Extend time parsing to include the date rather than just the time

The initial time_t -> struct tm code concentrated on the time portion.
While we don't display the date at present it will be necessary for
calculating DST and is generally useful for completeness.

diff --git a/clock.c b/clock.c
index 4c94a6805081b877e2e868870a27c61310e6baf2..241b64cf8aea4e5b9c6189cd5e31c33e8fef2c3e 100644 (file)
--- a/clock.c
+++ b/clock.c
@@ -90,8 +90,16 @@ uint32_t ICACHE_FLASH_ATTR get_time(void)
        return sys_ticks / 1000000 + sys_delta;
 }
 
+bool ICACHE_FLASH_ATTR is_leap(uint32_t year)
+{
+       return year % 4 == 0 && (year % 100 != 0 || year % 400 == 0);
+}
+
 void ICACHE_FLASH_ATTR breakdown_time(uint32_t time, struct tm *result)
 {
+       uint32_t era, doe, yoe, mp;
+
+       /* Do the time component */
        result->tm_sec = time % 60;
        time /= 60;
        result->tm_min = time % 60;
@@ -99,8 +107,27 @@ void ICACHE_FLASH_ATTR breakdown_time(uint32_t time, struct tm *result)
        result->tm_hour = time % 24;
        time /= 24;
 
-       result->tm_year = time / (365 * 4 + 1) * 4 + 70;
-       time %= 365 * 4 + 1;
+       /* Now time is the number of days since 1970-01-01 (a Thursday) */
+       result->tm_wday = (time + 4) % 7;
+
+       /* Below from http://howardhinnant.github.io/date_algorithms.html */
+       time += 719468;
+       era = time / 146097;
+       doe = time - era * 146097;
+       yoe = (doe - doe / 1460 + doe / 36524 - doe / 146096) / 365;
+
+       result->tm_year = yoe + era * 400;
+       result->tm_yday = doe - (365 * yoe + yoe / 4 - yoe / 100);
+       mp = (5 * result->tm_yday + 2) / 153;
+       result->tm_mday = result->tm_yday - (153 * mp + 2) / 5 + 1;
+       result->tm_mon = mp + (mp < 10 ? 2 : -10);
+       if (result->tm_mon <=2)
+               result->tm_year++;
+
+       /* result->tm_yday is March 1st indexed at this point; fix up */
+       result->tm_yday += 28 + 31;
+       if (is_leap(result->tm_year))
+               result->tm_yday++;
 }
 
 static void ICACHE_FLASH_ATTR ntp_udp_timeout(void *arg)
@@ -143,8 +170,9 @@ static void ICACHE_FLASH_ATTR ntp_udp_recv(void *arg, char *pdata,
 
        // Print it out
        breakdown_time(timestamp, &dt);
-       os_printf("%04d %02d:%02d:%02d (%u)\r\n", dt.tm_year, dt.tm_hour,
-               dt.tm_min, dt.tm_sec, timestamp);
+       os_printf("%04d-%02d-%02d %02d:%02d:%02d (%u)\r\n",
+               dt.tm_year, dt.tm_mon + 1, dt.tm_mday,
+               dt.tm_hour, dt.tm_min, dt.tm_sec, timestamp);
 
        // clean up connection
        if (pCon) {