	__kernel_time_t	tv_sec;			/* seconds */
	long		tv_nsec;		/* nanoseconds */
};
#endif

struct timeval {
	__kernel_time_t		tv_sec;		/* seconds */
	__kernel_suseconds_t	tv_usec;	/* microseconds */
};

struct timezone {
	int	tz_minuteswest;	/* minutes west of Greenwich */
	int	tz_dsttime;	/* type of dst correction */
};


/*
 * Names of the interval timers, and structure
 * defining a timer setting:
 */
#define	ITIMER_REAL		0
#define	ITIMER_VIRTUAL		1
#define	ITIMER_PROF		2

struct itimerspec {
	struct timespec it_interval;	/* timer period */
	struct timespec it_value;	/* timer expiration */
};

struct itimerval {
	struct timeval it_interval;	/* timer interval */
	struct timeval it_value;	/* current value */
};

/*
 * The IDs of the various system clocks (for POSIX.1b interval timers):
 */
#define CLOCK_REALTIME			0
#define CLOCK_MONOTONIC			1
#define CLOCK_PROCESS_CPUTIME_ID	2
#define CLOCK_THREAD_CPUTIME_ID		3
#define CLOCK_MONOTONIC_RAW		4
#define CLOCK_REALTIME_COARSE		5
#define CLOCK_MONOTONIC_COARSE		6
#define CLOCK_BOOTTIME			7
#define CLOCK_REALTIME_ALARM		8
#define CLOCK_BOOTTIME_ALARM		9
#define CLOCK_SGI_CYCLE			10	/* Hardware specific */
#define CLOCK_TAI			11

#define MAX_CLOCKS			16
#define CLOCKS_MASK			(CLOCK_REALTIME | CLOCK_MONOTONIC)
#define CLOCKS_MONO			CLOCK_MONOTONIC

/*
 * The various flags for setting POSIX.1b interval timers:
 */
#define TIMER_ABSTIME			0x01

#endif /* _UAPI_LINUX_TIME_H */