From: Ben Harris <bjh21@bjh21.me.uk>
Date: Sat, 3 Nov 2018 11:56:58 +0000 (+0000)
Subject: Make the "pulse" have non-zero width.
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~bjharris/git?a=commitdiff_plain;h=886a85f030cdbadd2e4bc696b20695e128f37907;p=clunk.git

Make the "pulse" have non-zero width.

Since I think most impulse clocks advance on the trailing edge of the
pulse, this requires subtracting the pulse width from the wake-up
time.
---

diff --git a/clunk.c b/clunk.c
index bba7013..821391f 100644
--- a/clunk.c
+++ b/clunk.c
@@ -3,11 +3,17 @@
 #include <stdio.h>
 #include <time.h>
 
+long const pulsewidth = 250000000; /* nanoseconds */
+
 static void
 pulse()
 {
+	struct timespec const ts = { 0, pulsewidth };
 	/* Dummy implementation */
-	printf("tick!\n");
+	printf("ker...");
+	fflush(stdout);
+	clock_nanosleep(CLOCK_MONOTONIC, 0, &ts, NULL);
+	printf("chunk!\n");
 }
 
 static void
@@ -25,7 +31,8 @@ run()
 		ts.tv_nsec = 0;
 		ts.tv_sec -= tm.tm_sec % 30;
 		/* Choose when next tick will be. */
-		ts.tv_sec += 30;
+		ts.tv_nsec = 1000000000 - pulsewidth;
+		ts.tv_sec += 29;
 		if (clock_nanosleep(CLOCK_REALTIME, TIMER_ABSTIME, &ts, NULL)
 		    != 0)
 			err(1, "clock_nanosleep");