Linux定时器-获取系统时间时区等信息

目录

测试代码

结构体 timeval

结构体 timespec

函数gettimeofday（）

---

测试代码

如下：每秒打印一次输出。

#include 
#include 
#include 


typedef signed char		int8_t;
typedef short int		int16_t;
typedef int			    int32_t;
typedef long int		int64_t;

typedef unsigned char		uint8_t;
typedef unsigned short int	uint16_t;
typedef unsigned int		uint32_t;
typedef unsigned long int	uint64_t;

/* General types */
typedef uint8_t             boolean;
#define TRUE                1
#define FALSE               0
typedef int8_t              int8;
typedef int16_t             int16;
typedef int32_t             int32;
typedef uint8_t             uint8;
typedef uint16_t            uint16;
typedef uint32_t            uint32;
typedef int64_t             int64;
typedef uint64_t            uint64;
typedef float               float32;
typedef double              float64;

#define USECS_PER_SEC   1000000

typedef struct
{
    uint32 sec;     /*< Seconds elapsed since the Epoch (Jan 1, 1970) */
    int32 usec;    /*< Microseconds elapsed since last second boundary */
} ec_timet;

typedef struct timer
{
    ec_timet stop_time;
} timert;


void timer_start (timert * self, uint32 timeout_usec)
{
   struct timeval start_time;
   struct timeval timeout;
   struct timeval stop_time;

   gettimeofday (&start_time, 0);
   timeout.tv_sec = timeout_usec / USECS_PER_SEC;
   timeout.tv_usec = timeout_usec % USECS_PER_SEC;
   timeradd (&start_time, &timeout, &stop_time);

   self->stop_time.sec = stop_time.tv_sec;
   self->stop_time.usec = stop_time.tv_usec;
}

boolean timer_is_expired (timert * self)
{
   struct timeval current_time;
   struct timeval stop_time;
   int is_not_yet_expired;

   gettimeofday (¤t_time, 0);
   stop_time.tv_sec = self->stop_time.sec;
   stop_time.tv_usec = self->stop_time.usec;
   is_not_yet_expired = timercmp (¤t_time, &stop_time, <);

   return is_not_yet_expired == FALSE;
}

//1 秒 = 1000 毫秒=1000,000 微秒 1 秒=1000,000,000 纳秒
void main()
{
    uint32 i = 0;
    uint32 s_count = 10;
    uint32 us_count=s_count*USECS_PER_SEC;
    timert timer1;
    struct timeval act_timer1 ;
    struct timeval last_timer1 ;
    timer_start (&timer1, us_count);//us
    do 
    {   
        i = i + 1;    
        gettimeofday (&act_timer1, 0);
        if (act_timer1.tv_sec != last_timer1.tv_sec)
        {

            printf ("Actual Secs = %ld\t, number = %d\n", act_timer1.tv_sec,i);//i = 每秒计算多少次。
            //printf ("number = %d\n",i);
            i=0;
        }
        last_timer1.tv_sec = act_timer1.tv_sec;
        
    /* wait for answer with WKC>=0 or otherwise retry until timeout */   
    } while (!timer_is_expired (&timer1));

    printf ("timer expried \n");

}

运行结果如下：

zzh@ubuntu:~/linux/learn/test_timer$ gcc timer.c 
zzh@ubuntu:~/linux/learn/test_timer$ ./a.out 
Actual Secs = 1690299755	, number = 1
Actual Secs = 1690299756	, number = 16901286
Actual Secs = 1690299757	, number = 20853513
Actual Secs = 1690299758	, number = 20693789
Actual Secs = 1690299759	, number = 20792398
Actual Secs = 1690299760	, number = 20695619
Actual Secs = 1690299761	, number = 20902803
Actual Secs = 1690299762	, number = 20854518
Actual Secs = 1690299763	, number = 20923948
Actual Secs = 1690299764	, number = 20872630
Actual Secs = 1690299765	, number = 20915321
timer expried 
zzh@ubuntu:~/linux/learn/test_timer$ 

 知识点总结:

结构体 timeval

/* A time value that is accurate to the nearest
   microsecond but also has a range of years.  */
struct timeval
  {
    __time_t tv_sec;		/* Seconds.  */
    __suseconds_t tv_usec;	/* Microseconds.  */
  };

该结构体只是包括： tv_sec 单位是秒，tv_usec单位是微秒。

结构体 timespec

struct timespec
  {
    __time_t tv_sec;		/* Seconds.  */
    __syscall_slong_t tv_nsec;	/* Nanoseconds.  */
  };

该结构体只是包括： tv_sec 单位是秒，tv_nsec单位是纳秒。

函数gettimeofday（）

/* Get the current time of day and timezone information,
   putting it into *TV and *TZ.  If TZ is NULL, *TZ is not filled.
   Returns 0 on success, -1 on errors.
   NOTE: This form of timezone information is obsolete.
   Use the functions and variables declared in  instead.  */
extern int gettimeofday (struct timeval *__restrict __tv,
			 __timezone_ptr_t __tz) __THROW __nonnull ((1));

获取当前时间和时区，为UTC时间，1970年以来的秒+微秒、时区信息。