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[][] = {"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 = ;

    switch(index)
    {
        //week
        case :
            {
                break;
            }
        //month
        case :
            {
                for(i =  ; i <  ; i++)
                {
                    if(strcasecmp(buf,g_month[i]) == )
                    {
                        t->mon = i+;
                        break;
                    }
                }
                break;
            }
        //day
        case :
            {
                t->day = atoi(buf);
                break;
            }
        //time
        case :
            {
#ifdef HWCLOCK
                buf[] = '\0';
                t->hour = atoi(buf);

                buf[] = '\0';
                t->min = atoi(buf+);

                t->sec = atoi(buf+);
#else
                sscanf(buf,"%d:%d:%d",&t->hour,&t->min,&t->sec);
#endif
                break;
            }
#ifdef HWCLOCK
        case :
            {
                t->year = atoi(buf);
                break;
            }
#else
        //cst
        case :
            {
                break;
            }
        //year
        case :
            {
                t->year = atoi(buf);
                break;
            }
#endif

        default:break;

    }

}

void GetTimeStruct(time_s *t,char *buf)
{
    int len = strlen(buf);
    int i = ;
    int j = ;
    int index = ;

    char temp[];

    if(!t || !buf)
    {
        return ;
    }

    memset(temp,,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,,sizeof(temp));
            j = ;
#ifdef HWCLOCK
            if(index == )
            {
                i++;
            }
            if(index >= )
            {
                return;
            }
#endif
        }

    }

    //printf("get %s \n",temp);
    index++;
    FillInElem(t,temp,index);
}

int GetHWClock(time_s *t)
{
    char buf[];
#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 ;
    }
    else
    {
        return ;
    }

}

int IsRunYear(YEAR y)
{
    if( (y %  == ) || ( (y %  == )&&(y %  != ) ))
    {
        return ;
    }
    return ;
}

unsigned long long GetTickCount(time_s *t)
{
    if(t)
    {
        unsigned long long temp = ;
        int RunYearNum = ;// run nian  365

        int i = ;

        //run nian
        for(i =  ;i < t->year ; i++)
        {
            if( IsRunYear(i) == )
            {
                RunYearNum++;
            }
        }

        temp += RunYearNum*  *  *  * ;
        temp += (t->year -  - RunYearNum)*  *  *  * ;
        //printf("%d run temp %llu\n",RunYearNum,temp);

        //month
        int day = ;
        for(i = ; i < t->mon ; i++)
        {
            if(i == )
            {
                if(IsRunYear(t->year) == )
                {
                    day += ;
                }
                else
                {
                    day += ;
                }
            }
            else if((i == ) || (i == ) || (i == ) || (i == ) || (i == ) || (i == ))
            {
                day += ;
            }
            else
            {
                day += ;
            }
        }

        temp += day***;
        //printf("day  %d temp %llu\n",day,temp);
        //day
        temp += (t->day - )***;

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

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

        //sec
        temp += t->sec;

        return temp;

    }
    else
    {
        return ;
    }

}

int main(void)
{
    time_s t;

    while()
    {
        GetHWClock(&t);
        PrintTimeStruct(&t);

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

    return ;
}