实现系统函数time，获取当前时间与UTC的间隔

因种种原因，最近很少上cnblogs了。刚写了一个实现time的函数，可以通过该函数获取当前时间与1970年1月1日 0时0分0秒的差值，精确到秒，可以用在某些没有时候使用time不正确而不得不调用硬件时钟的场合。把其中HWCLOCK打开即可，关闭的话使用的是date获取的系统时间。其中打开时是应用在PPC架构的嵌入式linux上，具体源码如下：

#include <stdio.h>

#include <stdlib.h>

#include <string.h>



typedef unsigned short YEAR;

typedef unsigned short MONTH;

typedef unsigned short DAY;

typedef unsigned short HOUR;

typedef unsigned short MIN;

typedef unsigned short SEC;



char g_month[12][4] = {"Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"};



#define HWCLOCK





typedef struct struct_time

{

    YEAR    year;

    MONTH    mon;

    DAY        day;

    HOUR    hour;

    MIN        min;

    SEC        sec;

}time_s;



void PrintTimeStruct(time_s *t)

{

    if(t)

        printf("%d-%d-%d %d:%d:%d\n",t->year,t->mon,t->day,t->hour,t->min,t->sec);



}



void FillInElem(time_s *t,char *buf,int index)

{

    int i = 0;

    

    switch(index)

    {

        //week

        case 1:

            {                

                break;

            }

        //month

        case 2:

            {

                for(i = 0 ; i < 12 ; i++)

                {

                    if(strcasecmp(buf,g_month[i]) == 0)

                    {

                        t->mon = i+1;

                        break;

                    }

                }

                break;

            }

        //day    

        case 3:

            {

                t->day = atoi(buf);

                break;

            }

        //time    

        case 4:

            {

#ifdef HWCLOCK

                buf[2] = '\0';

                t->hour = atoi(buf);



                buf[5] = '\0';

                t->min = atoi(buf+3);



                t->sec = atoi(buf+6);

#else

                sscanf(buf,"%d:%d:%d",&t->hour,&t->min,&t->sec);

#endif

                break;

            }

#ifdef HWCLOCK

        case 5:

            {

                t->year = atoi(buf);

                break;

            }

#else

        //cst

        case 5:

            {

                break;

            }

        //year    

        case 6:

            {

                t->year = atoi(buf);

                break;

            }

#endif



        default:break;

        

    }



}



void GetTimeStruct(time_s *t,char *buf)

{

    int len = strlen(buf);

    int i = 0;

    int j = 0;

    int index = 0;

    

    char temp[20];



    if(!t || !buf)

    {

        return ;

    }



    memset(temp,0,sizeof(temp));    

    for(;i < len ; i++)

    {

        if(buf[i] != ' ')

        {

            temp[j] = buf[i];

            j++;            

        }

        else

        {

            index++;

            //printf("get %s index %d\n",temp,index);

            FillInElem(t,temp,index);

            memset(temp,0,sizeof(temp));

            j = 0;

#ifdef HWCLOCK

            if(index == 2)

            {

                i++;

            }

            if(index >= 5)

            {

                return;

            }

#endif    

        }

        

    }



    //printf("get %s \n",temp);

    index++;

    FillInElem(t,temp,index);

}





int GetHWClock(time_s *t)

{

    char buf[128];

#ifdef HWCLOCK

    system("hwclock > time.txt");



#else

    system("date > time.txt");



#endif



    FILE *fp = NULL;



    if((fp = fopen("time.txt","r")) != NULL)

    {

        fgets(buf,sizeof(buf),fp);

        fclose(fp);



        GetTimeStruct(t,buf);

        //printf("get :%s",buf);

        system("rm time.txt");

        return 1;

    }

    else

    {

        return 0;

    }

    

}



int IsRunYear(YEAR y)

{

    if( (y % 400 == 0) || ( (y % 4 == 0)&&(y % 100 != 0) ))

    {

        return 1;

    }

    return 0;

}



unsigned long long GetTickCount(time_s *t)

{

    if(t)

    {

        unsigned long long temp = 0;

        int RunYearNum = 0;// run nian  365



        int i = 0;



        //run nian

        for(i = 1970 ;i < t->year ; i++)

        {

            if( IsRunYear(i) == 1)

            {

                RunYearNum++;

            }

        }



        temp += RunYearNum* 366 * 24 * 60 * 60;

        temp += (t->year - 1970 - RunYearNum)* 365 * 24 * 60 * 60;

        //printf("%d run temp %llu\n",RunYearNum,temp);

        

        //month

        int day = 0;

        for(i = 1; i < t->mon ; i++)

        {

            if(i == 2)

            {

                if(IsRunYear(t->year) == 1)

                {

                    day += 29;

                }

                else

                {

                    day += 28;

                }

            }

            else if((i == 3) || (i == 5) || (i == 7) || (i == 8) || (i == 10) || (i == 12))

            {

                day += 31;

            }

            else

            {

                day += 30;

            }

        }

        

        temp += day*24*60*60;

        //printf("day  %d temp %llu\n",day,temp);

        //day

        temp += (t->day - 1)*24*60*60;



        //hour 

        temp += (t->hour)*60*60;



        //min

        temp += (t->min)*60;



        //sec

        temp += t->sec;



        return temp;

        

    }

    else

    {

        return 0;

    }



}



int main(void)

{

    time_s t;

    

    while(1)

    {

        GetHWClock(&t);

        PrintTimeStruct(&t);

    

        printf("tick  %llu \n",GetTickCount(&t));

        sleep(1);

    }



    

    

    return 0;

}