From: Ben Harris <bjh21@bjh21.me.uk>
Date: Sat, 3 Nov 2018 23:06:07 +0000 (+0000)
Subject: Make the boundary between ADVANCE and STOP variable at compile time.
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~bjharris/git?a=commitdiff_plain;h=15f6b14a9f22615734e05bd044292594ba3b6bb5;p=clunk.git

Make the boundary between ADVANCE and STOP variable at compile time.
---

diff --git a/clunk.c b/clunk.c
index 6e6e191..669c8b8 100644
--- a/clunk.c
+++ b/clunk.c
@@ -6,6 +6,16 @@
 
 static long const pulsewidth = 250000000; /* nanoseconds */
 
+/*
+ * Maximum error to correct by advancing the clock rather than
+ * stopping it, in seconds.  The point where it's faster to stop the
+ * clock than to advance it is around 11:15 forwards (0:45 backwards),
+ * but this is set a little lower so that setting the clock back for
+ * the end of summer time is done by stopping, in accordance with
+ * Synchronome's documentation.
+ */
+static int const maxadvance = (10 * 3600) + (50 * 60);
+
 static struct tm displayed;
 
 static void
@@ -68,7 +78,7 @@ need_adjust(struct tm const *now)
 	if (diff < 0) diff += 3600 * 12;
 	diff %= 3600 * 12;
 	printf("diff = %ld\n", diff);
-	if (diff < 30 || diff >= (10 * 3600)) return STOP;
+	if (diff < 30 || diff >= maxadvance) return STOP;
 	if (diff < 60) return TICK;
 	if (diff < (10 * 3600)) return ADVANCE;
 }