8位单片机可用的 mktime localtime函数

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：

1 #include

2 #include

3 #include

4 #include

5

6 #if 0

7 struct tm {

8 int tm_sec; /* seconds after the minute, 0 to 60

9 (0 - 60 allows for the occasional leap second) */

10 int tm_min; /* minutes after the hour, 0 to 59 */

11 int tm_hour; /* hours since midnight, 0 to 23 */

12 int tm_mday; /* day of the month, 1 to 31 */

13 int tm_mon; /* months since January, 0 to 11 */

14 int tm_year; /* years since 1900 */

15 // int tm_wday; /* days since Sunday, 0 to 6 */

16 // int tm_yday; /* days since January 1, 0 to 365 */

17 // int tm_isdst; /* Daylight Savings Time flag */

18 };

19 #endif

20 static const char mon_list[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

21 static const char leap_mon_list[12] = {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

22

23 /*******************************************************************************

24 * Function Name : fun_mktime

25 * Description : 时间转为时间戳

26 * Input :

27 * Output :

28 * Other :

29 * Date : 2016.11.14

30 *******************************************************************************/

31 int32_t fun_mktime(struct tm *pT)

32 {

33 const char *pDays = NULL;

34 int32_t tmp = 0;

35 int16_t i = 0;

36

37 //计算总共有多少个闰年

38 tmp = (pT->tm_year / 4 - pT->tm_year / 100 + pT->tm_year / 400) - (1970 / 4 - 1970 / 100 + 1970 / 400);

39

40 //如果当年是闰年，需要减去当年的闰年

41 if ((pT->tm_year % 4 == 0) && ((pT->tm_year % 100 != 0) || (pT->tm_year % 400 == 0)))

42 {

43 tmp = tmp - 1 + (pT->tm_year - 1970) * 365;

44 pDays = leap_mon_list;

45 }

46 else

47 {

48 tmp = tmp + (pT->tm_year - 1970) * 365;

49 pDays = mon_list;

50 }

51

52 for (i = 0; i < pT->tm_mon - 1; i++)

53 tmp += pDays[i];

54

55 tmp = tmp + pT->tm_mday - 1;

56

57 tmp = tmp * 24 + pT->tm_hour;

58

59 tmp = tmp * 60 + pT->tm_min;

60

61 tmp = tmp * 60 + pT->tm_sec;

62

63 return tmp;

64 }

65

66 /*******************************************************************************

67 * Function Name : fun_localtime

68 * Description : 时间戳转为时间

69 * Input : struct tm *pT： 输出的时间缓冲区 uint32_t tim:当前时间戳

70 * Output :

71 * Other :

72 * Date : 2016.11.14

73 *******************************************************************************/

74 void fun_localtime(struct tm *pT, int32_t tim)

75 {

76 const char *pDays = NULL;

77

78 uint16_t index = 0;

79

80 memset(pT, 0, sizeof(*pT));

81

82 //year initialization

83 if (tim > 0x5685C180L) // 2016-1-1 0:0:0

84 {

85 pT->tm_year = 2016;

86 tim -= 0x5685C180L;

87 }

88 else if (tim > 0x4B3D3B00L) // 2010-1-1 0:0:0

89 {

90 pT->tm_year = 2010;

91 tim -= 0x4B3D3B00L;

92 }

93 else if (tim > 0x386D4380L) // 2000-1-1 0:0:0

94 {

95 pT->tm_year = 2000;

96 tim -= 0x386D4380L;

97 }

98 else

99 {

100 pT->tm_year = 1970;

101 }

102

103 //now have year

104 while (tim >= 366L * 24 * 60 * 60)

105 {

106 if ((pT->tm_year % 4 == 0) && ((pT->tm_year % 100 != 0) || (pT->tm_year % 400 == 0)))

107 tim -= 366L * 24 * 60 * 60;

108 else

109 tim -= 365L * 24 * 60 * 60;

110

111 pT->tm_year++;

112 }

113

114 // then 365 * 24 * 60 * 60 < tim < 366 * 24 * 60 * 60

115 if (!(((pT->tm_year % 4 == 0) && ((pT->tm_year % 100 != 0) || (pT->tm_year % 400 == 0))))

116 && (tim > 365L * 24 * 60 * 60))

117 {

118 tim -= 365L * 24 * 60 * 60;

119 pT->tm_year++;

120 }

121

122 // this year is a leap year?

123 if (((pT->tm_year % 4 == 0) && ((pT->tm_year % 100 != 0) || (pT->tm_year % 400 == 0))))

124 pDays = leap_mon_list;

125 else

126 pDays = mon_list;

127

128 pT->tm_mon = 1;

129 // now have mon

130 while (tim > pDays[index] * 24L * 60 * 60)

131 {

132 tim -= pDays[index] * 24L * 60 * 60;

133 index++;

134 pT->tm_mon++;

135 }

136

137 // now have days

138 pT->tm_mday = tim / (24L * 60 * 60) + 1;

139 tim = tim % (24L * 60 * 60);

140

141 // now have hour

142 pT->tm_hour = tim / (60 * 60);

143 tim = tim % (60 * 60);

144

145 // now have min

146 pT->tm_min = tim / 60;

147 tim = tim % 60;

148

149 pT->tm_sec = tim;

150 }

151

152

153 int main (void *parg)

154 {

155 struct tm *pT = {0};

156 time_t timep = 0;

157 uint32_t cur_tim = 0;

158

159 time(&timep);

160

161 pT = localtime(&timep);

162

163 printf("linux time t= %dn", (int32_t)timep);

164 pT->tm_year += 1900;

165 pT->tm_mon += 1;

166 printf("fun_mktime t= %dn", cur_tim = (uint32_t)fun_mktime(pT));

167

168 printf("localtime t= %d-%d-%d %d:%d:%dn", pT->tm_year, pT->tm_mon, pT->tm_mday, pT->tm_hour, pT->tm_min, pT->tm_sec);

169 memset(pT, 0, sizeof(*pT));

170 fun_localtime(pT, cur_tim);

171 printf("fun_localtime t= %d-%d-%d %d:%d:%dn", pT->tm_year, pT->tm_mon, pT->tm_mday, pT->tm_hour, pT->tm_min, pT->tm_sec);

172 return 0;

173 }

测试结果：

linux time = 1480133002

fun_mktime = 1480161802

localtime = 2016-11-26 12:3:22

fun_localtime = 2016-11-26 12:3:22

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