8位单片机可用的 mktime localtime函数

8位单片机可用的 mktime  localtime函数及源码

最近在做一个8位单片机项目，其中用到了时间戳转换函数，这个在32位机上一个库函数就解决了问题，没想到在8位单片机中没有对应库（time.h），没有办法只有自己来写。

目标：1，满足和库函数mktime  localtime所计算出的数据一至；2，考虑8位单片机的处理能力慢软件效率问题。

分享给大家，方便有同样需求的朋友。

gcc 环境进行测试：

测试程序：

 #include <stdio.h>
 #include <stdint.h>
 #include <time.h>
 #include <string.h>

 #if 0
 struct tm {
     int tm_sec;   /* seconds after the minute, 0 to 60
                      (0 - 60 allows for the occasional leap second) */
     int tm_min;   /* minutes after the hour, 0 to 59 */
     int tm_hour;  /* hours since midnight, 0 to 23 */
     int tm_mday;  /* day of the month, 1 to 31 */
     int tm_mon;   /* months since January, 0 to 11 */
     int tm_year;  /* years since 1900 */
 //    int tm_wday;  /* days since Sunday, 0 to 6 */
 //    int tm_yday;  /* days since January 1, 0 to 365 */
 //    int tm_isdst; /* Daylight Savings Time flag */
 };
 #endif
 static const char mon_list[]             = {, , , , , , , , , , , };
 static const char leap_mon_list[]        = {, , , , , , , , , , , };

 /*******************************************************************************
 * Function Name : fun_mktime
 * Description   : 时间转为时间戳
 * Input         :
 * Output        :
 * Other         :
 * Date          : 2016.11.14
 *******************************************************************************/
 int32_t fun_mktime(struct tm *pT)
 {
     const char *pDays = NULL;
     int32_t tmp = ;
     int16_t i = ;

     //计算总共有多少个闰年
     tmp = (pT->tm_year  /  - pT->tm_year /  + pT->tm_year / ) - ( /  -  /  +  / );

     //如果当年是闰年，需要减去当年的闰年
     if ((pT->tm_year %  == ) && ((pT->tm_year  %  != ) || (pT->tm_year  %  == )))
     {
         tmp = tmp -  + (pT->tm_year - ) * ;
         pDays = leap_mon_list;
     }
     else
     {
         tmp = tmp + (pT->tm_year - ) * ;
         pDays = mon_list;
     }

     for (i = ; i < pT->tm_mon - ; i++)
         tmp += pDays[i];

     tmp = tmp + pT->tm_mday - ;

     tmp = tmp *  + pT->tm_hour;

     tmp = tmp *  + pT->tm_min;

     tmp = tmp *  + pT->tm_sec;

     return tmp;
 }

 /*******************************************************************************
 * Function Name : fun_localtime
 * Description   : 时间戳转为时间
 * Input         :   struct tm *pT： 输出的时间缓冲区   uint32_t tim:当前时间戳
 * Output        :
 * Other         :
 * Date          : 2016.11.14
 *******************************************************************************/
 void fun_localtime(struct tm *pT, int32_t tim)
 {
   const char *pDays = NULL;

   uint16_t index = ;

   memset(pT, , sizeof(*pT));

   //year initialization
   if (tim > 0x5685C180L)            // 2016-1-1 0:0:0
   {
     pT->tm_year = ;
     tim -= 0x5685C180L;
   }
   else if (tim > 0x4B3D3B00L)       // 2010-1-1 0:0:0
   {
     pT->tm_year = ;
     tim -= 0x4B3D3B00L;
   }
   else if (tim > 0x386D4380L)       // 2000-1-1 0:0:0
   {
     pT->tm_year = ;
     tim -= 0x386D4380L;
   }
   else
   {
     pT->tm_year = ;
   }

   //now have year
   while (tim >= 366L *  *  * )
   {
     if ((pT->tm_year %  == ) && ((pT->tm_year  %  != ) || (pT->tm_year  %  == )))
       tim -= 366L *  *  * ;
     else
       tim -= 365L *  *  * ;

     pT->tm_year++;
   }

   // then 365 * 24 * 60 * 60 < tim < 366 * 24 * 60 * 60
   if (!(((pT->tm_year %  == ) && ((pT->tm_year  %  != ) || (pT->tm_year  %  == ))))
     && (tim > 365L *  *  * ))
   {
     tim -= 365L *  *  * ;
     pT->tm_year++;
   }

   // this year is a leap year?
   if (((pT->tm_year %  == ) && ((pT->tm_year  %  != ) || (pT->tm_year  %  == ))))
     pDays = leap_mon_list;
   else
     pDays = mon_list;

   pT->tm_mon = ;
   // now have mon
   while (tim > pDays[index] * 24L *  * )
   {
     tim -= pDays[index] * 24L *  * ;
     index++;
     pT->tm_mon++;
   }

   // now have days
   pT->tm_mday = tim / (24L *  * ) + ;
   tim = tim % (24L *  * );

   // now have hour
   pT->tm_hour = tim / ( * );
   tim = tim % ( * );

   // now have min
   pT->tm_min = tim / ;
   tim = tim % ;

   pT->tm_sec = tim;
 }

 int main (void *parg)
 {
   struct tm *pT = {};
   time_t timep = ;
   uint32_t cur_tim = ;

   time(&timep);

   pT = localtime(&timep);

   printf("linux time \t= %d\n", (int32_t)timep);
   pT->tm_year += ;
   pT->tm_mon += ;
   printf("fun_mktime \t= %d\n", cur_tim = (uint32_t)fun_mktime(pT));

   printf("localtime \t= %d-%d-%d %d:%d:%d\n", pT->tm_year, pT->tm_mon, pT->tm_mday, pT->tm_hour, pT->tm_min, pT->tm_sec);
   memset(pT, , sizeof(*pT));
   fun_localtime(pT, cur_tim);
   printf("fun_localtime \t= %d-%d-%d %d:%d:%d\n", pT->tm_year, pT->tm_mon, pT->tm_mday, pT->tm_hour, pT->tm_min, pT->tm_sec);
   return ;
 }

测试结果：

linux time      =
fun_mktime      =
localtime       = -- ::
fun_localtime   = -- ::

linux time 是库函数mktime计算结果，因为进行了时区处理，所以与fun_mktime计算出来刚好是8 * 3600 秒的差值

此函数在C51下进行过测试，符合要求。