Diff: platform/mbed_mktime.c

Revision:

184:08ed48f1de7f

Parent:

169:e3b6fe271b81

--- a/platform/mbed_mktime.c	Tue Mar 20 17:01:51 2018 +0000
+++ b/platform/mbed_mktime.c	Thu Apr 19 17:12:19 2018 +0100
@@ -16,14 +16,17 @@
 
 #include "mbed_mktime.h"
 
-/*
- * time constants 
- */
+/* Time constants. */
 #define SECONDS_BY_MINUTES 60
 #define MINUTES_BY_HOUR 60
 #define SECONDS_BY_HOUR (SECONDS_BY_MINUTES * MINUTES_BY_HOUR)
 #define HOURS_BY_DAY 24 
 #define SECONDS_BY_DAY (SECONDS_BY_HOUR * HOURS_BY_DAY)
+#define LAST_VALID_YEAR 206
+
+/* Macros which will be used to determine if we are within valid range. */
+#define EDGE_TIMESTAMP_FULL_LEAP_YEAR_SUPPORT 3220095     // 7th of February 1970 at 06:28:15
+#define EDGE_TIMESTAMP_4_YEAR_LEAP_YEAR_SUPPORT 3133695  // 6th of February 1970 at 06:28:15
 
 /*
  * 2 dimensional array containing the number of seconds elapsed before a given 
@@ -63,10 +66,10 @@
     }
 };
 
-bool _rtc_is_leap_year(int year) {
+bool _rtc_is_leap_year(int year, rtc_leap_year_support_t leap_year_support) {
     /* 
      * since in practice, the value manipulated by this algorithm lie in the 
-     * range [70 : 138], the algorith can be reduced to: year % 4.
+     * range: [70 : 206] the algorithm can be reduced to: year % 4 with exception for 200 (year 2100 is not leap year).
      * The algorithm valid over the full range of value is: 
 
         year = 1900 + year;
@@ -80,86 +83,108 @@
         return true;
 
      */ 
+    if (leap_year_support == RTC_FULL_LEAP_YEAR_SUPPORT && year == 200) {
+        return false; // 2100 is not a leap year
+    }
+
     return (year) % 4 ? false : true;
 }
 
-time_t _rtc_mktime(const struct tm* time) {
-    // partial check for the upper bound of the range
-    // normalization might happen at the end of the function 
-    // this solution is faster than checking if the input is after the 19th of 
-    // january 2038 at 03:14:07.  
-    if ((time->tm_year < 70) || (time->tm_year > 138)) { 
-        return ((time_t) -1);
+bool _rtc_maketime(const struct tm* time, time_t * seconds, rtc_leap_year_support_t leap_year_support) {
+    if (seconds == NULL || time == NULL) {
+        return false;
+    }
+
+    /* Partial check for the upper bound of the range - check years only. Full check will be performed after the
+     * elapsed time since the beginning of the year is calculated.
+     */
+    if ((time->tm_year < 70) || (time->tm_year > LAST_VALID_YEAR)) {
+        return false;
     }
 
     uint32_t result = time->tm_sec;
     result += time->tm_min * SECONDS_BY_MINUTES;
     result += time->tm_hour * SECONDS_BY_HOUR;
     result += (time->tm_mday - 1) * SECONDS_BY_DAY;
-    result += seconds_before_month[_rtc_is_leap_year(time->tm_year)][time->tm_mon];
+    result += seconds_before_month[_rtc_is_leap_year(time->tm_year, leap_year_support)][time->tm_mon];
+
+    /* Check if we are within valid range. */
+    if (time->tm_year == LAST_VALID_YEAR) {
+        if ((leap_year_support == RTC_FULL_LEAP_YEAR_SUPPORT && result > EDGE_TIMESTAMP_FULL_LEAP_YEAR_SUPPORT) ||
+            (leap_year_support == RTC_4_YEAR_LEAP_YEAR_SUPPORT && result > EDGE_TIMESTAMP_4_YEAR_LEAP_YEAR_SUPPORT)) {
+        return false;
+        }
+    }
 
     if (time->tm_year > 70) { 
-        // valid in the range [70:138] 
+        /* Valid in the range [70:206]. */
         uint32_t count_of_leap_days = ((time->tm_year - 1) / 4) - (70 / 4);
+        if (leap_year_support == RTC_FULL_LEAP_YEAR_SUPPORT) {
+            if (time->tm_year > 200) {
+                count_of_leap_days--; // 2100 is not a leap year
+            }
+        }
+
         result += (((time->tm_year - 70) * 365) + count_of_leap_days) * SECONDS_BY_DAY;
     }
 
-    if (result > INT32_MAX) { 
-        return (time_t) -1;
-    }
+    *seconds = result;
 
-    return result;
+    return true;
 }
 
-bool _rtc_localtime(time_t timestamp, struct tm* time_info) {
-    if (((int32_t) timestamp) < 0) { 
+bool _rtc_localtime(time_t timestamp, struct tm* time_info, rtc_leap_year_support_t leap_year_support) {
+    if (time_info == NULL) {
         return false;
-    } 
+    }
+
+    uint32_t seconds = (uint32_t)timestamp;
 
-    time_info->tm_sec = timestamp % 60;
-    timestamp = timestamp / 60;   // timestamp in minutes
-    time_info->tm_min = timestamp % 60;
-    timestamp = timestamp / 60;  // timestamp in hours
-    time_info->tm_hour = timestamp % 24;
-    timestamp = timestamp / 24;  // timestamp in days;
+    time_info->tm_sec = seconds % 60;
+    seconds = seconds / 60;   // timestamp in minutes
+    time_info->tm_min = seconds % 60;
+    seconds = seconds / 60;  // timestamp in hours
+    time_info->tm_hour = seconds % 24;
+    seconds = seconds / 24;  // timestamp in days;
 
-    // compute the weekday
-    // The 1st of January 1970 was a Thursday which is equal to 4 in the weekday
-    // representation ranging from [0:6]
-    time_info->tm_wday = (timestamp + 4) % 7;
+    /* Compute the weekday.
+     * The 1st of January 1970 was a Thursday which is equal to 4 in the weekday representation ranging from [0:6].
+     */
+    time_info->tm_wday = (seconds + 4) % 7;
 
-    // years start at 70
+    /* Years start at 70. */
     time_info->tm_year = 70;
     while (true) { 
-        if (_rtc_is_leap_year(time_info->tm_year) && timestamp >= 366) {
+        if (_rtc_is_leap_year(time_info->tm_year, leap_year_support) && seconds >= 366) {
             ++time_info->tm_year;
-            timestamp -= 366;
-        } else if (!_rtc_is_leap_year(time_info->tm_year) && timestamp >= 365) {
+            seconds -= 366;
+        } else if (!_rtc_is_leap_year(time_info->tm_year, leap_year_support) && seconds >= 365) {
             ++time_info->tm_year;
-            timestamp -= 365;
+            seconds -= 365;
         } else {
-            // the remaining days are less than a years
+            /* The remaining days are less than a years. */
             break;
         }
     }
 
-    time_info->tm_yday = timestamp;
+    time_info->tm_yday = seconds;
 
-    // convert days into seconds and find the current month
-    timestamp *= SECONDS_BY_DAY;
+    /* Convert days into seconds and find the current month. */
+    seconds *= SECONDS_BY_DAY;
     time_info->tm_mon = 11;
-    bool leap = _rtc_is_leap_year(time_info->tm_year);
+    bool leap = _rtc_is_leap_year(time_info->tm_year, leap_year_support);
     for (uint32_t i = 0; i < 12; ++i) {
-        if ((uint32_t) timestamp < seconds_before_month[leap][i]) {
+        if ((uint32_t) seconds < seconds_before_month[leap][i]) {
             time_info->tm_mon = i - 1;
             break;
         }
     }
 
-    // remove month from timestamp and compute the number of days.
-    // note: unlike other fields, days are not 0 indexed.
-    timestamp -= seconds_before_month[leap][time_info->tm_mon];
-    time_info->tm_mday = (timestamp / SECONDS_BY_DAY) + 1;
+    /* Remove month from timestamp and compute the number of days.
+     * Note: unlike other fields, days are not 0 indexed.
+     */
+    seconds -= seconds_before_month[leap][time_info->tm_mon];
+    time_info->tm_mday = (seconds / SECONDS_BY_DAY) + 1;
 
     return true;
 }