From: Alessandro Genova <ales.genova@gmail.com>
Date: Wed, 27 Aug 2025 01:44:00 +0000 (-0400)
Subject: Convert from timestamp to date_time once per second at most
X-Git-Url: https://git.earman.xyz/?a=commitdiff_plain;h=996d5d6679618e309a117437606bcec4e4365315;p=sensor-watch.git

Convert from timestamp to date_time once per second at most
---

diff --git a/movement.c b/movement.c
index d13146e..bc8b12f 100644
--- a/movement.c
+++ b/movement.c
@@ -614,8 +614,19 @@ watch_date_time_t movement_get_date_time_in_zone(uint8_t zone_index) {
 }
 
 watch_date_time_t movement_get_local_date_time(void) {
+    static struct {
+        unix_timestamp_t timestamp;
+        rtc_date_time_t datetime;
+    } cached_date_time = {.datetime.reg=0, .timestamp=0};
+
     unix_timestamp_t timestamp = watch_rtc_get_unix_time();
-    return watch_utility_date_time_from_unix_time(timestamp, movement_get_current_timezone_offset());
+
+    if (timestamp != cached_date_time.timestamp) {
+        cached_date_time.timestamp = timestamp;
+        cached_date_time.datetime = watch_utility_date_time_from_unix_time(timestamp, movement_get_current_timezone_offset());
+    }
+
+    return cached_date_time.datetime;
 }
 
 uint32_t movement_get_utc_timestamp(void) {
diff --git a/watch-library/hardware/watch/watch_rtc.c b/watch-library/hardware/watch/watch_rtc.c
index 1b0b5f4..114c1ee 100644
--- a/watch-library/hardware/watch/watch_rtc.c
+++ b/watch-library/hardware/watch/watch_rtc.c
@@ -91,7 +91,19 @@ void watch_rtc_set_date_time(rtc_date_time_t date_time) {
 }
 
 rtc_date_time_t watch_rtc_get_date_time(void) {
-    return watch_utility_date_time_from_unix_time(watch_rtc_get_unix_time(), 0);
+    static struct {
+        unix_timestamp_t timestamp;
+        rtc_date_time_t datetime;
+    } cached_date_time = {.datetime.reg=0, .timestamp=0};
+
+    unix_timestamp_t timestamp = watch_rtc_get_unix_time();
+
+    if (timestamp != cached_date_time.timestamp) {
+        cached_date_time.timestamp = timestamp;
+        cached_date_time.datetime = watch_utility_date_time_from_unix_time(timestamp, 0);
+    }
+
+    return cached_date_time.datetime;
 }
 
 void watch_rtc_set_unix_time(unix_timestamp_t unix_time) {