timefuncs: add dostime_localtime function

This does the opposite of dostime_mktime, converting time_t back to
the two dos date time values. We use gmtime_r for native because that
is what is available and acts the same as localtime_r on other platforms
with a regular libc available.

Change-Id: If79469d0aae2d7c5dcdd905fbf04963669aa1138

2 files changed, 18 insertions, 0 deletions

diff --git a/firmware/common/timefuncs.c b/firmware/common/timefuncs.c
index d87e6b67f2..66854dea13 100644
--- a/firmware/common/timefuncs.c
+++ b/firmware/common/timefuncs.c
@@ -46,6 +46,23 @@ time_t dostime_mktime(uint16_t dosdate, uint16_t dostime)
     return mktime(&tm);
 }
 
+void dostime_localtime(time_t time, uint16_t* dosdate, uint16_t* dostime)
+{
+    struct tm tm;
+#if (CONFIG_PLATFORM & PLATFORM_NATIVE)
+    gmtime_r(&time, &tm);
+#else
+    localtime_r(&time, &tm);
+#endif
+
+    *dostime = ((tm.tm_sec  /  2) <<  0)|
+               ((tm.tm_min      ) <<  5)|
+               ((tm.tm_hour     ) << 11);
+    *dosdate = ((tm.tm_mday     ) <<  0)|
+               ((tm.tm_mon  +  1) <<  5)|
+               ((tm.tm_year - 80) <<  9);
+}
+
 #if !CONFIG_RTC
 static inline bool rtc_dirty(void)
 {
diff --git a/firmware/include/timefuncs.h b/firmware/include/timefuncs.h
index 2e8ef01ca6..25e041b576 100644
--- a/firmware/include/timefuncs.h
+++ b/firmware/include/timefuncs.h
@@ -28,6 +28,7 @@
 #include "time.h"
 
 time_t dostime_mktime(uint16_t dosdate, uint16_t dostime);
+void dostime_localtime(time_t time, uint16_t* dosdate, uint16_t* dostime);
 struct tm *get_time(void);
 int set_time(const struct tm *tm);
 #if CONFIG_RTC